Exterior foundation waterproofing
Exterior waterproofing stops water at the outer face of the wall. The soil is dug away down to the footing, the wall is cleaned and coated, a drain is laid at its foot and the trench is filled back in. It is the most direct fix for a wall that takes on water, and the one that asks the most of your yard.
When it is the right approach
It tends to be chosen when one wall is clearly the problem, when the inside of the basement is finished and nobody wants the floor broken up, or when the masonry itself is being damaged by constant wetting. It is less often used all the way round a house, because of the cost of digging and of putting everything back.
The layers, from the wall outward
| Layer | Its job |
|---|---|
| Cleaned, patched wall | Loose mortar and old tar come off so the new coating can grip. Cracks are filled. |
| Membrane or coating | A rubbery layer sprayed, rolled or sheeted onto the wall. This is the part that actually keeps water out of the masonry. |
| Drainage board | A dimpled sheet that protects the membrane from stones and gives water a gap to run down. |
| Footing drain | Perforated pipe at the base of the wall, in washed stone, wrapped in fabric so soil does not clog it. It leads to open air downhill or to a sump. |
| Backfill and slope | The trench is refilled in layers and the surface shaped to fall away from the house. |
What the dig does to your yard
Everything along that wall is in the way: shrubs, beds, steps, a deck, the air conditioner's outdoor unit, walkways. Some can be moved and put back. Some cannot. Soil is piled nearby and a small excavator may cross the lawn. Rain stops work, and an open trench in heavy rain is a problem of its own.
Go round the outside with the company and agree, in writing, what is removed, what is replaced, and who does the replanting and re-laying.
Questions to ask about an outside job
- How deep will you dig? To the footing is the point. Stopping short leaves the wettest part untreated.
- Where does the footing drain empty? A drain with no outlet is a buried bathtub.
- How is the trench made safe while it is open? Especially with children or pets about.
- How will the soil be compacted? Loose fill settles and tips the surface back toward the wall.
- Who restores paths, planting and lawn? Often a separate price. Sometimes a separate firm.
Outside work questions
Can the outside of a crawl space wall be done this way?
It can, but it rarely needs to be. Crawl space walls are short, and surface drainage plus work inside the crawl space usually does more for less digging.
Does exterior work mean I will not need a sump pump?
Not always. If the footing drain cannot run downhill to open air, it has to empty into a sump and be pumped out.
Tell someone what you are seeing
Call and describe what is going on under the house or in the basement. You will be put through to an independent local waterproofing company that works in your part of Tuscaloosa County.
Calls may be recorded. The company pays this site for the introduction. See the referral disclosure.