bracing and infilling

Alexis · June 04, 2009, 07:04:35 PM

Hello,

just wondering: from my understanding, if a bent is infilled with a structural material ( cordwood, cob, papercrete, brick, stone...) there is no need for bracing because the infilling will be in compression if there is racking. Am I right in thinking that way or am I missing something?

moonhill · June 04, 2009, 08:57:28 PM

Alexis, no, I don't think it works that way. The harder the material is the more racking it can handle, concrete comes to mind, but cob would be on the very opposite end of the spectrum. I guess a different question could be, would you in fill in the frame or on the outside of the frame? I could see both, depending on the use of the structure. If it was my full time residence I would do an external wall system. On a seasonal use building I would be tempted to infill between the post and bracing.

Tim

Alexis · June 09, 2009, 09:32:13 AM

So if one would infill with a sufficiently strong material, braces wouldn't be required, right?

moonhill · June 09, 2009, 03:00:34 PM

How do you prove it is sufficiently strong enough? What infill system are you looking at? Bracing is relatively simple, cheap insurance, why leave it out?

Tim

witterbound · June 09, 2009, 10:01:03 PM

There is a young man who comes around the shop sometimes. He wants to build a "timberframe" with infill, but he really doesn't want to use braces. He doesn't want to use them because (1) he's a novice and cutting and fitting braces seems awfully hard to a beginner, (2) he wants to have a lot of windows, including where the braces would go, and (3) if he uses braces he can't figure out they work with the infill. Are they hidden by the infill, arranged toward the inside so the infill is continuous behind, or what? We tell him that he really needs the braces for strength, and he leaved scratching his head. So there might be someone else out there in this same kettle of fish.

moonhill · June 10, 2009, 07:53:07 AM

I suppose if the glass is thick enough it would handle the bracing issue.

Tim

Jim_Rogers · June 10, 2009, 01:59:45 PM

Quote from: witterbound on June 09, 2009, 10:01:03 PM
There is a young man who comes around the shop sometimes. He wants to build a "timberframe" with infill, but he really doesn't want to use braces. He doesn't want to use them because (1) he's a novice and cutting and fitting braces seems awfully hard to a beginner, (2) he wants to have a lot of windows, including where the braces would go, and (3) if he uses braces he can't figure out they work with the infill. Are they hidden by the infill, arranged toward the inside so the infill is continuous behind, or what? We tell him that he really needs the braces for strength, and he leaved scratching his head. So there might be someone else out there in this same kettle of fish.

First of all I'd like to talk about the infill. What is he going to use? The joint between the infill and the timbers is most likely always going to be a problem. Wood moves with age as it dries out. And from winter to summer. This can create gaps between the infill and the posts for example.

Creating an outer jacket of some type to enclose the frame seems better than an infill system.

Braces can be set to the inside of posts so that some type of infill can be placed behind them to insulate and enclose.

Braces can go from sill to post below the windows so that they don't interfere with windows.

Brace can go above the tie or girt instead of below so that they don't interfere with windows.

There are several ways to stiffen a frame.

Plank houses don't have braces and they are stiff.

Each individual frame design and enclosure system had to be looked at carefully to understand all that need to be done to make it the best it can be for the occupants.

Jim Rogers

Alexis · June 10, 2009, 08:10:48 PM

Hello,

just to be clear, I have nothing against braces and my frame will have them. I was just wondering from an educational aspect if the infill could be considered bracing. I see a lot of picture from cordwood houses where the frame is post and beam, infilled with cordwood and they have no braces. In my opinion, since the wood and the cement are strong in compression, even if there's a 1/8" gap between the beam and the infill, the frame should resist racking.

moonhill · June 11, 2009, 06:52:35 AM

They do build stand alone cord wood structures with no frame at all, these are usually on the small side. There are benefits to building a frame first, and most obvious, is it allows you to put the roof on and protect the cordwood as you build at your leisure. In this case I would be bracing the frame as well, you could use temporary bracing which is removed as you progress up ward. I would still use permanent braces.

Yes, Jim, true plank houses used no bracing, it was the pegging between the planks edges which added the shear to the walls. It works very well.

Tim

ljmathias · June 11, 2009, 07:13:52 AM

Hey, Tim Moonhill- didn't quite understand your statement about "pegging between the planks." Do you mean the planks were pegged to the posts and beams or to each other? Never thought of pegging a plank- wouldn't seem to have the holding power of nails or screws. Thanks.

Lj

moonhill · June 11, 2009, 09:00:44 PM

The pegs are on the edges, pinning one plank to the other, kind of like a biscuit joint. It makes the wall one large plank. Think of it this way, if you stand the planks up with no pegs in the edges and pushed them sideways they will slip, now drill holes and install the pegs and apply the load and the whole system will act as a unit, the pegs do not allow the planks to slip. In the past there were a number of way of attaching the planks to the light frame, some were morticed to the top plate and sill, some nailed, thickness ranged form 1-1/2" to 4" thick, there are variations where they used multiple layers of boards to achieve the same result. Not all of them used pegs on the edges, some were just nailed to the sill and top plate.

Tim

ljmathias · June 12, 2009, 05:42:37 AM

Thanks, Moonhill- would never have figured that one out and it sounds like a fascinating way to build. Love to find out more about plank houses- anyone got references like books or websites? Thanks.

Lj

moonhill · June 12, 2009, 07:59:59 AM

Housewright, has been doing a lot of work on the subject, they are found all over the world. There is not much info on them. I did build one and have plans for one here at my place this fall, 2" planks.

Tim

Jim_Rogers · June 12, 2009, 08:55:54 AM

I recently helped a friend remove some rafters from a plank house he was in the process of disassembling.
When he forwards the pictures he has taken, step by step of this disassembly, I'll post a few.
Don't know when that will be.....

moonhill · June 12, 2009, 12:49:36 PM

Jim, you should send some over to Jim D. I am sure he would find some interesting aspects.

Tim

Jim_Rogers · June 12, 2009, 12:55:07 PM

Tim, I invited him to come to the second crane day where we were going to lift off the 36' continuous timbers, but he never responded to my email.

And as it rained most of that week, I didn't go. I stayed here and milled lumber for an order.

I haven't heard from my friend lately about how it went.

I suppose he's upset with me not showing up to give him "free help"....

Jim Rogers.

frwinks · August 25, 2009, 10:21:59 AM

I found this pic of a braceless frame going through my tf folder, made me think of this thread

moonhill · August 25, 2009, 07:56:42 PM

Tell us more, please.

Tim

witterbound · August 25, 2009, 08:40:29 PM

I am using "straining beams" in some of my walls as bracing. We've just used 6x6 beams running parallel about 24 three feet below the plates. Same idea as your picture, but not as fancy as I think the verticle "slats" in your picture are nonstructural. Good looking frame.

shinnlinger · August 26, 2009, 07:23:36 AM

I have heard that the Japanese Timberframes don't have wind braces and they use exacting joinery to withstand racking.

Frwinks your frame has 2x members... Why??? Looks interesting..

Now, IF I cut a timber frame, which I have a few times, the last thing I want to do is infill and hide all my work and as SIPS and straw bale people know, if you run a continuous insulation barrier OUTSIDE the frame you get much better R-value to boot.

frwinks · August 26, 2009, 10:49:33 AM

this is just a pic I had in my pics folder guys ;) not my frame, personally I don't like braceless frames. I think braces, especially live, funky ones bring a lot of life to otherwise boring rectangular frames.... apart from their structural duties ;D
THIS is what I'm working on ;D