Bell Inspection Service

Secondary Water Resistance is a technique
used to protect the interior of the building when
the roof cover and underlayment blow off
during a storm. It can be applied to plywood
roof decks and is a self-adhering
polymer-modified bitumen roofing
underlayment (thin rubber sheets with peel and
stick underside located beneath the roof
covering and normal felt underlayment) with a
minimum width of 6" meeting the requirements
of ASTM D 1970 installed over all
plywood/OSB joints to protect from water
intrusion. These photos show this "rubber
sheet" being applied to a plywood deck.
Bell Inspection Service
Secondary Water Resistance
Secondary water protection
wind mitigation inspection
Very few homes in Florida have
Secondary Water Resistance (SWR).
A qualified construction professional
is needed to verify the installation of
SWR. It is an economical and highly
effective means of reducing losses in
windstorms, since a majority of
losses are caused by water damage.
All secondary water resistance
products must be installed per the
manufacturer's recommendations.

Note that roofing felt or similar paper
based products (30lb/90lb hot mop
systems) are NOT acceptable for
secondary water resistance. Hotmop
felt is often used under tile roofs as
the primary water resistance layer,
and are often confused with
secondary water resistance products.
Reduce your insurance costs
© Bell Inspection Service 2007