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-   -   Gap B/ween Ceiling Corner Rafter and Top Plate -- Acceptable Or Not? (http://www.diychatroom.com/f19/gap-b-ween-ceiling-corner-rafter-top-plate-acceptable-not-134078/)

amakarevic 02-17-2012 05:47 PM

Gap B/ween Ceiling Corner Rafter and Top Plate -- Acceptable Or Not?
 
2 Attachment(s)
I was wondering how much, if any, of a gap between a corner ceiling rafter and the parallel top plate would be. I guess no gap would be ideal so that drywall can have a firm back in both sides of the corner. Please consider the illustrations.

Thanks

coupe 02-17-2012 07:10 PM

I'm sure the illustration, is not drawn to scale? you're going to need to install a nailer of some sort at both ends, bottoms even with ceiling joists!

CplDevilDog 02-17-2012 08:15 PM

Every wall that runs parallel to the ceiling joists gets a "Nailer" for attaching drywall to (unless a joist falls within a few inches of the top plate). Usually a 2x6 set atop the wall plate overhanging on both sides.

If you are using trusses, you should use Nailers exclusively and avoid hard nailing your truss chords to your interior walls. Truss uplift will cause drywall cracks and in worst case scenario, lift the framing off the floor.

titanoman 02-18-2012 01:40 AM

Quote:

Originally Posted by CplDevilDog
Every wall that runs parallel to the ceiling joists gets a "Nailer" for attaching drywall to (unless a joist falls within a few inches of the top plate). Usually a 2x6 set atop the wall plate overhanging on both sides.

If you are using trusses, you should use Nailers exclusively and avoid hard nailing your truss chords to your interior walls. Truss uplift will cause drywall cracks and in worst case scenario, lift the framing off the floor.

Don't think that ever happened to me (though I use blocking between the trusses or some kind of deadwood on the wall in question to tie the trusses to)
With the catwalks keeping the trusses motionless, they hold the walls straight and in place.

CplDevilDog 02-18-2012 06:42 AM

I think it's a Regional thing. I'm not an Engineer but it probably has a lot to do with the size of the trusses and the quality of wood used in the truss chords as well.

We used to see it most aggressive on scissor style trusses in cathedral ceilings and usually the rest of the framing has to be pretty deficient for it to lift a wall.

They make hardware now (Simpson I believe) that allows the center of the bottom chord to rise and fall while still bracing them laterally to the center walls.

Gary in WA 02-19-2012 12:35 AM

The ends of the ceiling drywall can "float" to the wall requiring nailing within 7" or double nailing/screwing within 12". Depending which fastener used dictates the required distance from the wall to the ceiling joist. So a joist either 6" or 11" away is permitted from the drywall manufacturers, 5.2.1 = no backing on wall top for floating corner, Read all 4.9's for restrictions. Pics at Fig. 3, 4 here: http://www.lafargenorthamerica.com/G...%20English.pdf

You don't have to fasten the top of sheets on a wall top plates, or bottom plate, unless you want to, other than shear wall or fire ratings:
4.8.2 Fasteners at gypsum panel product edges or ends shall
be located not less than 3/8 in. (10 mm) from the edge or end.
Except as specified in Section 4.9, fasteners at edges or ends
in a perpendicular application shall be located not more than
1 in. (25 mm) from the edge or end. Perimeter attachment into
partition top and bottom (sole) plates is neither required nor
recommended except
where fire ratings, structural performance
requirements, or other special conditions require such
attachment.

I would ADA your exterior walls after caulking the sheathing/stud/plate joints: http://www.buildingscience.com/docum...wall-approach/

Gary

Joe Carola 02-19-2012 01:42 AM

Quote:

Originally Posted by amakarevic
I was wondering how much, if any, of a gap between a corner ceiling rafter and the parallel top plate would be. I guess no gap would be ideal so that drywall can have a firm back in both sides of the corner. Please consider the illustrations.

Thanks

It's a ceiling joist....not a rafter.

woodworkbykirk 02-19-2012 11:14 AM

regarding truss uplift.. insufficient insulation can cause it also.. by having too much of an extreme difference in temperature between the bottom chord and top chord can cause it

im with gbr on keeping drywall screws back 7" from the ege. it allows the sheet to flex just slightly without popping screws or the joint to crack

amakarevic 02-19-2012 05:00 PM

i still don't understand what exactly a nailer is

Gary in WA 02-20-2012 12:25 AM

My definition of a nailer is drywall backing on top the wall with its edge and some material hanging over to fasten drywall ceiling to. If you want the extra backing along the wall and it is a very tight space to install, sometimes I install a 2"x2" piece of continuous metal flashing to the wall top plate with the "L" shape screwed to the wall and other edge backs-up the ceiling drywall next to the wall. You could also screw the ceiling drywall to it as it won't move (with truss deflection during the seasonal changes) attached there.

Truss up-lift, others are talking about, not your ceiling joists: http://www.buildingscience.com/docum...d-but-strange/

Gary

amakarevic 02-21-2012 03:48 PM

1 Attachment(s)
is this what you mean by nailers?

Gary in WA 02-22-2012 12:41 AM

That will work, just keep them at the on-center spacing for the required span of the drywall thickness.

Gary

amakarevic 02-22-2012 01:16 AM

how about the room corners (the ones as viewed from the above, not the corners between the ceiling and walls)? what if i don't have anything to support the back of the drywall in the corner on the ceiling side (as shown in the exhibit), is there a danger of looseness?

thanks

CplDevilDog 02-22-2012 04:19 AM

Those are typically referred to as "ladder blocking" and are used when you want to cantilever your rim joist past the exterior wall (as in a brick veneer situation) or to add stiffness to the rim joist.

They will work but they are technically not Nailers.

Here is a short one. They typically run the length of the top plate (Production Housing for speed) or are short blocks following the nail spacing of the drywall (Green)

Also check out Drywall Clips. They are a metal fastener that takes the place of the wood nailer.

amakarevic 02-22-2012 03:23 PM

now, what if the last ceiling rafter was about 2-3" away from the top plate but not butted to it all the way, would that eliminate the need for a nailer? in other words, if the edge of the ceiling drywall was resting fully on the wall framing but was 2-3" away from the ceiling framing? what is the acceptable distance?

thanks


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