Secondary Water Resistance (SWR) Vs. Secondary Water Barrier (SWB)

As insurance rates continue to increase, homeowners are looking at ways to lower their insurance cost. Mitigating the home by installing “Impact” windows or shutters is a popular way of doing so. Installing a new roof, and retro-fitting the home with roof straps can also provide insurance discounts through the OIR-1802 Wind-Mitigation Inspection.  Lesser known and seldom way to get an insurance discount is to install a “Secondary Water Resistance/SWR”.  As a property inspector that has done more than 3,000 “Wind-Mitigations” inspections, my experience is that very few people are doing that. Looking back at my data for question#6 “Secondary Water Resistance or SWR” of the State of Florida “OIR-B1-1802 Wind-Mitigation Form”, only 10 out of those 3,000 inspections were for YES. The rest were answered with NO or Unknow. That is .0333333% for yes. Which means that less than 1% of the population in the state of Florida has a home that has an SWR. My experience has also been that question#6 is one of the questions that confuse homeowners and inspectors the most.  So why did the “Office of Insurance Regulators” include question #6 in their insurance form?, what exactly is SWR? , and why aren’t homeowners installing SWR?

By definition, SWR (also called Sealed Roof Deck) is a self-adhering polymer modified-bitumen roofing underlayment applied directly to the roof sheathing, or a foam adhesive SWR barrier (not foamed-on insulation) and applied as a supplemental means to protect the dwelling from water intrusion in the event of roof covering loss. SWR is often confused with “Secondary Water Barrier or SWB” which by definition a is a water-resistant /roof underlayment layer or product that is fastened to the surface of the substrate to which the primary roof covering is affixed that will resist water intrusion through seams in the plywood or other deck covering.  In laymen terms, the big difference between SWR and SWB is that SWR adheres to the roof sheathing, and SWB is nailed to the roof sheathing. It is important to know that an SWR is a “Florida Statute” and not a part of the Florida Building Code, or required by the Florida Building Code.  On the other hand, the SWB is part of the “Florida Building Code” and required when re-roofing. In tile roofs installation a new popular self-adhering roof covering is beginning to replace the 90LB roof covering with tar application that goes over the initial 30 LB  felt cover. Many people are confusing this new self-adhering roof covering as an “SWR” and unfortunately, it is NOT. This new self-adhering cover is a lot easier to install and cleaner, but it is not an SWR and does NOT qualify for a “Wind-Mitigation” discount. The reason is that the material it is going on top of another roofing material, and not the actual roof sheathing. The easiest way to install an SWR is by using a 6” Modified bitumen roofing strip on all seams of the plywood.

SWR on the seams of the plywood roof sheathing.

You cannot install a self-adhering material to the whole roof, only the seams of the roof sheathing. The reasoning behind that is for when you have to re-roof and replace the material. Removing a self-adhering material is not easy and could rip away part of the roof sheathing. That is why it is only recommended that it is installed directly on the seems of the plywood. You can also install a Foam adhesive SWR, which has to be “Closed” cell insulation on all seems of the plywood. Many people are also confusing sprayed foam insulation as an SWR. For the foam to be an SWR it has to be “Closed” cell, the popular foam insulations that are being installed are “Open” cell. There is quite a bit of a price difference between “Closed” cell, and “Open” cell insulation, with “Closed” cell being more expensive. In both methods of installation, to be able to get the insurance discount documentation of materials, and installation needs to take place.

SWR Closed Cell Foam insulation on the seems of the plywood roof sheathing, interior side.

So why did the Office of Insurance Regulations included an SWR statute on the 1802 Wind-Mitigation Form? The answer is very simple, and that is to provide an Insurance Discount/Credit and to promote better building practices. The problem is that the financial incentive is too low, and it is not required by the Florida Building Code. Past research has shown that when the roofing material gets ripped off home during a hurricane, the majority of water from the storm enters through the seams of the plywood. So in theory, protecting just the seams of the plywood first gives an extra level of protection against the water going into the home. Once the water goes inside the home, the insurance claim damage increases significantly. The Florida Building Code has not required roofers to install an SWR, they are only mandated to install an SWB. An SWR is considered code plus.

As one that is also a State of Florida General Contractor, I can tell you that installing an SWR is not hard, does not take up a lot of time, and does not cost much. On an average 1,500 sq. ft home you are looking at one day of installation, with a two-man crew averaging a total of $500 cost for the contractor. The insurance discount/credit, on the other hand, is for a 1,500 square foot home is around $27-$50 a year on a medium priced home. On homes that are a million plus, the discount could be more because discounts are based on percentages of the insurance policies. I would recommend everyone installing a new roof to ask your roofer or general contractor for an SWR regardless of the insurance discount. It is a great building practice.  If the OIR would increase the “Wind-Mitigation” credit/discount that it gave to their policyholders, and if the Florida Building Code required roofers to install an SWR in addition to an SWB, then maybe we would have fewer insurance claims and lower insurance prices.