What is mastic for foundation waterproofing, how to apply it correctly?

Selecting the appropriate materials is crucial for safeguarding the foundation of your house against water damage. Mastic, a type of sealant made especially for waterproofing, is one of the best options. However, what precisely is mastic, and how should it be used? We’ll explain all you need to know about mastic for waterproofing foundations in this article.

Mastic is a strong, flexible material that envelops your foundation in a waterproof layer. Usually, a mixture of polymers, bitumen, and other substances that offer superior adherence and water resistance are used to make it. The purpose of applying this sealant to the outside of your foundation walls is to stop moisture from penetrating and causing damage. It is particularly helpful for foundations that shift or settle because of its capacity to expand and contract in response to temperature changes.

While applying mastic may seem simple, getting the right application is essential to long-lasting protection. Prior to application, the surface needs to be dry, clean, and clear of any loose debris. It will be necessary to evenly distribute the mastic throughout the foundation using a brush or roller. It’s crucial to apply it in layers and to wait for each layer to dry completely before applying the next. This aids in creating a solid, impermeable barrier that guards against water damage to your foundation.

Knowing how to use mastic correctly will help you protect your foundation and increase the lifespan of your home, whether you’re building from scratch or remodeling an old building. Keep checking back as we go deeper into the detailed procedure and advice on getting the best results possible from mastic waterproofing.

What is it, properties and composition

The word "mastic" describes semi-liquid mixtures that are applied to the foundation’s surface to create a moisture-impermeable layer that shields structures from damage without the need for extra rigid reinforcement.

The material is composed of fillers, a water- or organic-based solvent, and a bitumen binder (black petroleum bitumen BN70/30 or modified alloys of different grades). The capacity for uniform distribution and strong adhesion are two of mastics’ general characteristics.

Scope of application

The purpose of foundation mastics is:

1. Obtaining a complete protective layer when carrying out external or internal waterproofing of structures in contact or buried in the ground up to 5 m. These include foundations of any type, floors, walls of basements and garages, plinth strips. The exact purpose depends on the brand; the range includes both universal and specialized formulations.
2. Installation or repair of rolled waterproofing materials, including on vertical surfaces. Coating the panels with mastic eliminates the formation of voids between the layers and makes the protection monolithic.
3. Preparation of foundations for installation of other hydro- or heat-insulating materials.

The foundation’s depth determines the waterproofing layer’s thickness. Protecting structures down to a depth of 3 m requires applying a minimum of 2 layers of mastic to the surface, each layer having a thickness of 2 mm. For structures deeper than 3 m, this is equal to 2-4 layers, each with a thickness of 2 to 4 mm after drying.

Advantages and disadvantages

These compositions have the following benefits:

1. Creation of seamless, highly adhesive, waterproof, durable and sufficiently elastic coatings that follow the contour of any type of foundation. The need for reinforcement arises only in difficult areas – joints of structures, corners or over possible cracks.
2. Ease of application, relatively high speed of waterproofing work.
3. High resistance to biological factors, temperature changes and ultraviolet radiation.
4. Filling small pores and voids in concrete.
5. Simplification of subsequent thermal insulation work. Insulation boards adhere more easily to a slightly sticky surface; when using brands without toxic solvents, the mastic does not destroy the structure of polystyrene foam and allows you to create monolithic protection.

The drawbacks consist of:

1. Strict requirements for the condition of treated surfaces and work conditions. Applying mastics to wet, weak, icy or dirty substrates is considered a gross violation of technology.
2. Increased consumption on uneven surfaces (including masonry) and the likelihood of rupture of coatings in the presence of sharp protrusions or cavities.
3. Relatively high water absorption of the formed bitumen coatings. Even for the best brands this figure varies from 0.5 to 4%; such water protection is not designed for constant moisture resistance. As a result, with a depth of structures of more than 2-5 m (the exact value depends on the type of mastic and parameters of the site), the construction of the base on aggressive soils and high risks of the base (groundwater level above 1.5 m) is selected another way of waterproofing the foundation. In particular, mastic is combined with roller materials.
4. The need for tracking the thickness and uniformity of the applied layers (in particularly important cases – with the control of the probe) and the time of their drying. Also, when working with modern compositions, it is important to check the date of their release and storage conditions.

In general, benefits predominate: mastic is regarded as the most reliable and affordable waterproofing material when the foundation is operated under standard conditions.

Classification of waterproofing material

Separation conditioning:

1. According to the method of installation and readiness for use, hot and cold applied compositions are distinguished; the former require heating to at least 190 ° C and special equipment, the latter can be one- or two-component. In private practice, the most popular (up to 95% of the market) are ready-to-apply one-component cold mastics that do not require mixing with other materials.
2. Based on the type of base, there are water-based products and brands diluted with organic solvents. The former are valued for their ease of application (including mechanized methods), accelerated and complete hardening, environmental friendliness and safety. The latter can be used at sub-zero temperatures, but are considered more dangerous when applied and dried. In particular, if it is necessary to waterproof basements in use, solvent-based mastics are abandoned in favor of water-based ones, or the resulting coatings are subsequently covered with other materials.
3. According to the composition and type of filler, there are bitumen mastics on a mineral basis (with the addition of cement, chalk, ash, peat chips or asbestos), emulsions (aqueous solutions with finely ground modified bitumen, applied in 4-5 layers or used in preparing the foundation for insulation work ) and complex compositions with additives of polymers and rubber. The latter are more expensive, but benefit from elasticity and water resistance.

Mastic is an essential component of foundation waterproofing, which fortifies and stretches the barrier to keep water out of your house. The proper application of mastic necessitates surface preparation, uniform application, and adequate curing. This post will guide you through the crucial procedures for applying mastic for foundation waterproofing in a way that will keep your house safe and dry.

Common brands

The most reliable metrics and user feedback have:

• all lines of TechnoNIKOL mastics;
• Grid cold bitumen mastics, in particular a specialized brand for foundation waterproofing – MGH-G;
• Icopal waterproofing mastic – a composition based on high-quality bitumen and solvent with the addition of corrosion inhibitors and antiseptics;
• Bitumast – mastic for coating waterproofing of foundations, compatible with almost all bitumen and bitumen-polymer materials;
• Suho Izowax – water-based cold mastic.

Which one is better to choose??

For foundations and floors, ready-to-apply waterproofing mastics are preferred because they have low (ideally, no more than 1-2%) water absorption rates after drying and can tolerate brief exposure to water under pressure greater than 0.003 MPa.

The following factors are considered when selecting a particular brand:

• adhesion indicators with concrete and rolled materials (the higher they are, the better);
• declared consumption and proportion of dry non-volatile substances in the mastic residue;
• heat resistance of the mastic (ideally above 100 °C, but not less than 70);
• appearance and weight of the composition – high-quality mastic has a uniform plastic structure and weighs less than water, in practice this means that its weight should not exceed the volume of the container; heavier, cheaper brands crack faster and collapse after 1-2 years.

These requirements are satisfied by the specialized brands Technonikol and Grida MGH-G. Universal mastics, or roofing mastics, can only be used in dry, non-aggressive, permeable soils with low groundwater levels and shallow foundation depths.

Preparing the foundation surface

In order to prepare the foundations, in this order:

1. The strength and moisture content of hardened concrete is checked. It is recommended to start waterproofing work at least a month after concreting. When working with old bases, the surface is cleaned of weak and flaking particles, all possible cracks are covered with a solution and reinforced with fiberglass mesh.
2. The evenness of surfaces is checked and possible imperfections are eliminated. At this stage, sharp protrusions larger than 2 mm are removed or hidden, masonry seams and cracks are covered. Problem areas and joints, if necessary, are reinforced with mesh.
3. The foundation walls are cleaned, dusted, treated with primer or antiseptic primer and dried well.

An optional but crucial step to lower mastic consumption and enhance adhesion quality is impregnating concrete with primer. This work should not be neglected if there are no additional insulating layers; diluted versions of the same mastic can serve as an affordable substitute for pricey primers.

Execution of work

Mastics are distributed using brushes, spatulas, or rollers, following the manufacturer’s instructions.

Among the technology’s primary requirements are:

1. Carrying out work under conditions allowed in the instructions. Particular attention is paid to the temperature of the air, the base and the mastic itself; even “winter” types cannot be applied to a frost-covered foundation.
2. The need for uniform distribution of the composition, the absence of unpainted areas or drips.
3. Tracking the thickness of applied materials after each layer has dried.
4. Allow each applied layer to dry completely.

While lengthy pauses during waterproofing are not harmful, they are not recommended; every layer needs to be applied completely. PPE will be used while working, and all tools and equipment will be quickly cleaned up after.

Price

The most well-known brands’ prices (see the table below) are essentially the same; with them, a one-meter square of foundation coated in two layers should cost between 120 and 250 rubles.

This section contains all the information you require regarding foundation waterproofing.

Knowing what mastic is and how to apply it will make a big difference in the waterproofing of your foundation. This adaptable, strong material ensures the longevity and stability of your structure by acting as a dependable barrier against moisture.

Correct application of mastic is essential to getting the best results. To begin, give the surface a thorough cleaning to get rid of any debris or loose particles. Before starting the application process, make sure the area is dry.

Apply the mastic to the surface evenly using a brush or roller. Particular attention should be paid to joints and corners since these are common places where water can seep in. Let the initial layer fully dry before adding any more layers, if necessary.

Your foundation will benefit from routine upkeep and inspection, which will enable you to identify possible problems early. You can prevent water damage to your house and maintain a dry, healthy living environment by using mastic correctly.

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