DIY Chatroom Home Improvement Forum

DIY Chatroom Home Improvement Forum (http://www.diychatroom.com/)
-   Building & Construction (http://www.diychatroom.com/f19/)
-   -   framing a vaulted ceiling (http://www.diychatroom.com/f19/framing-vaulted-ceiling-144582/)

dwoolver 05-22-2012 11:51 PM

framing a vaulted ceiling
 
2 Attachment(s)
Hi:

I'm planning to create a partially vaulted ceiling with skylights at the top as part of a remodel on a 1960's ranch. The existing room is 15' wide and the roof has a 5/12 pitch. I want to open part of the ceiling to the roof rafters and then punch holes for the skylights. See attached images. Gray joists are existing and blue ones will be added.

It seems smart and may even be required by code to double the ceiling joists at the opening because they are supporting both the ceiling and the skylight tunnel. The existing joists are 2x6 x 15' long. There's no way to bring them in through the attic/crawlspace because they're too long. And I really don't want to make 3 new holes in the roof just to install these joists. I'm wondering if there's a way to double the existing joists using shorter lengths of 2x6 or some time of composite. For example, I could use two 7.5' long joists -- one from each sidee -- and strengthen them in the middle. is there a recommended method? Or I could build up the 1-3/4 thickenss with OSB or plywood in overlapping layers.

I would appreciate any suggestions that save me from putting extra holes in the roof.

Thanks.

Douglas

joecaption 05-23-2012 07:15 AM

Is this trusses in your attic now?
You would be far better off to open up this roof to do your framing then trying to just patch pieces in.
Your going to have to space your lights further apart then your showing in those pictures.

ddawg16 05-23-2012 07:53 AM

It looks like your ceiling joists are also rafter ties.

I think this is one of those that will require input from an engineer. I'm the perpetual DIY'er....but somethings need to be run by an expert.

FWIW.....I like the idea of what your doing......I'm a big fan of natural light and skylights.....especially if they are the type that open.....on those days where it's not quite warm enough to really need the AC....open up the skylights and get some natural air moving....

cortell 05-23-2012 07:58 AM

A joist needs to be continuous from rafter base to rafter base, or must be supported by a beam or load bearing wall wherever there is a break in continuity. Anything short of that is a hack. I wouldn't do it, and it's doubtful it would pass inspection.

Laminating a second joist to an existing joist to increase stiffness in a bouncy floor is a different matter altogether. That additional member need not add to the design strength of the floor, in which case the new joist technically need not rest on supports (though it will be more effective if it does). In your case, you're looking to remove joists, which reduces strength. Sistering adjacent joists are the prescribed method of adding the strength back. If those joists don't rest on support, then the sistering will not be successful.

dwoolver 05-23-2012 09:18 PM

framing a vaulted ceiling
 
Quote:

Originally Posted by joecaption (Post 927064)
Is this trusses in your attic now?
You would be far better off to open up this roof to do your framing then trying to just patch pieces in.
Your going to have to space your lights further apart then your showing in those pictures.

It's not a truss, but the joists are rafter ties and there are collar ties as well. Why do you think the skylights are too close together? Flashing?

Gary in WA 05-26-2012 04:40 PM

Depends on which Code you are under per location. IBC will let you frame a 4' opening in the ceiling joist or rafters without doubling anywhere, as long as the spans are within Code: http://publicecodes.citation.com/ico...008_par053.htm

IRC requires both header joists/rafters to be within 3' of bearing without doubling the trimmers; http://publicecodes.citation.com/ico...002_par030.htm

Spans for existing joists/rafters; http://publicecodes.citation.com/ico...002_par023.htm

The center ones will require doubling as they carry 1/2 of each side's load.

Gary


All times are GMT -5. The time now is 05:56 AM.


Copyright 2003-2014 Escalate Media LP. All Rights Reserved