Waterproofing of Elevator Pits

Elevator pits are nearly the lowest level areas in buildings. These areas are quite difficult to isolate both in terms of waterproofing and drainage. In new buildings, elevator pits must be isolated with drainage and foundation waterproofing. Since elevator pits are the lowest level in buildings, there is always a risk of groundwater accumulating here. Therefore, as shown in Figure 1, a small submersible pump sump should be prepared as a precaution.

Figure 1

In Existing Buildings:

For elevator pits in these buildings, materials based on negative-pressure injection from within the structure are recommended. In addition to taking waterproofing measures, the principle "control the water you cannot prevent" — an important concept in water insulation — should be followed, and precautions should be taken as shown in the diagram above (with a small submersible pump sump). In both types of structures (existing and new), if water accumulation is high, a sump can be dug outside the building, positioned lower than the elevator pit sump, and water can be pumped out from the external sump to lower the groundwater level. Elevator pits can suffer from moisture and even water leakage problems over time due to inadequate waterproofing, lack of drainage, deterioration of insulation, or cracks in concrete. Before waterproofing the elevator pit, if pressurized water exists, the first stage is to stop the water pressure.

1-Stopping Pressurized Water:

• Holes where water leaks are drilled deeper with a drill to allow water to flow freely to reduce water pressure. • If leakage occurs from multiple locations, holes of sufficient size are drilled toward the lower sections of the wall to allow water to flow freely. • A thin plastic tube is fixed to the hole with plugging mortar, ensuring water flows only through the installed tubes. • Holes are thoroughly cleaned and one coat of Fixa Aquafix Crystalline waterproofing material is applied. • While Fixa Aquafix Crystalline waterproofing material is still wet, the hole is completely plastered with Fixa Aquafix Crystalline waterproofing material plaster form (around the plastic tube) and allowed to cure for 24 hours. • After the waterproofing of the surface areas other than the holes is completed, the tube is removed and the hole from which the tube was withdrawn is plugged with Aquastop shock plug powder. • The plugging mortar is pressed with a gloved hand for approximately 1-2 minutes until it hardens. • After Fixa Aquafix Crystalline waterproofing material plaster form has cured, waterproofing is completed by applying Fixa Aquafix Crystalline waterproofing material in slurry form around the hole.

2-Bottom Surface Preparation and Elevator Pit Waterproofing Stages:

• Tie holes, if present, particularly in concrete walls, create weak points under waterproofing. If not properly sealed, they will cause problems with waterproofing in the future. • To repair these holes, a filler material that does not shrink and provides perfect adhesion to existing concrete must be used. Normal mortar loses volume as it releases water and becomes a cylinder smaller than the original hole. • The most common mistake is attempting to seal these holes by injecting polyurethane foam. PU foam loses its elasticity shortly after application, begins to crumble, and thus the space under the waterproofing becomes hollow. • Generally, tie holes located underground are difficult to access. Fixa Repairgrout Expan is an ideal product for this application. First, iron bars and plastic pieces in the tie holes are removed. Hole openings are roughened. Horizontal and even overhead applications can be easily performed. • Waterproofing elevator pits from the outside is generally not possible. In such cases, waterproofing must be applied from the inner surfaces using materials resistant to negative water pressure. • The surface to be treated must be clean and sound, free from oil, rust, cement laitance, paint residue, curing materials, mold release oils, and water-repellent materials such as silicone. • Static cracks, i.e., cracks in non-moving sections, should first be widened (V-shaped), then moistened and repaired with plaster containing Fixa Aqualatex or repair mortar (Fixa Repairgrout Expan). • Sharp corners and areas prone to cracking, such as horizontal/vertical joints, should be chamfered and rounded. • If pressurized water comes from the wall, Fixa Aquastop should be used to block the incoming water. • The surface should then be thoroughly saturated with water and kept moist throughout application. • Fixa Aquafix Crystalline waterproofing material is placed in a clean container and mixed with 10 liters of water for brush application or 7 liters of water for trowel application using a low-speed drill (approximately 3 minutes) until a homogeneous mixture is obtained. Water must always be added to Fixa Aquafix Crystalline waterproofing material, never the reverse. The total water to be added should not be added all at once but gradually. • After mixing, the material must be used within 30-40 minutes. Water should not be added again to hardened material. • Fixa Aquafix Crystalline waterproofing material is applied with a brush, roller, or trowel in at least two coats. • Each coat should be applied while the previous coat is beginning to set but not yet fully dried. • Each coat should be applied at a right angle to the direction of the previous coat. • Fixa Aquafix Crystalline waterproofing material should not be applied at temperatures below +5°C or above +35°C. • Crystal formation and penetration depth depend on concrete density and surface porosity. • The crystals created by Aquafix can create an unattractive appearance. To prevent this, the final coat of Aquafix should be plastered while still wet, and paint should be applied over the plaster.

Aquafix 1st and 2nd Coat Application

• After the final coat is applied, the surface should be smoothed with a soft, damp sponge. • After application, Fixa Aquafix Crystalline waterproofing material should not dry quickly; it should remain damp for 5-7 days. For this, it is beneficial to lay damp burlap, plastic sheeting, etc., or to spray the concrete with water. Fixa Aquafix Crystalline waterproofing material must be protected from sun, frost, wind, and poor weather conditions during the curing period. • If ceramic or tile is to be applied to the perimeter walls surrounding the elevator pit, ceramic adhesive should be applied directly over freshly applied Aquafix. • If these applications are to be applied over cured Aquafix, the crystals on the surface should be removed with diluted hydrochloric acid or bleach, then plastered over. This cleaning process only removes surface crystals and does not damage crystals that have penetrated into the concrete. • In addition to crystalline application, the application of Aquacement® 2K 251, a two-component cement and acrylic-based, super-elastic, crack-bridging waterproofing material suitable for negative and positive water pressure, is recommended. When applied at a minimum thickness of 3 mm at +23°C, Aquacement® 2K 251 (EN 14891), which has crack-bridging capability up to 1.50 mm; up to 1.75 mm when reinforced with mesh between coats, will provide effective waterproofing in elevator pits. In elevator pit waterproofing, the entire process from water drainage to waterproofing application must be under the control of the applicator for the long-term and proper functioning of the recommended materials. Permanent and comprehensive solutions now exist to counter water leakage in elevator pits. Elevator pit water insulation is one of the most important insulation requirements that cannot be neglected. Insulation against water leakage in elevator pits is applied with crystalline materials from inside to outside (negative direction). With insulation created by crystalline materials, it is possible to eliminate water leakage from both outside and inside. Additionally, this provides a dry environment by preventing factors such as odor, moisture, and mold that may develop indoors. Crystalline material that penetrates into the concrete structure advances toward the water source through cracks, protecting steel reinforcement from corrosion and rust. Water bridges, tierod holes, wooden wedges, tensioning bars, cold joints, construction joints, and segregation areas that form within the concrete structure are repaired with waterproof concrete repair mortars, and these points are sealed with necessary waterproofing work. After the necessary procedures, crystalline material that has been moistened and brought to a mortar consistency is applied over the concrete structure like wall plastering, and the process is completed. Semagül Köprülü Architect – Technical Product Manager Fixa Yapı Kimyasalları