Damp & Wet Basements: What To Do

by George Pappas

By far the most common home problem is a damp or wet basement. Not unique to older homes, this problem affects about 90-95% of all homes, including those built after 1960. Wetness or dampness can mean any amount of water from occasional or seasonal dampness on the foundation walls to significant flooding. With many homeowners utilizing lower levels for additional living and recreational space, there are genuine comfort and health concerns.

Generally, basement contractors are specialists in remedying a situation, they do not always have the resources or ability to diagnose the true cause of a wet basement. Nine times out of ten, contractors will recommend digging up the soil at the exterior walls to significant flooding. With many homeowners utilizing lower levels for additional living and recreational space, there are genuine comfort and health concerns.

Generally, basement contractors are specialists in remedying a situation, they do not always have the resources or ability to diagnose the true cause of a wet basement. Nine times out of ten, contractors will recommend digging up soil at the exterior walls of the home, then applying "parging" (a cement facing), then applying the "damp proofing" materials on the walls, adding weeping tiles (properly called drainage tiles) and finally backfilling to solve the wetness problem.

Proper Diagnosis Saves Thousands of Dollars

A home owner called us because he had a stream of water coming into the basement. He had called several contractors and all four of them had the same response: dig – parging – damp proofing, and weeping tiles. Quotes ranged from $11,000 to $23,000. He called us because he was rather skeptical and rather confused to say the least.

Our inspection and subsequent discussion with the home owner revealed that the water comes in about 15 to 20 minutes after it rains. We concluded that the stream of water had to be coming from rainwater as opposed to a high water table or an underground river or springs. Because it came relatively quickly from the start of the rain it most likely was due to downspout was connected outside to an original clay storm sewer at the north driveway wall adjacent to where the stream of water in the basement was coming from.

We advised the owner that the underground clay storm drain was most likely cracked, split, or had an opening in it and the downspout water was leaking out of this clay pipe into the soil and into the basement. We advised him on how to test our recommendations before commencing repairs.

The next day the client called and said that he had done the test and it confirmed that the cause of the problem was indeed the broken storm drain as we predicted. On our advice, he purchased 20ft. of eavestrough and an elbow and extended the downspout to the front lawn. Problem solved! Total cost was less than $30., plus a consulting fee of $250.00 for a total cost of $280. This was a saving of $10,720 to $22,720 compared to the basement contractor quotes received.

Corrective Actions

Polyurethane Crack Injection

Can be performed from the interior of the foundation. Seals the crack to prevent further penetration of water. Easiest and cheapest repair method for cracks only will not work with capillary action of moisture.

Damp Proofing the Exterior Foundation Wall

Effective repair for preventing capillary action or 'wicking' of moisture through the concrete or masonry wall. Masonry walls must be parged. Requires excavation of the wall to the footing level. It is recommended that measures be taken to control the source of water in conjunction with this repair.

Installation of Below Grade Drainage Products

This is used most commonly today in new construction. Various products are available from different manufacturers. The product should be tested and approved for use in Ontario. The function of the drainage layer material is to channel water to the weeping tile. This eliminates water pressure build up on the foundation wall by controlling the water on the exterior of the wall.

Installation of Interior Air Gap Membranes to Control Water Penetration

This is a common repair used when eliminating the source of water is impossible and excavating the foundation is not practical. This repair allows water penetration through the wall and controls it on the interior by draining it to a floor drain and sump pit where it is mechanically pumped out to the ground surface or storm drain.

Installation of Weeping Tiles with Stone Cover at Footing Level

This repair is required to prevent water from standing at footing levels hence allowing access to the basement through capillary action or seeping up through the floor slab and footing junctions. The tile should be installed at footing level, have stone cover to protect from silt and clay blockage and must drain to a sump pit or storm drain. Weeping tile controls water source from rising ground water levels.

Waterproofing the Exterior of the Foundation Wall

This is your most expensive option and should be considered where controlling of water source around your foundation is impossible hence creating high levels of hydrostatic pressure on the wall. Waterproofing membranes should be tested and approved for use in Ontario and must withstand water pressure. Sump pumps should be installed with a back flow preventer or check valve. Battery back up is always a good idea for times during power failure.

Excavating a basement for waterproofing or dam-proofing repairs and installing weeping tiles can be difficult and expensive. When considering this repair it is important to remember that cost is influenced by many factors, including accessibility for heavy equipment, site improvements, stairs, landings, private sewage systems, landscaping, abutting structures etc.

Corrective measures for damp and wet basements should always start on the ground surface by identifying and eliminating the source of moisture. This can be the easiest and simplest repair that is often over looked. Grading of your site is of major importance when it comes to preventing water from entering your basement. Look for the signs in your basement indicating moisture penetration and relate it back to what is present on the ground surface in that area. Penetrations through your foundation wall such as septic system pipes and electrical conduits can create pathways for water to enter your basement. Water leaking through these service penetrations can be rectified simply and cost effectively by properly sealing around the penetration.

It is important to remember that in many older homes the basements or cellars were not constructed or designed to prevent moisture penetrations. However, many of these homes have had their basements finished thus, when water problems become evident the methods utilized to rectify the problem can become quite expensive.