Foamed roof repairs

Old 11-01-18, 11:50 PM
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Join Date: Mar 2014
Location: USA
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Foamed roof repairs

Thank you all in advance for the helpful advice I know I will get.

I have a nearly flat roof (slope = 2 per 10) that was foamed several years ago. There are a couple of bubbles where the foam has lost adhesion to the deck. They are not large. One is about 10 inches in diameter and there are two smaller ones about 6 inches across.

In the past on other roofs, I have done this:
Cut out the bubble.
Slice the removed foam into approx. 2X2 pieces.
Put these pieces back in the hole using generous amounts of Elastomeric Seal.
Give that two days to dry and then top it off with a piece of self-adhesive rolled roofing.

This seems to be a reasonably good quality repair, but I would rather fix foam with foam.

The foam repair process seems rather straight forward:
Cut out the bubble.
Spray new foam.
Strike off quickly (like 30 seconds) to control height.
Coat with Elastomeric the next day to seal the surface.

My problem is locating the materials.

What I think I need is a 2-component polyurethane spray foam at 3.0 PCF.
But I am having a problem finding that in a small kit. Everything seems to be 100+ board feet and $300+. All the small kits in the $50 range are <2.0 PCF and appear to be intended for insulation rather than roofing.

So my questions are:

Does my approach seem sound?
Is the 3.0 PCF product what I need?
Any suggestions on where to find that in a small quantity kit?
Old 11-02-18, 05:36 AM
Join Date: Oct 2015
Location: Ct.,USA
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Other than appearance, what is the problem with the bubbles? Maybe the foam is not repairable because a watertight seal between the old and new foam is not possible. What about making a hole(s) in the bubble and injecting (using straw or eye dropper) the elastomeric seal. Place a weight on the bubble until the seal cures.

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