Dryvit Backstop Flash & Fill: Joint Filler

Dryvit Backstop Flash & Fill is a flexible, waterproof material designed to fill sheathing joints, protect rough openings and act as a transition membrane. Backstop Flash & Fill is vapor permeable and eliminates air infiltration for above grade construction. Questions? Contact Us.

Dryvit Backstop Flash & Fill is designed to fill sheathing joints up to 1/2 in (12.7 mm) and is used to provide an effective water-resistant transition membrane. Backstop Flash & Fill provides continuity of the Dryvit Backstop NT air and water-resistive barrier across various substrate materials (refer to data sheets, DS455, Backstop NT and DS806 Backstop NT For Use Beneath Claddings Other Than Dryvit EIFS).

Filling Joints, Seams and Cracks
•Sheathing board gaps shall not exceed 1/2 in (12.7 mm) and the surface must be flat within 1/4 in (6.4 mm) in any 4 ft (1.2 m) radius.
•Substrates shall be free of foreign materials such as dirt, dust, oil, paint, wax, water repellants, or other materials that inhibit adhesion. Backstop Flash and Fill will bond and cure in wet weather and on damp surfaces.
•Apply a bead of Backstop Flash & Fill to all sheathing joints, seams and cracks and strike smooth with a dry joint knife, trowel or spatula. Joint widths up to 1/2 in (12.7 mm) may be treated with Backstop Flash & Fill without backer rod.
•Use a dry joint knife, trowel or spatula to tool and spread the Backstop Flash & Fill a minimum of 1 in (25 mm) beyond the sheathing seams on each side to a thickness of 12 – 15 mils(0.30 – 0.38mm).
•Spot fastener heads and strike with a dry joint knife, trowel or spatula.
•Allow Backstop Flash & Fill to skin prior to installing the Backstop NT water-resistive barrier

Acceptable Substrates:
a. Core treated exterior grade gypsum sheathing meeting ASTM C 1396.
b. Core treated exterior grade gypsum sheathing with fiberglass mat facers meeting ASTM C 1177.
c. Exterior fiber reinforced cement or calcium silicate boards meeting ASTM C 1325.
d. APA Exterior or Exposure 1 Rated Plywood, Grade C-D or better.
e. APA Exterior Grade Fire Retardant Treated Plywood.
f. APA Exposure 1 Rated OSB.
g. Unpainted, unsealed concrete and CMU.
h. Galvanized metal and alluminum.