Framing attic ceiling


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Old 01-31-16, 12:14 PM
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Framing attic ceiling

I was just curious as to what the options were for framing a ceiling in my attic. Right now it is your basic triangle shape structure and I plan on building knee walls and framing a flat 8 foot ceiling. Would it be best to nail each individual 2x4 to the existing trusses or frame sections on the ground and lift up and nail in place? My only concern with rah individual 2x4 is keeping the entire ceiling level. Thanks!
 
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Old 01-31-16, 12:44 PM
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Is the ultimate goal to create living space such as a bedroom? The reason that I ask is that you have to be sure that the floor joists can withstand the weight. You don't want to do all that work & realize that a problem exists. What is the size of the floor joists? Hopefully, they are 2x8s.
 
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Old 01-31-16, 01:24 PM
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Do you really have trusses? There are almost never designed to be used as a floor.
 
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Old 01-31-16, 05:21 PM
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Way more to it then your thinking possibly for all the reasons already mentioned and more.
Going to need way more info.
Add a bedroom or even a closet up there and your going to open up a whole can of worms with zoning, health dept. building dept.
Going to need permits, egress windows, legal stairway to name just a few issues.
In your area R50 of insulation is needed in that ceiling, no way is a 2 X 4 bay going to cut it.
Needs to have venting from the soffits to the ridge.
 
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Old 02-01-16, 01:13 AM
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I've had many people weigh in on the subject and say there shouldn't be a problem structurally. The soon to be floor consists of 2x8s spanning about 11' and on 16" centers. I will be replacing the small windows with windows up to code for fire escape. I will also be installing a Werner fire escape ladder being that it will be used as a full time bedroom for one of my kids. I have been planning this out for a few months now and the only thing I am stumped on is the framing of the ceiling.
 
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Old 02-01-16, 04:01 AM
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If your main concern is the ceiling, what final height will you be able to attain with a ceiling? How low are your current collar ties installed? Even building knee walls, you may not be able to have a regular flat ceiling depending on the height. In that case, you would need to provide insulation for the rafters that would either be solid sprayed foam, or air baffles and insulation tacked under it. The latter is often an inferior way of doing it as the R value needed can't be attained.
 
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Old 02-01-16, 04:53 AM
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The ceilings will be 8'. The rafters run perpendicular to the floor joists so there should be no need for the ties. However there are abut 5 throughout the space about 7' up. This house was built in 1912 if that helps any
 
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Old 02-01-16, 05:11 AM
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The rafters run perpendicular to the floor joists
I'm not following - based on this statement, your roof would run straight up into space.
 
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Old 02-01-16, 05:33 AM
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I agree with everything mentioned so far regarding the insulation and ventilation being compromised. And hope you have some way to get good hvac supply and return up there. So, I hope you have all that figured out. Assuming it's structurally sound to continue...

Framing ceilings in an old house is tricky because the framing is no longer straight or level. A rotary laser would be a big help... you can rent one if needed. The main concern is getting the drywall corner bead to look straight once it's done. IMO level is not as critical as straight. But you will have to determine what's possible based on how bowed the rafters are. You might lose space, but to get everything "perfect" you would put ceiling joists alongside rafters, (they will act as new collar ties) making them all level with the rotary laser... then frame your new knee walls under those new ceiling joists (snap two parallel chalk lines) rather than putting them right under the existing rafters. This would assure you would make everything plumb, level and square while also making sure you aren't blocking the rafter spaces.

If your roof is sagging or bowed, you might need to spend some time shoring it up temporarily while you frame under it. Leave the existing collar ties in place unless you need to replace them with temporary ones as you straighten the roof. The minute you cut those collar ties the roof can sag so it's best to wait to cut them out until your new ceiling is framed.

Your insulation above your knee wall will be the weak point of this plan and may create new ice dam problems higher on the roof than ever before due to heat being retained/lost closer to the roof decking.
 
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Old 02-01-16, 06:09 AM
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I'm not following - based on this statement, your roof would run straight up into space.
The direction the rafters run will either be parallel with - or perpendicular to the direction that the ceiling joist run.
 
 

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