Water Intrusion Reductions

Increased Roof Strength Data

Roof sheathing is installed with a 1/8" to 1/4" space at the seams. Therefore, this leaves gaps of 12 to 24 square inches per4x8 sheet of sheathing. A 4,000 square foot building can have approximately 200 sheets of sheathing; thus, a fully exposed roof deck could have up to 33 square feet of open space for water to enter the building. This is the equivalent of 1 full sheet of plywood not installed.

Testing at ITW Foamseal's Technical Center shows that the application of Foamseal Hurricane Adhesive to the sheathing seams reduces water intrusion. Roof coverings (shingles and tile) are usually the first things to fail in high winds like those experienced during hurricanes. Once the roof covering fails, water intrusion is likely and significant damage to the building and contents occurs even if the roof sheathing stays in place.

Testing at Clemson University's Civil Engineering Department shows that roof structures can be strengthened to increase uplift resistance from 2 to 4 times the strength of nails alone.

Building Code required nailing patterns should develop sufficient uplift resistance for winds developed in lower category Hurricanes (Category I, II and III). However, if the building envelope is breached, internal pressures can double, thus exceeding sheathing uplift resistance. That causes roof failures. Category IV and V hurricanes may develop sufficient uplift to remove roof sheathing without window or door failure. Increasing the uplift resistance of a roof structure can easily be accomplished in many instances through the application of Foamseal Hurricane Adhesive.

Expansion & Contraction of Roof Structure

Reduction in Average Loss Estimates

Roof movement due to expansion and contraction of the roof structure is necessary and common in all types of buildings. The application of Foamseal Hurricane Adhesive does not significantly limit expansion and contraction of the roof assembly. Independent testing laboratory reports show that the average movement measurements differ by 0.003" for assemblies with and without Foamseal applied.

An independent study by Applied Research Associates, Inc. examined the potential reduction in average losses in selected residential structures. The analysis indicates that the application of Foamseal Hurricane Adhesive to the underside of a roof deck is a cost effective means of reducing hurricane induced losses.

The level of loss reduction depends upon several factors. The above chart reflects typical estimated reductions in average losses using impact resistant protection devices on all openings and using Foamseal Hurricane Adhesive.