Reply To: POLYURITHENE FOAM COATING TO ROOFS

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#291908
Jerry Peck
Participant


In reply to message posted by Robert Stephen Morton:
I am interested to get feedback from other interested people or Plumbing/Roofing Contractors as regards to histories or horror stories following the application of this product.
For those who do not know of this product, it is a spray of polyurithane foam aprox 15-20mm thick onto (normally leaking) roofs with a thin membrane of Acrylic paint to seal the polyurithane.

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Any feedback?
Regards Bob


I know this is an old post, but replied anyway.

The material you are describing is still in use today (unfortunately), however, I have not seen one application correctly done.

One typical installtion was like this (I still have the core samples in my office):

There were seven lifts (layers) installed one on the other, making a total combined thickness of 1 1/2″ inches. The top coating consisted of one sprayed on coating approximately 7 mils in thickness. The roofer came back and ‘re-applied the coating’, only both coating layers combined for 10 mils thickness. Several surfaces between the lifts were ‘burned’ from sunlight. The top lift was ‘burned’ to such an extent that the protective coating did not adhere to it.

These are some of the minimum installation requirements:

1) Each lift must be 1/2″ thick minimum, 3/4″ thick maximum. (Seven lifts would be 3 1/2″ thick minimum.)

This is for uplift resistance reasons. Less than 1/2″ thick lifts do not spread the uplift forces out across a large enough surface area, and greater than 3/4″ thick allows the foam to separate and shear within a single lift.

2) The previous lift is not allowed to burn (the foam is not sunlight resistant and ‘burns’ when exposed to sunlight).

The ‘burned’ surface is hard, slick and the next layer does not adhere properly to the ‘burned’ surface. A top lift with a ‘burned’ surface does not provide the required adhesion properties for the top coating.

3) The protective top coating is required to be a minimum of two layers, with each coating layer being a minimum of 20 mils thick, and the two combined coating layers being a minimum 50 mils thick (i.e., one 20 mil layer requires a 30 mil second layer).

This coating not only provides protection from sunlight (the foam is not sunlight resistant), but from physical damage. The coating thickness is CRITICAL, as are the two required coating layers.

Final analysis: The material has too many critcal application requirements to ensure proper performance that normal construction delays, workmanship errors, potential for damage from adjacent work, etc., that these roofs are not practical. This is my opinion only, based in large part on the fact that I have not seen one installed properly.

As previously stated by others, once these foam roofs leak, the water is in and under the foam. All wet foam and the foam over the wet areas must be removed before any other repairs are effected.

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