Foundation insulation – what should you know?

foundation insulation

If you skip the thermal insulation of the foundations, the heat from the house will escape towards the ground. Learn how to insulate foundations.

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The most important rule

The most important rule for proper insulation is to surround the entire building with a continuous layer of insulation to eliminate thermal bridging. Walls, foundation slabs and floors on the ground should always be insulated. During prolonged frosts, the soil maintains a temperature above 0 only below the freezing zone. If the foundation is not insulated, heat from the interior is retained by insulation on the external walls and under the floor on the ground, but it migrates along the wall structure, and then through the foundation wall until it escapes to the ground. In this place (the connection of the wall with the floor), the surface inside the building cools down strongly, and water vapor condenses on the surfaces, causing moisture and the possibility of mold growth. Correct foundation insulation combined with wall insulation effectively stops this heat leakage.

Lightweight foundation insulation

It is used when the building is located above Groundwater level on permeable soils: sands, gravels or rubble. It is made of bituminous or polymeric mass. These masses are Flexible and easy to apply, while the polymer-based mass can also be used at low temperatures. They perfectly fill all unevenness and surface defects. They should be applied in two layers, one layer horizontally and the other layer after drying the first one vertically.

Medium foundation insulation

This type of insulation should be used when the building is located above Groundwater level on impermeable grounds (clay) and when it is expected that the Groundwater level may be higher (e.g. during spring thaw) than the lowest foundations of a given building. Such insulation is made of bituminous and polymeric sands and two layers of roofing felt glued. It is important to use one type of roofing felt and glue: tar-tar or asphalt.

foundation insulation

Heavy insulation of foundations

It is used in buildings erected on cohesive soils such as clay, sands, loams. These types of soil keep water in their structure long-term, and thus – around the foundations. It is also recommended to make it when the Groundwater reaches above the foundation level or may periodically exceed it. In such cases, the walls are permanently exposed to water under the hydrostatic pressure. Waterproofing materials alone do not ensure Sufficient tightness. That is why basement walls and floors are recommended to be made of reinforced watertight concrete to form a reinforced concrete basin.