A Powered Roof Vent Booster (Model RVB3) is a simple and safe way
to increase attic ventilation. RVB’s allow you to
avoid the hassle and danger of working from your
roof. They install from inside the attic
underside opening of standard roof vents up to 11
sq. in. They boost ventilation by over 3 times that
of passive roof vents, helping to keep the upper
roof deck below 32º during below freezing weather.
No attic hot spots = no ice dams.
arms secure the booster in place between roof
rafters/trusses up to 32” across. No wiring is
necessary, just plug the Powered Roof Vent Booster into an
outlet. Operates on only 60 Watts. When using more
than 1 RVB plug one fan into another
for multiple unit operation through a single power
source. Position Powered Roof Vent Booster(s) near roof
vents where ice damming is most severe.
How to determine the number of Powered Roof Vent Boosters
Calculate the cubic area of the attic by multiplying
the length x width x
one half the
height (assumes a pitched roof). Divide this number by 10 to determine the minimum
CFM necessary to
fully ventilate the space in 10 minutes.
Example: 20' wide x
40' long x (1/2) 6' high attic = 2400 cubic ft.
2400 cubic ft. ÷ 10 minutes =
240 CFM of ventilation. Choose one RVB3.
Choose one RVB3 for every 300 CFM, rounding up.
More on Increasing Ventilation to
Eliminate Ice Dams
Powered Roof Vent Boosters are the easy way to reduce or
eliminate Ice Dams. Ice Dams are a common
problem in regions that regularly have snow.
They are caused by upper portions of a roof
surface warming to over 32 degrees, which melts
the snow. The resulting water refreezes near the
roofs edge where surface temperatures are lower,
forming a dam of ice. When the water can no
longer flow down over the dam it backs up the
roof and underneath shingles causing interior
destruction and shingle damage.
Recommended Procedures for eliminating Ice Dams:
Find and seal any air
leaks from the heated living space such as
bath fans, heating or dryer exhaust ducts.
Add insulation to the
floor of the attic.
Ventilate the space
better so that the underside of the upper
roof surface stays below 32 degrees.
More on Increasing
Ventilation to Cool Attics
Roof Vent Boosters can be
used in place of traditional attic fans to
increase attic ventilation and decrease cooling
costs during the hot summer months. Exhausting
pent-up attic heat will decrease the amount of
energy needed to cool your home. Unlike
traditional attic fans, RVBs do not require the
installer to get up on the roof making
installation safer and easier--truly a
Do-it-Yourself project. If a large amount
of ventilation is required, the RVB units can be
daisy-chained with one unit plugging into the
next so that only one power source is needed for
|Typical roof vent,
||Typical roof vent,
against roof vent