How to insulate the foundation at home outside

Making sure the foundation of your house is adequately insulated is just as important as the walls and roof. A vital step in preserving energy efficiency and shielding your house from moisture and temperature swings is to insulate the foundation from the outside.

Applying insulation materials to the foundation’s outer walls below ground level is known as exterior foundation insulation. This technique can help prevent cold spots in your crawlspace or basement by reducing heat loss through the creation of a thermal barrier. In addition to protecting the foundation from the elements, external insulation can increase the foundation’s longevity and avert structural damage.

It is crucial to determine the exact insulation requirements for your home as well as the state of your foundation before beginning any insulation project. The selection of insulation materials and installation techniques will be influenced by various factors, including soil composition, climate, and the depth of the foundation walls.

Mineral wool, spray foam, and rigid foam boards are common insulation materials for exterior foundation insulation. These materials were selected due to their strength, ability to withstand moisture, and insulating qualities. Certain materials might be more appropriate than others, depending on the local building codes and climate.

Materials Needed	Steps to Insulate Foundation
1. Insulation boards (XPS or EPS)	1. Clean foundation surface thoroughly.
2. Waterproof membrane or coating	2. Apply waterproof coating or membrane.
3. Drainage board (optional)	3. Install drainage board if needed for water management.
4. Fasteners (screws, anchors)	4. Fasten insulation boards securely.
5. Tape (for sealing joints)	5. Seal joints with appropriate tape.
6. Backfill material (gravel or soil)	6. Backfill around insulated foundation.
7. Protective barrier (for exterior finish)	7. Apply protective barrier before final exterior finish.

Requirements for insulation

The house’s foundation is frequently subjected to moisture, increased weight, and harsh temperatures. When frosts arrive, the moisture that has accumulated freezes and destroys the material. The cold then seeps into the house through the cracks in the concrete. Because of this, the house’s floors are never warm. Dampness, condensate, or—in the event of a severe frost—hoarfrost—protrudes on the walls from beneath the skirting boards. The following qualities must be present in thermal insulation for it to be effective:

• low thermal conductivity;
• water resistance;
• good mechanical strength;
• resistance to temperature differences.

There are several requirements that the foundation’s insulation material must meet.

Although there are no hard and fast rules regarding a material’s vapor permeability, low vapor permissive capacity insulation is typically utilized, such as in the very concrete foundation. The underground portion of the building is the least vulnerable to fire hazards, so it doesn’t really matter if the material is combustible.

The insulated foundation in the picture

Insulating your foundation from the outside has two major advantages: it will increase energy efficiency and shield your house from moisture. Through adequate insulation of this frequently disregarded region, homeowners can minimize heat loss, avoid moisture problems in the basement, and improve the overall longevity of their building. This guide will assist you in making well-informed decisions to increase comfort and reduce energy expenses by examining useful techniques and factors to take into account when insulating the exterior of your home’s foundation.

Which insulation to choose

The worst choice for a foundation is a mineral water heater because they easily absorb moisture, lose their ability to insulate against heat, and break down under mechanical stress. The material will shrink due to the pressure of the soil, rendering insulation completely ineffective.

A mineral wool slab used as foundation insulation

Prices for mineral wool

Minvata

However, polymer insulation completely satisfies the requirements and lacks such flaws.

Using polystyrene foam for foundation insulation

Think about each of their traits in greater detail.

Foam polystyrene

Good foundation insulation helps prevent a large amount of heat loss.

Polystyrene foam, also known as polystyrene, is extensively utilized in thermal insulation arrangements. Because it is lightweight and its sheets are the right shape, even a novice master should have no trouble installing it. The material has different densities and thicknesses, and its application is dependent on these factors. Only the densest sheets—those with a minimum thickness of 50 mm—are appropriate for use as foundations; the remaining sheets are better suited for use as wall and partition insulation.

Polystyrene foam outperforms wood, expanded clay, and mineral wool insulation in terms of thermal conductivity. He is a great sound insulator, hardly absorbs water, and is resistant to shrinking and deformation. Additionally, when exposed to weak acids, soap solutions, salt, and chlorinated water, polystyrene foam plates completely maintain their characteristics. The insulation may come into contact with cement plaster, bitumen mastics, lime, and adhesive water-soluble solutions.

Polystyrene foam with psb-S-50 labeling is required for slab foundations and highly buried bases because it can sustain heavy mechanical loads and offers dependable protection against soil swelling. PSB-S-35 brand foam is used for both standard strip foundations and columnar ones.

Because of the sheets’ low density and fragility, none of the other varieties are appropriate for use as foundations.

Options	Meanings
Density	12-35 kg/m3
Operating temperature range	from -60 ° C to +80 ° C
Thickness	from 2 to 10 cm
Dimensions	100×50 cm, 100×100 cm, 200×100 cm
Life time	20-30 years

Extruded polystyrene foam

Polistyle foam produced through extrusion far outperforms foam in every way. It is extremely moisture-proof, multiple times stronger, and has the lowest thermal conductivity and vapor permeability indicators. It also does not harbor microorganisms, even when exposed to moisture for an extended period of time.

The foundation’s insulation is made of extruded polystyrene foam, or EPPS.

Slabs made of EPPS that are thinner have a far bigger impact. In temperate climates, 40 mm of thickness is sufficient for thermal insulation of the foundation; in northern climates, approximately 60 mm is needed (two-layer plate laying is recommended for a 30 mm thick layer). Slabs are grooved to make installation easier and to lay material at a higher density.

Polystyrene foam that was extruded and grooved

Using plate dowels and glue solution, they are fastened to the base.

Thermal insulation fastening

When warming column and strip foundations, Epps slabs can be laid both vertically and horizontally (when arranging a slab foundation).

Swedish slab insulation and water heating system

Unlike foam and polyurethane foam, the material does not flatten or shrink as a result of its increased strength, and it can perfectly withstand the load from the concrete layer. Foam and Technology are the most widely used brands of extruded polystyrene foam.

Principal attributes

Options	Meanings
Density	15-36 kg/m3
Operating temperature range	from -50 to +75 ° C
Dimensions	600×1200 mm, 600×2400 mm
Thickness	20-100 mm
Life time	more than 40 years

Poliuretan foam

When warming the foundations, sprayed thermal insulation, or PPU, is being used more and more. Poliuretan foam creates a seamless, incredibly durable coating that is impervious to damage. Additionally, it does waterproofing and steaming at the same time, which makes the job much easier. The high adhesion of this insulation to the base is another advantageous feature. It fills even the smallest cracks and sticks just as firmly to stone, concrete, brickwork, and wooden structures. It can be applied easily to difficult-to-reach places.

PPU in comparison to alternative building materials and insulation

Polyurethane foam’s thermal conductivity in comparison to other materials

There are two methods for applying polyurethane foam: pouring and spraying. Since the first option is more expensive and time-consuming, it is rarely used to warm private homes. The entire extension, from the roof to the foundation, is actively warmed using the second technique. Prior to application, the ingredients are combined with air in a foaming unit, and the resulting mass is then poured under pressure onto the work surface. The composition hardens in a matter of seconds, so you can begin finishing as soon as you’re done working. The only drawback to this type of insulation is that installation is required, which adds to the expense.

Application of polyurethane foam using a pistol-pilvelizer

Options	Meanings
Thermal conductivity	from 0.019 to 0.035 W/m*K
Density	30-80 kg/m3
Water absorption	1-3%
Lifetime	40-50 years

You can use bulk materials, especially expanded clay, for foundations in addition to the insulation that has been described. It is affordable, has good heat-insulating qualities, is safe for the environment, and can be used for both vertical and horizontal insulation. However, expanded clay is less and less used as insulation because it can absorb moisture while losing some of its properties and because the process takes longer and more effort. It is also less effective than more contemporary and efficient materials.

It is uncommon to use expanded clay to warm the foundation.

Prices for polystyrene foam

Foam polystyrene

One of the most important things you can do to keep your home energy efficient and shield your interior from moisture and temperature changes is to insulate the outside of your foundation. You can build a barrier that keeps your house cool in the summer and stops heat loss in the winter by insulating the foundation.

The exterior of the foundation can be insulated using a variety of techniques. Using rigid foam insulation, which is strong and offers superior thermal resistance, is one typical strategy. Prior to backfilling, this insulation is directly applied to the foundation’s outer walls. Spray foam insulation is an additional technique that creates a seamless barrier against heat transfer and moisture infiltration by expanding to fill gaps.

To stop air leaks, all joints and seams must be properly sealed during the installation of foundation insulation. This improves the insulation’s efficiency and aids in the foundation’s long-term structural integrity maintenance.

It’s important to speak with experts when thinking about insulating your home’s foundation to find the best materials and installation techniques for your unique climate and foundation type. You can improve your home’s energy efficiency and create a more comfortable living space for years to come by making the right insulation investments.

Video on the topic

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DIY APPLICATION

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