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#29828 - 11/23/12 01:51 PM Re: Infill and Half Timbering * [Re: Jon Senior]
Gumphri Offline
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Registered: 01/18/08
Posts: 83
In northern climates it is a big issue. I'm not sure we really understand the science of it. Where I live even the location of the vapour barrier is in review. I've seen several different routes for sealing joints between different materials on details where new and existing buildings joined.

These are what I view as the issues that need to be addressed with the joint
-the outside needs to keep moisture out
-the vapour barrier needs to be located in the correct location for your climate
-any vapour that does condense needs to have an escape out of the wall.
-the joint has to accommodate for movement in the timber.

I think if you are set on having timbers exposed on the inside and the outside you are on the right track with the expanding foam strips.

Another question is how do you plan to heat this home? Might a breathable wall infill made of log or straw better suit your needs? There are also wood fiber and OSB SIPs available near you.
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Leslie Ball
NaturallyFramed.ca

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#29830 - 11/23/12 05:47 PM Re: Infill and Half Timbering [Re: Gumphri]
Hylandwoodcraft Offline
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Registered: 03/23/11
Posts: 141
Loc: Western NY
Gumphri,
I need to get some more details from the architect as far as the heating/cooling details of the house. I'm assuming that the wood fiber sips you mentioned are Stramit panels, made from wheat straw. I make my own insulated panels for my houses, so I could conceivably use Stramit panels and laminate them to ply or osb.
I've been interested in Stramit panels for a while. I would love to use them in a project.
It looks like the weatherstripping that Jon Senior mentioned is basically poly ester foam. I think that if done right that foam would do let any possibly trapped moisture move out. I suppose that in my climate any problem moisture would originate from inside the house.

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#29833 - 11/24/12 02:57 AM Re: Infill and Half Timbering [Re: Hylandwoodcraft]
Jon Senior Offline
Member

Registered: 05/04/11
Posts: 112
@Hylandwoodcraft: The weatherstripping is a polyurethane foam impregnated with resins (direct translation). If you are aware of alternatives that serve the same function I'm interested as I'll be installing windows early next year and would love to find a cheaper alternative. Currently the weatherstripping is running at about 25% of the cost of the windows themselves!
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Jon

Contemporary Norman longhouse in Normandy

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#29835 - 11/24/12 02:54 PM Re: Infill and Half Timbering [Re: Jon Senior]
Hylandwoodcraft Offline
Member

Registered: 03/23/11
Posts: 141
Loc: Western NY
OK. So it is a bit more than just polyurethane foam. The website I pulled up on the product you mentioned was all in French, so I couldn't tell the specifics. There are a lot of products on www.foamtapes.net . Wow, 25% the cost of the windows is pretty significant. Let me know what you think of the products at foamtapes.net, their prices are really reasonable, if you can find something comparable.

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#29838 - 11/25/12 10:40 AM Re: Infill and Half Timbering [Re: Hylandwoodcraft]
D Wagstaff Offline
Member

Registered: 02/17/12
Posts: 248
Hello,
A pretty fragmented story seems to be emerging. There is another conceptual model that might be useful though not really widely grasped yet especially among architects and that is a systems approach. Instead of looking at individual components in isolation, site, frame, infill, roofing, sealing, insulating, heating, air quality... why not look at how all these things interact more intensively. I mean to say, it is really getting back to a rational approach.
We imagine wanting to improve on shortfalls of the way a half timbered frame has evolved and begin with the interface between the frame and infill where those openings develop and supposedly let the air in. So we seal everything up. It is the cause of two main unintended effects. A moisture build up and retention within the frame and reduced air circulation inside. Not only is the inside climate negatively impacted but the seeds of self destruction are planted within the very core of the building. I think the second law of thermodynamics is doing fine without any extra help, thanks.
What about an appropriately integrated shell of timber and say clay brick, for example - only because this is in between the two extremes of kiln fired brick and wattle and daub - which can be permeable on all counts, it will not seal the inside off so there will be a constant and desirable exchange leading to more efficient warming of the inside air - trapped motionless air constantly takes on and holds moisture becoming harder to warm - through a centrally located radiant heat source, the thermal mass of the walls will even out seasonal fluctuations of temperature and humidity for example as it regulates or maintains the ambient room temperature. The ambient temperature is what is important because it is what people in the room experience. The ambient temperature is the average temperature of all the combined exposed surfaces of the space. A final influential factor is the micro environment where the building is situated which can be planned appropriately. You see how it becomes difficult then to think about the infill only.

Greetings,

Don Wagstaff

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#29839 - 11/25/12 11:41 AM Re: Infill and Half Timbering [Re: Hylandwoodcraft]
Jon Senior Offline
Member

Registered: 05/04/11
Posts: 112
I've managed to track down an equivalent product in the US market (foamtapes stock Lamatek products and they don't appear to manufacture an equivalent); Schul Sealtite. There may be others but I've not found them yet.

DL Chemicals Topband & Pressband and ISO-CHEMIE's ISO-BLOCO 600 are products that have English language datasheets if you want more information on what they do.

The crucial differences between these types of products and those offered by foamtapes are:

Pre-compression - Very high compression to ensure that the joint can be fitted during installation without damage and that post-installation, the gap will be effectively filled.

Large range of working thickness - Ensures that the joint can cope with movement in one or both of the surfaces.

25% of the cost of the windows is for the HPE version which is a funky, designed for timber frame product. The narrower versions which don't offer quite the same thermal insulatative properties are much cheaper.

I've seen people using Neoprene gaskets to fulfill some of the joint sealing applications offered by these tapes (Bensonwood use them for sealing their wall units together and to the floor), but I think it's the permeability to water vapour and gap-filling qualities that make them interesting. There are versions that have a working range of 24-42mm (~1" - 1.5"). That's quite a gap to be able to reliably fill!

All in, on paper, I'm very impressed with these tapes. How impressed I am once I come to install our windows remains to be seen! :-)

Edit to reply to Don Wagstaff

In principle I agree, but the reality is that an airtight house will always be easier (read, use less energy) to heat and cool to a given temperature, than a leaky one. Relying on permeability of the walls to provide appropriate air exchange is unlikely to be successful, and using traditional window vents means that window placement becomes critical for air exchange. Managed ventilation (mechanical ventilation or even appropriate use of the stack effect) ensures improved air quality within the house, while minimising heatloss. You can still have a well-sealed house which has breathable (vapor-permeable) walls.


Edited by Jon Senior (11/25/12 11:48 AM)
Edit Reason: Reply to another post
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Jon

Contemporary Norman longhouse in Normandy

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#29869 - 12/02/12 05:46 PM Re: Infill and Half Timbering [Re: Jon Senior]
Hylandwoodcraft Offline
Member

Registered: 03/23/11
Posts: 141
Loc: Western NY
Hi everyone,
It looks like the project is going to go forward. We'll be using W. Oak for the frame. I'm going to order a few different gasket materials and see what I think. I'll keep everyone updated as it progresses. Thanks for all the feedback....

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