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When adding a straw bale addition to an existing straw bale house, you have to be sure to create a connection between the two walls (old and new). One way to do this is with dowels or rebar embedded into the old wall and laid in place in between courses of new wall. This allows you to leave the existing plaster in place and still accomplish a connection. Another way is remove the plaster from the existing wall and then use plaster lath on the top of each new course that is bent at 90 degrees and pined to the old wall surface. Use landscape pins on the old and new walls to attach the plaster lath. You will want to offset the new walls in either application so they are not in line with each other. In other words, add a right angle turn from the old wall and offset the new wall by at least one foot. This will help when you plaster because it gives you a stopping point (the corner). Without it, you will see a large plaster scar or will be required to plaster the entire wall (both old and new) to a corner.

Popularity: 30%

Do you live in a Tropical Rain Forest?

I am a big believer in the merits of straw bale construction. That’s probably obvious by now; however, there is one major drawback to working with bales: climate conditions. Bale homes are ideal for dry and mostly dry climates, acceptable in wet climates, and difficult to deal with in very wet and humid climates.

The big demon is not water, in the form of rain at least. In stead, it is humidity. Rain can be handled with proper design so even the wettest climates can accommodate straw bale structures. Humidity, on the other hand, cannot easily be designed out of a structure. It pervades everything and gets into everything. A bale house can stay dry from rain and still be saturated with moisture inside the plaster due to the acclimation of the bales to the area’s relative humidity. Everything eventually settles on a moisture content that is in direct relation to the relative humidity of its surroundings. Therefore, if the humidity is high, so too is the moisture content of your bread, your clothes, and your bales!

Let me give you an example, I used to live in Northern California, where humidity was often very high due to the coastal fog. My wife put her leather boots under our bed for a month and when she took them out, they were covered in green mold! Our house seemed fine and we surely did not expect to see that kind of mold anywhere near the inside of our house. But, the space under the bed is dark and has limited air movement, kind of like the space in between your layers of plaster.

What to do? Well, you must first consider if your climate is right for straw bale construction. If you have really high humidity and very little dry season each year, you may want to consider something other than bale construction. Another option is to consider mechanical help. If you install a whole house de-humidifier, you can minimize the amount of moisture in your house and therefore in your bales. Remember that when pressurized under normal living conditions, air moves out through the walls. If the air is dry, it is safe to pass through the walls. Systems like this can be installed into your HVAC system, if you have one, or can be stand alone units utilizing 4″ duct work.

Remember to design and build for the water and humidity. You not only need to design to keep water out, but also to allow it to escape should it get in (nature has a way of blowing even the greatest plans!) Plan for both, and you will be okay. Nevertheless, if you live some where that you think is too risky, ask for advice and then make whatever decision you feel is best around the use of bales in your home. And know that this is coming from some one who loves bale construction so I’m trying to talk you out of your dream!

Popularity: 31%

I have spoken before about the use of these easy application products and I want to once again speak in favor of them. The products are engineered and thus easily accepted by almost any building official. Their installation is relatively simple and speeds the construction of the home considerably. Be sure you know exactly where they will go in the house before you pour your foundation because the anchor bolts need to be placed in the exact spot in the concrete so they will properly line up with the panels during the framing stage. That said, it is possible to omit the bolts during the pour and drill them in later with the use of a rotary hammer drill and some rated epoxy. Some building officials may not feel as secure with this option; however, most companies that offer shear panels will accept this as a suitable installation of the panels.

Popularity: 17%

I just went through a humbling process on a new home construction project. I used a soils report prepared by a geotechnical engineer and provided by the land owner for a home site I was to build a custom home on. The soils report showed that there was fill from ground level to 3 feet down and that below that (from 3′ to 7′, the depth of the test pit) was “medium stiff, red-brown clayey SILT; moist.” That spelled out native soil to me and the report further stated that the foundation requirements for such soils were standard spread footers over a compacted rock base of roughly 4″ thickness.

Here’s where the humility comes in: I actually proceeded as if this engineered report was accurate. That seems like a fair assumption, but proved very expensive. The report was a couple years old, and when I compacted my gravel base on the site, the City wanted a new geotechnical report report they would approve the compacted fill and allow me to form my footers. I called my own geotech and asked him to come out for a site visit. he had us dig a test pit and when we did so, he was not convinced the soils that were quoted at 3′-7′ were in fact native. He asked my backhoe driver to keep digging. It was not until 13′ down that we knew he was right. We starting bringing up 40 year old garbage! The “soil” the previous geotech had identified was in fact 40 year old fill over an old personal garbage pit in the old property owner’s back yard.

A simple foundation changed to something very elaborate. We had to follow the native soils below the fill line all the way around the house and pour a sand/cement slurry to fill the now very deep, three feet wide holes. All of the rock had to be removed from the site so it would not end up contaminated and then replaced on the finished grade after the slurry was poured. The ultimate cost of this work was over $7000 and a time delay of one month ensued from the date of the geotech report request to that of completion of the new requirements. Yikes! So, know your ground. Know what is under your ground. Be certain that what you are building on is solid and can hold your structure. Although this was a slow pain in the rear end to deal with, I always prefer to deal with potential problems up front rather than having to fix them after the fact. The time and money spent on this project far outweighs the potential disaster that could have occurred had we not been required to get a new report. Of course, the fact that I relied on a previous geotech report is something of a frustration. The report, although 2 years old, should have been accurate and it was not. You can be sure I will write a letter to the company owner of the old geotechnical engineers on that one!

Popularity: 23%

Perhaps the most important aspect of any home construction project is a critical path. This is the time line that you must create for the completion of your home. The path is so important because it shows you exactly when things need to happen in order to keep the house on track for a desired completion date. This is the only way to ensure that the project does not go on forever! With a good critical path, you can inform sub contractors when they will be needed on site long before they actually need to be there. Of course, when you miss specific deadlines, it will affect the rest of the critical path so be sure to update it frequently. Whenever you update the path, be sure to contact all affected parties (subs and suppliers) and give them new dates for their work. your subs and suppliers will appreciate the amount of lead time and detail you are giving them and it will make the whole job easier to handle and predict.

Creating a critical path takes a lot of understanding about what is involved in the home construction process and it also takes an understanding of how long each phase should take. Creating a critical path with no building experience is not a good idea so be sure to hire some one who has the experience you need to create a realistic critical path for your job. Editing the critical path as adjustments are made is more simple and can be handled by anyone with basic computer knowledge and a grasp on the construction process at hand.

I offer critical path services for those of you interested in building your home with a guideline and map to success. The path is often offered as part of my consulting services, and I also offer them as individual packages for home builders. I can’t say enough how important these paths are so if you don’t know how to create one yourself and you don’t want to hire me, then hire a contractor in your local area who knows how to build with bales to create a path for you. It is well worth the investment!

Popularity: 21%

Having built a number of straw bale houses now, my crews have started to focus on production. By this I mean they are always looking for ways to make the bale stacking, tying, and meshing go faster. We have developed a better straw bale needle in that effort (the plans for which can be purchased on my website), as well as other tools like “the salad fork.”
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Popularity: 20%

I have received a lot of messages in recent days asking about the cost of straw bale construction. The basic question is: what does it cost per square foot to build a bale home? It is all but impossible for me to answer this question because there are so many factors involved in calculating cost. What region is the home built in? What design features does it have?
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Popularity: 32%

Here is a response to a student doing a case study of straw bale homes in North Carolina. He had a good question about how the bales of an existing structure in Alabama might be connected to the foundation. I think the details of the connection are worth mentioning here as well.
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Popularity: 13%

When you build with bales, one thing is almost 100% guaranteed: you will be plastering your walls. Knowing that, you may be surprised to discover that there is a cost that you should definitely put into your budget that may otherwise be overlooked. That cost is the electrical bill during the plastering phase.
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Popularity: 14%

There is a conversation happening right now on another list serve about woodpeckers destroying plaster on a house. This is not the first time I have heard of this. If you use earthen plasters that are based on local soils, you may encourage local birds to try and nest in your walls.
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Popularity: 12%

I had a very close call on a job I am working on this week. While I was in Maine on vacation, $10,000 worth of cork flooring was delivered to the job site and set for installation. My project manager noticed that there were blemishes on the cork and stopped the crew from installing it. He had the crew open a random number of boxes of the material and all of them had the same blemishes.
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Popularity: 14%

Wow. Time flies. It has been a week since I last posted and I sure don’t want to start making that the norm. Sorry to all you daily blog readers for the long gaps in between blogs. I have been really busy in the field and thus short on time at the computer. Anyway, let’s get to it!
We are currently building a house where the architect has called for base board trim to be used throughout. That is fairly standard delivery for most homes; however, is much more difficult in bale homes due to the undulations in the bale walls and the large curves in corners.
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Popularity: 17%

I was recently asked if it is possible to do an earthen or cement skim coat over a slab foundation. The answer is yes, you can do a skim coat of either clay/straw (earthen floor) or cement over the top of a concrete slab; however, there are minimum thicknesses that need to be maintained. At least 3″ of concrete are required unless a specialty skim coat is used (this takes extra skill).
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Popularity: 18%

Welcome to the December 2006 “Building Green” podcast. This is my monthly Q&A session where I answer your green building and straw bale construction questions. This month I answer the following questions:
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Popularity: 13%

Perhaps the most important aspect of straw bale building has nothing to do with bales. In fact, it has everything to do with holes in the walls. Windows and doors present the most likely areas for water infiltration and bale damage in the entire house. For this reason it is extremely important to pay extra attention to these areas during construction. For windows, I use two part flashing. The first is called counter flashing and is put in place before the window or door is set in the opening.
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Popularity: 10%

It is often difficult to tell the quality of any home, let alone a straw bale home once it has been in existence for a few years. With bale homes, there are usually not experience home inspectors who can help as in conventional homes as the details of straw bale homes are often beyond the scope of what inspectors know. For that reason, you may be left inspecting the home yourself. Here are some things to consider.
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Popularity: 14%

Many areas that have a building code that recognizes straw bale construction call for protection against rain splash. The most common form of protection comes in the use of roofing felt or building paper. Many jurisdictions require that the protection be wrapped around the bottom courses of the bales in a wall assembly, usually extending up to the third course of bales. The biggest problem with this requirement is the wrapping of the bales with the paper.
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Popularity: 4%

It is very common for home owners to want a fireplace these days and the addition of flames into a straw bale wall assembly is often a cause for concern to the local building inspector. Most of today’s stoves, either direct vent gas units or wood units, are designed to have minimal clearance around them to flammable materials.
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Popularity: 4%

Exactly where the top course of bales will end depends directly on the size of the bales and the height of the wall. In addition, the way the frame is built will also have an effect. For example, if the floor/ceiling joists are sitting on top of the beam, then there will be a section of framing that will need to be notched out of the bales whereas if the floor/ceiling joists are hanging on the beam the bales will end tight to the floor/ceiling system without any notching for the beam.
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Popularity: 4%

If you are building a straw bale addition as an infill structure, in other words with a frame other than the bales that will support the roof, then all you need do is attach the frame of the addition to the existing home where the two meet. That can be as simple as adding a stud in the corner at the transition and nailing it or lag screwing it into the existing frame.
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Popularity: 4%