Dimensions to sheathing

[SH_Canada]

5 minutes ago, LevisL said:

 

The one thing I found you have to watch for... the truss designers will sometimes assume the sheathing will be flush and they subtract 3/4" from the truss span...

yes when I did an outbuilding on my own property, the truss guys asked that very question. Is it flush to the stud or flush to the sheathing and what is that dimension. I said to him, wouldn't everyone want it flush to the stud so when they sheath the heel (heels here are high in order to get more insulation in) it would be flush with the wall. He said no some want it to the sheathing, but he did not no why. I'm now guessing the interpretation of the plans he gets are the same problem as this post. He does not know where the actual stud is landing.

 

...But at least he asked.

 

[Chrisb222]

2 hours ago, jasonN said:

I'm wondering, is this what everyone does on their plans?

 

Not me. We always use 7/16" sheathing and plans are dimensioned as the exterior wall being 4" or 6"

 

That 1/16th is never gonna be an issue

 

As a builder who (used to) frames and a plan designer, I would never introduce 1/8s or heaven forbid 1/16s into a set of plans. Holy crap, what an unnecessary PIA!

 

Whole inch on foundation plans, with 1/2" being smallest fraction on framing plans.... 1/4" ONLY when absolutely unavoidable, and avoid those whenever possible!

[Chrisb222]

40 minutes ago, jasonN said:

so when they sheath the heel

 

I would only ever sheath the heels if I had a crazy high heel like 24" that would be exposed and need to be covered with the exterior finish.... which rarely happens here.

 

Trusses are made to the sheathing, which is the same as the foundation. And the floor framing.

 

All the same dimension.

[parkwest]

We always sheath raised heels... adds shear and keeps the blown insulation out of the soffits.

[SH_Canada]

1 hour ago, Chrisb222 said:

Not me. We always use 7/16" sheathing and plans are dimensioned as the exterior wall being 4" or 6"

I like this solution as then there is only 1/4" actual difference, and that will get absorbed somewhere. even if it was the bathroom and the framer framed at 59-3/4", I think the tubs here are 59 3/4, so it would just fit. 

 

We have a min R value requirement up here for roofs. I think its up to around R50 now. So the heel can get quite tall. If someone was building their own and wanted to do fiberglass batt, R50 would be about 15" plus air gap, so at least 16" tall. so for a 5:12 roof with 18" eave and 2x6 fascia, it would only come down around 13" (of course one could cheat the Rvalue above the top plate as it had been done for decades) So trusses would need to be shortened to be inside the sheathing. Plus for ridge beam plus half trusses, the height is typically at least 16"

[LevisL]

8 minutes ago, jasonN said:

...of course one could cheat the Rvalue above the top plate as it had been done for decades

 

It's not really cheating... it's allowed in the Code! Up here where half my projects are in zone 7B (or 7A without HRV), it would be a fairly high heel to get the full R60 + air space under the heel. For a 6/12 or under roof, I usually try to have a min. 12" heel and that usually leaves about 2ft around the perimeter with reduced insulation.