Comments on: Vapor Barriers

By: Andrew

Andrew — Mon, 27 Apr 2009 18:33:22 +0000

Hi Justin. This is a tough one. If I read your post right, you want to have interior bale walls, like between say a bedroom and the living room. This takes up a lot of space. Then I see you are considering using chainsawed bales to make them more space efficient. I think this would be a waste of time for you. You can get a better insulation value out of standard insulation at that thickness. In terms of sound, it travels through the studs so if you want to eliminate it, you need to build two walls separated by an inch air space or use sound proofing materials.

For the exterior walls, I think you will find it easier to install the bales into the frame (with the roof on) and then plaster the exterior face of the wall with a scratch coat, After the scratch coat has dried, then install the cedar. You can use a rain screed installation with a vent between the bales and the siding for best results.

By: Justin

Justin — Tue, 07 Apr 2009 15:17:02 +0000

My wife and I are building a 1200 sq ft cabin/loft. We want to incorporate straw bale into the home, but without many “straw” experienced contractors in our area and even less experience between ourselves, we have decided to go with a framed straw-infill home. We want to have cedar siding on the home and use the strawbales on all interior walls that do not have plumbing. I was planning on having the contractor frame, roof, and put the cedar siding on the entire house, and then we will do the majority of the interior work ourselves.

Would we be able to get the same insulation advantages and sound proofing on the interior walls, albeit not to the extent of 18″ thick bales, if we used say 4-6″ chainsawed bales inside the framing instead of blown in insulation and drywall?

Also for the interior walls that are parallel with the exterior cedar sided walls, would it be sufficient to just lime plaster the back sides of the bales and stuff them in place and then finish plaster the interior facing walls? Would I need to leave an “air gap” of a few inches between the cedar and the “insulating” straw bale walls? Any advice or suggestions would be greatly appreciated.

By: Andrew

Andrew — Mon, 02 Mar 2009 23:25:38 +0000

When on edge, the strings of the bales are in the way for notching around posts or creating decorative niche. The face of the bale that is exposed is more slippery and does not hold plaster well. The bales are off center, i.e. taller than they are wide, so they are not as stable. These are the main reasons.

I prefer lime and sand only because it is more flexible and breathes better than cement based plasters.

By: BARNIE Says:

BARNIE Says: — Sun, 01 Mar 2009 16:33:11 +0000

Hi Andrew. Thanks for the answer. Please give more detail about the reasons why you dont like building side up with the bales. Please, what is the difference between lime for plastering and a good mix of cement, lime and sand for plstering. I have come accross people doing it that way.I am not sure about amount of sand, lime and cement they use. Can it work if I have a problem to get the right lime.

By: Andrew

Andrew — Wed, 18 Feb 2009 23:01:36 +0000

Hi Brian,
Do you ever get any dry weather where you want to build? I would be concerned about the moisture issues inside the walls if there is never a chance for them to dry out. As you may have read above and in other places in the blog, figuring out how to translate relative humidity into moisture content is difficult. A test wall might be a good idea. Build it and let it sit for a year. You can then monitor or tear down the wall and look for signs of failure or success. Hope that helps.

By: Brian

Brian — Wed, 18 Feb 2009 20:16:14 +0000

Andrew,
Have been wanting to attend your workshop, but wanted to make sure that building with strawbale is feasible in my area (Mississippi)due to temp and humidity. It is on my farm, no permits required, just hot sticky days in the summer, cold wet during the winter. Figured large overhangs, positioned correctly, slab….. The zip code is 38901, any concerns or advice?

By: Andrew

Andrew — Wed, 18 Feb 2009 18:40:18 +0000

Jamie,
I prefer to put my frame to the outside for the reasons you named; however, it is very possible to place that frame to the inside so it can be exposed. Don’t try the center option as it will drive you nuts. There are some other posts in the blog about placing your timber frame on the interior. Take a look and you will find some important details about how to accomplish this well.

By: Andrew

Andrew — Wed, 18 Feb 2009 18:38:28 +0000

Hi John. I have a whole blog entry about this subject that I think will clarify your questions for you. Do a search for “Water isolation walls” at the top of the home page making sure that “StrawBale.com is checked before you search.

By: Jamie McKay

Jamie McKay — Wed, 18 Feb 2009 01:57:04 +0000

Andrew,

It appears that you place your post and beam structure to the outside of the bales. Is this a preference or does it just work best for the roof, window, and door structures? I thought that I would place them on the interior to expose them (the look) and not have any differential strinkage problems on the exterior – interior is not subjected to the same temp./humidity fluctuations. Other opions are to hid them in the middle, but I assume that is a pain to knotch. Or, place them, knotched, on the inside and outside, like a ladder (I can’t remember the technical term).

Thanks again for the advise,

Jamie.

By: john de Bogdan

john de Bogdan — Wed, 18 Feb 2009 00:59:38 +0000

great information !! i thank you all for the input and related comments. i also have questions concerning placing shower/kitchen on bale walls, and am planning on using limited amounts of ” wall board” or concrete drywall where sinks and showers are going to be placed. tell me more about spacing for venting. i was planning on placing one or two 4X8 pieces to protect a corner shower, (both walls bale). i am open to your recommendations.. . how does one contact you off line? feel free to send me an e mail. again thanks for the info