# Old house, sealed rafters, & cathedral ceiling project



## scootermcrad (Jul 23, 2012)

Hey everyone!

First official remodel project for the home we just purchased. I could use some input on a ceiling change.

First, about the house. It's a 1937 Tudor Style brick home. I'm doing a renovation to part of the family room that has a low ceiling. The intention is to open this small portion of the room (10' x 12') up, by raising the ceiling.

I opened up the ceiling a couple nights ago, to see what I'm up against. What I found was that the trusses in the section of interest are a 2x6 construction with a ridge board, connecting chords to keep it all together, and a 14-12 pitch. Roofing is shingles over planks and no evidence of water damage, or anything of concern. This area has NO soffit vents or roof ventilation. Fiberglass insulation batting, paper side down, above the ceiling, no vapor barrier. So, essentially just a sealed roof construction. This section to be raised is trapped between a brick wall (interior living space on other side) and the garage attic space, which will get a wall to separate and seal it off.

The plan (see attached pen drawing) is to add 2x6 collar ties at top, add hurricane straps/brackets to tie rafters to top plates, add uprights at wall location to triangulate the rafters and chords, and remove connecting chords between uprights. From there, run the new electrical for two dropped light fixtures, insulate and seal it all up.

QUESTIONS:

1- A sealed cathedral/vaulted ceiling space should work as long as NO AIR can be exchanged, correct? 

2- Will I need a vapor barrier between either the insulation and the roof and/or ceiling dry wall board if going with a "sealed roof space"? 

3- Should I consider blue board for this, as well?

4- Should I consider running stringers between each of the cut chord/upright locations for additional lateral support at rafter-top plate locations and providing additional sealing measures? (similar to the "sealed roof space" picture attached)

5- Any additional material suggestions for this project?

6- Recommendations for insulation types? R-30? Something else?

Wish I could do the proven soffit and ridge vent construction for this, but I just don't have the soffit configuration to make it work.

I would really appreciate any feedback you guys can give. Ready to dive in and get this done! Raising this ceiling will make a WORLD of difference for this room! :thumbsup:


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## Gary in WA (Mar 11, 2009)

The collar ties you suggest will only hold the rafter tops from coming apart in a high wind. They will not hold the walls from blowing outward or the ridge board from coming down (if you remove the rafter ties). http://www.finehomebuilding.com/how-to/qa/removing-collar-ties.aspx
You need a structurally engineered ridge *beam* to hold up 1/2 your roof. 

Scroll down to pp. 131: http://books.google.com/books?id=E5S9qrSNxx0C&pg=PA130&dq=structural+ridge+roof+framing&as_brr=3&cd=1#v=onepage&q=structural%20ridge%20roof%20framing&f=false

Gary


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## scootermcrad (Jul 23, 2012)

Okay. So let's disregard the bottom sketch I did, and I'll provide a little more info about the structure.

The span between walls is 10 feet, and let's assume (for the sake of discussion) that the length of the roof is 12 feet, and trapped between two walls. Ceiling height from floor to bottom of ceiling joists is 7'-6".

How would you (or anyone else reading) go about raising this ceiling?

I'll be looking at things a little closer tonight, and I'll see if I can get some better details on the ridge board, as well as how this roof structure is actually tied to the walls at either end.

If what I sketched up isn't doable, that's fine. This is why I'm asking. I would like to know how to do this correctly.


GBR in WA said:


> The collar ties you suggest will only hold the rafter tops from coming apart in a high wind. They will not hold the walls from blowing outward or the ridge board from coming down (if you remove the rafter ties). http://www.finehomebuilding.com/how-to/qa/removing-collar-ties.aspx
> You need a structurally engineered ridge *beam* to hold up 1/2 your roof.
> 
> Scroll down to pp. 131: http://books.google.com/books?id=E5S9qrSNxx0C&pg=PA130&dq=structural+ridge+roof+framing&as_brr=3&cd=1#v=onepage&q=structural%20ridge%20roof%20framing&f=false
> ...


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## scootermcrad (Jul 23, 2012)

Here's the real basic and simplified sketch of the situation. (sorry so dark)


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## scootermcrad (Jul 23, 2012)

Just stumbled on this article on "Fine Home Building" that is very similar to what I'm trying to do. There is no suggestion of an engineered top beam, as long as the collar ties are only moved up 1/3 the rafter length:

http://www.finehomebuilding.com/how-to/qa/framing-cathedral-ceiling.aspx

Am I missing something here?


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## scootermcrad (Jul 23, 2012)

Thinking about the article I stumbled on, I did a little math. If I do it the way they suggest, it gets me almost two more feet of ceiling height (see attached math). Then I got to thinking, is that really the feel that I want. Sure, it's more than what I have, but maybe not quite the dramatic feel I was hoping for. How about constructing scissor trusses in-place?

Should all this be moved to another part of the forum?


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## Gary in WA (Mar 11, 2009)

This forum is fine. You may want to consult a Structural Engineer for your plan. Once you move the rafter tie above that 1/3, it gets "iffy"; http://myconco.com/ComEngProb.html They will give the fasteners, size, spacing, etc. for your safety and take the liability for your H.O. Insurance carrier. Let's see some pictures when completed!

Gary


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## scootermcrad (Jul 23, 2012)

GBR in WA said:


> This forum is fine. You may want to consult a Structural Engineer for your plan. Once you move the rafter tie above that 1/3, it gets "iffy"; http://myconco.com/ComEngProb.html They will give the fasteners, size, spacing, etc. for your safety and take the liability for your H.O. Insurance carrier. Let's see some pictures when completed!
> 
> Gary


Good article! Thanks Gary! I appreciate it!

Absolutely I'll post some pictures during the process.


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