Collar ties / attic finishing

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  #1  
Old 01-02-01, 12:33 PM
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I would like to finish off my attic (for storage at the moment, maybe eventually for living space), but I have a few questions on the feasability of the project. House is a two story, stick built on slab. 2x6 framing (walls, rafters, 2nd floor ceiling joists).

I have a very steeply pitched roof with plenty of head room in the attic, but the collar ties are currently located approximately midway between the ceiling joists below and the ridge beam above (would allow only about five feet of headroom). What is the code for placement of collar ties? Could they be shortened and moved up? I could live with them in their current location if the attic is only used for storage, but they would obviously have to be relocated for a living space.

Also, if this was to be living space, I wouldn't be concerned about compressing the blown-in insullation with a subfloor, but while it is serving as storage space, what should be done about the blown-in insullation (currently 12 in. deep - live in mid-atlantic)? If it is compressed to 5 1/2 inches by the subfloor, what R-value am I now looking at?

Thanks in advance.
 
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  #2  
Old 01-03-01, 02:01 AM
some help
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Hello
The collar ties can be moved up, you should not remove the old ones untill the hew one is installed. Install the new collar ties at the hight of the ceiling and on each rafter
this will be the ceiling joist of the rooms so use 2x lumber large enough to make the span and hold the sheetrock.
Check the roof load if you if you have a concrete tile you may want to add strong back and brace ti of of the walls below. 2x6 ceiling joist whould not be large enough for floor joist in a living area unless it is well supported from below. Insolation when it become to compacted 12" to 6 1/2" will have very litle R value you need to have air space to keep any R value. if compacted it will be like any other soled material like wood heat/cold will go right through it that is why you need 2x6 wall for R-19
 
  #3  
Old 12-14-07, 11:47 AM
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Attic floor framing

I am also planning on finishing my attic. My question is not in the roof rafters but in the floor joists. As typical the joist which make up the ceiling for the main floor living space are 2x6's. I now want them to serve as the floor joist for my planned attic. I know that a 2x6 is not adiquate for supporting floor load and they should be 2x10 or 2x12. If I add another 2x6 to the top of the existing 2x6, bond with construction adhesive and nailer tie plates, will I acheive the strength and deflection properties of a 2x12 or get close to it and would this violate any construction codes? I have seen the use of sister joists but this would put the joist along side of the existing joist which I would have to cut out for all the conduit runs which I believe would defeat the purpose of gaining strength. Thanks for any assisatnce.
Phil B.
 
  #4  
Old 12-14-07, 01:34 PM
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Re: Collar ties, look here:

http://www.inspectionnews.net/home_i...tie-issue.html

(You will need to register if you wan to see the diagrams, but the discussion is public access).
 

Last edited by Michael Thomas; 12-14-07 at 02:09 PM.
  #5  
Old 12-14-07, 03:22 PM
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Attic finishing/floor framing

Michael Thomas, thread #4, Are you replying to my question?
because the link you sent is all about rafter ties and my question is about attic floor framing and I didn't see a response that fit. If I'm responding to the wrong person, my appologies...
 
  #6  
Old 12-14-07, 04:21 PM
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POebing - I think you kind of hijacked the OP's thread. Better to start a thread of your own. There is less confusion that way.

I would not move collar ties without having a knowledgeable person look at what you have. Things like roof loading, rafter size/span/spacing, roof shape etc. must be considered. If you decide to convert the attic to living space you will also need to determine floor loading. Attics are typically designed for a 10#/psf floor load while living spaces are required to be 30#/psf.
 
  #7  
Old 12-14-07, 06:46 PM
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Originally Posted by pebing View Post
Michael Thomas, thread #4, Are you replying to my question?
because the link you sent is all about rafter ties and my question is about attic floor framing and I didn't see a response that fit. If I'm responding to the wrong person, my appologies...
That was in reply to:

"What is the code for placement of collar ties? Could they be shortened and moved up? I could live with them in their current location if the attic is only used for storage, but they would obviously have to be relocated for a living space."

Many people mistakenly believe that collar ties are there to prevent rafter sag or outwards movement of the rater ends at the top of the walls, in fact a "collar tie" functions to prevent spreading of the rafters due to wind lift; that's why the IRC specifies that they can be as smalls as 1x4"s:

2006 IRC: R802.3.1... Collar ties or ridge straps to resist wind uplift shall be connected in the upper third of the attic space…(and of a) a minimum of 1x4”… spaced no more than 4 feet on center.

What the poster may have be referring to are rafter ties, which are placed lower in the attic.

The first half of the thread I referenced is a discussion of the difference.
 
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