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-   -   Sheathing after wood shingles (http://www.diychatroom.com/f9/sheathing-after-wood-shingles-178250/)

ronle 04-28-2013 01:18 AM

Sheathing after wood shingles
 
I have a comp roof over wood shingles. I'm assuming there are 1x4s across the rafters under the wood shingles. When I tear all the old shingles off, should I but the new sheathing on top of the 1x4s or tear them off as well and put the sheathing directly on the rafters? It seems like it would be easier and sturdier to go on top of the slats. Does the IBC address this?

OldNBroken 04-28-2013 01:44 AM

Over the existing skip sheeting.

ronle 04-28-2013 02:22 AM

you're saying put another comp on and not tear off anything? I think my insurance guy said I couldn't do that.

mgp roofing 04-28-2013 03:12 AM

Tear off both layers of shingles, put the plywood over the 1x4s.

OldNBroken 04-28-2013 11:09 AM

Quote:

Originally Posted by mgp roofing (Post 1168578)
Tear off both layers of shingles, put the plywood over the 1x4s.

That ^^^^

jagans 04-28-2013 11:14 AM

Follow MGP. If you have spaced sheathing, chances are you have a turn of the century home. If you do, chances are the rafters are not particularly on center. The 1 x 4's will allow you to use 1/2 inch (OK 15/32) Plywood. Use Fir, 4 ply minimum and space it 1/8 inch at all edges. You will be good to go.

Oh and everything has to come off after two roofs by code. You must have Horsefeathers up there to allow an asphalt roof over shakes.

ddawg16 04-28-2013 11:34 AM

Quote:

Originally Posted by ronle (Post 1168550)
I have a comp roof over wood shingles. I'm assuming there are 1x4s across the rafters under the wood shingles. When I tear all the old shingles off, should I but the new sheathing on top of the 1x4s or tear them off as well and put the sheathing directly on the rafters? It seems like it would be easier and sturdier to go on top of the slats. Does the IBC address this?

I hate to think how that looked.

Follow the above advice....you will end with a much better looking roof....

Gary in WA 04-29-2013 02:44 PM

IBC requires 2-1/2" minimum length nails (footnote "I"), approved staple lengths per sheathing thickness listed, into framing members- through skip-sheathing boards or not; http://publicecodes.cyberregs.com/ic...?bu2=undefined End or edge joints must break on framing for full fastener penetration.

Gary

ronle 04-29-2013 06:06 PM

Ok
 
So, if the plywood has to break on framing, the 1x4s don't make it that much easier, just more stable as I'm working on it, and less work to take off. And it sounds like I have to get 4" nails - 2.5" into the framing, 3/4 for the 1x4, and 1/2 for the plywood?

The 1/8" gap around the plywood is new to me (haven't decked a roof in 35 years). With those 1/4s, I wouldn't have to put the little clips between sheets, or are those what ensure the 1/8" gap?

OldNBroken 04-29-2013 09:37 PM

Quote:

Originally Posted by ronle (Post 1169624)
So, if the plywood has to break on framing, the 1x4s don't make it that much easier, just more stable as I'm working on it, and less work to take off. And it sounds like I have to get 4" nails - 2.5" into the framing, 3/4 for the 1x4, and 1/2 for the plywood?

The 1/8" gap around the plywood is new to me (haven't decked a roof in 35 years). With those 1/4s, I wouldn't have to put the little clips between sheets, or are those what ensure the 1/8" gap?

How many roofers actually make sure all the joints are hitting framing when they resheet over skip sheeting?

No you don't need the clips and we have always just made sure while we are fastening we hit the framing and at least one fastener per skip sheeting on the ends.

ronle 04-30-2013 12:43 AM

Yeah, I thought the 1x4s more than compensated for a joint not meeting over the frame. I would thinking going over the 1x4s to make sure they're all nailed down properly would provide the connectivity to the frame needed. Then, maybe use screws instead of nails to fasten the plywood down to the 1x4s? Or at least around the perimeter of each sheet to not worry about hitting rafters?

But, I guess that's not what the code says.

ronle 04-30-2013 12:47 AM

Hey Jagans, I haven't actually looked in the attic and just assume there are 1x4s spaced under the wood shingles, but come to think of it, all those houses I roofed years ago like that were turn-of-the-century. This home was built in the early 60s; what did they nail wood shingles to in those days? A saw a YouTube of guys tearing off wood shingles by rolling them up in the felt underneath, but all those old house I roofed didn't have felt under the wood shingles. Do you think this one would?

r

OldNBroken 04-30-2013 03:10 AM

Quote:

Originally Posted by ronle (Post 1169882)
Hey Jagans, I haven't actually looked in the attic and just assume there are 1x4s spaced under the wood shingles, but come to think of it, all those houses I roofed years ago like that were turn-of-the-century. This home was built in the early 60s; what did they nail wood shingles to in those days? A saw a YouTube of guys tearing off wood shingles by rolling them up in the felt underneath, but all those old house I roofed didn't have felt under the wood shingles. Do you think this one would?

r

60's odds are it's solid ship-lap decking.


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