Basement Waterproofing; Need & Different Membranes Used For It

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basement waterproofing
Basement Waterproofing

Basement water ingress can lead to problems with a building. Underground water and groundwater is the main source of water which will enter a basement. If the water table rises above the level of the basement floor water can enter the basement through the sidewall. Basement waterproofing thereby becomes important. It involves techniques and materials used to prevent water from penetrating the basement of a structure. Waterproofing a basement that is below ground level can require the application of sealant materials, the installation of drains and sump pumps, and more. The spaces of basements are particularly prone to wetness and moisture development. Water in the soil causes hydrostatic pressure to be exerted underneath basement floors and walls. This hydrostatic pressure can force water through cracks, which can cause major structural damage as well as mold, decay, and other moisture-related problems.

Why do we need basement waterproofing?

If you haven’t waterproofed your basement, rain and groundwater can find several ways into your building and wreak havoc on the structure and your belongings. Water seepage in basement and crawl spaces usually occurs over long periods and can be caused by numerous factors.

  • Concrete is one of the most commonly used materials in home construction. When pockets of air are not removed, or the mixture is not allowed to cure properly, the concrete can crack, which allows water to force its way through the wall.
  • Foundations (footings) are horizontal pads that define the perimeter of foundation walls. When footings are too narrow or are not laid deep enough, they are susceptible to movement caused by soil erosion.
  • Gutters and downspouts are used to catch rainwater as it falls and to discharge it away from houses and buildings. When gutters are clogged or downspouts are broken, rainwater is absorbed by the soil near the foundation, increasing hydrostatic pressure.
  • Weeping tile is a porous plastic drain pipe installed around the perimeter of the house. The main purpose of the external weeping tile is to prevent water from getting into a basement. However, these pipes can become clogged or damaged, which causes excess water to put pressure on internal walls and basement floors.
  • Water build up inside window wells, after heavy rain or snow, can lead to leaks through basement window seams.
  • Ground saturation is another common form of basement leaks. When the footing drain fails the ground around the basement can contain too much water and when the saturation point is met flooding can occur.

Signs of basement water damage in basement

  • Cracked walls: Cracks may be horizontal, vertical, diagonal or stair-stepped. Severe pressure or structural damage is evident by widening cracks.
  • Buckling walls: Usually caused by hydrostatic pressure. Walls appear to be bowed inward.
  • Peeling paint: Water seeping through walls may lead to bubbling or peeling paint along basement walls.
  • Efflorescence: White, powdery residue found on basement walls near the floor.
  • Mold: Fungi usually grow in damp, dark areas and can cause respiratory problems after prolonged exposure.

Different types of basement waterproofing membrane

There are different types of basement waterproofing membranes available in the market depending on the needs and requirements each of them is used. Each of them is explained below.

Single-ply rubber membrane – It is used in the basement waterproofing. It is manufactured from synthetic EPDM rubber. The EPDM rubber waterproofing membranes are techno-commercially much better than substitutes.

Portland cement-based membrane – This type of membrane helps in resisting positive and negative pressure under 100m head in water retaining and below ground structures.

Cement-based membrane – It is applied to a concrete surface, the active chemicals combine with the free lime and moisture present in the capillary tract to form insoluble crystalline complexes. These crystals block the capillaries and minor shrinkage cracks in the concrete to prevent any further water ingress.

Types of basement waterproofing membrane

Fiber-reinforced membrane – It is a compound system consisting of a rubberized bitumen emulsion with additives and a powder component. The application is easy even around details such as pipe penetrations, inner and outer corners, wall-floor junctions, etc.

Cell mesh membrane – This type of membrane uses cell mesh that bonds with freshly placed concrete which acts as a seal. This prevents water ingress. It can be installed rapidly, with no need for blinding concrete, priming, or protection and can be trafficked immediately after application.

Polymer modified thick film membrane – It is suitable for waterproofing building structures inside and outside as well as foundation skirting. It cures rapidly even in adverse weather conditions. It is a polymer modified thick film sealant.

Bitumen/tar-based membrane – Cold-applied asphalt/coal tar is a common below-grade waterproofing. It is good only for damp proofing.

APP modified bitumen membrane – Membrane It has superior puncture resistance, high tensile strength and can withstand structural stresses. Sometimes it is reinforced with a fiberglass mat that is completely impregnated and coated with an elastomeric modified bitumen compound.

Self-adhesive membrane – It is a modified bitumen membrane that has superior low-temperature application and good flexibility. Due to its flexibility and presence of a tough and durable top surface. The membrane is protected on the self-adhesive side usually with a silicone coated release film.

Preformed membrane – This type of material masks the surface with in-situ membranes with bonding adhesives. Since membranes are factory-made, quality control for thickness is possible, and they are suitable for high water tables, deep and large basements.

EPDM membrane – This is a single-ply rubber waterproofing membrane that is being used in the basement waterproofing. It is the best material for waterproofing in a high water table, which is applied as a loose lay.