Vaulting Old Roof

juicybaka

I am considering vaulting my old roof and might not go with trusses as this has to be done in stages since its our home. I've framed many new homes with vaulted/cathedral ceilings. And I was wondering if I put ridge beam under ridge board and tied them together would that suffice. It makes sense when I think about it and it would be higher than typical 1/3 collar tie rule. Thanks, Mike

cleveman

what are your thoughts regarding insulation?

juicybaka

I was thinking of adding 2x10's off of new ridge beam with heel cut at bottom- so ceiling height would project out from wall 8" or so and then up to ridge beam?

TaitINC

i don't know if it’s just me, or a term i'm not familiar with but...ridge beam under ridge board? maybe someone can clarify for me? i'm also curious how you're going to project out 8" with a heal cut on a 2x10?

spencer

neolitic

Maybe he's framing under existing?????

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juicybaka

Yes I was planning framing under existing. The difference between a ridge board and beam is that a beams consits of lvls intended for structual loads. The heel cut is a guess. I think the roof is a 6/12 meaning I would cut enough to rest on plate and remainder would project back inside. Anyone have ideas why this might not work. Its a 20' span and was planning on using 3- 12 1/4 lvls.

neolitic

Check the manufacturer's span charts,
or better yet have your lumber yard
spec it out.
The detail at the wall/ceiling angle
seems problematic to me.
You can cut a sort of reverse
birds mouth, and let the bottom
of your false rafter continue to
intersect the wall plane.

BTW: The new rafters may not be
structural, but the beam will be.

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TaitINC

the only problem i see with this is; both ridges have to be supported. if they are not and you remove ceiling joist or collar ties you will have outward force that is not restricted. if the existing upper ridge is supported but not the lower it will push the walls out, causing the existing ridge cuts to open. if the lower is supported and not the upper the upper will start to settle onto the new, causing the existing rafters to slide outward.

the only way i see possible would be to tie them together as you mentioned. the new ridge would have to support the old and carry the load of the old plus the new. it would have to be support on either end with solid blocking to the foundation.

i maybe incorrect in my thoughts, but that is what i came up with give the information provided.


i'm no engineer
spencer

Joe Carola

Mike,

You can do it. It has to be designed by an Architect or Engineer. I did it as mu cousins house 2 years ago. I don't remember the exact dimensions , but I think the Glulam was 7-1/4x18. I set it right underneath the existing ridge. It spanned the whole widtyh of his house posted down on both sides of the foundation.

I also had to install collar ties as per plans. The existing rafters were 2x6's about 14' long with a 5/12 pitch.I nailed 2x4's on edge on the bottom with 2x4's nailed square to them and nailed into the rafters, for insulation reasons. There is a thread on here where I posted pictures. I'll try to find the thread.

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Joe Carola

Joe Carola

The run was 12'6 and the pitch was 5/12 with a 2' overhang. Rafters 13'6 to the outside plate. The 7-1/4 x18" beam was 23' long from block to block. The beam sat right underneath the existing 2x8 ridge and the top of the collar ties hit the bottom of the beam. I installed 2x6 collar ties.

I found the pictures.

Attached Thumbnails

     

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Joe Carola

Joe Carola

One more picture.

Attached Thumbnails

 

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Joe Carola

rakuz66

Joe, did you run 2x4's against the old rafters for a nailer and then place a 2x4 underneath the old rafters to gain insulation and strength?

Joe Carola

Yes. I don't like to just toenail the edge of the 2x4 to the bottom of the rafters. The bottom ends were nailed into the top plates and the top were nailed to the collar ties.

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cleveman

I don't know your location, but here I would be happy to have more insulation than you can fit in a 2x10 space, even if these are below the original rafters somewhat.

I don't fully understand the problem with building trusses in place, using the existing rafters as top chords.

Is the following feasible:

1. empty the attic of all obstructions including insulation.
2. get a scissor truss design which meets approval and works for you.
3. build a truss.
4. repeat step 3 as necessary.
5. strip the ceiling (sheetrock).
6. remove ceiling joists.
7. sheetrock new scissor vault.
8. insulate and finish.

Wouldn't this be less lumber and less disturbance? I would think you'd be able to shoot up the truss pieces through some small hole in the ceiling where no one would be disturbed. And the additional insulation should be nice.

juicybaka

Joe, thanks for posting those pics, great minds think alike. Has the ceiling cracked at all? The only thing I'm concerned about is getting yelled at by the misses