The strip foundation is one of the most common structural solutions for the device foundation for a private house. It has sufficient strength potential, but the walls and bottom require good insulation. It is especially important to implement high-quality insulation of the strip foundation, not only in the outer part, but also inside the structure.
Thermal Insulator Selection
Usually FS 20 expanded polystyrene is used. It is advisable to install panels with profiled edges that prevent the formation of cold bridges at the joints. You should also consider the inadmissibility of a combination of polystyrene foam and solvents, which may be present in liquid waterproofing compositions - mastics, tar and xylamite dissolve similar materials. For this reason, it is worthwhile to apply insulation of the strip foundation with Penoplex, which in itself can act as a waterproofing coating. Special plate models suitable for protecting the structure from groundwater are selected.
No less popular heat insulators in the form of mineral and glass wool are used only in cases where their density is at least 110 kg / m3. The remaining versions let water through, which is also undesirable for a base insulation.
Another option is expanded clay. This is a loose insulation, resistant to frost, moisture, fire and biological destruction processes. But it is recommended to fill it up with the foundation device on the bottom of the foundation pit due to structural expediency.
Which tool will be needed?
A specific set of tools is determined by the material and the insulation technique. As a rule, the following devices are involved:
- Shovel (bayonet and shovel).
- Assembly tool for working with concrete, metal and wood (formwork). It can be a puncher, an electric drill, a hammer, a jigsaw, etc.
- Tools for the preparation and application of insulators are spatulas, rollers, a rule and a gun for mounting foam.
- If it is planned to warm the strip foundation with liquid bitumen waterproofing, then a gas burner will be needed.
Among auxiliary materials and consumables, a geotextile, fasteners, adhesives and tapes, adhesive tape, primer and sealant may also be required.
General recommendations for thermal insulation
Initially, you should keep in mind the following tips from specialists involved in the construction of strip foundations:
- The methods and tactics of isolation should be selected based on the results of geotechnical studies on the ground. At a minimum, such a report will determine the requirements for protection against groundwater, which adversely affect almost all heat insulators.
- Particular attention during installation is given to joints and gaps. They form the bridges of cold, which become the main cause of heat loss.
- It is important to adhere to a balanced approach both in the choice of an insulator and during installation. For example, insulation of a strip foundation with polystyrene foam should be made with a thickness of about 3-5 cm and no less. It also makes no sense to increase the insulation parameters, since this deviation from the technology will affect the structural reliability of the insulation.
- Saving on fasteners is a common mistake of novice builders. Experts note that it is impossible to shift the necessary force of fixing the heat insulator to the subsequent structural layers. Each element should receive sufficient fastening precisely in its structure at a specific level.
Site preparation
Installation of heat-insulating plates is carried out only on a flat base. The construction of the strip foundation from different sides must be cleaned and, if necessary, primed in places with defects. It is important to eliminate and efflorescence on the surfaces, as they will not allow to provide sufficient adhesion. Liquid and roll insulation of a strip foundation with a waterproofing barrier is carried out only on surfaces primed with a bitumen mixture. Also, by the time of installation operations, a heat-insulating material should also be prepared - it must first be laid down in a dry room, not have defects and other signs of damage with integrity violation. If necessary, the plates can be cut to the desired size with a regular hacksaw or jigsaw.
Waterproofing device
Protection against water and moisture in relation to foundations is almost always used. Exceptions can be attributed only to cases when rubble stone or waterproof concrete is used in the structure itself, but this is not common in strip foundations. To protect against groundwater with soil moisture, use vertical and horizontal hydrobarriers. The function of vertical waterproofing to a lesser extent is manifested in the system of warming a shallow strip foundation, since groundwater is almost not afraid of it. It is enough to perform film or bitumen protection of wall surfaces with a small entrance to the ground up to 30-50 cm. This barrier will retain mainly atmospheric and groundwater. As for horizontal waterproofing, it is laid in two places - at the junction of the foundation walls and external walls, as well as in front of the bearing pillow of the structure across. This layer should cut off water, which will get to the structure of the walls and, as a result of capillary suction, contribute to their destruction.
Technology for performing external thermal insulation
Thermal insulation in the construction of the strip foundation should be laid to a depth of about 50 cm. Installation of extruded polystyrene foam, in particular, is carried out after waterproofing. If polyurethane foam is used, then it should also be covered with a film waterproofing from the outside. The thickness of the mounted plates should be 3-4 cm for expanded polystyrene, and 5 cm for expanded polystyrene. Mineral wool is laid in a layer of 6 cm.According to the technology of warming the strip foundation from the outside, fastening should be carried out on acrylic glue (pointwise) and dowels with a length of about 12 cm.In addition, a plastic reinforcing mesh can also be laid, fixing it on the sides at the joints to the wall.
Performing internal thermal insulation
Many experts are skeptical of the device of internal thermal insulation for the foundation, relying on the complete insulation of the walls of the house along the entire height. This is due to the fact that inside the same polystyrene foam does not exclude cold bridges, if they were not removed from the outside. Nevertheless, it is in this part that mineral wool can be well manifested. We use mats with a thickness of 10 cm, which are mounted in the design of the crate and closed with film waterproofing. The insulation of the floor of the strip foundation, in which it is worth using bulk materials, is also mandatory. In addition to expanded clay, sawdust and other environmentally friendly waste from natural industries are used in this part. Above the first layer of the lag an underground niche is located on the grillage. Its thickness can be 10-15 cm, which will be enough to fill bulk insulators, and to lay tile materials even without fixing.
Insulation Protection
From the outside, the layers of arranged insulators must be protected from mechanical damage. For example, during the backfilling of the foundation, the pebbles contained in the soil and various debris may well deform the insulation boards or break the sealing in certain areas. Therefore, to protect the insulation layers of the strip foundation outside, it is necessary to use thin and durable polymer sheets or foil film. This material is mounted on a moisture-resistant adhesive base or on silicone sealant, but without the use of hardware.
Conclusion
The thermal insulation of the foundation is the basis for the conservation of thermal energy at home. The approach to solving this problem should be comprehensive, taking into account the operating conditions of the material and environmental factors. So, when warming the strip foundation, both the requirements for isolation from groundwater and the structural characteristics of the walls are taken into account. In the choice of material, such qualities as wear resistance, vapor impermeability, rigidity and compatibility with adjacent surfaces, primarily concrete, should be calculated. Do not forget about the internal insulation, since cold bridges with condensate negatively affect the condition of concrete surfaces from the back. A properly organized complex thermal insulation will provide a comfortable microclimate in the house for many years.