At present, the most commonly encountered is a spray on a vapor permeable membrane or a formwork. This mainly concerns the isolation of the attic. The minimum temperature of the substrate in this case is 10oC. Other materials used in construction which are excellent for good adhesion with open-cell foam are: gypsum board (spraying on partition walls) and concrete (spraying on ceilings). It is necessary to cover the foam layer, eg with OSB boards fixed to wooden beams, to avoid accidental damage.
IMPORTANT: Do not apply directly to the roof tile.
While spraying the attic, first apply foam on the place of contact of the rafter with the formwork or membrane, then on the space between the rafters. This prevents the air from being trapped in the “corners”. Some contractors use a spraying method from bottom to top along rafters. Then the last layer is applied in the opposite direction. For membrane spraying, there is no problem with pressing the membrane to the sheet metal, etc. (the membrane must be properly tightened).