Peter here, making his blog debut! As the handful of thorough readers may have gleaned by now, both Katie and I have a very particular set of design and material needs with this project. We are hoping to mix the Passivhaus energy concepts with the straw bale elements that Katie has become enamored with from her experience in Washington state with Andrew Morrison and his workshops (see other posts on that topic).
You may be asking yourself, “Peter, why would you ever make your blog debut on a topic where Katie is clearly the more knowledgeable between the two of you?” Great question. I’m still looking for the answer. We have a lot of topics to cover and the COVID-19 stay at home orders give me a lot of time to help fill the word count (for future readers: remember this is 2020 and we have been at home for almost a month now while we work as a society to build a roadmap of how to as responsibly as possible reopen our economy during a pandemic for which we don’t yet have a vaccine). I also work in renewable energy and am at least somewhat familiar with/have been paying attention to our design plans. Plus, I just lean on my wife to fill in my knowledge gaps and keep typing along. Back on topic, though, an example of the challenges of blending passive house and straw bale construction came up this week that may be of interest to you, dear reader. The topic was window placement. Not where they go on the wall (though that has also been discussed to ensure proper daylighting and structural stability and may come up in a different post), but rather where they go in the wall. One of the challenges (and great opportunities!) with straw bale construction is that the walls are ~21-22” thick. If you put the window on the inside of the wall, you have the widest in-swing range for your windows. You are left with a challenge, though, of keeping water from pooling on the sills and at some point seeping into the bales below (would be a HUGE problem). If we wanted to take this approach, we would need to have full metal sill wraps, with an additional waterproof layer on the bottom sill to make sure that the metal didn’t have any condensation problems that still could lead to water seeping in. The waterproofing layer almost assuredly wouldn’t meet Katie and my requirements for eco-friendly materials. On the other hand, if we put the windows on the exterior edge of the walls, the windows can’t open as far, but we get the cool aesthetic elements of window seats or shelving. We have the struggle, though, of structural stability. Attaching the windows directly to the bales would be incredibly challenging and not structurally sound. We need to build a box beam to support the window. The downside here is that the traditional box beam construction uses plywood, a material that isn’t on our desirable list either because of the glues used in its creation. There are some middle options, but they ultimately just end up taking the negative elements of both of the above options without providing any real benefits, so we will leave them out for now. What should we do? We had to make a compromise either way. Ultimately, we ended up moving the walls to the exterior wall. I personally like the window seat/shelf component and it gives us much more security that we won’t have any moisture issues with the straw bales, which is priority #1 for us as people that want to live healthily in this house. The windows won’t open as far, but we have also found that with tilt-turn windows, we more often tilt the window anyway, so neither of us are as concerned. I imagine Katie will tell me to cut out some of the narrative elements above to get to the point sooner (which I’m sure many of you will thank her for), but I appreciate you all humoring me in my debut!
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AuthorKatie Jones and Peter Schmitt chronicle their building adventure. Archives
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