4.1001.7 Vented Roof Deck—Preparation for SPF

Topic: 
Attics
Subtopic: 
General Preparation
Desired Outcome: 
Backstop or substrate provided to prevent SPF SPF Spray polyurethane foam from entering soffit areas while ensuring required attic ventilation is provided
For supporting material, see Referenced Standards, General Information on Spray Polyurethane Foam (SPF), Calculation of the Infiltration Credit and Building America Solution Center.
TitleSpecification(s)Objective(s)
4.1001.7a
Surface preparation

All surfaces where SPF SPF Spray polyurethane foam is applied will be clean, dry, and free of contamination and degradation

Substrate surfaces will be wiped, blown, or vacuumed to be free of excessive dust and dirt

Grease and oil will be removed using appropriate cleaners or solvents

Moisture content of all wood substrate materials will be checked to ensure it is below 20%

Ensure proper bonding of SPF SPF Spray polyurethane foam to substrate surfaces
4.1001.7b
Installation of vent chutes

Vent chutes will be installed between all rafters or trusses to ensure a continuous ventilation path between the eave or soffit area and the ridge or roof vent

Vent chutes will penetrate dams as needed

Allow ventilation of underside of roof deck sheathing while creating an unvented, conditioned attic space
4.1001.7c
Installation of insulation dams

Dams will be fastened to underside of roof deck and outside edge of exterior wall top plate to prevent SPF SPF Spray polyurethane foam insulation from entering soffit area

Installation will allow for the highest possible R-value above the top plate of the exterior wall

Ensure insulation R-value is not reduced

Minimize waste of SPF SPF Spray polyurethane foam

Provide a ventilation path from eave or soffit to ridge vent when a vented roof deck is required

Ensure continuous insulation and air seal of top plate and roof deck
4.1001.7d
Removal of existing insulation and vapor retarder Vapor retarder A material that slows the passage of water vapor and contains a perm rating above 1

All existing attic floor insulation and vapor retarder Vapor retarder A material that slows the passage of water vapor and contains a perm rating above 1 will be removed

Ensure the new conditioned space is coupled with the house