Basement walls form underground space. At the height of more than 2 m, they form a basement, if the heigh is less – crawl spaces. Such crawl spaces, as basements, from the outside are closed with sole plate or side board and have heat-insulated basement covering, however they have less permanent internal thermal behavior. The floor of crawl space, in comparison with the basement, is more affected by temporal temperature spans.
Crawl space waterproofing
When constructing the foundation it is necessary to pay special attention to foundation and crawl space waterproofing. It is important for buildings without basement, if groundwaters are aggressive. The groundwater humidity protection is provided by horizontal and vertical waterproofing.
Horizontal crawl space waterproofing is made of two layers of tar paper or rubberoid, attached as appropriate with pitched or bitum mastic, or of a layer of cement mortar (of composition 1:2 with ceresite) 2-3 cm thick.
Vertical waterproofing is provided by careful painting of outside surfaces of foundation walls, adjoining with pound, heated bitumen. With groundwater level height from 0.2 to 0.8 meters membrane waterproofing, consisting of two layers of rubberoid based on bitum mastic, is used. It is also recommended to make a puddle trench of a waged wet clay for crawl space walls. There also exist other methods of crawl space waterproofing.
Crawl space protection from water penetration
In order to prevent the penetration of rain and melt waters to underground parts of a building, they perform the area reclamation leveling for building construction, creating a necessary slope for surface-water diversion from the building. The perimeter walk of solid waterproofing materials (asphalt, asphalt concrete and others) are constructed around the building along outside walls. The perimeter walk width is usually not less that 0.5 meters with 2-3% inclination from the building. Special precast slabs are also used for perimeter walk construction.
Basement protection from pressure-proof underground water is provided by the installation of uniform waterproofing flooring of 2-4 layers of asbestos felt, sealing membrane, glass fibre cloth and other rot-proof rolled materials adhered by appropriate mastics. Horizontal flooring is placed in the mass of the floor on concrete setting bed, is flown through basement walls and is lead to the surface of outside walls to the height exceeding the possible level of groundwaters for 0.5 meters. Underlying concrete layer, equilibrating water pressure is applied to horizontal flooring. If position head is more than 0.8 meters, a uniform reinforced concrete slab, squeezed in basement walls, is being installed.
Picture source: http://midwestbasementtech.com