Waterproofing is used to keep moisture out of the lower levels of your home or building. It prevents groundwater or other moisture from coming through the foundation walls. This saves the foundation’s structural integrity as well as protects anything that may be stored in basements or lower levels. In addition to protecting furniture or boxes, interiors and flooring, it prevents the growth of mold, mildew or other dangerous substances.
Basements are usually poured concrete walls or masonry block. Sometimes you can see the top of the foundation walls from the ground level. Older homes may have rubble stone basements or fieldstone walls. Urban dwellings and other buildings are often constructed with little space between them, making excavation difficult. Depending on the structure, the mason will use various techniques. Most suburban residences can be accessed from both the exterior and interior.
A responsible waterproofing company will begin by locating all of the utilities that have underground connections. Coming across a hidden gas service line can be dangerous. Usually the utilities will mark the areas so that the excavation can be conducted safely. All of the soil and clay will be removed and stored safely. Trenches adjacent to the foundation walls are dug down to the footing level and about four feet wide. If only one wall is being treated, the excavation will still continue around the corners to be sure the entire wall has been secured.
The trenches are shored to ensure the safety of the workers and to create a more easy access. After the foundation walls are exposed, they are cleaned using power washing and brushing. Any repairs are completed and the surface is prepared. Tuck-pointing is performed on joints and loose or missing mortar is replaced. Poured concrete walls are treated with hydraulic cement to fill any cracks, voids or divets.
The workers use trowels to apply cement parging to offer a clean and smooth surface for the waterproofing materials. The parging mix uses a liquid concrete boding agent so the waterproofing material will stick to the existing wall surface. The materials are then allowed to completely dry and cure.
After the curing period, the actual waterproofing elements are applied. A liquid coating with an asphalt base or bituminous coatings can be applied with a trowel or some are able to be sprayed. A popular option is using a poly sheeting after the liquid coating. Some people choose to use self-adhering membranes. There are also dimpled plastic sheets that are mechanically applied. These are to reinforce the waterproofing measures already taken
Down at the footing level, new plastic weeper pipe is connected from each corner to the other and is backfilled with crushed gravel and the soil that was previously removed. It is usually a good idea to add more soil and be sure the area is fully compacted and then a positive drainage established by sloping the soil away from the structure.
Recessed window wells may also need to be waterproofed. The addition of plastic covers helps divert the water from the wells. It may be necessary to reroute the downspouts or to reconnect those underground downpipes.
Finally it is time to return the sod and any landscaping as well as repairs to any pathways.
A good waterproofing job should last at least twenty years. The costs will vary depending upon the amount and type of products used and the amount of effort it will take to access the foundation walls.
Interior waterproofing is different. To begin, the basement floor next to the affected wall will need to be broken in order to install weeper drainage pipes. This will divert groundwater into the main drains.
Each interior wall project is different depending on the surfaces and amount of shifting, if any. It is always best to have a professional assess the current condition and damage. In some circumstances it is a good idea to have an engineer involved. This will assure that all the the electrical, plumbing and other appliances are dealt with during the scope of the project.
It is possible that the internal weeper tile system can be directed into a sump pump. If there is no current sump pump, an area would need to excavated and a pump installed.
Stone basements can involve loss of the cement that holds the stones in place. Sometimes you can simply repair the mortar or sometimes it is necessary to pour new exterior footings prior to the waterproofing process. Structural integrity is the key to this decision.
Newer constructions use insulated concrete forms for better heating efficiency. If that is the case with your home and you have a leakage problem, there are specific alternatives that are recommended for the external waterproofing.