PROJECT: Waterproofing under the Foundation and on the Shear Wall, Drainage System, and Thermal Insulation on the Basement Floor (by Ayçanur Yeler and Kadir Burak Özköylü)
Waterproofing under the Foundation
During the first construction of the building, before the foundation concrete was poured after the excavation, about 10 cm lean concrete was applied and ground leveling concrete was applied. For waterproofing, a piece of roll-shaped, bituminous membrane, a kind of plastic material (black) was laid on lean concrete. Another piece is laid to sit on it, and by heating between these two membranes, the material is melted and combined. Thus, an impermeable structure is obtained. Moreover, synthetic covers (such as PVC, TPO, ECB) are widely used for external tanking basic insulation solutions. This insulation has been applied to the bottom and sides of an entire foundation and this will be carried upwards. Later, while manufacturing the foundation iron, lean concrete and protective concrete were poured over this insulation so that this insulation would not be damaged or torn. For basic waterproofing, a double layer of insulation was made under the foundation with bitumen membrane. After the application, lean concrete, protection concrete, foundation reinforcement were manufactured and the basic insulation was preserved at this stage. After the lean concrete has dried, the foundation concrete is poured after the irons and molds are laid.
In addition to waterproofing applications under the building foundation, a drainage system was also needed to reduce the water level around the building or in the field and to remove water from the building. However, drainage applications around the foundation will only be effective in reducing the pressure of groundwater; preparing the concrete with waterproofing additives does not provide a complete waterproofing. For this reason, insulation has also been applied to the foundation shear walls. By using polymer modified bitumen rubber-based products and bitumen-polyurethane-based products, waterproofing application with external tanking method has prevented all these negativities.
Since the basement floors are located under the ground, they must be well protected with waterproofing and water ingress must be prevented. In these areas, the building's concrete shear walls should be used tanking method from the outside and shear wall waterproofing should be made to prevent the ingress of water. For shear wall waterproofing, bitumen membrane applications that have been used today, but now all sliding-based materials are used much more instead. While bitumen membrane insulation is used on horizontal surfaces, sliding insulation is applied on verticals.
In the construction of the building we handled, the bitumen membrane has risen up from the walls to wrap around the foundation from the bottom. After the tanking method is implemented on the foundation, it is protected and filled. XPS board and drainage boards are the materials used during protection. Later, liquid membrane, which is a sliding-based waterproofing material, will be used. Liquid membrane insulation materials are formed by combining materials such as bitumen, rubber, acrylic, cement using various techniques. Sliding membrane is a waterproofing material such as bitumen that is applied to the walls, with a certain coefficient. The reason for this is that it is applied to the entire surface in one piece and without any joint, leaving no opening point. However, before applying liquid membrane isolation, an izotum bituminous liquid primer, which adheres to the applied surface with high adherence, evaporates and forms a waterproof film on the surface, will be used. In this way, the adherence of the insulation material to the wall will be increased and it will prepare the ground for the liquid membrane material to be applied. In the last stage, the sliding material and the integral membrane will be turned and joined from the foundation.
After the shear wall waterproofing application, it must be protected with thermal insulation plates such as XPS and EPS. Since as much as the importance of waterproofing application, it is necessary to protect the building foundation shear wall waterproofing applications and to fill with filling materials suitable for details.
While waterproofing is applied to wet areas of the building, thermal insulation is applied throughout the building and covers the entire structure. In the continuation of the construction, the basement ceiling of the building will be insulated with uncoated fiberglass mats, XPS placed between the floor beams and will be covered with wire, fishing line or spring metal supports called "tiger claw" and heat insulation will be provided. Additionally, polyurethane foam that provides insulating, airtight and moisture barrier will be used. Besides of them, some other materials can be used for thermal insulation such as cellulose, mineral wool, EPS. Polyurethane spray foam is installed to provide air sealing and insulation of this space. Besides, the foam will be covered with fire-resistant material throughout the basement ceiling. In this basement floor of the building, there is no thermal insulation except the ceiling because the insulation on the ceiling will prevent cold air from the floor from the non-heated level.
Government of Canada. (2016, February 12). Keeping The Heat In - Chapter 6: Basement insulation. https://www.nrcan.gc.ca/energy-efficiency/energy-efficiency-homes/how-can-i-make-my-home-more-ener/keeping-heat/keeping-heat-chapter-6-basement-insulation/15639
