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#25255 - 01/20/11 04:46 PM Infill and Half Timbering *
D L Bahler Offline

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Registered: 05/17/10
Posts: 946
Loc: Indiana
I am working out the details of the enclosure of my shop, and need to decide between 2 different traditional styles. The first is a half timbered exterior and interior, the second is an infilled wall with a board clad exterior.

I like the look of half-timbering, but I have to wonder if it would be appropriate for my climate. I live in Central Indiana where humidity levels are quite high, it rains frequently, and super cell thunderstorms com by often with their heavy rains and high, driving winds. Half timbering was not designed for this climate, and I wonder if it would leave the frame too susceptible.

I would not use wattle and daub, it simply would not survive our weather. My infill would be a German style, using brick, stone, or clay/loam. It would have a generous coating of plaster inside and out. What I worry though is if the interface between infill and timber would attract too much moisture.

The wood is not going to be oak, rather it is going to be assorted locally available wood. This includes rot-proof species like cherry and walnut, but it also includes rot-susceptible species like hard maple and hickory. The timbers, however, will be thoroughly sealed and painted on all faces that may come in contact with moisture (it's a part of the tradition) The roof overhang is also very wide, so it will provide a good deal of protection.

I wouldn't despair if I had to abandon the half timbering and clad the frame with some nice boards, I like the all wood look too
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#25259 - 01/20/11 08:12 PM Re: Infill and Half Timbering
Gabel Offline

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Registered: 11/18/03
Posts: 687
Loc: Georgia
I love the brick infill look. Some nice examples in Old Salem, NC.

After a lot of research and thought on half timbered systems, my take is that whether you use traditional or modern materials and methods you're going to need to do thorough annual or at least biennial maintenance. Most folks won't keep that up and I can't say I blame them.

Let us know how the planning progresses.
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#25263 - 01/21/11 07:18 AM Re: Infill and Half Timbering
TIMBEAL Offline
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Registered: 12/10/07
Posts: 1875
Loc: Maine
The term "half timbered" as pointed out by Ken Hume, I believe, refers to the timber being split in half and not necessarily the infill system. I like that explanation of half timbered as a better description.

Too bad we can't take the time to maintain a simple, down to earth system. I owe, I owe, so off to work I go.

What is the difference between clay bricks and wattle and daub? Are you planning on using fired brick or raw? Aren't they made from similar material? What makes wattle and daub inferior?

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#25265 - 01/21/11 07:58 AM Re: Infill and Half Timbering
mo Offline
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Registered: 11/04/06
Posts: 850
Loc: Charleston, SC
I find this thread interesting, and have many questions on it as well.

I'll just start with one though. smile

DL, when you talk about painting the surfaces that are subject to moisture, are you talking about at joinery abutments or the any face that is exposed to the weather? What does one do for say, exposed posts? Do you choose the best wood characteristics to expose to the weather? Is there some other protectant one applies to the timber?

Ok, more than one question.

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#25268 - 01/21/11 10:35 AM Re: Infill and Half Timbering
D L Bahler Offline

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Registered: 05/17/10
Posts: 946
Loc: Indiana
Mo, Look at some historic examples from Europe (Google Fachwerkhaus and Riegelhaus for German, and look at some English and French houses)and you will see that the entire exposed faces of the timbers are painted, usually a dark brown or a dirty red.

Wikipedia says the following regarding the term Half Timbered:
"One of the first people to use the term half-timbered was Mary Martha Sherwood (1775–1851), who employed it in her book The Lady of the Manor, published in several volumes from 1823–1829.
By 1842, the term "half-timbered" had found its way into The Encyclopedia of Architecture by Joseph Gwilt (1784–1863)."

It may have meant something else at one time, but this seems to be the understood usage now.

Gabel, just googled Old Salem. Sure are some nice examples. Did some research -the infilled structures were built by the Morravians, a German religious group. I thought the buildings looked German.

My ideas about wattle and daub being weaker are handed down to e from the Germans. It is said that part of the major influences for the development of Fachwerk was so that better materials could be used as infill. The claim is that daub cracks easily, is badly damaged by weather, and is cold and drafty. Brick and stone are said to be the best choices.

There is another infill choice that I have been studying a lot lately, and I think may be the answer I am looking for. It is called in German Bohlenwand or BohlenStänderbau or Ständerbohlenbau. Basically it is the use of thick boards or blocks placed between timbers, tied into grooves at either side.

nails are then driven into the boards on the outside face, and are covered with a coating of straw-clay to insulate and then with lime to waterproof.

This system, due to the boards being inset into the posts, does a good job of keeping out drafts.

Were the interface of board and timber sealed with tar or some such then water would not have the opportunity to penetrate.

This also gives for a very attractive all wood interior. Alternately the plastering can be swapped so that the exterior is all wood. There are a few examples I have seen where there is no plastering, but these tend to be drafty and uncomfortable.

Bohlenwand was invented in Medieval Switzerland to be a cheaper alternative to brick and stone houses.

pictures are from de.Wikipedia article http://de.wikipedia.org/wiki/Bohlenwand

a brief tour of European Half timbering vie Google Images:
France:


England:


Denmark:

Low German:

High German:



Hopefully that's enough to inspire...
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#25269 - 01/21/11 02:01 PM Re: Infill and Half Timbering
D L Bahler Offline

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Registered: 05/17/10
Posts: 946
Loc: Indiana
Eureka!

While thinking about the Bohlenwand technique I got inspired. And I think I have come up with a system that could work well for a modern house and be suitable for modern ideas of comfort.

In Europe the modern twist on Bohlenwand is to use special manufactured panels that are made of foam sandwiched between layers of wood. This is a good system and works well, but the only problem is we can't get those panels here.

So I thought of an idea. Instead of 1 single panel sandwich, what if there were 2 completely separate layers of wood each in its own key in the posts, and the insulation (preferably foam of some sort) is placed between these layers. It would look something like this:

or a plan for a plan drawing that makes the various aspects a bit clearer maybe:

This system, I think, has the potential to work better than the European version. The reason is that It can be tightly sealed quite easily.
The outer layer of boards should be the first to be put in. They would be standard 1x stock set back from the outside edge perhaps 3/4". It should be noted here that this is designed to be used in a close posted system, 3/4" boards are plenty stable over 3 or 4 feet but over 12' or more they would be far too wobbly and would require studding.
These boards would be plastered over on the outside with clay and lime to make the infilled panels flush with the outside of the timbers. On the inside spray foam would be used to seal off all of the joints from drafts.
The inner layer could also be 3/4 boards, but I think that thicker boards would work better. The reason is that it would allow you to take advantage of wood's thermal mass on the inside of the structure where it is the most beneficial. I have shown here 2x stock set back 3/4 inch from the inside face of the timbers. This would allow a little bit of timber exposure. Keep in mind though that any setback from the inside reduces the size of the insulation cavity, but a certain amount of setback is required so that the boards can have a channel to key into the posts.
The inside can use nice boards for an all wood finish, or you could use cheaper wood and coat with plaster.
The insulation layer can be just about anything; it could be cellulose, spray foam, foam board, straw, wool, shredded tires, or whatever you could dream up. You have a very large cavity surrounded on 4 sides by solid wood.
Part of the beauty here is that this system can easily take advantage of both thermal insulation and thermal mass. It can be easily adapted to different climates simply by changing the infill material and the width of the inside boards.
Obviously this is not going to be a super insulated house, but it's not designed to be. However, it could be with 1 minor variation. eliminate the outside layer of boards and replace it with foam sheathing nailed or screwed directly to the posts on the oustside (you may want a layer of wood or plywood for rigidity). This of course would not give you a half-timbered exterior however.

Now this is kind of a side track from my original question, which still stands. That question being whether or not a traditional infill system would be suitable for a shop building in Indiana's wet, stormy climate. My current line of thought is that clay based infills would be too susceptible to wind-driven moisture and high humidity, but that a Bohlenwand style wall with thoroughly sealed joints might do the trick.

As a side note, The use of clay on the exterior of the Bohlenwand seems like a very good idea to me, provided it is sealed by the plaster. This is because a silt-clay loam is highly hygroscopic (unlike pure clay) but does not retain high levels of moisture (unlike pure silt). This means it draws water more readily than the wood will, so it effectively keep the wood dry under normal conditions, and it at the same time will readily diffuse the water into the atmosphere after the moisture event has passed.


Edited by D L Bahler (01/21/11 02:02 PM)
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#25270 - 01/21/11 03:11 PM Re: Infill and Half Timbering [Re: D L Bahler]
Gabel Offline

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Registered: 11/18/03
Posts: 687
Loc: Georgia
Originally Posted By: D L Bahler

As a side note, The use of clay on the exterior of the Bohlenwand seems like a very good idea to me, provided it is sealed by the plaster. This is because a silt-clay loam is highly hygroscopic (unlike pure clay) but does not retain high levels of moisture (unlike pure silt). This means it draws water more readily than the wood will, so it effectively keep the wood dry under normal conditions, and it at the same time will readily diffuse the water into the atmosphere after the moisture event has passed.


Would the clay plaster have a lime plaster on top of it? Or at least limewash?

It seems that clay exposed to weather wouldn't last.

I do like the way moisture would be managed. I wonder if adding foam in the cavity would cause problems with that...
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#25271 - 01/21/11 04:09 PM Re: Infill and Half Timbering
D L Bahler Offline

Member

Registered: 05/17/10
Posts: 946
Loc: Indiana
Yes the clay would be covered with lime, at least a finish coat to seal it all off.

I wonder the same about the foam. I don't think it should be a major problem though as it does not seem like water would make it that far.
I would be worried though about the foam holding water there in the case that moisture does penetrate that far.
If it is a major concern a heavy clay could be plastered on the inside in stead, but wouldn't be quite as air tight. Remember that the whole reason for the spray foam is to stop drafts. As such it COULD be considered an extra feature and is not absolutely necessary.

Right now I am trying to work out in my mind how the system would be executed around braces. One drawback is that this all has to be put in place as the frame goes up, before horizontal timbers such as plates top off the cavities. order of assembly suddenly becomes very important!
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#25272 - 01/21/11 04:37 PM Re: Infill and Half Timbering
Gabel Offline

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Registered: 11/18/03
Posts: 687
Loc: Georgia
I'd like to be able to make a system like this meet building regulations.

We've done one with a groove in the posts/studs/braces but instead of boards it had hardibacker - a fiber cement sheet product. And yes, it's tough to put in as the frame goes up.

We didn't groove the upper face of any braces, sills, or other horizontal or diagonal members. All of these had a bevel cut in them in the hopes that water would drain away from the panels.

The groove was wider than the panel's thickness and foam backer rod was stuffed in the groove and then a polymer chinking material was used around the perimeter of the panels where the panels met wood. The finish for the rest of the panel was typical stucco.

We didn't design the system and we only took it as far as cutting each panel and installing it as the frame was raised.

I haven't been back to see how it's holding up -- it's about a 12 hour drive from here -- but I hope to someday soon.
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#25273 - 01/21/11 05:53 PM Re: Infill and Half Timbering
bmike Offline
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Registered: 01/09/08
Posts: 918
Loc: Burlington, VT
what material would you use that could be exposed to the weather - and not shrink tremendously, opening up issues of checking / vapor drive / and your seal breaking...
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