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1. Damp-proofing Of Slab On Grade
This section presents typical waterproofing methods under different conditions and with various materials.
1. Damp-proofing of a building without a basement - single-ply modified bituminous thick membrane:
Clean the slab of dust and dirt, and repair cracks wider than 1 millimetre. Prime the dry surface with a cold bituminous coating and the wet surface with a bituminous emulsion. For the prepared slab, lay the horizontal waterproofing membrane under the load-bearing walls with a 10 to 15-centimetre overlap. The floor waterproofing follows only after the load-bearing walls are completed, thus ensuring the continuation of the horizontal waterproofing of the walls.
On the horizontal surfaces it is enough to weld the membranes in the line of the overlapping and at various points with specific dimensions.
The waterproofing membrane on the floor is also rolled up 10 centimetres high on the wall, and the joints are thoroughly rolled everywhere.
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2. Damp-proofing Of Cellared Building
2. Damp-proofing of a building with a cellar can be done by fixing the membranes to the cellar wall or by tanking.
a) Damp-proofing of a building with a cellar by fixing the membranes to the cellar wall - using double-ply bituminous thin sheets:
Again, first clean and repair the slab and apply a bituminous primer. Here, the horizontal waterproofing of the wall is done first, as previously described, with an overlap of 10 to 15 centimetres. The top layer of the overlap must not be adhered to allow for a double joint.
Once the cellar wall is built, lay the floor waterproofing and join it to the horizontal wall-waterproofing, folding the sheets 10 centimetres up the walls. The sheets are laid by flame welding again with the required joint widths and they need to be rolled down in the end. Then, prime the external walls of the cellar and install the vertical wall waterproofing. The waterproofing is applied up to the height of the plinth with the required joint widths and join with the horizontal wall waterproofing at the bottom. The bottom of the sheets is folded down to the side of the foundation. Finally, place the waterproofing extruded polystyrene sheets and backfill the soil.
b) Damp-proofing of a building with a cellar by tanking - using a single-ply PVC membrane
For tanking, you first build the walls that support the waterproofing on top of the foundation. Then, form the bends at the junction of the walls and the slab with a radius of 1.5 centimetres.
Completed surfaces must be dusted, before carrying out the usual levelling: plastic felt must be laid over the entire surface. The vertical and horizontal wall waterproofing is placed simultaneously, suspending the plastic waterproofing from the wall supporting the waterproofing. To affix the sheet, we screw aluminium or tin foil tape to the wall.
The 5-centimetre horizontal joints are secured by hot air welding. Vertical joints are made similarly, but in this case, the bottom sheet is welded to the tin foil tape screwed to the wall and the top sheet is welded over the joint, with at least a 5-centimetre overlap.
On the horizontal surface, we also need to ensure the possibility of creating a joint by extending the sheets over the width of the future cellar wall. The corners should be given a reinforcing strip of plates around the perimeter. The next step is to build the cellar walls, which should be made of concrete blocks for partition walls or hollow concrete blocks with a 10 to 15-centimetre thickness. During construction, we fill the gap between the walls with 2 to 3 centimetres of protective-confining mortar. In the case of a heated cellar, extruded polystyrene boards can be used instead of mortar to prevent the waterproofing from sliding off. For waterproofing the floor, form the necessary joints and lay the waterproofing boards on the basement wall up to a minimum height of 10 centimetres. Finally, by proceeding further on all sides the same way, the entire floor is waterproofed against ground moisture.
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3. Waterproofing With Tanking
3. Waterproofing tanking against hydrostatic pressure - using double-ply modified thick membrane
The initial step in tanking against groundwater is to create a 10 to 12-centimetre-thick reinforced concrete slab for the floor waterproofing substrate, on which the wall supporting the waterproofing can be built. The wall must be sized for the hydrostatic pressure, so a minimum of 15 to 20 centimetre-thick wall made from concrete hollow blocks must be built. The wall height should be calculated so that vertical waterproofing against groundwater can be installed 20 to 25 centimetres above the defined groundwater level. Above this height, it is sufficient to waterproof only against soil moisture.
Dust surfaces and repair any cracks, and make a 4 to 5-centimetre-diameter bend at the corners. Subsequently, reinforce the surface with a bituminous coating or bitumen emulsion, as described above. The two wall and floor waterproofing layers are done in one phase by flame welding, with a 10-centimetre overlap laterally and 15 centimetres longitudinally. Fix the layers of vertical waterproofing with half offsets over the entire surface, while forming a reinforcing strip of plates between the two layers at the bends.
After completing the vertical surfaces, lay the horizontal waterproofing and make double joints on the horizontal surface. Then, form the protective layers of waterproofing with 2 to 3 layers of PE film or one layer of bituminous thin sheet. Finally, build the other structures: the slab foundation and the basement walls which resist the hydrostatic pressure and prevent floating with their mass.
To reinforce the slab foundation, prepare a 5-centimetre-thick blinding concrete to protect the waterproofing. Place a trim of the same height as the foundation on the sides of the slab foundation. Build the cellar wall once the foundation has been poured and solidified. At the construction stage, the 2 to 3-centimetre space between the cellar wall and the waterproofing should be filled with a layer of confining mortar. After the wall is completed, the waterproofing can be continued against soil moisture above the wall supporting waterproofing. Finally, the soil can be backfilled into the working pit around the cellar.
