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#32898 - 04/02/15 11:33 PM Re: Wrap and Strap..how it works? [Re: Snickare]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 480
Loc: Vermont
Right you are Tim!!

As can be told from my views...I don't recommend or like "airtight" architecture but rather "draft proof" with only permeable insulation and no "house wrap"...

However...

If going the way of "airtight" and wrapped in foam...I haven't seen one work yet that does have an "air exchanger" system to make them work...


Edited by Jay White Cloud (04/02/15 11:33 PM)
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#32900 - 04/06/15 09:30 PM Re: Wrap and Strap..how it works? [Re: Snickare]
Hylandwoodcraft Offline
Member

Registered: 03/23/11
Posts: 141
Loc: Western NY
This is an interesting thread. I have done quite a few projects with a fairly standard SIP approach. I increasingly feel the limitations of this type of approach, and really want to be able to spend some R&D time on alternatives. I am particularly interested in a "Chip and Slip" type non load bearing wall. I just need to find the time (and a competent plasterer).

For the time being, I am trying to increase the workability of the Sip type enclosure with cold roofs, rainscreens, EPDM gasketing, etc. It's hard to escape the feeling though, that the sip enclosure may be overly complicated to properly detail.

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#32901 - 04/06/15 10:43 PM Re: Wrap and Strap..how it works? [Re: Snickare]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 480
Loc: Vermont
Hey Sean,

Good to hear from you!

The more the years go by, the more I become impressed with the "old" traditional systems and our new knowledge of them. I also grow less and less impressed with what modernity has to offer and the damage it does to human and planet health while making billions for large industries...

Lite straw clay slip infill methods (and related others) are nothing more than traditional "insulative" methods of cobb and related "wattle-daub" work. As an infill and/or overlay system they are proving each year to not only be efficient, but healthier and more in balance with our goals as sustainable builders (and Timberwrights.) I see these systems being "revitalized" with modern understanding while still incorporating traditional wisdom. Set to work in concert with other "permeable materials" like mineral wool board/batt we can achieve highly effective thermal envelopes, without issues of trapped interstitials moisture all to common with the "airtight" concepts...
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#32947 - 04/20/15 10:45 PM Re: Wrap and Strap..how it works? [Re: Snickare]
collarandhames Offline
Member

Registered: 07/03/08
Posts: 191
Loc: Peterborough, Ontario
While not getting all fancy with building wrap, vapour barriers etc works for some, those of us in cold climates up north need to realize that many months of sub zero temps can provide breeding grounds for mould if not detailed properly.
Up here in canada, we have a motto. Seal tight and vent right. Which means continuous vapour barrier on the inner third of the insulation (or better yet, on the inner face), and yes, mechanical ventilation. I live in a war time story and a half, and the first year I lived in it, I replaced all windows and sealed up all outlets, switches etc. as well as replacing the old chimney furnace with a high efficiency furnace, thus eliminating the air exchange in the house.The second winter we all fell sick as I had made my house simlar to placing your head in a plastic bag. Third winter , I had installed an HRV, and we all breathed better. The HRV was 1500 bucks installed, but now with our sealed tight vented right house, the natural gas bills are around 400 bucks a heating season.
Those who want to tell me I'm wrong, hey,, how cold is your winter? It is an issue.
hope this helps. Cold climate building is another thing.

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#32948 - 04/20/15 10:48 PM Re: Wrap and Strap..how it works? [Re: Snickare]
collarandhames Offline
Member

Registered: 07/03/08
Posts: 191
Loc: Peterborough, Ontario
I should note that we are currently experimenting with pre-fabricated straw bale walls, which do "breathe". They will take on moisture threw the plaster, but as long as the seasonal inner condensation is less than the amount let back in the warmer months, it's a good system.
Building enveloping, a new thread?
dave]

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#32949 - 04/20/15 11:49 PM Re: Wrap and Strap..how it works? [Re: Snickare]
Jay White Cloud Offline
Member

Registered: 11/06/08
Posts: 480
Loc: Vermont
Hello Collarandhames,

I don't believe I can agree with many of the perspectives you just shared about vapor barriers, yet understand that view is common. I would love for you to join Permies.com and perhaps read some of the information there and engage in a the same conversation there about these concepts of "airtight" architecture. Not to dissuade you at this time, but I think you would enjoy reading some of the other perspectives in natural/traditional building modalities.

Hope to see you there,

j
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#32958 - 04/30/15 10:05 PM Re: Wrap and Strap..how it works? [Re: Snickare]
collarandhames Offline
Member

Registered: 07/03/08
Posts: 191
Loc: Peterborough, Ontario
Jay, I am eager to learn of others ideas. I do know that a lot of air flow threw a small hole in interior stucco will lead to condensation at dew point. It's all relative. If the ambient air is being ventilated in areas of high moisture , like bathrooms and kitchens, then I think we are all good.
I will look at the site you reference, and look forward to learning more.
dave

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#32959 - 04/30/15 10:17 PM Re: Wrap and Strap..how it works? [Re: Snickare]
collarandhames Offline
Member

Registered: 07/03/08
Posts: 191
Loc: Peterborough, Ontario
Jay, I had a quick look, and knowing you are in vermont helps. However, we have such cold temperatures for such a long time, I am concerned with the amount of moisture that can enter the wall cavity over successive seasons, and the longevity of the wall. My partner is planning on doing some prefabricated straw bale panels this summer, and I will chat with him in hopes of enlightenment. A lot of the folks on this Permies.com page have no experience with our wickedly cold long winters. Again, I have a good basis of the building envelope in normal construction, and have seen where too much lack of detail can cause studs to rot, but am eager to learn more of how it works in my environment. We have a super green builder in town -Chris Magwood, who is pushing the building envelope, and I'll try to chat with him. I actually helped install the steel roof on canada's greenest home. I'm totally into it, however, as I can't help it, will be naturally skeptical until I understand the properties involved with the wall system in my climate. Always eager to learn. dave

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#32970 - 05/15/15 05:05 AM Re: Wrap and Strap..how it works? [Re: Snickare]
Jon Senior Offline
Member

Registered: 05/04/11
Posts: 112
A well-wrapped building requires (mandates in fact) a form of mechanical ventilation... which itself needs to be correctly sized and well thought out. My personal view is that as we increase the insulation in a house, leaving it "leaky" becomes less of an option. Putting 30+cm of insulation in walls serves no purpose if you allow uncontrolled airflow. Mechanical ventilation also allows you to introduce fresh air where it is required, which may not correspond with the placement of windows and to ensure a logical airflow throughout the house, where humid air (such as in a bathroom / kitchen) is not circulated through "dry" rooms before being extracted. Here in Europe, passive houses are fitted with mechanical ventilation systems that extract calories from the "used" air and thus pre-heat the incoming air, and the remaining heat in the air is passed through a heat pump to be used for heating domestic hot water. This is admittedly a highly-technological solution.

If you're prepared to treat the envelope as a "living" structure where low-cost walls can be cheaply replaced or rebuilt as necessary (straw bale + clay render for example) then to a certain degree the risks of moisture incursion can be ignored as the material cost (environmental and monetary) is low, but this has to be considered as a part of the ongoing maintenance of the building.
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Contemporary Norman longhouse in Normandy

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