DIY hydro and thermal insulation of the foundation

Recommendation points

Thermal insulation will warm the walls in winter from sudden temperature changes, thereby reliably protect the foundation.

Therefore, even at the first stage of building the foundation, start thinking about competent insulation and high-quality waterproofing of the basement of your house under construction. Most developers, due to lack of funds or extra time, postpone this business until better times and continue further construction without completing the main work on the foundation. They begin to regret what they did after a few years. Firstly, wintering, even for just a year or two, can gradually destroy the outer layers of the foundation due to constant freezing and thawing of the soil in winter. Secondly, the base is often buried. Over time, the earth is compacted, the house shrinks, and here the excavation of the earth begins around the perimeter of the house and the process of insulation and waterproofing itself. After re-digging the foundation, the house may crack on the walls or sag unevenly.

Cleaning the foundation

After the foundation has been erected, floor slabs have been laid or a continuous screed is poured, it is necessary to clean the basement from dirt and dust. The best way to do this is to use a regular brush with hard synthetic fibers. The foundation has pores even on the outer surface. Such a brush will be able to clean out all fine dirt and sandy inclusions in hard-to-reach places..

Aligning foundation walls

The walls at the foundation usually have irregularities not only on the surface itself, but also at the corners. Therefore, it is first necessary to bring them to their normal form. It is recommended to apply the method of leveling the walls of the foundation along the beacons. The most accessible and widely used method in this case. For this, perforated guides are used, which are installed in increments of 1 to 1.5 meters between each guide. Next, mix the solution. The best mortar composition for leveling work is cement grade 500 in a ratio of 1: 4 with sown sand. Dilute with water so that the consistency of the solution is thick enough, but not dry. The grout will creep off the wall immediately after application. The solution is thrown onto the walls with a trowel with a sharp movement of the hand from top to bottom. The work is done in several stages. Therefore, between applying all layers, it is better to wait about 1-2 days for complete fixation. With slight differences in the walls in the foundation, the second layer of mortar will carry the final leveling function. Smooth the surface itself with an aluminum construction rule with a length of 2 meters, producing wave-like movements along the wall. The cycle is repeated about 5-6 times.

If the walls of the foundation have drops of 2.5 centimeters, it is advisable to use additional reinforcement. The ideal option for this would be a chain-link mesh attached to the wall with metal brackets. In the absence of a chain-link, ordinary reinforcement of a small diameter (8-10 mm), connected with a knitting wire, will do.

When the surface is leveled and at least a month of time has passed (a prerequisite for the complete evaporation of moisture from the wall), acro-glue is applied as a third layer using a spatula, intended as an adhesive for foam boards, in order to reduce the adhesion (porosity) of the surface.

Wall leveling foundation for waterproofing
This photo shows that the process of leveling the wall has not yet been completed. The lighthouses are spaced 1.5 meters apart, and the foundation is awaiting a second layer of mortar for finishing. After applying it, they start cleaning, and then waterproofing..

Now you can start waterproofing.


The best base for waterproofing has always been liquid bitumen, which is applied with a roller to the entire surface of the foundation. Its disadvantages: it melts for a long time, freezes quickly without constant heating, harmful vapors emanate from it when applied (therefore, it is advisable to use a mask or respirator), and you will also have to accept that it will take a very long time to wash after such work (by the way, it copes with this perfectly acetone). Therefore, many categorically do not accept this method of waterproofing and recommend using TechnoNicol sheets, gluing it with a gas burner. But such waterproofing as from bitumen with technonikol cannot be achieved. Its only plus is the ease of installation. And, in the end, you still have to apply it over the bitumen. So, confining yourself only to gluing TechnoNicol, you will skip the most important step – filling all the pores and small cracks on the surface, which is actually what is achieved when waterproofing.

You can buy bitumen in bars, then you need to melt it. An excellent option for this is a 200-liter metal barrel, pre-installed on several bricks. In advance, it is necessary to add any waste oil to the barrel at the rate of 50 liters of mining for 130-150 kg. bitumen. The oil is suitable for both diesel and gasoline engines. The essence of adding mining is to impart plastic properties to bitumen after application to the surface. In ordinary language – so that the bitumen does not crack from frost and other weather conditions. It should be applied with a roller on all sides of the foundation that are underground. And from the outside – also above the surface of the earth.

When bitumen is applied, proceed to gluing TechnoNicol. As already mentioned, using a burner. We glue the sheets from top to bottom, constantly smoothing them and releasing the formed air under them. Important note: the burner must not be held close to the sheets! The best distance is 20-25 cm, otherwise they will melt. After completing work with TechnoNicol, grease the joints of the sheets with mastic.

When the waterproofing is completed, you can proceed with the thermal insulation.

Foundation wall coated with bitumen. Bitumen is applied not only to the area below the ground, but also to the top for the integrity of the layer. When the work with waterproofing is over, you can proceed with thermal insulation.

Thermal insulation

When choosing a material for thermal insulation, you should not save. Thermal insulation can be made in one of two versions: use expanded polystyrene (popularly – polystyrene) or expanded polystyrene (is extruded polystyrene in the form of foam). But the disadvantages of polystyrene are obvious: over time, it bakes in the sun, it has high thermal conductivity, is fragile and easily crumbles, it is not resistant even to slight mechanical damage, losing its original appearance. Penoplex, with its low density of 35 kg / m3 and a cost 2 times more than polystyrene, has a number of weight advantages over expanded polystyrene. For example, rigidity, high moisture resistance and thermal insulation. Penoplex is produced in the form of slabs with notches around the perimeter, helping to dock them together more tightly.

For the installation of such plates according to SNiP, it is recommended to use dowel-nails (umbrellas) with plastic nails, which excludes the formation of cold bridges when installing thermal insulation. Calculating the size of the dowels is simple. If you use 50 mm thick penoplex for insulation, which is the best option, umbrellas are required in the following sizes: diameter – 10 mm, length –120 mm. When calculating the number of dowels, on average, 1 m2 it takes about 5-6 pcs. dowel-nails.

To mount the plate, you need a perforator drill. Depending on the material of the base, the operating mode of the perforator must be set as follows: when working with concrete – rotation + impact; with gas silicate – only rotation.

When laying sheets on walls, they should be placed vertically to each other.

The drill for making holes for the installation of dowels is used SDS / plus with a diameter of 10 mm. and a length of at least 160 mm. Holes are made at least 4 in the corners and 1-2 in the middle. First, the dowel itself is hammered until it stops, and then the nail.

After installing the dowels, you need to cover the depressions from them with acro-glue in the same plane with the teploplex and be sure to let them dry for 6 hours, subject to good and dry weather.

Thermal insulation
When mounting each slab, holes for dowels are made 1 at each corner and 1-2 in the middle. It is not recommended to make more holes.

After installing the penoplex, it is clear that the level of the foundation is equal to the level of the wall. In order for the wall to be a canopy for the foundation, in the future, the insulation is installed on the wall. The thickness of the insulation is usually 2.5-3 cm.

Thermal insulation
Penoplex plates should fit snugly to each other without the formation of gaps and gaps. Each slab has special grooves, due to which the integrity of the installation and the absence of gaps are achieved.

Final surface leveling

Next, a reinforcing layer is applied. For its device, all the same acro-glue is needed (Polish-made glue is widely popular today – an excellent ratio in price and quality) and a facade mesh based on fiberglass. Many are mistaken and use the net for interior work on the street. As a result, the savings on this are very small, and the consequences are irreparable. Such a mesh is not suitable for the street due to the fact that under the influence of weather conditions, its destruction will begin in 7-10 years.

Average consumption of glue is 3-4 kg / m2 depending on how carefully the installation of the foam boards is done, plus 1-2 bags just in case.

The reinforcing mesh is cut into pieces in length and glued with glue using a construction trowel with an overlap of about 10-15 cm between each sheet to avoid the formation of cracks and chips at the joints of the mesh attachment. It is necessary to pass with acro-glue in 2 layers: the first one is for gluing the mesh to the penoplex, the second one is for fine leveling at an interval of at least a day, and perforated metal corners should be used at the corner joints. The next day, all irregularities in the second layer can be finally leveled with a hard foam trowel.

After complete drying, after 3-5 days, you need to go over the entire surface with a primer solution. The most convenient way to apply the primer is with a soft fiber roller. The foam roller is not suitable for this type of work.

Leveling the surface after waterproofing
The reinforcing mesh is glued, placing it horizontally relative to the wall. In this way, a large number of seams are avoided, which further affects the possible appearance of cracks..

By placing the mesh horizontally, the seams will only be at the corners.

After all the procedures, there is an important condition – the main wall should protrude at least 3 cm relative to the basement wall. This will serve as a kind of canopy for the top of the foundation to prevent moisture from entering. Ideally, the total thickness of insulation and plaster should be 3.5 cm.Therefore, when erecting walls, it is necessary to take this into account and slightly displace the first row of material from which the wall will be made along the outer edge.

Now the main work on insulation and waterproofing is over. This “layer cake”, the composition of which is described above, is a prerequisite for waterproofing and basement construction. Then you can proceed to the subsequent work on the foundation: making a blind area around the house, installing decorative stone, facade tiles, or simply painting with moisture-resistant paint.

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