3.5 inch cap nails/foam attachment methods

yanmars · Dec 5, 2011

I got a good deal on over 100 sheets of 2.5 inch foam to put on the roof of my pole barn. Good if I can get it attached. If I could find 3 1/2 inch cap nails I could nail it to the nailers. I could make my own "caps" out of thin plywood and use regular nails or any special type of construction adhesive?
I have less than $3 a sheet in the foam, I would still like to keep the method of fastening reasonable also.
The nailers are 2 foot on center, the rafters are 9 feet apart and most of the foam is 4x8, some 4x4. The foam has a thin, mineral mesh backing on both sides if you will.
Ideas are appreciated. It looked a little funny, foam 24x8x4 on my trailer. Strapped down, trailered well.

5030 · Dec 5, 2011

Lowe, Menards and Home Depot have them, by the box and cheap too.

I looked funny too...with 30 sheets on the roof rack of my Tracker. Drove slow with it strapped down. No weight but a lot of wind resistance......:laughing:

I went on the nailers (purlins) as well. I also taped each seam between the sheets with foil tape available at the above places....

yanmars · Dec 5, 2011

That was a quick reply. I am using the insulation to hopefully eliminate the condensation water drip I get from the roof when it cools and rains inside.
It is much better since it dried up inside over the last two years but I still get some.

5030 · Dec 6, 2011

Quick because I read your and it related to my (experience), especially the hauling part......:laughing:

I'd tape (with adhesive backed foil tape) every seam. Makes for a much nicer job. My foam is foil on one side so the foil side faces out for better light reflectivity. The tape is the same stuff HVAC installers tape their duct joints with....

The nails come with plastic caps or metal, your choice. I used the plastic myself. You only need 9 per sheet., 3 top, 3 middle and 3 bottom but you could get by with 6 (in a pinch), 2 top, 2 middle and 2 bottom....