Advantages and disadvantages of using roofing material to protect the foundation from groundwater, the technology of fastening the product to the surface, the choice of materials to create the enclosing layer. Waterproofing a foundation with roofing felt is the creation of a rigid continuous waterproof covering of sheet material. It is considered the best option for protecting the underground part of the base. We will talk about how to attach the product to the wall in our article.
Features of waterproofing the foundation with roofing material
Roofing material is a material consisting of a flexible base covered with bitumen. Its purpose is to prevent water from contacting the wall. Standard products are made from cardboard of various densities, but more modern models are made on the basis of fiberglass and fiberglass. Sold in rolls longer than 3 m.
The sheet is glued to the partition, creating a water-impermeable coating. Its use is justified when the distance from the basement floor to the groundwater level is less than 1 m. For fixing to the base, it is recommended to use mastic in a hot or cold state, mechanical fastening is unreliable. If moisture comes close to the surface, pasting will not be enough, it is necessary to build a drainage system.
When waterproofing a foundation, the material is applied to vertical and horizontal surfaces. In the second case, the sheets are laid on a concrete pad even before the walls are erected. It protects the structure from moisture penetration from below.
When working with hot bitumen, adhere to safety rules. The main requirements are to wear only closed clothes, with long sleeves. Contact with the skin will cause severe burns. Use goggles and respirators to protect your eyes and respiratory system. When applied to a damp wall, hot drops are formed and scatter in all directions, so rest in rainy weather.
Advantages and disadvantages of waterproofing the foundation with roofing felt
Covering the foundation with roofing felt is an affordable and inexpensive option for protecting the structure from water. The owners point out numerous positive aspects of using this isolator:
- The use of the product in construction is beneficial, because it is inexpensive.
- The coating is highly water resistant.
- The service life of the material is several decades.
- The ability to close cracks and other problem areas.
- Oxidation resistance.
- Lack of reaction with salts that are present in soil and groundwater.
- Withstands large temperature drops.
- The styling technology is quite simple. The work can be done independently.
- The insulator is lightweight.
The home owner should be aware of the problems that may arise when using the material:
- The canvas is not elastic enough, its structure is fragile. In the event of shrinkage, the building may burst.
- The product is classified as a fire hazardous substance.
- Afraid of sunlight. Under the influence of ultraviolet light, the service life is reduced to several years.
- Over time, the sheet can peel off from the base.
- Not resistant to external influences, it should be protected with solid shields.
Foundation waterproofing technology with roofing felt
The formation of a protective coating is carried out in several stages. At the first stage, issues related to the choice of types of insulator and bitumen, as well as the determination of their quantity, are resolved. Then the surface is prepared and the material is fixed to the wall.
Material selection
For waterproofing the foundation, durable and moisture-resistant products of the RPP or RKP brand are suitable. The first letter means "roofing material", the second - the type, "roofing" or "lining", the last - the type of powder (dusty or coarse-grained). Numbers in the designation - cardboard density, g / m2… The larger the value, the denser and thicker the canvas.
It is preferable to use samples of the RPP brand (for example, RPP-300), these are ordinary smooth sheets of low cost. In the store, they are sold in rolls with an area of 20 m2… You can also use RCP-350, 400.
It is recommended to choose the brand of roofing material for waterproofing the foundation among special products. TechnoNicol is suitable with a base made of synthetic fabrics.
The composition of the material affects its field of application. Modifications on a cardboard base for horizontal waterproofing are not used. Cloths based on fiberglass or fiberglass have little flexibility and tear when deformed, so it is not recommended to glue them to vertical walls.
To work, you need to stock up on bitumen or bitumen mastic, which not only fix the sheets, but also close the pores in the wall. The first type includes solid samples, which are melted over a fire to a liquid state before use. When heated, water is completely removed from the solution.
Mastics are diluted with special liquids and do not require preheating. There are several varieties of the mixture, which differ in composition and cost. The type of impregnation depends on which roofing material you decide to use for waterproofing the foundation.
Inexpensive brands include the usual solvent-based bitumen mastic. In other formulations, special components are added to improve their qualities. They are used in special cases where the appropriateness of the application justifies the high price. For example, sheets glued with rubber-bitumen mastic have better water-repellent properties and can protect the base even in water. The durability of the coating is doubled.
A primer is necessary to increase the adhesion of the wall to the resin. On construction markets, special solutions for roofing materials are sold - primers. They are already diluted to the desired consistency and are ready to use. In addition, the tool can be prepared by hand. To do this, dissolve the product of the BN70 / 90 or BN90 / 10 brand in gasoline in a ratio of 1: 3 by weight. You can soak the wall with a liquid mastic with a heat resistance above 80 degrees.
When buying, choose a product only in good condition, because it is very difficult to repair a poor-quality foundation covering in a residential building. Pay attention to these points:
- Do not purchase items that are crushed, damaged or overheated in the sun. Otherwise, you won't even expand it.
- Do not buy products with damaged edges and tears in the web. A maximum of two tears with a length of not more than 30 mm are allowed along the edges.
- In the roll, the ends must be at the same level, protrusion up to 15 mm is allowed.
- Examine the section of the sheet, light spots indicate poor impregnation of the canvas with bitumen. The "cake" of a quality roofing material should be brown.
- The roll is wrapped at the factory with a paper strip more than 50 cm wide.
- The label must contain an inscription that the product complies with GOST 10923-93 and TU of a specific manufacturer. The company stamp has dimensions of 150x200 mm. Make sure that there is a date of issue of the goods, the name of the manufacturer, the batch number.
The number of rolls and the volume of mastic depends on several factors - the area of the base, the density of the material, the proximity of groundwater. In order not to be mistaken with the volume of purchases, use our tips:
- The rolls are always marked with the length and width of the product. Calculate the surface area of the wall, divide by the area of one roll and find out the required number of sheets. If you plan to lay two layers, multiply the result by two.
- To cover 1 m2 vertical wall, you need 300-900 g of resin, horizontal section - 1-2 kg.
- To reduce consumption, control the layer depth using thickness gauges or improvised means.
Preparation of the foundation for the installation of roofing material
Foundations can be waterproofed both at the construction stage and during the operation of the building.
If the house is residential, dig a moat nearby to the full depth of the structure. The width of the trench should be at least 1 m so that nothing interferes with the process.
Surface preparation is performed as follows:
- Examine the wall for damage, determine options for their elimination.
- Expand the slots and seal up with cement mortar.
- If you find a large number of sinks, fill them with a special fine-grained cement mortar. Reworking is necessary to avoid the formation of bubbles during the application of bitumen.
- Using a grinder, round off sharp corners and protrusions that could damage the canvas.
- Remove dust and other dirt from the surface.
- Make sure the wall is dry. The degree of moisture can be determined using a moisture meter. The maximum allowable value is 4%. If the device is not available, cover the area with plastic wrap 1x1 m in size, secure with adhesive tape and leave for a day. If a damp spot appears under it, the partition must be dried using a construction hair dryer.
Waterproofing with roofing material is often combined with other methods of protection - coating and penetrating. With a shallow groundwater table, it is recommended to build a drainage system.
Preparation of bitumen for waterproofing the foundation
The mastic is diluted with a solvent or melted over a fire until smooth, convenient for spreading.
To work with solid material, you will need a metal container, the size of which depends on the volume of work. Pour the raw materials into the tank and make a fire under it. It is allowed to add waste engine oil to the solution in an amount of 20-30% of the resin volume, which will increase the adhesive ability of the substance and improve protection against moisture.
Bitumen hardens quickly enough, so 1-2 assistants are needed. One person will be busy preparing the solution, the rest will apply the mixture and glue the samples.
The mastic is liquefied without fire. Pour the pre-crushed substance into a container (or pour if it is semi-liquid), fill with solvent and stir until the desired condition. Do not ignore fire safety regulations due to flammable solvent fumes.
Vertical waterproofing with roofing material of the foundation
Vertical waterproofing is required to protect the side surfaces of the foundation. Perform the work in the following sequence:
- Brush primer or other primer onto the wall in one coat. On areas covered with fresh cement-sand plaster - two. Wait for the partition to dry.
- Pour liquid bitumen into a bucket and transfer to the work site.
- Dip a wide brush into the solution and brush from top to bottom. Perform the next layer with an overlap on the first.
- The installation of the roll insulator consists in melting the working side of the roofing material with a blowtorch and gluing it to the prepared wall in the direction "from bottom to top". If the resin is cured, heat it up with a blowtorch.
- Place the roll with the working side (without powder) to the resin, warm it up with a blowtorch, roll it out and press down. Do not overheat the sample so that it does not lose its quality. If there is drainage, the insulator should be glued below the level of the drain pipes.
- On the next canvas, coat the edges of the sheets with mastic (strip width 15-20 cm) and glue with an overlap on adjacent samples.
- In areas with high humidity or in places where the soil is very wet, lay a second layer of roofing material. To do this, coat the already fixed sheets with mastic and repeat the previous operation. It is recommended to glue two rows in case of seeping water, three - if the hydrostatic head is more than 0.1 MPa. The optimum "cake" thickness is 5 mm.
- To protect the coating, lean a sheet of plywood or other material against the roofing material and backfill the trench with earth.
You can cut the roofing material across or along. In the first case, you can use a knife. In the second - with a saw on a tree, heated by a wire, even a chainsaw. If the quality of the cut is not important, the material can be chopped with an ax. However, it will be very difficult to clean the tool from the resin. Wet the roll with water before cutting to make the process easier.
Horizontal waterproofing of the foundation with roofing material
Work is carried out only at the stage of construction of the building. To protect the strip and monolithic foundation from water, it is laid in two places - between the foundation and the ground, as well as between the foundation and the wall of the building.
The formation of the lower level of the horizontal waterproofing of the foundation with roofing felt, which is also called cut-off, is performed in the following sequence:
- At the bottom of the pit, pour a layer of oily clay 20-30 cm thick and tamp it.
- Pour it with concrete 5-7 mm thick, level the surface to the horizon. For work, you need a very high quality cement.
- After the screed has completely dried (after 10-15 days), carefully coat it with bitumen.
- Put the first layer of roofing material on the mastic with an overlap of 15-20 cm on the adjacent sheets. Weld the joints with a gas burner. The canvas should extend beyond the walls by 15-20 cm, so that after the erection of the partition, you can wrap it up.
- Re-coat the floor with mastic and glue the second row perpendicular to the first.
- Wait for the resin to harden and fill the base with 5-7 mm concrete.
- After building the foundation, fold the sheets up and fix them with resin to a vertical surface. The room will turn out to be completely closed from below from groundwater. Thus, a barrier is created for the capillary rise of liquid along the walls.
It is not necessary to waterproof the entire basement floor. Often, the panel is laid only under the foundation of the building. To do this, a piece is cut from the roll, the width of which is 15-20 cm wider than the width of the partition on the side. Laying is carried out in the same way as in the previous case.
Two hydro-barriers are installed above the soil - the first is 20 cm above the ground, it protects the base from groundwater from the capillaries of the partition. The second is directly under the wall of the building. If the base is concrete, it must be poured in two stages - before and after installing the insulator.
To properly lay the material, fill the upper surface of the base with a cement screed to eliminate unevenness. After the solution has dried, coat it with bitumen and lay roofing material on top. Excess pieces should hang from the wall. Repeat the procedure twice. Bend the edges of the product down and glue with mastic.
Watch a video about waterproofing the foundation with roofing felt:
In this article, we examined the most common method of waterproofing a foundation - using roofing material. The work can be performed without the involvement of professional builders, but for this it is necessary to choose the right materials and not deviate from construction technology. Then the base will not require repair for a long time.
