Cathedral/Vaulted Ceiling (Exposed Beams) – Installing STYROFOAM Square Edge and STYROFOAM WALLMATE
1. Install vapor retarder, such as #30 roofing felt, over the wood plank deck.
2. Over the vapor retarder, install wood nailers 3.5 inches wide by the thickness of the foam insulation. Wood nailers are installed parallel to the roof slope on 16" or 24" centers and around the perimeter of the roof deck, at valleys, ridges and anywhere flashings will be attached. Since 2x4 lumber is 1.5 inches thick, 2" thick foam insulation will require the thickness of the lumber to be adjusted to 2" by adding a 1/2" thick strip of plywood or foam insulation under the wood nailer. Cut strips of 1/2" thick plywood or foam insulation 3.5" wide and staple to the wood nailers. Install nailers with foam or plywood side down against the vapor retarder. Screw or nail wood nailers securely to roof deck.
3. Install STYROFOAM™ Square Edge insulation tightly between the wood nailers, nailing minimally.
4. Install a second layer of foam insulation perpendicular to the wood nailers keeping all joints tight and nailing minimally into the wood nailers.
5a. If a non-vented (hot) roof is desired, install plywood/OSB shingle base over the foam insulation, staggering all joints versus foam joints. Run plywood/OSB perpendicular to the wood nailers and ensure end joints in plywood/OSB are located over a wood nailer (wood nailers are under top layer of foam insulation). Secure plywood/OSB to the wood nailers.
5b. If a vented (cold) roof is desired, install a second set of wood nailers over top layer of foam insulation and directly over existing wood nailers which are below top layer of foam insulation. Fasten top wood nailer into existing wood nailer. Alternatively, STYROFOAM WALLMATE slotted insulation may be used as a single layer directly over vapor retarder or as the top layer in a two layer system. Install plywood/OSB shingle base perpendicular to the wood nailers and ensure end joints in plywood/OSB are located over a wood nailer. Secure plywood/OSB to the wood nailers. Vented roofs require vents at the eaves and at the ridge that are connected via the air space under the shingle base.
6. Install roofing felt, shingles, flashings, etc.
7. Avoid penetrating the vapor retarder when installing light fixtures.
NOTICE: No freedom from any patent owned by Dow or others
is to be inferred. Because use conditions and applicable laws may differ
from one location to another and may change with time, Customer is
responsible for determining whether products and the information in this
document are appropriate for Customer's use and for ensuring that
Customer's workplace and disposal practices are in compliance with
applicable laws and other government enactments. Dow assumes no obligation
or liability for the information in this document. NO WARRANTIES ARE
GIVEN; ALL IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A
PARTICULAR PURPOSE ARE EXPRESSLY EXCLUDED.
COMBUSTIBLE: Protect from high heat sources. Local
building codes may require a protective or thermal barrier. For more
information, consult MSDS, call Dow at 1-866-583-BLUE (2583) or contact
your local building inspector. In an emergency, call 1-989-636-4400.
Building and/or construction practices unrelated to
insulation could greatly affect moisture and the potential for mold
formation. No material supplier including Dow can give assurance that mold
will not develop in any specific system.
