Case file — Silver Spring, Montgomery County, MD. One of the 25 jobs in our 250-home series. New here? Start with our open letter.
At a glance
| Location | Silver Spring, Montgomery County, MD |
| The problem | A long crack in the foundation wall, with water arriving at one specific stretch of the outside of it |
| The fix | The crack injected and finished, then fifteen feet of exterior French drain, a buried downspout and a solid discharge line |
| Scope | One wall section, inside and out |
The number that makes this case worth reading
Fifteen feet.
That is the entire length of the exterior French drain on this job. Not the perimeter. Not one full elevation. A fifteen-foot stretch of trench, dug exactly where the water was arriving, with a perforated pipe in geotextile and gravel backfilled to grade.
Most people have never been quoted a fifteen-foot drain, because most people are quoted a perimeter.
Why the whole perimeter is the default quote
Two reasons, and only one of them is about your house.
The good reason: if water is arriving along several elevations, or the grade falls toward the house on more than one side, a partial drain moves the problem rather than solving it. Whole-perimeter drainage is genuinely the right call on plenty of houses.
The other reason: a perimeter is easy to quote. It does not require anyone to work out where the water is actually coming from. Linear feet times a rate is a number you can produce in a driveway, and it is always a bigger number than the truth.
What fifteen feet requires
To install a drain this short you have to know, before you dig, which fifteen feet matter. That comes from the inspection, not the estimate: where the grade falls, where the roof discharges, which part of the wall is wet and which part never has been, and where the crack runs on the inside.
On this house, the answers all pointed at one stretch of one wall. So that stretch got a drain, and the rest of the house got left alone — which also means the rest of the landscaping, the walkway and the plantings got left alone, at no cost, because nobody dug them up.
The rest of the scope
The crack, injected with polyurethane grout under low pressure and then finished — packers cut flush, excess removed, surface patched. This was a substantial crack, priced well above a routine one, which is usually a sign of length or of a path that wanders through the wall.
A buried downspout, so the roof water on that elevation goes underground instead of onto the ground the new drain is sitting in.
About fifteen feet of solid pipe, sloped, backfilled, finished with a pop-up emitter. The perforated pipe collects; the solid pipe carries. They are different pipes doing different jobs, and a drain with only the first one is a drain that moves water from one side of your foundation to the other.
What to take from this
Ask any company quoting exterior drainage a single question: why this length?
A good answer describes your yard — the grade here, the downspout there, the wet stretch of wall. A bad answer describes their system. If the length of the trench does not change with the diagnosis, then the diagnosis is not changing anything, and you are buying a product rather than a repair.