Repairs
How much filler the cracks and spalls will take
Cracks, joints and broken-out patches are line items a quote can leave out, and they are a part of the job you can measure before anybody buys anything. A chased crack is a prism. A spall is a shallow dish. Both convert to gallons through one number: a US gallon is 231 cubic inches.
Repair material required
1.74 gal
across 5 containers, in three different product classes
Each defect type, priced as its own product
These are not interchangeable materials, so the takeoff keeps them apart. A rigid filler in a moving joint can tear as the slab moves; a flexible filler in a static crack stays soft, and the coating over it can mark where wheels cross.
| Defect | Volume | Gallons | Containers | Product class |
|---|---|---|---|---|
| Chased static cracks | 99 cu in | 0.429 gal | 1 | Rigid crack filler — a semi-rigid epoxy or polyurea |
| Movement and saw-cut joints | 60 cu in | 0.260 gal | 1 | Flexible joint filler over backer rod |
| Spalled and broken-out patches | 48 cu in | 0.208 gal | 1 | Epoxy mortar, resin gauged with graded sand |
| Low areas brought up to plane | 194 cu in | 0.842 gal | 2 | Patching resurfacer or self-levelling underlayment |
The geometry, stated so you can check it
- Cracks. Length in feet times twelve, times the chase width, times the chase depth. A straight prism, and the reason we ask for the chased dimensions rather than the visible crack.
- Joints. The same prism, but the depth is the fill depth above the backer rod rather than the depth of the saw cut.
- Spalls. Length times width times depth times two thirds, because a spall is a dish and not a rectangular hole. That two thirds is an approximation and it is stated rather than buried.
- Low spots. Area times the deepest measurement times one half, because a low area is a bowl whose depth is not uniform.
- Each of them converts to gallons by dividing by 231. A cubic foot is 7.4805 gallons, if you prefer to work that way.
That divisor is the one sourced figure on this page, and it is a legal definition rather than a coatings convention. The two-thirds and one-half shape factors are our own assumptions, stated below.
Statements of fluid measure shall be in terms of both the U.S. gallon of 231 cubic inches and quart, pint, and fluid ounce subdivisions thereof and SI metric liters or milliliters
What that changes for your floor Because the gallon is fixed by regulation rather than by custom, the crack and joint figures are exact arithmetic on your measurements. The spall and low-spot figures add the two shape assumptions below, so the uncertainty in the answer above sits in the measuring and in those two factors.
Joints are not cracks, and filling them like cracks can crack the floor
A saw-cut joint is there so the slab cracks along a chosen line. Filling one rigidly does not stop the slab moving, and the movement can open a crack somewhere else, where it can show through the new floor.
The treatment this takeoff assumes is backer rod pushed to a controlled depth, then a flexible filler on top. The rod sets the fill depth and keeps the filler off the bottom of the joint, so it can stretch rather than tear. This tool flags a fill deeper than 2 times the joint width; that ratio is our planning threshold, and the joint filler's own width-to-depth guidance governs.
There is an exception: on a floor with hard-wheeled traffic, a joint can be filled with a semi-rigid product chosen to support the joint edges. That is a decision for someone who knows how the slab moves, not a default.
When repairs happen in the sequence
- Prepare the slab first. Grinding before repair exposes the sound concrete the filler needs to bond to.
- Cut spalls back square to sound material. Filler laid over a loose edge takes the loose edge with it.
- Chase cracks open rather than filling them at the surface.
- Fill, let everything cure (16 hours at the quantities above, our planning allowance; the repair product's data sheet governs), then grind the repairs flush.
- Only then coat. A repair left proud of the floor can show through the coats over it.
What the measurements you entered suggest
Nothing flagged by the numbers you entered.
Biggest swing factor The chase dimensions. Doubling the chase width doubles the filler, so measure the groove you will cut rather than the hairline you can see.