Drainage systems Waterproofing

Waterproofing Of Underground Structures And Parts Of Buildings

Waterproofing of underground structures and parts of buildings
Written by David J

Table of Contents

Features of underground waterproofing

Waterproofing of any surfaces underground below level is necessary to protect them from exposure:

  1. Water – The penetration of water into structural elements, such as concrete and brick, gradually destroys them.
  2. Aggressive environment – In groundwater and other waters there are impurities and minerals that destroy it when in contact with concrete.

Underground waterproofing is applied to that part of the building or any other structure that is below zero level or ground level. These underground parts of the structure are more susceptible to water and moisture.

The underground construction of a building or any other structure requires high-quality waterproofing. Building codes define it as the treatment of a surface or part of a structure to prevent the impact of moisture, aggressive environment, or water on the building material from which the structure is built. The task of insulation is also to prevent the passage of water under hydrostatic pressure inside the structure.

Which structures are located underground, are subject to waterproofing:

  1. Foundation slab
  2. Foundation walls
  3. Cold concreting joints
  4. Communication entry points

All elements of the structure located underground require protection using waterproofing, and this is regardless of whether the building is located together with low or high groundwater since humidity penetrates into the ground only from underground, but also from the surface – rainwater and water formed as a result of snow melting.

Moist and water-soaked soil, in turn, gives all the moisture into concrete, brick, or block from which the foundation and walls of a building or house are made, which, in the absence of good insulation, leads to the destruction and leaks.

Important: Regarding the availability of groundwater, do not forget that there are quite a lot of water channels and streams underground, and if you have low groundwater today, this does not mean that it will always be so. And when designing structures, it is necessary to take this into account. 

For example, there are often situations when construction work begins near your house or building, for example, on the construction of a new house, thereby violating the underground space and how the water passes there. As a result, the same water appears in the basement of your building.

If the waterproofing of the underground part of the building is done with violations, then the following consequences may await you:

  • Flooding of premises – If your building has a basement or underground Parking, then in the absence of proper waterproofing of the walls below ground level, water can get inside from the outside and lead to the formation of water in the operated premises. This circumstance may damage the existing decoration, property, etc…
  • Cracks in the wall and foundation – In the absence of reliable waterproofing, moisture is absorbed into the base of concrete or other material, and then due to temperature differences, freezes in winter and thaws in spring, which leads to the formation of microcracks, pores, and voids in concrete. The resulting microcracks are growing every year and after some time can develop into a serious cracks, the repair of which will cost a lot of money.
  • Mold and mildew are dangerous to health – When underground moisture from the outside is absorbed into the foundation, it can form a wet spot inside. Due to excessive humidity, fungus and mold are formed on the walls. They grow and threaten human health.

Design of waterproofing of underground structures and parts of buildings

Choosing the right waterproofing for your particular project or construction is not always an obvious choice. To make the right choice when designing, it is necessary to consider a wide range of issues.

The issues to be considered should include:

  • Requirements of the project itself;
  • Geological surveys and geotechnical reports – will help to identify some of the possible conditions that you will have to deal with when designing a structure – underground groundwater, soil, possible pollutants, chemicals, etc. This can dramatically affect the choice of waterproofing of the building.

    For example, a bentonite-based system can be negatively affected underground by contact with salt water (Salts can prevent the clay from swelling and make it less effective). Today there are more advanced bentonites that are more resistant to the effects of salts and are specially designed with this in mind.
  • Availability of ground water– If available, in addition to waterproofing, it is also recommended to install a drainage system to drain water from the foundation of the building;
  • Working site conditions where the building will be;
  • The budget for the construction and insulation of the building is below zero.

When a new building or structure is being built, when designing, one or another waterproofing is always put into the project, depending on the budget, the features of the construct or structure, field conditions, etc… At the same time, designers do not always make the right choice, since not all design companies specialize in waterproofing.

Most design companies are mainly focused on the design of buildings and structures as a whole and more than once forget to pay due to the topic of waterproofing structures in their project. Accordingly, before applying the designed insulation material, it is recommended to consult with an engineer or a specialist of a large contractor whose specialization is waterproofing and drainage.

Important: The protection of the underground part of a structure or building is needed not only to protect against the penetration of a liquid medium into the structure itself, but also to prevent its further destruction. 

Concrete, brick, aerated concrete blocks, etc..., these are all materials that absorb moisture, which in turn, with a change in temperature and climatic conditions, expands, narrows and has a negative impact on these materials, which, without proper protection, will eventually lead to destruction and cracking.

Diagram of the underground protection and waterproofing arrangement:

Diagram of the underground protection and waterproofing arrangement

Types of underground waterproofing

Today there are quite a lot of different types of waterproofing coatings. For each case, it is necessary to select your own type of insulation.
The main types of waterproofing used to protect the underground part of the building and other structures:

Outside – primary waterproofing:

  • Surfaced and pasted membrane insulation – In the first case, the presence of an adhesive base subjected to heating is implied, for the second type bituminous mastics are used.
  • Mounted PVC membranes – To be fixed to the base mechanically with the help of special rails. The seams are sewn together using a special construction hair dryer.
  • Waterproofing with liquid rubber – Applied manually or by spraying. Forms a homogeneous membrane without seams and joints, with 100% adhesion to the surface and an elasticity coefficient of 800%.
  • Polyurethane waterproofing is a seamless membrane with 100% adhesion to the base and a high coefficient of elasticity. The material can be applied either manually or by spraying.
  • Waterproofing with polyurea – Polyurea is sprayed in most cases. As a result, a strong homogeneous coating is obtained.

From the inside – secondary waterproofing and repair:

  • Injection waterproofing – Injection resins or gels are injected into seams, cracks, or the body of the structure under pressure using special equipment.
  • Veil waterproofing – is when the insulating compound is injected from the inside, behind walls, or problem areas, thereby forming a protective film between the ground and the wall.
  • Penetrating compounds – This type of insulation penetrates into the structure of the concrete due to abundant moisture. Upon penetration into the base, a protective film is formed that prevents water from passing inside. This type of water protection is not very effective and is suitable exclusively for walls made of high-quality concrete, which today can be found quite rarely.
  • Polymer-cement insulation, that works on negative water pressure – Compounds that keep the water pressure from the outside to the inside.

Injection waterproofing of underground structures and parts of the building:

The injection method is one of the most effective waterproofing methods used from inside the room. This method is ideal for repair work and stopping leaks in the underground part of a house or building when there is no access to its walls from the outside. When performing injection work, polyurethane resin penetrates into all microcracks, voids, and pores of the concrete or other bases, expands, squeezes moisture out of there, and fills them with a hydrophobic composition.

Injection waterproofing is also used for:

  1. Sealing seams – Seams are the weakest point in any design and they are ones that start to let water pass through in the first place. The injection method is used to seal them. Polyurethane resin is pumped into the seam, thereby filling all voids and stopping the water.
  2. Sealing of the places of entry of communications – If there are leaks in the places of entry of underground communications or pipes, then they can be stopped by injection. Waterproofing of the base made of concrete, FBS blocks, and bricks – When polyurethane resin is injected into the body of the structure, it fills all voids and destroyed areas and does not allow water and moisture to pass inside.
  3. Sealing cracks – Cracks are stitched, and a special sealant is sealed there and then injected.
  4. Cut-off waterproofing – Injection can be used to restore broken or unfulfilled cut-off waterproofing. This method of protection is able to prevent the rise of capillary moisture from the bottom of the foundation upwards.

Underground waterproofing materials

The durability and reliability of protecting your building, house, or structure from the water will depend on the choice of insulation material and type of waterproofing. In each type or method of protection from moisture, there is a large selection of materials and their manufacturers, here are some of them:

  • Technonicol Foundation – Is deposited on all structures below ground level using a burner. It is applied in at least 2 layers to cover the seams between the sheets.
  • Sika PVC membrane.
  • FlexLock liquid rubber– Applied manually or by cold spraying. During installation, it forms a seamless, elastic coating with 100% adhesion to the surface. This material is ideal for waterproofing foundations, walls, and underground concrete structures.
  • Polyurethane PolyFlex mastics.
  • HydroInject injection formulations.
  • HydroPaz polymer-cement mastics.

Materials for waterproofing underground structures and constructs: How to choose them correctly and not make a mistake?

The range of underground products and solutions is very large. Many manufacturers offer several product lines, each of which has its own specialization, and characteristics and is suitable for certain areas of work. For example, one material is used for an underground flat concrete wall, and another is used for the construction of brick inserts or technical holes.

Here are some recommendations:

For waterproofing the part of the structure or construct that is below the zero level, materials with the following advantages are best suited:

  1. Lack of seams – Seams are the most vulnerable places in any waterproofing system.
  2. 100% adhesion to the base – Does not allow water and moisture to walk in the voids and cavities formed under the coating.
  3. High coefficient of tension – Prevents the insulation coating from tearing or dispersing during shrinkage of the building or its dynamics.
  4. Ratio, price, quality.

One of such materials is liquid rubber of FlexLock type by the German company Hydro. Unlike common surfaced and PVC membranes, liquid rubber after an application has no seams and joints. After application to the structures, a homogeneous elastic membrane with 100% adhesion (adhesion) to the surface is obtained.

Important: The manufacturer of waterproofing works is responsible for the guarantee against water penetration and leaks. When choosing a material, pay attention to the guarantee provided by the contracting company, the greater the guarantee for a certain technology, the more reliable it is.

Waterproofing services for underground structures

When choosing a protective composition, it is best to consult with a specialized organization that deals directly with waterproofing and uses different methods and types (if the organization specializes in only one method of insulation, then it will most likely recommend it).

When choosing, it is not recommended to consult with the manufacturer of specific waterproofing material, since manufacturers will always advertise their product and claim that it is the best and suitable in any situation (they also need to sell it).

To get the right advice, it is best to call a representative of a specialized organization to your facility so that he can independently look at your design. It is a professional who will be able to correctly assess which waterproofing compounds are best suited.

Important: The durability of the underground coating depends not only on the product itself, but also on the quality of its application or installation.

Recommendations when choosing a contractor for underground waterproofing:

  • Clear specialization in waterproofing. It is best to choose a company whose specialization is waterproofing and drainage (drainage), since they have a lot of experience in this, respectively, they will be able to choose the right product and apply it.

    Firms, engaged in construction in general or any other specialized construction, for example, pouring foundations, in any case (so that they do not declare) will approach the issue of waterproofing superficially, since they hardly have waterproofing specialists (at best, their employees are generalists) and most likely their work will have to be redone.
  • There is no connection to a specific material. It is best to choose a contractor whose specialization is waterproofing, while he performs work with different waterproofing materials since such a contractor will be able to correctly evaluate your project and offer the right type of insulation.
  • A large company. It is best to choose a large contractor, with a staff of employees, own equipment, fleet, etc… As a rule, the larger the organization, the more experienced and more responsible it is to work since reputation is important to it and it has something to answer for in the event of warranty obligations. It is not difficult to identify a large organization – talk to their engineer (you will immediately see his qualifications).

    Look at what he came to you on, if these are branded cars of the organization, then a company has a large fleet (and it hardly consists of 2 persons). Look at the company’s advertising brochure (its presence is a good sign). Look at the portfolio of completed works.

    And finally, visit their office, see that people work there, there are desks and computers (there are situations when small firms of 2 persons, sometimes even without any office, try to impersonate a serious organization and professionals).
  • Warranty. A serious company gives a high-quality waterproofing material, a guarantee of 6-7 years. This guarantee should be spelled out in the contract. If you were given a lower warranty, it means one of two things – either the contractor is not confident in his abilities, or the waterproofing material used is of poor quality.

The cost of waterproofing underground structures and constructs

The indicated prices and costs are preliminary. To get the final price and cost estimates, you need to contact us by phone, email, or call our engineer to inspect your facility.

Cost of works, performed outside:

Description of worksUnit of measurementPrice in %
The arrangement of surfaced waterproofing on the horizonm210
The arrangement of surfaced waterproofing on the verticalm215
Arrangement of a self-adhesive membrane on the horizonm211
Arrangement of a self-adhesive membrane on a verticalm215
Arrangement of PVC membrane on the horizonm220
Arrangement of PVC membrane on the verticalm225
Application of polyuream240
Application of mastic waterproofingm210
Application of liquid rubber sprayingm210
Applying liquid rubber manuallym215
Application of cement-mineral double-component waterproofingm220
Polyurethane waterproofing arrangementm220
Application of penetrating compoundsm220
Application of primerm25

The cost of work, performed from the inside:

Description of worksUnit of measurementPrice in $
Waterproofing of cold joints: -Works on the arrangement of indenting -clearing the indenting -layer-by-layer sealing of non-shrinkable compositionrunning meter30
Waterproofing of interblock joints: -Works on the arrangement of indenting -clearing the indenting -layer-by-layer sealing of non-shrinkable compositionrunning meter25
Waterproofing of deformation joints: – Works on the arrangement of indenting -clearing the indenting -sealing of the elastic profile -sealing of non-shrinkable composition -complex of works on injectionrunning meter290
Инъекционная гидроизоляция швов / отсечная гидроизоляция -Works on the arrangement of indenting -clearing the indenting -layer-by-layer sealing of non-shrinkable composition  – Works on the arrangement of boreholes and assembly of packers -a complex of works on injection -dismantling of packers and sealing of injection holesrunning meter100
Injection waterproofing into the body of concrete -marking, Works on the arrangement of boreholes and assembly of packers -a complex of works on injection -dismantling of packers and sealing of injection holesm2120
Injection waterproofing into the brick body -marking, Works on the arrangement of boreholes and assembly of packers -a complex of works on injection -dismantling of packers and sealing of injection holesm2150
Cement-mineral waterproofingm230
Penetrating waterproofingm230
Waterproofing of entry places of communications: -Works on the arrangement of indenting -clearing the indenting -layer-by-layer sealing of non-shrinkable composition -Works on the arrangement of boreholes and installation of packers -a complex of works on injection -dismantling of packers and sealing of injection holespiece300

Underground Waterproofing Cost Calculator

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David J

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