Solve backwards
How much basement wall will my waterproofing coating cover?
- 20 galThe example worked below
- Basement Wall Waterproofing Coating Coverage CalculatorEvery figure is its own
You have
How much waterproofing coating?
That is 20 gal(75.7 L). Worked by the Basement Wall Waterproofing Coating Coverage Calculator at the settings below.
The settings it uses
- Coverage Rate per Coat
- 40 ft²/gal
- Number of Coats
- 2
What it will do
400 sq ft of basement wall
37.2 m²
One basement wall. Enough for a basement wall 50 ft long and 8 ft high.
Or several. Less than one basement wall of the size the Basement Wall Waterproofing Coating Coverage Calculator opens on (a basement wall 81.3 ft long and 8 ft high).
Check it forwards
- Wall Area
- 400 sq ft
- It asks for
- 20 gal
- You have
- 20 gal
The Basement Wall Waterproofing Coating Coverage Calculator asks for 20 gal at that size.
If you had more, or less
Around your amount
Each worked by the Basement Wall Waterproofing Coating Coverage Calculator at the same settings.
Half
10 gal
200 sq ft
a basement wall 25 ft long and 8 ft high
Yours
20 gal
400 sq ft
a basement wall 50 ft long and 8 ft high
Half as much again
30 gal
600 sq ft
a basement wall 75 ft long and 8 ft high
Double
40 gal
800 sq ft
a basement wall 100 ft long and 8 ft high
Common amounts
What each amount of waterproofing coating covers
The sizes it is usually sold in, each worked by the Basement Wall Waterproofing Coating Coverage Calculator at the settings above.
| You have | It covers | As one basement wall | Average basement walls |
|---|---|---|---|
| 5 gal(18.9 L) | 100 sq ft(9.29 m²) | a basement wall 12.5 ft long and 8 ft high | under 1 |
| 10 gal(37.9 L) | 200 sq ft(18.6 m²) | a basement wall 25 ft long and 8 ft high | under 1 |
| 20 gal(75.7 L) | 400 sq ft(37.2 m²) | a basement wall 50 ft long and 8 ft high | under 1 |
| 40 gal(151.4 L) | 800 sq ft(74.3 m²) | a basement wall 100 ft long and 8 ft high | 1 |
A membrane is not a paint film
Rubberised asphalt and spray elastomerics run around 1 m² per litre, roughly 40 square feet per US gallon, and trowelled systems can be under half that — where a masonry paint covers five to ten times as far. That is why the calculator opens at 1 m² per litre and why the data sheet, not paint experience, is the figure to use.
Two coats to close the pinholes
Most waterproofing coatings need at least two coats to form a continuous, pinhole-free membrane, and the calculator opens at two. Rough or porous block absorbs more and covers less, and voids have to be filled before coating rather than by it — so the wall here assumes a sound, prepared surface.
The coating is one layer of a system
Drainage board, a protection layer, the perimeter drain and the sump or outfall it discharges to are all outside this figure. And a coating made for the outside of a wall will not necessarily work painted on the inside; positive-side and negative-side products are made for different situations.
How the answer is worked
Nothing here is a second formula. The Basement Wall Waterproofing Coating Coverage Calculator runs forwards — a size in, a quantity out — and this page grows its own starting basement wall in proportion until the quantity it asks for is what you have. Where it rounds up to whole containers, the answer is the largest size before the next one would be needed.
Where the calculator adds an allowance for cuts or breakage when you order, the same allowance comes off here, because it is the same calculator: a stack you already own finishes less than its face value. Where it adds none, neither does this page — the settings beside the answer say which.
Basement Wall Waterproofing Coating Coverage Calculator
runs it forwardsCalculate the waterproofing coating needed for a basement wall based on coverage rate and number of coats.
Work out what to buy insteadSolve backwards
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Solve backwards
Start from what is already in the yard
Paint, sheets, rolls, bags and pieces, each read the other way by the calculator that orders it.
The calculator's own figures
Nothing is estimated twice: the page runs the same calculator you would order with.
The largest size that fits
Where a calculator rounds up to whole containers, the answer stops before the next one.
Both unit systems
Gallons and litres, square feet and square metres, side by side.
Frequently asked questions
- How much basement wall does 20 gal of waterproofing coating cover?
- At the Basement Wall Waterproofing Coating Coverage Calculator's own settings, 400 sq ft (37.2 m²) — a basement wall 50 ft long and 8 ft high. Every figure follows the settings, which you can change in the calculator.
- How much basement wall does 80 L of waterproofing coating cover?
- At the Basement Wall Waterproofing Coating Coverage Calculator's own settings, 40 m² (431 sq ft) — a basement wall 16.7 m long and 2.4 m high. Every figure follows the settings, which you can change in the calculator.
- How many square feet does a gallon of foundation waterproofing cover?
- Heavy-bodied foundation coatings cover about 1 m² per litre per coat, roughly 40 square feet per US gallon, and trowelled systems less. At the usual two coats a gallon covers about 20 square feet (1.9 m²) of wall. The product's data sheet gives its own rate and thickness.
- Can I waterproof a basement wall from the inside?
- Only with a product made for the negative side, where water pushes the coating off the wall rather than onto it. A coating designed for the outside of a foundation will not necessarily hold when painted on the inside, so the product is chosen for the side before the quantity matters.
- Why does basement waterproofing coating run out so fast?
- Because it is applied to a wet film thickness to form a membrane, not spread thin like paint, and a rough or porous wall drinks more still. At around 40 square feet per gallon per coat, a basement takes many times more material than the same walls would in paint.