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MrUnderhill 07-18-2012 03:48 PM

Truss Spacing for Shed
 
I am building a 10x12 shed off of plans from Better Barns. The plans call for 24" o.c. spacing on the trusses. The stud spacing on the side walls (by plan; already built and erected) is as follows (all o.c.): 20-1/4", 25-3/4", 24", 24", 25-3/4", 20-1/4". I guess my question is: is it a problem that the trusses won't be directly over the studs? If it is, what should I do? Thanks.

framer52 07-18-2012 04:27 PM

If you have a double top plat, no problem at all.

MrUnderhill 07-18-2012 05:45 PM

I have a single top plate, guess I should have mentioned that. That's what the plans called for. So now what?

kwikfishron 07-18-2012 06:01 PM

You can always add another plate.

Why is the stud layout weird like that?

You said it was per the plan but I find that hard to believe.

MrUnderhill 07-18-2012 07:43 PM

1 Attachment(s)
Quote:

Originally Posted by kwikfishron (Post 969011)

Why is the stud layout weird like that?

You said it was per the plan but I find that hard to believe.


I have no idea why it is weird. See for youself, though...I attached a photo. I already put the siding on the shed, so do I have any alternatives to putting another top plate on? Can I just reposition the trusses over the studs or is the spacing critical? If I do nothing, will I run into problems? Sorry for all of the questions, I just don't know if this is a big problem. Thanks, again, for the responses

mae-ling 07-18-2012 11:49 PM

The weird spacing is because of the windows.

tony.g 07-19-2012 02:14 AM

1 Attachment(s)
Lets consider the figures from an engineering point of view. Assume a worst-case scenario, with your trusses central over each gap (see sketch).
The critical problem will be the maximum bending stress induced in the timber top plate by the point load from the trusses. Assuming your timber has a maximum allowable bending stress of 800lbs/sq.in., then the maximum load from each truss should be no more than approx. 250lbs.
If your shed is 10ft wide. then this would translate to a total allowable load of 25lbs /sq ftwhich is not a high figure.
Anything above this would probably be too much for the top plate. However, because your trusses are nowhere near as offset, the stress will be very much less than the maximum allowable. IMO you will be absolutely fine. [To work out the actual maximum bending moment (and hence the maximum stress) for the offsets you have would be complex and time-consuming, probably requiring a computer, but it would show the stress being well below 800 lbs/sq.in.]
There is a very knowledgable civil/structural engineer on this forum. See if he chips in and I'm sure he will confirm the figures.

kwikfishron 07-19-2012 05:24 AM

Quote:

Originally Posted by MrUnderhill (Post 969039)
I have no idea why it is weird. See for youself, though...I attached a photo. I already put the siding on the shed, so do I have any alternatives to putting another top plate on? Can I just reposition the trusses over the studs or is the spacing critical? If I do nothing, will I run into problems? Sorry for all of the questions, I just don't know if this is a big problem. Thanks, again, for the responses

Quote:

Originally Posted by kwikfishron (Post 969011)
You said it was per the plan but I find that hard to believe.

Well, I stand corrected….I see the reason for the odd layout as mae-ling pointed out. I’ve never come across that before since I’ve never put a wood shed kit together before. If I did we’d be running back for some more wood to properly frame in the windows and likely the door too. but that’s me.

For less that $20 you can add another top plate. Not sure if the extra height would affect the siding or not but an extra piece of trim outside could fix that.

It’s just a shed, there’s all kind of things you can do improve the quality of it and make those four walls and roof just as strong as any house but again, “it’s just a shed”.

If you don't want to spend anymore money on it then stick to the plan. What's the roof plan call for?

MrUnderhill 07-19-2012 05:35 AM

The roof has 7 trusses (the two end trusses have gable extensions). The plans say to space them 24" o.c. (although, that won't quite work out). The roof sheathing was supposed to be 1/2" CDX, but I substituted 1/2" OSB. The roof pitch is 10/12. I knew the window framing was wrong, but it called for simple barn sash windows so I figured it was fine. I just assumed the plans were going to call for placing the trusses over the studs, but now that I'm near that point I saw the spacing and started to worry. Thanks for everyone's input, I really do appreciate it.

joecaption 07-19-2012 07:26 AM

Double top plates also help to lock the tops of the walls together if there over laping the plate below.
Poor set of plans in my opion.


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