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Basement and foundation walls

Exterior Waterproofing

Exterior waterproofing stops water before it reaches the foundation wall. The wall is dug out, coated and given a drain at its base. It is thorough and it is disruptive, so it pays to know when it is really needed.

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What is done

  1. Dig

    A trench is opened along the wall, down to the footing. It has to be wide enough for someone to work in safely.

  2. Clean and coat

    The wall is cleaned, cracks are filled, and a waterproof membrane is applied. A dimpled drainage board usually goes over it to protect the coating and give water a path down.

  3. Drain

    A perforated pipe in washed stone is laid beside the footing. It runs either to open ground lower on the lot or to a sump basin.

  4. Backfill

    The trench is filled with material that drains, and the surface is shaped to fall away from the wall.

What it does to the yard

This is the most disruptive way to waterproof a house. Shrubs, flower beds, walks, steps, a deck or an air conditioner pad along that wall may have to come out. Soil is piled on the lawn. A machine needs a way in. On a tight lot, or where a driveway or porch sits against the wall, digging may not be practical, and that is a fair reason to choose an inside system instead.

Buried lines come first

Gas, power, water, sewer and cable lines often run along or through a foundation wall. In Tennessee anyone who digs has to notify Tennessee 811 beforehand, and the company doing the digging has to hold the locate ticket in its own name. Ask to see that it has been done. The local guide has the notice period and what 811 does not mark.

When it is the right choice

  • The leak is on one wall, and that wall can be reached.
  • The inside is finished, and opening it up would cost more than the digging.
  • The wall is being exposed anyway, for a new drain line or other repairs.
  • You want the wall itself kept dry, not only the floor.

Questions to ask

  • How deep will you dig, and how is the trench kept from caving in?
  • Where does the new drain pipe empty?
  • What goes back in the trench: the soil that came out, or stone?
  • Who replaces the plants, walk or steps that come out, and is that in the price?
  • Does grading or digging on my lot need a permit?

Compare with inside basement waterproofing before deciding. Many houses end up with a mix: one wall dug out, the others drained from inside.

Call (423) 555-0114