Roof And Nailer Issues

jsabbitt

Hello everyone,

I am a GC in Florida and am having some issues with a roofer. The guy was installing a TPO system on a flat roof w/ asphalt shingles on the mansard. When he was installing his tapered ISO board (under the TPO membrane) he sloped the panels so that at the roof edge the top of ISO was .5" butting up to a 2x4 perimeter wood nailer. There is a valley all the way around the perimeter of the roof, and of course the resulting bird baths! His "solution" is to replace the 2x12 nailer with a 1x12 nailer. I don't really like this idea, because I feel like the 1x12 nailer will be too thin and will crack over time when it tries to cup. Does anyone have any experience with a situation like this? Please see attached images showing the condition.

Thanks

Attached Thumbnails

   

Ed the Roofer

There is more water ponding on that roof than at just the perimeter nailer.

Was the thickness or height of the isocyanurate insulation less than the Total Height of the perimeter nailer?

It could have been remedied at the insulation installation time by increasing the thickness of the insulation along the perimeter edges, but that would have been more costly.

Who designed and specified the perimeter nailer, the tapered insulation layout and the total thickness of the insulation to be used?

Yes, by using a thinner perimeter wood nailer, you would eliminate the moat around the edges. You can consider a synthetic 1" trim board around the perimeter if your concerns about cracking and cupping are typical. If pilot holes are drilled for the fasteners, to attach to the wall and plate portion of the structure, less potential for initial cracking will occur. As far as the cupping, adding more fasteners could take care of that.

Doesn't the cupping come as a result of wet/dry cycles and and loss of moisture content in the wood? If so, then by it being encapsulated, that should not be too great of a concern.

Ask the Decking Contractors which 1" synthetic board would be most practical if that is the route you may consider.

Ed

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jsabbitt

This is a roof replacement. There was an existing 2x nailer that was replaced. This nailer was not taken into account when the insulating panel system was designed. Therefore the panels arrived on site the wrong size. Rather than getting new materials, the roofers proceeded to cut and trim the panels as necessary, attempting to make the panels work. Instead they created low spots at the roof where the ISO was lower than the top of wood.

1. Yes. The thickness of the ISO was less than the total height of the perimeter nailer.
2. If they had increased the thickness of the ISO then the roof would have no slope at the perimeter.
3. The roofer designed the system, their supplier designed the layout of the ISO, and the nailer was not ever taken into account.
4. The synthetic board is a pretty good idea. Thanks.

roof-lover

Do not inquire about the 1" synthetic board.

You need a 1/2 inch synthetic board max. Let me explain.


What you have is exactly as you have described.
You have a 2x4 nailer. That measurement is actually 1 1/2 inches.
Your polyiso starts out there at 1/2 an inch.
SO you have a Fat 3/4 inch raise on the edge.

You need to order all new metal. Pull all the 2x4 out and put in a 1/2 inch insulation board.
It would be super nice if it could be tapered from 1/2 inch to almost nothing.

I can taper my own fiber board with the bottem of my foot sanding it down.