DAS Products - Roof Coating Maintenance Procedures

Type II – Moderate Repairs

On occasion, an inspection will reveal isolated areas of poor quality foam, wet foam, foam blisters, foam delamination or mechanically damaged areas that are too large to be treated as Type I repairs and cannot be corrected by caulking or re-coating. Such areas require removal and replacement of foam and coating. If these areas are limited and not larger than 2 square feet in size, than can be easily repaired.

Foam replacement can be made by using proper density spray foam. Some manufacturers do not permit the use of froth-pack foams for warranty repair work. The coating replacement can be accomplished by use of a brush or roller. Overcoating of larger areas included in Type II repairs with sealant is not permitted.

The procedure for repairs is as follows:

Using a serrated or razor knife, cut away distressed foam and coated area back to the point where foam is clean, dry and firmly adhered to a minimum depth of 1/2 inch.

Bevel cut the foam edge at approximately a 45-degree angle around the perimeter of the opening to the depth of the penetrations.

Sand or grind the roof coating from the foam for 6 – 12 inches around the perimeter of the repair area to prevent foam overspray onto the coating.

Special Note – Frequently, foam blisters and delamination do not occur at the roof deck surface but will be found, due to loss of adhesion, at interlaminate spray pass lines. This is caused by the presence of moisture, contamination, or UV degradation at certain levels of the foam during original foam application. Often removal of a foam blister or delaminated foam will reveal a smooth skin surface. Normally, it is not necessary to remove foam beyond this depth; however, the surface skin should be abraded with a stiff wire brush or cut away before foaming in the repair opening.

Brush back loose granules, dirt, dust or other debris from around the repair opening.

Spray-apply foam into the prepared area.

Permit the foam to rise and set so that the repair opening is completely filled. Allow in-place foam to cure for a minimum of 1/2 hour. Larger repairs may require slightly longer to dissipate heat in the foam and for the foam to become firm enough for cutting and trimming.

If, after repair, the area is underfilled, a second or third application of foam may be required to completely fill the void.

Once foam in the filled void is cured or firm, trim away excess foam with a serrated knife or hand saw to the nominal level of the adjacent foam surface; then grind, rasp or sand smooth.

Remove all foam dust and bits or foam debris from the repair area. After permitting the foam to cure for at least an hour, proceed with the new coating application and addition of granules, if required.

In working over the cut and sanded surfaces of foam as described in this procedure, it is strongly recommended that at least three brush or rolled coats of new coating be applied to obtain 20 mils minimum DFT (dry film thickness). It is especially important that the first coat be worked thoroughly into the cut and open cells of the foam surface to compensate for the fact that no skin exists.

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