Day 23: Cleanup, control joints and more

Today was a welcome low key day after the pour. We removed all of the wooden forms around the home. We began to lay a 3rd course of APEX block. We also began building a door buck with the 3X8 pressure treated wood delivered last week.

Cesar from Diamond D Concrete arrived to cut control joints in the slab. These joints are about 1/8 inch wide and 1 inch deep and should be the first locations where shrinkage and settling cracks occur. The idea is that the crack is hidden at the bottom of the joint and runs straight instead of randomly across the slab. I chose where I wanted the joints located. Cesar snapped chalk lines to identify where to cut. Some joints will be hidden under interior walls and cabinets, and some will be exposed. The joints are usually filled with grout and can become a decorative and defining feature of the floor pattern. Cesar used a SOFF CUT saw to cut the long joints as shown in the pic below.

Then he used a hand held saw to cut joints in areas that were difficult to access – see vid below.

Finally, Cesar rinsed the slab to wash off the concrete dust produced during the cutting process. Here is a pic of the joints near the center of the family room.

For the next several days I will sprinkle water on the slab. This helps slow down the concrete drying process resulting in a stronger slab. Here is a pic of the wet slab from the East at the end of Day 23.

Green comment for today:
When cleaning up on the job site, sort out all recyclable and compostable materials. Try to think of another purpose for materials that would be sent to a landfill. We say we are throwing things away, but there really is no such thing as “away”.

Thanks for reading. Feel free to leave a comment

Day 22: Pouring the concrete slab

I worked late yesterday (Tuesday) preparing for the slab pour, so I did not post. Some of the tasks completed Tuesday were:

• Completed routing of the remaining 4 PEX heating circuits.
• Pressurized the PEX heating tubing to 70 psi to identify a failure if one occurs before or during the pour
• Built wooden supports for the corners and window openings to prevent them from distorting outward when the concrete is poured
• Built a variety of wooden forms to create 1) a concrete curb detail around the shower, 2) notches in the door openings for the doors to seat into and 3) a depression for a tile mosaic art piece in front of the sliding glass door
• Photographed, measured and sketched all conduits and tubes that are under locations where fasteners may be anchored into the slab, i.e. interior walls and kitchen cabinets.

Here is a picture from the end of Tuesday.

On Wednesday, the slab was poured. The folks from Diamond D Concrete, Las Animas Concrete and Pacific Coast Concrete Pumping showed up early. Diamond D used a laser level to create a line around the inside of the home that represented the finish height of the slab. I am going to let pics and vids do most of the talking. In the following vid you can see concrete being pumped in the foreground and application of a rough screed in the background.

A perforated roller screed is then used to push down the larger aggregate and leave smooth textured concrete on top (called cream).

The cream surface is then finish screed by hand.

The surface is then rough troweled by hand.

A power screed is then run over the surface.

The guys then worked the surface further twice more with hand trowels to get the finish I desired – not too rough and not too smooth…just right. The guys really did a great job! All of the hard work and preparation from the past several weeks paid off. The day went by with few troubles. I’ll close with a pic from the East at the end of the day.

Green comment for today:
Consider concrete as your finished floor. Less material is required to stain the concrete than to cover it with carpeting or wood. The results of stained finish floors are limited only by your imagination - check out Diamond D's gallery.

Thanks for reading. Feel free to leave a comment.

Day 20: Water, water everywhere

It was an all-plumbing Monday. Coady, Adam and Erik showed up to run all the water supply plumbing that will be cast into the concrete slab. The main drinking water supply was run into the utility room, and all of the fixtures were supplied with hot and cold water lines (sinks, washer, showers). The pic below shows the larger white supply line entering the utility room from the bottom. The blue utility sink and washer hot and cold lines can be seen on the far wall. Once all of these lines were positioned, they were capped off and the entire system was pressurized with water at 90 psi. Pressurization ensures that any damage before or during pouring of the slab can be identified and repaired.

The other plumbing task started today was routing of tubing for the underfloor hydronic heating system. For this system, PEX tubes carry warm water pumped from a storage tank into the concrete slab to heat the home. The PEX tubing is supplied on 1000 foot rolls. A device called a decoiler (see pic below) makes unspooling the PEX simpler than I had imagined.

My floor has 6 PEX tubes - called circuits - each about 175 feet long. They all start and end at the utility room. In between they run back and forth and are spaced apart appropriately to deliver uniform heat into the slab. The runs are spaced closer together near exterior walls where heat loss from the slab is greatest. The coils are spaced further apart near the center of the home where heat loss from the slab is least. The tubes are also routed to avoid being under cabinets and the refrigerator where heating is not required. The following pic shows some of the white PEX runs in the kitchen.The PEX tubing is fastened to the top of the rebar so it does not move during the concrete slab pour. Two of the 6 circuits were completed today.

Green comment for today:
Consider some form of radiant heating for your home. The advantages over a forced air heating system are:

• Greater energy efficiency because the warmth is supplied closer to where we humans want it - near our bodies. Hot air from a forced air system quickly rises to the ceiling and forces the system to turn on more often to maintain the same comfort level as a radiant heating system.
  
• The system is quiet.
  
• It is the most comfortable form of heat. We humans would rather be kept warm with radiant heat than warm air.
  
• There are no fans blowing dust around the home.

Thanks for reading. I enjoy your comments.

Day 19: Electrical preparations and more rebar

Today we completed routing all of the electrical and Cat5 conduits that will be cast into the concrete slab - see pic below. I like having the Cat5 cables in conduits. If technology for wired data in the home changes in the future, I just need to pull new wires through the conduits.

Victor and Fernando from Monterey Bay Rebar were back today to place the concrete slab rebar. Once again, they made the job look easy and finished quickly - see pic below. Three inch thick dobies were placed on the sand to support the rebar approximately at mid height of the 6" thick slab.

Thanks for reading. Please leave a comment if you like.

Day 18: Ready for pro beach vollyball

Today we placed the remainder of the Insul-Tarp and spread approximately 2” of sand over the top. The inside of the house looked like a beach at the end of the day – see pic below. It spread much more easily than the gravel.

The use of sand is questioned given results of the "sand under concrete slab" search I did. Nonetheless, it is required per California Building Code.

Some other tasks completed today:

• The remainder of gravel was spread in the utility room.
• A vapor barrier was placed over the gravel in the utility room. Insulation is not required because the room is not heated.
• Sand was placed over the vapor barrier in the utility room.
• 5 inch diameter joles were drilled at the top of the 1st course of APEX block at every other vertical core where a rebar will connect to the concrete slab – see pic above.
• Big Creek Lumber dropped off the window buck material – see vid below. The window bucks for my home are pressure treated 3X8 douglas fir beams that will frame the window and door openings. They provide a stable surface to attach the windows and doors.

Green comment for today:
When designing a home in a winter heating season climate, place the majority of properly shaded window surface area on the south wall in the northern hemisphere, and on the north wall in the southern hemisphere. This will take advantage of free winter heat from the sun. This is one of the fundamental concepts of Passive Solar Design. Start with a value of 50% to 75% of your total window area. Then use a building energy analysis tool like HEED to compare designs with more and less window area with your starting point. You will find a percentage that provides the lowest heating energy need annually. This percentage is the most thermally efficient for your home. There may be reasons other than energy efficiency to increase or decrease the window surface area, but at least you will have a starting point to deviate from.

Thanks for reading. Please leave a comment if you like.

Day 17: The gravel spreading is complete and insulation

Gravel spreading was completed in the main home today thanks to Trevor. Only the utility room remains undone, but it is small. After a bit of cleanup, a product called Insul-Tarp was rolled out over the gravel – see pic below.

With a concrete slab floor, the following items should be addressed:

1. Heat leaking out of the home through the floor
2. Moisture vapor entering the home from under the floor

Insul-tarp addresses both concerns. I was convinced of the insulation characteristics as soon as I knelt down on the surface to tape the seams. I immediately felt about 10 degrees warmer from the heat reflecting off the surface. I am convinced the product will help make my home more energy efficient.

Here is a pic from the West showing the Insul-Tarp installed over half of the floor.

Green comment for today:
Insulate under a concrete slab floor to reduce heat loss. Energy use will be lower, and the blue marble will be a little happier.

Thanks for reading. Feel free to leave a comment.

Day 16: June rain...

There was no post on Tuesday evening because I needed to prepare for rain. The action was more of the same as Monday. A 2nd course of blocks was added and shimmed. In the pic below you can see three gaps in the 2nd coursw on the long wall to the left. These are the approximate locations for the South sliding patio doors. It is exciting to see the home taking shape.

See that pile of sand off to the left? It means more hard labor coming soon. Fortunately, it is much easier than spreading gravel.

Thanks for reading. I appreciate your comments.

Day 15: Shimming blocks

There is not much new to see today. We spent the entire day adding shims underneath the first course of blocks to make their top surfaces level. This is a time consuming but very important step on the first course. Once we are complete, the remaining courses will go up faster.

A couple other things happened today:

• Coady the plumber stopped by to pack some fine soil around the plumbing pipes positioned within the gravel layer. The soil prevents abrasion from the gravel.
• Erik Dazey, the electrician, stopped by to begin laying out the plastic electrical conduit that will carry electric utility power into the utility room, as well as some smaller conduits that will be positioned under the concrete slab to carry wires from the distribution board to outlets and appliances in the home.

Green comment for today:
Try to locate and use materials on the job site if possible. It minimizes manufacturing of new materials. Two examples from today:

1. Rather than purchasing sand, Coady spent some time sorting out fine soil from the recent excavation for use in protecting the plumbing.
2. Trevor used a piece of scrap wood I found over the weekend to cut some shims rather than using new shims.
   

Cindy and I spent last weekend together on site. She helped with some hard labor. While I cut a few small footings, she moved some gravel. Here is a pic of her in action. I've never seen such a big smile on someone schlepping gravel.


Thanks for reading. Feel free to post a comment if you like.

Day 14: Spreading gravel and laying out the first course of block

We started spreading the pile of gravel today. There is no maneuvering room for heavy equipment inside the walls, and a gravel pump does not exist, so we moved it by hand. We first placed some gravel around the pipes close to ground level. Then we loaded the wheelbarrow and moved little piles around the subgrade. It was harder work than moving APEX block the day before. My appetite has increased.

We also started laying out the 1st course of APEX block. This was fun and challenging. It is rewarding to see the blocks fit well over the rebar and have dimensions match what is on the plans. The corners present little puzzles. My walls are not an exact number of blocks long, so the last block must be trimmed to fit. Horizontal L shaped corner rebar must be placed. We will probably try several different methods before we come up with a solution that works best.

Here is a pic of the site from the East.

Green comment for today:
Consider manual labor now and then. It does take more time, but it has some advantages:

• It’s quiet, so you can and hear the tunes playing on the solar powered radio. If you are working with someone else, you can have a conversation.
• It saves fuel.
• It’s great exercise... if you don’t throw out your back.

Thanks for reading. Post a comment if you like.

Day 13: APEX blocks arrive, and more Plumbing

Correction from the plumber:

The reason the ABS pipe is wrapped in foam when in concrete is to allow expansion and contraction of the pipes so they don't wear and fracture over the years. Thanks Coady!

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The APEX wall building blocks arrived today. The road I live on is not wide enough at my driveway to provide access for the large delivery truck. For this reason, the material was moved off the delivery truck to a smaller flatbed for shuttling about 1.5 miles to the job site. A forklift removed pallets from the delivery truck – see pic below.

The pallets were transferred to a flatbed truck. The pallets arrive shrink wrapped, but they were a bit top heavy. The shrink wrapping was cut and the top 2 or 3 rows were restacked by hand. The following pic shows unloading from the flatbed at the jobsite.

The forklift broke down at one point, and 5 full pallets were moved by hand. Each pallet contains 24 blocks, so a total of 576 blocks were moved today. Each block weighs 52 pounds, so almost 15 tons were moved. It was a day of hard work, and everyone was ready for a beer when we were through. Here is a pic of about half the material that was moved by hand.

These will turn into walls over the next several weeks. Here is a pic of 2 blocks shown in position over the rebar.

While the crew was shuttling blocks, Coady and Adam finished up most of the preliminary plumbing. The kitchen and shower drains and vents were completed. Here is a pic showing all of the plumbing so far.

The pipes that come into contact with concrete get wrapped in a white foam material. The foam acts as a cushion providing a bit of protection during an earthquake. There is a pair of French drains installed below the slab. This is an unusual location for a French drain. They are usually installed outside the walls to drain water away from the foundation. These French drains will remove any Radon gas, which is heavier than air, from below the slab. We live in an area where Radon gas may be present at levels high enough to create a health concern.

Green comment for today:
Consider building with a recycled wall material. The APEX blocks contain 85% by volume recycled Expanded Polystyrene foam (EPS). On the one hand, I don’t like perpetuating the use of polystyrene. But on the other hand, the recycled foam blocks have some advantages:

• Recycling the foam keeps it out of landfills. Let’s face it, the use of polystyrene is not stopping today. That material needs to go somewhere.
• Petroleum is an incredible material with many uses. EPS provides an insulation R-value of 4 per inch which is comparable to other available materials.
• The block makes a great Insulated Concrete Form (ICF) resistant to rot, fire and termites.

I leave you with a pic of Justin and his cute puppy Stella – the construction mascot. She’ll grow to nearly full size during this project.

Thanks for reading. Your comments are welcome.

Day 12: Plumbing started

Coady Barnum and Adam White showed up to begin plumbing. They made measurements and planned the positions of drains and vents. The finish floor is a concrete slab, so it is very important to get all of these positions correct. There is no opportunity to make changes after the slab is poured. Coady used a laser level to establish the finish floor position. This allowed the drain for the most important seat in the house (the toilet) to be positioned – see the pic below. The big open tube pointing up is the toilet drain. The smaller tube heading off to the left is the vent, which will eventually go all the way up through the roof.

In the next picture you can see the utility room sink, washing machine and floor drains.

Besides this plumbing work, Granite Rock delivered 2 truckloads of drainage rock that will eventually be spread out evenly on the subgrade.


Green comment for today:
Building a home with one bathroom minimizes plumbing materials and complexity. This works for us because there are only two living in the home.

Thanks for reading. I appreciate your comments.

Day 11: Pouring footings

The footing trenches passed inspection by Santa Cruz County in the morning. Concrete for pouring the footings was requested immediately after passing inspection. A concrete pump is used to distribute concrete into the trenches more easily than moving the concrete truck around. Here is a pic of the Pacific Coast Concrete Pumping set up.

The Las Animas concrete truck showed up soon after the concrete pump. The truck parked so that it could pour concrete directly into the inlet of the concrete pump – see pic below.

The pump was turned on and a person on the end of the hose directed the concrete into the trench – see vid below.

Approximately 25% of the Portland cement in the concrete mix is replaced with fly ash, a by product of coal combustion. The use of fly ash has several benefits:

• it replaces Portland cement - a material with high embodied energy - with a material that was once considered a pollutant and waste product
• it makes the concrete stronger
• it makes the concrete easier to pump
  

The crew followed behind the hose. People poked shovels into the concrete to help it settle. Several people hand troweled a smooth top surface while one person checked with the laser to make sure we had a level footing – see pic below.

After 2 empty concrete trucks and a couple hours, the work was finished – see pic below.

Thanks for reading. Feel free to post a comment.

Day 10: Rebar

Raul, Victor and Fernando from Monterey Bay Rebar showed up Friday morning. They brought a trailer full of rebar in a variety of diameters and configurations needed to meet my structural drawing requirements.

The first two rules of mechanical engineering are:

1. don't push on a rope
2. don't pull on a brick

Rebar is cast into concrete to comply with that 2nd rule. Concrete does not resist tension forces very well. That's why you typically see things hanging from strong wires or cables. Rebar has ridges to help grip and transfer tension forces from the concrete.

My foundation needs three horizontal rebars running the entire length of the footings. Every 16” on center, a 48” long vertical bar penetrates the top surface of the footing. All of the horizontal rebars must be spaced a minimum of 3” from the footing trench soil. The trick to rebar placement is twofold.

• rebar must be held in the trench before concrete is poured
• rebar must stay in place during the concrete pour until the concrete sets

Victor and Fernando made the job look easy. They used steel wire to tie the vertical bars to the horizontal bars in such a way to make a self-supporting assembly. Then they supported the tied rebar assembly off the footing trench floor with small precast concrete blocks called dobies. Here is a pic of Raul, Victor and Fernando followed by a picture of a dobie in place.


A horizontal rebar is tied along the top of the vertical bars to keep them spaced properly during the pour. This piece will be removed after the concrete has set. Steel wire loops connect the top of the corner vertical rebars to the batter board spikes. These loops are twisted up which turns them into turnbuckles keeping the entire structure stiff enough to stay standing during the concrete footing pour. Here is a pic of a turnbuckle followed by some pics of the completed work.



Thanks for reading. Feel free to post a comment if you like.

Day 9: Almost a day off

There was not much action on site today. We met with a rebar contractor to talk about the foundation. I pulled some scotch broom which is kind of a meditative process. I thought about how invasive homebuilding really is. It may be called green building, but ripping out tree roots and running over all the vegetation is nothing but green. I have to stay focused on the end result - a permaculture design that uses the energy on site more effectively than before I arrived. That's all for now. Thanks for reading.

Day 8: Initial grading completed

All the preliminary grading steps were completed today. Water supply and electrical conduits were placed, and the trench was backfilled. A large section of the site was leveled for storage of building materials. All the last little piles of soil were smoothed out.

The geotechnical engineer made another site visit and approved the footing trenches for concrete pour.

All the other pics from today are pretty boring and technical, so I am closing with a pic of a snake we found hiding in a tarp last week. I think it is a scarlet kingsnake.

Thanks again for reading. I appreciate your comments.

Day 7: More trenching

The footing trench for the West wall was completed today. The main sewer line was run from the existing septic tank pipe and capped next to the home for future connection to the drains. Utility room footing trenches were completed. The water supply trench was completed. As the initial grading portion of the project is coming to a close, Steve is smoothing out and redistributing the assortment of dirt piles. The site is really taking shape. It is further along than I expected at this stage of the project. Following is a pic looking West down on the home site from the hill to the East.

Thanks for reading. Post a comment if you like.

Day 6: Cutting trenches

Strings were set up at the 4 foundation corners to create a line for the backhoe to follow when cutting footing trenches. The backhoe cut 2 foot wide footing trenches for the North, East and South walls. The laser level was used periodically to check that the trench depth was accurate to within a few inches. Two people with shovels kept the trenches clean of small debris as the backhoe progressed. This work went quickly after all the good preparation done in previous days. Batter boards were set up at the 4 corners to get ready for positioning the walls on the footings. The diagonal measurements to the outside of the footings were accurate to within an inch. That is great for the footings. Here is pic of the trenches as we finished Saturday.


Trenches for the water supply and phone line were also cut today. We made good progress and ended early. It was quite hot and everyone was ready to start the weekend after a hard week.

Thanks for reading. Feel free to post a comment if you like.

Day 5: Laying out foundation stakes

The remainder of the concrete slab subgrade was completed today. It was compacted one last time. The geotech engineer performed a final moisture-density test which we passed.

We positioned the foundation perimeter location on the subgrade and pounded stakes at the 4 corners indicating the outside edge of the footings. Here is a pic showing the SW and SE corner stakes. The NE corner stake is partially hidden by a little pile of dirt in the back corner. The NW corner stake is too far left to be in the pic.

The cut for the utility room was nearly completed, and the cut for the south patio was started. The whole site is starting to look like what I have imagined for a long time.

Thanks for reading. Post a comment if you like.

Day 4: Pounding sand...again

A short post today - more of the same as yesterday. The 3 foot deep hole was filled with about 1 foot of soil at a time. Each of these fills is called a lift. The foot of soil was compacted a few inches, then another lift was applied and compacted. The geotech engineer showed up for another moisture-density test after approximately 2 feet of lifts.

We passed the test and started filling up the remainder of the hole and leveling out the entire subgrade. Here is a vid of me driving the compactor (maximum speed, 50 feet per minute :-)

At the end of the day, the full subgrade for the concrete slab is really beginning to take shape. Here's a pic from where the West entry will be.

Thanks for reading. Feel free to post a comment.

Day 3: Pounding sand...in a good way

If pictures tell a thousand words each, then videos should be even more.

The day began with cleaning out the Western 3 foot deep section of subgrade. Here is a vid of a tree root being removed.

After flattening the 3' deep section, a sheepsfoot compactor is used to, duh, compact the soil. It has a vibrating sand filled steel drum for a front tire. It is driven back and forth over the soil many times like in the following vid.

The goal is to get the soil to 90% of its maximum possible density and as close to optimum moisture content as possible. The geotechnical engineer took a soil sample yesterday to determine the density versus moisture curve for my site soil. Look here for an example curve. We called in the the geotechnical engineer again today to see if the soil was dense enough. He used a machine called a Nuclear Surface Moisture-Density Gauge. First he pounds a pin into the soil at least 6". He then inserts the probe of the gauge into the hole and pushes a button. The results are compared to the lab sample curve in seconds. We passed! The soil is nearly the density of concrete. Here's a vid of those last few steps. Sorry it's 90 degrees off. My old camera doesn't adjust when I rotate it, so you'll have to turn your head.

Finally, I leave you with a picture of Gabby (Steve's dog), the grading mascot.

A good day today. Thanks for reading. Don't be shy, leave a comment.

Day 2: Setbacks (not those lines on the site plan your building must stay clear of)

Unfortunately, we discovered today that the water supply line for my neighbor's home was run underneath my foundation location. In the picture below, the trench on the left contained my neighbor's water line. The trench on the right is where the water line had to be rerouted to avoid my foundation. The majority of the day was spent solving this problem. Another couple hours were lost while a leaking backhoe hose was replaced.

The geotechnical engineer made a site visit to check out soil quality in the foundation cut. He ordered that the top 3 feet of soil on the West half of the subgrade be removed and replaced with soil more suitable for compaction. The sandy "topsoil" I mentioned yesterday will be adequate to mix with the removed soil. At least the on-site material is acceptable, just in the wrong place ;-)

On the upside, the level spreader trench was dug and the crew's porta potty was delivered. I hope tomorrow moves a little bit more in the positive direction. Until then, thanks for reading, and feel free to leave a comment.

Day 1: Groundbreaking

After many months of home design and permit application, groundbreaking day began!

At 10:00 am, Steve began digging out the roots of the oak tree. There was a large amount of nice looking "topsoil" down around the roots. This soil was piled up separate from the more sandy soil located on top. During final landscaping, the topsoil will be spread out for the garden.

After a day of digging and moving soil around the site, the initial cut for the home is nearly complete. Here Georg, the GC from Integral Construction, and Steve are seen checking flatness of the slab subgrade with a LASER level.


I feel good now that things are started. Today was a pretty dramatic change for the site. Until the next post, thanks for reading.

Catching up to the 21st century, part 14...Stick-Frame vs. Rastra

***WARNING: This information is specific to Santa Cruz, California!***

After I ruled out strawbale as a wall material, the remaining materials on my short list were:

• Rammed Earth
  
  
• Rastra
  
  
• Stick-frame
  

The excavation of my neighbor's foundation yielded soil that was promising for rammed earth construction. However, in my opinion, there are 3 primary reasons why rammed earth is unsuitable for my home.

1. Like strawbale, rammed earth walls are quite thick (18" minimum). My 1,200 ft² maximum floorplan area would lose a considerable amount of usable living area to wall thickness.
   
2. Rammed earth construction costs are more than standard construction methods. My limited budget requires that I try to reduce cost wherever possible.
   
3. I live in the strictest zone for earthquake design in the US (seismic zone 4). Building heavy walls that need extensive reinforcement to meet earthquake design requirements does not make sense to me.

This left Rastra and stick-frame. I have one neighbor who built with 10" thick Rastra walls, and another who built with 2X6 stick-frame walls. I like both homes. They are comparable in cost. Stick-frame is the most common residential wall construction method in the US. There are more design specialists and contractors familiar with this type of construction. Rastra is less common, but is similar to Insulated Concrete Form (ICF) construction. Design specialists and contractors familiar with ICF construction would have the experience necessary to design or build with Rastra.

Advantages of Rastra compared to Stick-frame:

• high resistance to rot and insect infestation should result in long life
• can be used as a stem wall if waterproofed
• insulation R-value is more stable over time than batt insulation
  

Advantages of Stick-frame compared to Rastra:

• wall is 4" thinner than Rastra resulting in more usable living area
• running electrical and plumbing within the walls is a common process
  

When I started creating plans in January, 2008, my home design was 1,200 ft² on a single story. In May, 2008, I had an epiphany and changed the design to 1,000 ft² with a 200 ft² loft. Cindy and I were very enthusiastic about the loft floor plan. The advantages of a single story design compared to a loft are:

• no area "wasted" for a staircase
• easier to grow old in a single story home - no stair climbing

The advantages of a loft design compared to a single story are:

• smaller slab and foundation - reduced cost
  
• generally requires less energy to heat

I decided to evaluate the thermal performance of stick-frame and Rastra to determine if the results showed a compelling reason to pick one wall system over the other. I ran an energy analysis using HEED software to answer this question. I created analytical models of the single story and loft designs. For each type of design (Single Story and Loft), I compared the annual space heating energy need with stick-frame and Rastra walls. I used a free software tool called OPAQUE to determine the U-factor, time lag and decrement factor variables for both stick-frame and Rastra. These variables are required by HEED to calculate heat loss through the walls. Data for stick-frame wall materials is built into the OPAQUE material database. I obtained data for Rastra wall materials from Rastra president, Karl Holik. The results of the analysis are shown in the graph below. My home design is all electric, so energy units are in killowatt-hours (kWh). You can convert to other energy units using the online conversion website.

The main conclusion from this analysis is that Stick-Frame and Rastra wall systems perform differently with different home designs. For my single story home design, Rastra walls would require about 15% more heating energy than stick-frame walls to maintain the same interior temperature. However, for my loft design, stick-frame walls would require about 32% more heating energy than Rastra walls. To put these energy needs in perspective, 2 of my PV solar panels will produce the 581 kWh difference between 2X6 stick-frame and 10" Rastra walls for the loft design. Even though the heating energy required for any of these designs is relatively small compared to an average American home, I'm happy to know that my Rastra loft is the best performing design.

The moral of the story is than an energy analysis of your home design can predict your energy needs. The analysis may also help if you are undecided on your wall system. Thanks for reading. As always, your comments are appreciated.

Catching up to the 21st century, part 13...strawbale wall thickness woes

Floor area is defined as that area within the exterior walls, including wall thickness. This definition poses a problem for my straw-bale home design which is limited to 1,200 ft² of floor area. Straw-bale walls are thick compared to stickframe construction. Assuming 24 inch thick straw-bale walls, my 1,200 ft² floorplan would have 936 ft² of usable floor area (the area within the interior surface of the exterior walls). In contrast, a 1,200 ft² home with 6" stickframe walls would have 1,131 ft² of usable floor area. I love straw-bale homes, but not enough to sacrifice 195 ft² of usable living area.

In May, 2007, with the help of friends, a local architect/straw-bale building advocate and a local straw-bale builder, I wrote a letter to my county planning department and district supervisor requesting a special interpretation of floor area for straw-bale homes. I argued that only 6" of straw-bale wall thickness should be included in the floor area calculation. The county replied in June, 2007. They said that I raised an interesting topic for future green building standards, however, the current floor area definition was not subject to interpretation. I have therefore abandoned my straw-bale design.

Catching up to the 21st century, part 12...neighbor's home construction

July, 2007

Construction started on my land partner's (K) home. This created several opportunities to share infrastructure costs - one of the advantages of sharing land with another party.

• Septic System - K and I installed a 2000 gallon septic tank with a leach field approved for both his home and my home. The system uses chamber leaching devices which are slightly more environmentally friendly than rock trenches due to their smaller footprint.
  
  
• Water Supply System - In my county, a home requires a 5000 gallon water storage tank hooked up to a hydrant for the fire department to use in case of a fire. Both K and I bought 5000 gallon tanks, but we shared the pressurization pump and fire hydrant. The hydrant had to be located between 50 and 150 feet from both homes. Fortunately, I knew roughly where my home would be built. We found a convenient location for a shared hydrant.
  
  
• Drainage System - On my property, the roof runoff through gutters must be directed to a device called a level spreader which diffuses the runoff and spreads it over an appropriately sized land area. K and I shared in the trenching and installation of the level spreader and water lines leading to the level spreader.
  
  
• Electric - The local utility (PG&E) required a connection to the main transformer supplying power to our parcel and the 3 parcels that neighbor ours. K and I shared this connection fee as well as the cost of trenching the underground conduit to a splice box near our future home's utility room.
  

Each of these systems will be ready for a simple hookup in the future when my home is built. Thanks for reading. As always, your comments are appreciated.

The Lowdown on Low-E

***WARNING: This information is specific to Santa Cruz, California!***

Low-emissivity (Low-E) glass coatings are an awesome window feature. With multiple pane insulated glass windows, there are several potential glass coating combinations. The standard offerings from window manufacturers generally perform well thermally in climates that require heating and cooling, but may not apply in all situations. What about coastal climates like mine that have very low cooling demand? What about a home design like mine with a large expanse of South facing glass for passive solar heating?

For this post, I ran an energy analysis of my home using HEED software. I ran the 4 different glass coating scenarios listed below.

1. All double pane windows with LoE³-366^TM on surface #2 (inside surface of exterior pane) and Argon fill.
   
   
2. All double pane windows with LoE²-270^TM on surface #2 (inside surface of exterior pane) and Argon fill.
   
   
3. All double pane windows with no coatings (Clear).
   
   
4. All double pane windows with LoE-179^TM on surface #3 (inside surface of interior pane) and Argon fill.

All other characteristics in the model remained the same for each analysis scenario. I compared total annual heating energy for each of the 4 scenarios. My home design is all electric, so the energy units are kilowatt-hour (kWh). The graph is shown below.


A few comments about the results:

• Two of the coating offerings from one of my potential window manufacturers (LoE³-366^TM and LoE²-270^TM) perform poorer than using no coatings at all (Clear). The reason is that they are designed to reduce solar heat gain in the summer as well as insulate in the winter. In my moderate coastal climate, these characteristics are detrimental to thermal performance. My design wants maximum solar heat gain in the winter. Passive solar heat gain through the windows during the day more than offsets the heat lost at night. The summers in Santa Cruz are not hot enough to require these coatings.
  
  
• LoE-179^TM is an ideal coating for the windows in my passive solar home design. It allows about 90% of the solar heat gain of clear glass, yet limits heat loss to about 66% of clear glass. I will need to specify this coating as a window option. Any added cost from this option is offset by a reduction in solar panels needed to generate heating energy.
  
  
• The analysis was kept simple for posting. All windows within each scenario were kept the same. Further performance gains can be obtained by tweaking individual windows or window groups. For example, windows on the North wall (in the Northern hemisphere) could use high U-value coatings like LoE³-366^TM.
  
  
• Thermal performance can be further improved by using thermal shades at night.
  

The bottom line is that home designers should be careful when specifying window glass coatings. Various climates require various coatings. Fortunately, glass companies can provide suitably coated glass to the window manufacturers for incorporation into your windows. Simple analysis tools can help determine the best coatings for any application. All that's left is to tell the window manufacturer what you want.

Thanks for reading. As always, your comments are appreciated.

Catching up to the 21st century, part 11...scotch broom

Scotch broom is a perennial leguminous shrub that is considered an invasive species in California. If left unmanaged, it can quickly take over a land area. Every year in spring, we practice the ritual of "pulling broom" to keep it under control. We pull in spring because the soil is loosened up from rain, making easier work.

I have questioned the effectiveness of pulling because the scotch broom always reappears. I have heard that there can be an 80 year supply of seeds in the soil around plants that have been freely reproducing year after year. Pulling one of these plants exposes seeds that were buried in the soil around the roots. These seeds germinate in the disturbed soil resulting in another patch of scotch broom next year.

I decided to try an experiment comparing pulling to cutting. In the middle of February, 2007, we pulled waist-high scotch broom west of a north to south running landmark. We cut broom east of this landmark. The nice thing about cutting is that it is quicker and requires less effort. The before and after photos are shown below. Notice how the orange road safety cone came into view - yes it was there before removal.

Before Removal

After Removal

Flash forward to February of 2008. The verdict? In this case, the pulled broom side had fewer plants of smaller size than the cut broom side. I guess you get out what you put in. Cutting takes less effort in a given year, but requires the same - or possibly more - effort year after year. Pulling requires significantly more effort the first year. However, in my experience, it looks like the effort will taper off with continued maintenance.

Thanks for reading. Let me know if you have a scotch broom or other invasive species story.

Catching up to the 21st century, part 10...soft water

February, 2007

My well water is very hard. I would prefer to use well water only for fire suppression (sprinklers) and irrigation. I would prefer all fixtures in the home to be supplied with low or medium hardness water. I do not want to use a conventional water softener because salt (or potassium) is added to:

1. the water as a result of normal use
2. the environment as a result of filter regeneration

What is an unconventional water softener, you ask? Mother nature will drop about 23,000 gallons of rain on my rooftop during an average year. A rainwater harvesting system has the potential to store about 18,000 gallons of this free, soft water. The stored water can either be kept separate and treated for domestic use. Or, it can be mixed with well water, treated for domestic use and supply fire sprinklers. Mixing the water is a little simpler than having separate storage systems for sprinkler and domestic use. Mixing soft rainwater with very hard well water will result in a hardness somewhere between the two extremes. The primary green features of rainwater harvesting are:

• free water softening - without using salt or potassium
• reduced fixture maintenance from hard water scale when mixing treated rain water with well water for domestic use
• preserving groundwater supply by reducing well usage
  

Catching up to the 21st century, part 9...Pyrolox well water filter

January, 2007

Our well water has a barely acceptable level of Iron (Fe) and a barely unacceptable level of manganese (Mn). Capitola Pump, the well installer on our land, recommended an ozonator from Triple O to treat the well water. Ozonators reduce Fe, Mn, hydrogen sulfide (H2S - rotten egg smell) and kill bacteria too. The Triple O is set up with a recirculation pump to continuously filter water in the storage tank resulting in drinking quality water. I heard from people I trust that these units perform well. However, I was concerned with periodic filter and bulb maintenance and continuous electricity use. In a green home design, I think all purchases should strive to reduce initial material use as well as ongoing maintenance and power usage. I decided to use the ozonator as my baseline and try to find a greener solution for my specific application.

A little research on well water treatment comes up with Pyrolox iron filters. These filters reduce Fe, Mn and H2S by catalyzing a reaction which causes the contaminants to precipitate out of the water as Fe, Mn and H2S oxides. Periodic backwashing with water removes the oxides from the filter and rejuvenates the Pyrolox filter media. How often to backwash depends on the quality and quantity of filtered water. More contamination or water use requires more frequent backwashing. Note that Pyrolox filters do not reduce bacteria levels.

I estimated that a Pyrolox filter alone could reduce our Mn to acceptable levels. Two important things are required for a Pyrolox filter to adequately remove Fe, Mn and H2S without additional filtering systems.

1. Contaminant levels must be low enough for Pyrolox to work alone. If levels get too high (>10ppm Fe, >5ppm Mn or >3ppm H2S), another oxidation system like chlorination or aeration must be used along with the Pyrolox. Our Fe level was 0.29ppm (<0.3 required), and our Mn level was 0.089ppm (<0.05 required).
   
   
2. The well pump must produce a high enough flow rate in gallons per minute (gpm) to effectively backwash the filter. High backwash flow rates allow adequate precipitate removal and long filter media life. Our well pump produces 15gpm which meets requirements.
   

A Pyrolox filter backwash valve timer continuously uses electricity, but only about 1/3 that of the Triple O ozonator. With our low contamination levels, the Pyrolox filter media should last at least 15 years (probably much longer). The final factor that settled my decision was that the Pyrolox filter cost 1/2 that of the Triple O ozonator. In my opinion, the Pyrolox filter was a greener solution than an ozonator for Mn reduction in my specific application.

We purchased our Pyrolox filter from Clean Water Store in Santa Cruz. After installation, water quality testing showed that the Pyrolox filter reduced Fe to <.05ppm (a factor of 6 reduction) and Mn to <.o1ppm (a factor of 9 reduction). I have the money saved from this purchase to apply towards a bacteria filter to get equivalent performance of an ozonator. I'll cover that in a future post. Thanks for reading! Your comments are appreciated.

Catching up to the 21st century, part 8...home design continued

January, 2007: I am thinking of doing the home design myself because of my 3D CAD experience. I tried demos of the following programs:

• Chief Architect
  
• Envisioneer
• Sketchup
• Softplan
• Vectorworks

My preference for a decent program focused on home design is Chief Architect.

I modeled a 2 story loft in more detail and started solving problems such as the spiral staircase location. It wants to be centered on the EW width of the house and split 50/50 on the south edge of the balcony. But the upper bedroom closet extends beyond the centerline of the EW width. The bedroom closet will be modified to allow the staircase 25% pie slice to be cut out of either the E or W quadrant of the balcony.

I have been thinking more about water systems and black/grey water systems. I want a pond and a constructed wetland. A consultation with Rana Creek (an ecological design company) on site in late January confirmed my worries about cost and permits. It looks like these design elements will not be included in our plans. We will go with a standard septic and plumb for grey/black water split. We will use low flow or composting toilets to reduce black water output.

January 27, 2007: Met Michele Landegger of Boa Constructor at the Sullivan home tour. She seemed to be the truly wonderful person we heard from everyone. At the Sullivan house she showed pictures of some of her work and told a few stories of her experiences. We went to a local Mexican restaurant to discuss our project. She only had ½ hour, so we quickly ran through our list of questions.

• organic straw, she would love to work with it, but hasn’t yet, hard to find, she prefers 2 string
• she will work $/hour as a consultant or GC, whatever we need, shift along the way is OK
• she is OK with our 2 year design time, she plans to be away for 2 months in the winters by then, so we need to plan around that
• her crew uses Vectorworks CAD
• she has her construction details on paper only and says they are constantly being updated because the state of the art keeps changing
  
• her crew does electric, paint and carpentry, plaster, subs out remainder and has an A-team of people in mind
• her subs have a good long-term relationship and work together well.
• her crew has what she says is "a great earth plaster guy"
• Pat Split and Sharron Block are title 24 people Michele said I should talk to
• She had reclaimed/recycled timber stamped on site for structural reuse or uses sustainably harvested lumber. Issues with reclaimed are knots and straightness. Can increase cost of labor because the crew takes more time to deal with these issues.
• her crew works time & material
• she builds post & beam frame
• 2 story home will cost more to meet the engineering requirements, X bracing etc.
• a 6” wall allowance has precedent in the county and doorways and window seats do not count. There is a new person in the county that she will talk to about posture towards strawbale before we commit.
  

1/27/07: I tested our well water with pool test strips. It's mid range hard, and the pH is near 7. I took a sample and mailed to a system provider at Home Depot for free testing and likely marketing materials for water systems. I never received results.

Catching up to the 21st century, part 7...permaculture & more home design

6-6-06
Cindy picked up a permaculture book at the library. Heavy stuff…it includes just about every progressive idea I’ve read about on all relevant issues: social, economic, agriculture, politics. My biggest take away so far is the idea of damming water and using it to gain more yield from a site rather than letting it drain off the site unused. In Santa Cruz, for example, the water could get harvested from the roof into a little pond near the home, then overflow in winter into a larger pond near the road at the western border of the site. Or, just have one pond for all water. The idea is that enough water is saved from winter rain to water the garden all summer until fall rains set in. Don’t let water run off the property without storing it for useful purpose - this would increase entropy! Get something out of the water. Plant a variety of shrubs and trees on the northeastern slope to make it more stable against landslide, get some nuts and fruits out of the deal, and create habitat for wildlife.

We have been talking about ducks. They hunt slugs and are natural habitants of a pond. The 2 could go well together. Same with coy. The pond could be an ideal final step in processing gray water after initial treatment in a constructed wetland.

Talked with Cindy about hands on natural building. She is not interested in talking classes. She just wants to be a worker bee taking direction, just like her gardening desires. I am interested in taking an extensive applied permaculture course. Need to read more and think about this.

6-8-06
Did a little research on Cor-ten. It comes in corrugated and standing seam forms. There is a distributor in norcal.

7-20-06 to 7-25-06
During tour 3 as volunteer rangers in the Alps (North Fork), Cindy and I came to the conclusion that a lofted pair of bedrooms on a 2nd floor would be the best compromise to reduce our floorplan but still provide a desirable space. Three visits to our friend's home in Ukiah let the concept of the loft and cathedral ceilings sink in. Cindy came with on the last visit and jumped all over the loft idea. I think this design with a 30’ wide floorplan may save Big Oak. A 30’x28’ first floor (840 sq-ft) is near square and has the best aspect ratio for thermal loss. Hopefully there is still enough room for up to 12% window area on the S wall to capture solar insolation. Some aspects of the design: approx 9x11 studio, full bath, kitchen, entry/pantry, great room and office nook on first floor, 2 symmetric bedrooms and closets in the loft. Approx 18’ cathedral ceiling peaking right above railing of loft. Approx 6’ ceiling on north wall of loft, 8’ on south wall of first floor. Close to 30 degree pitch on south roof face for optimum annual solar gain (assumes net metered). Either a very steep pitch stairway or spiral staircase to loft. Under and behind the stairs would be the library/office nook with built in bookshelves. Timber frame structure with strawbale or straw/clayslip infill. Adobe floor.

I ran HEED calculations on this design and although preliminary results show more electric heating required than a single story design, the increase is manageable. Operable thermal shades are an “ace in the hole” that can be used to reduce heat loss at night and should be incorporated. In fact, the use of these shades may allow for increasing the window area on the south face closer to 12% while maintaining the heat during the nights and decreasing the required radiant electric heating. ***The new version of HEED now has water heating incorporated. This allows better approximation of annual water heating needs by comparing summer usage to HEED’s summer usage. By multiplying the ratio of these 2 values by HEED’s annual usage, you arrive at your approximate usage. HEED assumes local average values for groundwater temperature. Our usage would be less than this when using solar water heating, but it is better to be a little conservative here than to shoot in the dark. The solar fraction calculator from Go Solar California (or similar tools for your local area) can be used to estimate how much of the water heating energy is replaced by various solar water heating systems.

Experts needed in our green home design: permaculture (me/us), tree, foundation, timber frame, plumber, roofer, strawbale, electrician , earth/lime plasters, adobe floors, finish carpentry.

Some thoughts on water. Harvest rainwater from the roof into a small pond near the house and above the elevation of the garden. The problem is that this amount of water would likely be gone before the rainless summer is over. A possible solution is to have a larger pond to collect land runoff. Could ultimately have a creek running down to a larger pond (near the road). The larger pond collects land runoff and neighbor’s roof runoff. A pump moves water from the large pond up to the small pond where it overflows via a little waterfall into the creek. This aerates the water and creates a unique habitat. Upper pond is used to water the garden by gravity feed off of a timer. The only downside I can think of is evaporation. However, evaporation is a natural characteristic of water features and will help create a unique microclimate.

Sept 16 to 29, 2006: OAEC permaculture class! I already posted about this class, but I need to say once again that it was a life changing experience for me. If you are interested in committing 2 weeks to a permaculture course, than I can't recommend highly enough the OAEC offerings.