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Jeremy165
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# Posted: 27 Jan 2013 08:45pm
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Hi all,
I got great advice from everyone regarding my venting/insulation question. Now what about siding? I just don't know what to do. My buddy offered me a big stack of rough cedar can'ts from the mill but I don't know what to do with it. I also have look into cedar shingles or shakes, plain lapsiding... I don't know what to do. I drew some sketches. What do you think? Can you come up with anything better? The doors, windows, structure is all in place, so now we're only designing window/door trim and the siding.
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MtnDon
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# Posted: 27 Jan 2013 11:53pm
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Just an observation... that end wall has so much space taken up with the door and the windows there is literally no lateral bracing. Coupling that with the huge "sail" of a roof you should hope the winds never really test the structure.
There's not much you can do about it at this point other than leave out one window and frame and install a full sheet of 4x8 OSB (or equiv) as a brace wall panel.
Is the cabin sheathed on the exterior? Siding, like lap siding, offers virtually no lateral bracing either. If it was mine I'd re-think the framing and sheath it with osb with one full panel for every 25 feet of horizontal wall length as code calls for.
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TomChum
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# Posted: 28 Jan 2013 01:00am
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Agreed. I don't think you can have that window next to the door. An end wall of my city house is all windows, with a 2nd floor, something like what you have. They made us shearnail a column about the size of that window, connecting 2nd floor to the wall plate, and we had to put steel brackets tying double studs to the foundation. Had to sheet & shearnail on the inside too. I could draw a pic if you want. If you use an "L" shape sheet 4 feet wide, shearnailed halfway across the other window it will get pretty strong.
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Jeremy165
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# Posted: 28 Jan 2013 10:54am
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I understand what you guys are saying regarding the shear wall and lack of support. But first, I just want to confirm that you guys aren't looking at the trim on my tudor style drawing and thinking that is the framed structure. It is obviously framed in the standard way with 2x4s 16" OC. I'm sure you guys saw that. 2 other things.
First - Why didn't someone bring this up a year ago!? The door and windows have been framed like that for over a year! I'm just slowly moving along.
Second – I don't know if I actually need that shear strength or shear wall as you described. On my cabin, I refer to the long walls (2x6, 16" OC, 16 feet long with no penetrations) and the short/end walls (2x4, 16" OC, 12 feet long with window and door penetrations). The way my cabin is structured, all of the roof weight is on the 2 long walls, not the short/end walls. I built the long walls first. I then attached the loft joists (2x10, 16" OC), then bolted my rafters to the loft joists. I even sheathed the entire roof before I built the short/end walls. So the cabin stood for awhile with no lateral bracing coming from the end walls. Those end walls were stick framed in place, and though they do add some shear support to the long walls now, it's minimal, and the cabin stood for a long time without them built yet.
Yes there currently is ½" sheathing on the whole outside of the structure. The bottom plate of my long walls has a tie-down of sorts with a bracket and thru-bolt going through the bottom plate and the plywood sheathing. There are hurricane ties from the stud walls up to the loft joists. The loft joists are bolted to the rafters and the loft joists function as cross-ties for the rafters. There is a gusset plate at the top tieing the rafters from both sides together. I hope I'm not being incautious but I think the structure is fine with the windows how they are. If you think I really should sheath the interior of the end walls, I could do that at this time since the interior is unfinished.
No one said anything about siding ideas. As I see it, the realistic options are:
Lap siding
Cedar shingle or shakes
Board and batten
T1-11
The tudor sketch I made which I think I would accomplish with groove-less t1-11 and 1x6
Any major ones I'm missing?
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MtnDon
Member
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# Posted: 28 Jan 2013 11:05am
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pretty good wall brace article
http://www.engr.psu.edu/phrc/Publications/BB0807PART1WallBracing.pdf
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Jeremy165
Member
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# Posted: 28 Jan 2013 02:19pm
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Do you think I should let-in a stud under the horizontally sliding window? Would that help much? Is there something I could do with strapping? Thanks
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MtnDon
Member
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# Posted: 28 Jan 2013 05:24pm
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Quoting: Jeremy165 First - Why didn't someone bring this up a year ago!?
Well, I don't read everything posted here. That's my excuse. I pick and choose randomly or by what grabs my attention at the time. Other times I intentionally ignore whatever issue I see as pursuing is likely to consume more time than I want. That maybe sucks as a reason, but that is the way it is; the time available never seems to increase but the tasks I have to deal with never seem to shrink.
There is little doubt that the long walls are designed strong enough. You are correct in that they support the vertical load of the roof. The end walls do not support much more than the weight of their components. That's all vertical load.
Shear wall strength is aimed at bearing the lateral loads which mainly come from wind loads. Tall walls and tall roofs can generate large forces from wind. A shear wall or brace wall as they are also called is designed to keep the wall in a square or rectangle shape when sideways forces are applied. Window walls don't have much lateral strength as a rule when there is little full sheathing. It has stood up so far with no problems. It may do so for a hundred years. However, we can't tell if you will be hit with some high speed gusts at some future time. That is what this is about, that is what the codes try to cover.
There are many things done in manners that will have a structural engineer shaking his head. Many of those will not fall down or blow over. However that does not make them proper design.
So I should have probably kept my mouth shut this time too. It probably won't get blown over but it is not the best end wall design if the potential for high winds is taken into account.
Diagonal strapping is okay but has to be continuous from top to bottom plates to be effective. Straps only work in tension so to brace a wall properly there needs to be two diagonals like an "X", though they need not cross as in an "X"... they could be in a "V" shape. The problem with the end wall as illustrated is there is no room for a strap top to bottom with anything approaching a 30 to 45 degree angle.
Having rafter ties or ceiling joists across the wall tops is a very good thing. That will turn the roof assembly into a very strong triangle. But that triangle sits on top of a square/rectangle that has very little lateral resistance. Sounds like the balance of the structure is tied together well.
Sometimes the only reason I mention something I see as deficient in some manner, is to alert other readers still in the planning stage about the potential issues.
I did not realize the long walls had no windows although I should have thought of that on my own. That explains the reason for wanting as many windows in the end as possible. However, that does not make the end wall okay as shown. If it was me I'd have one full width, top to bottom sheet nailed in place at the corner with as large as possible a window beside it. Maybe use a door that has a large fullheight window in it as well.
I'm sorry if this comes late in the game.
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Jeremy165
Member
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# Posted: 28 Jan 2013 08:12pm
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I'd always rather have all the information and everyone's opinion. I'd rather have the bad news now than later. So don't apologize.
I am in a heavily treed area and receive almost no wind. So I hope it will be okay.
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MtnDon
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# Posted: 28 Jan 2013 08:14pm
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I hope that was clear.... the short thought process is.... there is a strong triangle (roof assembly) sitting on top of a small box. There is a box at each end of the cabin. The 2x4 studs nailed to the top and bottom plates have little strength from racking or tilting. A 4 ft wide osb panel nailed to the top & bottom plates and studs lend rigidity to the wall. Minimum by IRC is one such panel for every 25 feet of length.
That panel nailed in as prescribed serves, more or less, to turn the panel into a bunch of triangular bracing points. Triangles are the epitome of a rigid structure.
FWIW, when the panel is built according to code it is called a brace wall. When it is designed by an engineer it is called a shear wall. They do the same job, serve the same purpose, but one is pre determined, out of a book, a cookbook answer. The other is calvculated by a P>E> for each and every case and costs $.
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ShabinNo5
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# Posted: 29 Jan 2013 08:07am
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Jeremy,
I am not an engineer and defer to the knowledge provided by MtnDon.
However a thought. It would not bring things to code, but if you sheeted the inside using the same material as the outside it should improve the strength (at least it would be better than just sheetrock or T&G on the inside). Then you could still cover with sheetrock or T&G.
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Jeremy165
Member
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# Posted: 1 Feb 2013 12:54pm
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Bump to top.
Someone please give some input on the siding drawings. What should I do? I need to draw up a board and batten setup also. I'm open to all exterior trim and siding ideas. Even weird ones!
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MtnDon
Member
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# Posted: 1 Feb 2013 02:56pm
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I am a lap siding fan; traditional lap siding with trim on the corners and around windows and doors. No extra trim to make it look Tudor-ish or whatever. And IMO, it is not even necessary to paint the trim a different color than the lap siding. We did do that on our cabin, dark green lap siding with light tan trim. But our home in the 'burbs has the trim and lap siding the same tan color. The doors are a contrasting color. The eve trim though is the same color as the roof.
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