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Caulk and insulate with a foam insulation spray

The various connections between different materials, through walls, shutter boxes... are all potential weak points vis-à-vis thermal and acoustic losses. A simple solution is used to treat these delicate points: expansive foams (but also impregnated foams for joinery joints) based on polyurethane. They constitute a complement of fixing for the assembly and the insulation of the joinery, filling of hollow spaces of the passages of pipes in the walls and in the partitions, soundproofing of the doors, thermal and sound insulation of the coffers of shutters, insulation of the systems of air conditioning... the list is not exhaustive.

Necessary material

  • Expansive foam bomb
  • Cutter for sharpening


  1. Apply insulating foam
  2. Spoon the expanded foam

Apply insulating foam

The insulating foam is presented in cartocuch of under pressure with injection tube.

Insulating foam in pressure cartridge (here Sika Boom®)

1. Start by thoroughly cleaning the supports so that they are free of dust, grease or rust. Protect areas that should not be covered with foam with masking tape. You can also moisten the stand with water.

Insulation and caulking of a duct passage to the ceiling.

Insulation and caulking of a duct passage

2. Then screw the flexible supply tube onto the bomb, shake it for 30 seconds. You can then go to the extrusion phase. In this case, it is a question of filling the void left by the passage of a stovepipe in a ceiling. The use of the spray foam is time-saving, the intervention is clean (no plaster to be allowed to dry), as well as a recognized safety, the foam being classified as difficult to ignite and weakly combustible.

Passage of a water drain pipe into a wall.

Passage of a water discharge pipe

3. It will also be necessary to fill the outlet of a sewage pipe. This operation will avoid maintaining a thermal bridge, a source of losses. Once extruded, the foam will fill the space by its ability to expand. For that, it is enough to fill in foam the equivalent of only 30% of the cavity. When the volume to fill is important, you can make a second pass, taking care to shake the bomb again and moisten the face of the first layer already applied.

Spoon the expanded foam

Flaring of the expanded foam with the blade of a cutter.

Flaring of the expanded foam

1. Once the expansion is complete and stabilized (after 24 hours of drying at 20° C), cut the foam with a cutter to obtain sufficiently level surfaces. These surfaces will then be protected with mortar, plaster, or paint.

Caulking trimmed and ready for finishing. the product can also be used outdoors if it is protected from the sun's rays.

Caulking trimmed and ready for finishing

2. The product is designed to be used indoors or outdoors, if it can be protected, foams degrading in contact with the sun. During the installation phase, the room must be well ventilated. Be sure to apply all safety conditions for aerosol containers.

(photos / visuals: © Sika, except special mention)

Caulk and insulate with a foam insulation spray: foam

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