When adding foam insulation to the walls, several essential steps must be taken before installation begins. First, cover the area with plastic sheeting and clean any debris. Next, drill two holes in each stud cavity to ensure that the new foam insulation is fully inserted into the wall. The manufacturer of the insulation should specify the exact size of the holes.

Spray foam insulation

Spray foam insulation is an effective way to improve the insulation levels in walls and ceilings. It can be applied in various ways, but the most common is filling voids and cracks between studs. It goes in after the wiring has been run and before the drywall has been installed. The process is very simple and does not require cutting or measuring. Once it is applied, the foam will expand and fill in the gaps between the studs.

Certain types of insulation are injected directly into the wall cavity, using small holes from 1/2 inch to two inches. These holes are usually small enough to allow the insulation to penetrate deeply into the wall cavity. Some types of spray foam are open cells and contain particles of cellulose.

Before installing spray foam, it is essential to prepare the walls. The area around the studs should be insulated with a layer of batt insulation. The thickness of the insulation should be at least R-12. Higher insulation values can cause freeze-thaw cycles and may not be as effective. If you are unsure how much insulation to install, contact your local building authority for guidance.

Vapour barrier

A vapour barrier is a thin membrane that helps to prevent moisture from escaping from the wall. In an air-conditioned building, the vapour barrier helps to prevent moisture from escaping to the exterior. The barrier also prevents the inside of the wall from becoming moist. Its installation requirements are similar to those for polyethene sheets.

When adding foam insulation to the walls, it is crucial to consider the dewpoint of the wall. This is the temperature at which water vapour starts to turn to liquid. Vapour can be trapped in a wall because warm air condenses more moisture than cold air. The difference between the outside air and the inside air determines the dewpoint of the wall. A vapour barrier is necessary to prevent this moisture from forming.

When adding foam insulation to the walls, it is essential to seal the space around them. This is an integral part of the insulation process, providing the primary air barrier system. It is also necessary to use dry lumber when framing the walls, as wet lumber may twist.


The cost of foam insulation in walls varies according to the type of foam used, how much insulation is applied, and the size of the project. While traditional polyurethane foam is the most common, greener varieties also exist. Choosing a greener type can reduce the environmental impact and create a healthier home. In addition to polyurethane, there are soy-based, water-based, and vegetable-oil-based spray foam options.

Open-cell spray foam is cheaper but offers a lower R-value than closed-cell foam. The open-cell type is 3.5 to 3.6 inches thick but needs a vapour retarder. This type of foam also adheres to wood, brick, and PVC.

The cost of spray foam insulation varies depending on the amount of insulation that you want to apply. It can be applied to entire walls or just specific areas. Older homes will typically cost more than new ones. The thickness of the insulation also contributes to the cost. The more insulation you need, the more expensive it will be.


While you may be tempted to tackle this DIY project yourself, you may want to consider hiring a professional. While this is possible with home insulation materials, spray foam is best left to professionals like Insulation Co. Although this type of insulation can be applied easily by homeowners, some companies prefer to sell their products to trained technicians. Depending on the type of foam insulation you choose, it will vary in price.

Before installing the insulation, prepare the area with plastic sheeting. Then drill holes in each stud cavity, as specified by the manufacturer of your insulation. This will ensure that the foam insulation covers the entire interior of the wall. In some cases, the manufacturer will provide specifications about the size of the holes.

Rigid foam board insulation is typically available in large sheets of four feet by eight feet. However, you can also buy more miniature sheets – 2 feet by 8 feet or 4-foot by four feet – to use on smaller areas. The most extensive sheets often come with shallow cuts, which you can use to snap the insulation in half without a saw. However, these cuts won’t help you with between-stud installations.