Small rooms are mostly edge
Cove base is the item that scales wrongly against intuition. Floor area grows with the square of the room and perimeter grows linearly, so the smaller the room the larger a share of the job the walls are.
| Room | Floor | Perimeter | 4 in cove | Cove as a share of floor |
|---|---|---|---|---|
| 10 x 10 ft store | 100 sq ft | 40 ft | 13.3 sq ft | 13.3% |
| 24 x 20 ft garage | 480 sq ft | 88 ft | 29.3 sq ft | 6.1% |
| 60 x 40 ft bay | 2,400 sq ft | 200 ft | 66.7 sq ft | 2.8% |
On the warehouse bay the cove is a rounding error. On the store room it is an eighth of the material and considerably more than an eighth of the time, because cutting in a cove is slow work done kneeling. Ordering a small room off floor area alone is how people end up a quarter of a kit short with the last wall to do.
Why a pad only adds its sides
An equipment pad standing on the floor has a top, four sides and a footprint. The top is exactly the same area as the piece of floor it covers, so the two cancel: coating the top instead of the floor underneath it is the same amount of material. What the pad genuinely adds is the sides, which is the perimeter of the pad multiplied by its height.
A 4 by 3 foot pad standing 6 inches proud has a 14 foot perimeter and adds 7 square feet. That is a small number and it is easy to leave out, but pads come in groups, and a row of six of them is 42 square feet of slow vertical work that nobody measured.
Columns work the opposite way. A column occupies floor that is not there to coat, so its footprint comes off, and then all four faces get added for however far up the coating goes. A 12 inch square column coated 4 feet up removes 1 square foot of floor and adds 16 square feet of wall, which is a net gain of 15 square feet per column.
The deducts people get wrong
A trench drain is a hole, not a floor, and its open mouth comes off. Fixed cabinets that are staying put come off. What does not come off is anything that is being lifted and put back, since the floor under it still gets coated. And the wall length with no cove base is a real deduct that people miss in the other direction: an overhead door opening is a long stretch of perimeter with nothing to cove against, and on a two-car garage it can be a fifth of the wall.
What to do with the figure
This number is bare coated area with no allowances in it at all. Feed it to the spread rate calculator if you are working from volume solids and a film thickness, or to the garage floor coating calculator if you have a published coverage figure, and let one of those add the loss allowance and the profile allowance once rather than twice. The same area drives the preparation hours in the grinding production calculator, and how much of it one mixed batch can reach is the pot life batch size calculator. For painting the walls above the cove rather than the floor below it, the arithmetic is different and lives in the paint calculator.
Questions people ask
Should cove base go in the same square footage as the floor?
For ordering material, yes, because it is the same product coming out of the same kits. For planning the day, no, because a vertical inch is slower than a floor inch and is usually done first, by hand, with a different tool. That is why this page prints the split between floor and vertical rather than only the total. On a large open bay the distinction barely matters. On a small room where the cove is over a tenth of the area, treating it as ordinary floor area will make the labour estimate wrong even when the material order is right.
Why does an equipment pad add so little area?
Because the top of the pad replaces floor you would have coated anyway. The pad footprint comes off the floor and the pad top goes back on, and those two cancel exactly, so the only new surface is the sides. Perimeter times height is the whole addition. It looks like an undercount the first time you see it and it is not. Columns behave differently because a column has no coated top: the footprint comes off the floor and four faces get added, so a column is a net gain rather than a wash.
What do I put in the girth box for a curb?
The distance a tape travels over everything on that curb that gets coated. Lay the tape at the floor on one side, run it up the face, across the top and down the other side to the floor again, and read the total in inches. If only one face and the top are being coated because the other side is buried, measure only that path. It is asked as a girth rather than as height and width because curbs are rarely a clean rectangle in section, and measuring the actual path over the profile is both easier and more accurate than describing the shape.
Does this include waste and extra coats?
No, and that is deliberate. This page produces bare coated area, once. Loss allowance for what stays in the pail and on the roller, the extra the surface profile absorbs on the first coat, and the number of coats all belong to the material calculation, and adding them here as well would double-count them. Take the total from this page, put it into a coverage or spread rate calculation, and let that one add its allowances a single time.
How do I measure an L-shaped room?
Switch the mode to area and perimeter and measure both directly. Area you can get by splitting the shape into rectangles and adding them. Perimeter you get by walking the tape along every wall the cove base will actually follow, including both returns into the bay of the L, which is the part people forget: an inside corner adds wall on both sides of it and takes no floor away. If the room has an alcove that the coating stops short of, leave that wall out of the perimeter rather than deducting it later, since the deduct box is for floor area rather than for wall length.