There are several ongoing issues with strawbale construction, that seem to be giant thorns in the side of the system.
- Moisture from the exterior… big porch areas… no second stories
- moisture from the interior…. permeable exterior coatings, that allow exterior moisture problems.
- Low load bearing capacity… No second stories.
- Excessive labor for plastering bales.
I could probably write more, but I think I can solve all those, right now, and that makes a good day’s work,
Below is a link to structure, that I believe can be the inspiration to a really great strawbale structure..
I have a few concerns about this little structure, but it is curved, well insulated and low cost, so I think that is a great start. I have been searching for places, where I think strawbales really excel. I think there is much potential here. I do not really like the cob layers in between the bales, and I suspect that they did not vent their roof, so it is good that it is in New Mexico, but those issues seem solvable enough, for designing a strawbale Gothic Arch for most any climate.
Here are some of the issues and question I see… so far
– A simple way to fur out the curved roof, vertically, for a -¾” to 1½” vent space, under the metal roofing, …..1x_ could be used, but might require soaking, in order to take the bend. Layering and gluing plywood strips, could work. How is the furring to be held to the bales? How about 15# felt over the bales, as a drainage plane, for when the roof ever leaks. The metal roof, in the sun, will literally bake any moisture out of the bails. That is one huge problem with the standard remedy of big porches. Not only do the walls not get the sunlight they need, for drawing moisture from the walls, the overhangs will keep the walls cooler than the surrounding environment, so in humid weather the ambient moisture may condense out onto the walls. Metal fencing can be used as reinforcing between bale courses.
– While on this subject, how are the bales connected vertically?
…..It seems that metal rods could be used to hold the bales together until the arch is complete. Do they need wooden stakes, driven in, to remain in place. Is it necessary to do any plastering on the outside of the bales…under the metal roofing?
– A way to insect, and vermin-proof the lower vent.
….I would assume: 1) the bottom bales need to start well above the ground with proper barriers, etc. 2) the exposed lower bales, under the overhang of the roof, get plastered. Standard continuous soffit vents should work. The metal roof should stand out from the bale wall/roof at the bottom, to form a soffit.
– How about log wedge slices, instead of cob, to shim the bales, into the curve of the arch.
– What is the best metal for the roof?
– Here is the big twist. Instead of building the walls with bales, and the roof with wood framing, we build the roof, with bales, and no wood framing, then build the walls (at least the lower story structure) with wood framing, or some other wall system, that does not require the huge overhangs. The building is already using as much, or more bale construction, as most bale houses. If the lower walls (and end walls) are built with other than bales, they only need the small overhang of the strawbale Gothic Arch roof. No need to increase the cost with big overhangs, all the way around. I can see one of these Gothic Arch roofs, setting atop a stone, or a plastered wall that doesn’t use bales in the lower storey, which might even be a walk-out, built back into the side of a hill.
So…to review the points at the top of the page, which this approach eliminates:
1) Moisture from the exterior…big porch areas
The bales are under the vented metal roof, where moisture can not get to them, so porches are not needed.
2) moisture from the interior….permeable exterior coatings, that allow exterior moisture problems.
The bales are vented, under the metal roof, which will literally bake the moisture out of the bales, and vent it up and out the ridge vent.
3) Low load bearing capacity…No second stories.
The bales are used in the second story wall/roof, instead of the lower story. This also eliminates the need for the porches.
4) Excessive labor for plastering bales.
The exterior plastering of the bales is eliminated, by the metal roofing reducing the plastering to less that 50%. (maybe)