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What is a crawl space, what does heat loss have to do with it ?

The crawl space is an accessible or non-accessible space between the ground and the second floor of the building. Its main function is to keep the floor of the building away from the ground and the moisture of the earth. Considered as a non-habitable and non-developable area, the first floor must be raised a few centimetres (minimum 20 centimetres to a maximum of 1.8 metres) in order to comply with the Building Code. In addition, there must be no access hatch with stairs, no combustion appliance and no habitable room must be built. In other words, the crawl space must not have any other function than to raise the floor of the building.

Considering the location of the crawl space, here are some disadvantages:

  • The floor of the building remains cool at all times, the waterlogged earth and humidity explain this coolness.
  • High humidity is noticeable in the house due to poor ventilation of the original crawl spaces. This also affects the indoor air quality of the house.
  • The building has no protection against radon (an underground carcinogenic gas responsible for 16% of lung cancers).
  • In cold winter weather, heat loss through the crawl space is significant.

Heat loss? Neglecting your crawl space could cost you!

If your building is not properly insulated and your crawl space is not inspected, you may encounter many obstacles. These can be harmful to you and to everyone in the house. Air quality could be greatly reduced. Unfortunately, unpleasant surprises are common in crawl spaces. The cold, damp and dark environment attracts a surprising number of unwanted friends (rats, viruses, insects, mold and fungi). Ignoring the condition of your crawl space can also have significant repercussions caused by the presence of stagnant water or sewage, humidity problems as well as exposure to radon, freezing of pipes or important heat loss, discomfort of humidity in addition to an excessive heating bill.

Heat loss? Insulate your crawl space in 3 steps:

  1. Cover the natural soil with polythene insulation. In order to remedy the problems of humidity coming from the ground and thus control the possible infiltration of underground gases, we recommend the installation of a polythene type insulation with a vapour barrier of 6 thousandths of an inch. Be sure to seal the joints with vapour barrier tape.
  2. Insulate the walls of the foundation, avoid heat loss. This process will help ensure humidity control and heating management. Also, you will need to insulate and then seal the foundation walls as well as the rim joists. Excess humidity will be reduced considerably and the crawl space will be less cold. Your heating bill could drop considerably. Also, your water pipes will now be protected from freezing during the winter. To achieve this, you must first ask professionals to apply 3 inches of urethane in the rim joist and 2 inches on the foundation walls. Urethane is known to adhere to all surfaces and will ensure an optimal seal against humidity and cold. To seal the vapour barrier on the floor, staple it to a 2X4 that will be sealed with the urethane sprayed on during insulation. Now the cold and humidity will stay outside!
  3. Keep the temperature between 15 and 18°C. After properly insulating the building foundation, install an electric heating system. Now that the building is well insulated, install two electric baseboard heaters at the joists or columns (located at the ends of the crawl space). The recommended temperature is sufficient to remove moisture and coolness. This will make the crawl space optimal for heating (without losing heat) and your building floor comfortable. Finally, using a humidity monitor (hygrometer), make sure the humidity is below 50%.

A result that pays off!  Quality indoor air, savings on heating and comfort for your feet.

Take the time to properly inspect your crawl space. Regardless of its current condition, quality insulation will make this space functional, comfortable and durable to prevent the growth of mold. From now on, your crawl space will no longer be a nuisance for your family and your health. The comfort of the occupants of the house as well as their air quality will be improved. The energy performance of your house will be optimized and your heating costs will be reduced.


Call for your vigilance: annual or biennial inspection

Towards the end of May AND/OR mid-October, a visual inspection of the basement is highly recommended. Also, it is recommended that a radon test be performed at least once during the life of the building.



The Residential Thermographie Team

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