Dale Walker wrote:
I'm going to be building a small cabin this summer in northern new england. The cabin is around 350sqft on slab. heat will be with RMH. ventilation will be either exhaust only or passive with windows, or a combination of that.
My goal is for a fairly tight envelope that doesn't trap moisture inside the wall, significant passive solar gain, and high interior thermal mass.
My question is about a walls ability to dry to the interior. the assembly that I'm planning is below:
from interior to exterior:
-2x4 wall frame with dense pack cellulose
-zip system wall sheathing - taped
-4" rigid foam
-3/4" air space/rain screen/strapping
-wood siding, probably vertical board/board or board/batten
curious what peoples thoughts are about this choice.
Terry Ruth wrote:Bill, I'm guessing the thing to do when clay plaster gets wet is let sorption do it's thing.
Terry Ruth wrote:I struggle finding a sealer that makes earth (plaster, rammed earth, etc) less friable in the US, there all over in Europe.
Terry Ruth wrote: I tried a spray lime wash like 7-8 coats through an agriculture spray pump at 50-50 lime/water ratio on rammed earth to a point where I could brush coat it thicker...Did ok until I hit it with vacuum, or a kid beating on walls would not be good. You can pigment it but loose the beauty of the rammed earth striations. I tried an acrylic sealer that went on white and dried clear to a satin natural look, also available in semi and gloss....better....I wonder if that Siloxane do the trick? It is very low voc, 100 % permeable, few choices of products on the market, and siloxane sounds great it gets the surface pores to manage liquid water and allows the wall to breath.
Terry Ruth wrote:How are you burnishing the lime?
Terry Ruth wrote:I talked to some lime manufacture chemist when I was developing a hemp binder that told me gypsum is used as a filler to cut cost, does nothing chemically to the calcium and/or magnesium oxides in lime. What is the gypsum doing in your mix?
Terry Ruth wrote:You say you put it down first as a base then a burnished lime finish?
Terry Ruth wrote:Nice seeing first hand the pics of different natural pore sizes, great stuff!
Jay C. White Cloud wrote: I have Douglas Fir and White Pine both that has been outside for 8 years...Its as yellow as the day it came out of the shop. Then again, we use traditional treatments of pine rosin, beeswax, flax oil, tung oil, citrus oil and a little UV stabilizer that seems to all work great...Food grade on most of the materials we use. All are classified as naturally and safe...including the fire retardant we sometime have to apply for frames that are in "high risk flash zones."
Terry Ruth wrote:Bill, yes very interesting informative book and you know what just baffles me is I have been told that "no measurable data exist" and these methods are controversial. There is all kinds of data that results from measurements above. So the next time someone claims that we can point them to this thread
I am using 1:1 type s hydrated lime to local pumice/ash mix.
Terry Ruth wrote:
The clay data seems consistent, lime varies with surface finish. 1:2, 1:3, them pumice/lime sounds great as insulating and water proofing with high perm. If the surface is burnished to close structure more of a water barrier is created if that what one wants, with the smaller the pore size. What mix of lime and pumice and what type lime are you using?
Well, I just picked up my first 2000 lb superbag from the Limestrong plant. They are a new start-up that produces an exact replica of Roman concrete(pozzolanic lime this is the Holy Grail to me). Little bags are 1000 lb and sell for $350. They have asked me to distribute, so send me a pm if you want a bag. This pumice is within 1-2% in all chemical analyses of Vesuvius, where the Roman builders got their pumice/ash.
Terry Ruth wrote:
Where do I get pumice? Scoria" or other insulating rock that drains well? I know I can get perlite at Walmart in spring but it's a little expensive around here and large quantities, small bags to a job site does not seem very appealing.
Terry Ruth wrote:
Dursiol, has me a little confused. They have a very open pore, permeable, ICF form with excellent properties it appears but they support an exterior petro barrier and have no test results on the burnishing of lime you mentioned with their product, or other test results of natural barriers. From what I can tell at this time anyway by the data, that closed pore surface finish will produce a barrier and allow high permeability we want under slabs, exterior walls...or option 3 or 4 above. Durisol suggest a "parge coat" of portland cement/sand to close pores for stucco's on their product, cladding with vent gaps behind it. I need to call again and talk to an Engineer not sales....the book has more on Durisol later, which, if you wanted to take the manufactured product route for fast ease of construction looks to be one of the better ones. Far better than most SIPs. Don't let the lower r-value fool you, another myth discussed soon. What I figure is as George said (full breathable walls is not always desired) in some cases such as Durisol where the material has a high ability to store vapor on the interior side and prevent diffusion it to the concrete or to exterior barrier that does not have an ability to absorb or dry fast, then get trapped by an exterior barrier I question. My concern is if the warm humid inner wall saturates to the exterior barrier that does not allow drying to the outside if it is dry, purhaps their studies have shown indoor humidty drive at 100% this will never happen. Think I wall call them today. Air barriers (completely different than vapor, or some such as plastics can do both) they say can be anywhere, air transports heat/cold through the walls making up a critical part of breathable walls to exchange air in small amounts/hour...more on thermal mass soon
Terry Ruth wrote:Here are some good sources for lime types and applications: Our hydrated types in the USA are similar to hydraulic in Europe or NHL 2, 3.5, 5, the lower have less cement/strength or MGO like high calcium we use.
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