Foundation Crack Repair Kit Size Calculator

Kit size comes down to two numbers: the total length of your cracks and how many injection ports they need. Enter each crack below and the calculator picks the cheapest mix of kits that covers both.

How much crack repair kit do I need?

Add up every crack you plan to inject, then allow 8 feet per 10 ft kit and 30 feet per 30 ft kit. The calculator does this for you and also counts ports, since several short cracks use more ports than one long one.

The calculator is for vertical and diagonal cracks in poured concrete walls. It won’t size a kit for a block wall, a crack wider than 1/4 inch or a sideways crack, because those need an engineer first.

How far does a 10 ft foundation crack repair kit go?

About 8 feet of crack, not 10. The kit’s data sheet says it covers approximately 6 to 10 linear feet and that you should expect to use all of the surface paste on an 8 foot crack.

The ports set the other limit. The instructions put the first port at the bottom of the crack and another every 8 inches, which is the usual wall thickness. The 10 ft kit comes with 15 ports, and an 8 foot crack uses 13 of them.

The kit’s product page says it handles cracks up to 3/8 inch wide. On this site, a wall crack wider than 1/4 inch goes to an engineer before any kit, because width that large can mean the wall moved.

10 ft vs 30 ft kit: what’s the difference?

The 30 ft kit holds about three times the material and adds its own dispensing gun. The 10 ft kit uses single cartridges that fit a standard caulk gun you supply.

Concrete Sealers USA foam kit product pages and technical data sheets

Price is what tips it. At current prices, two 10 ft kits cost less than one 30 ft kit, and three cost more, so the switch point is about 16 feet of total crack.

How do I measure a crack for a kit?

Measure along the crack from its lowest point to its highest, in feet. A diagonal crack is longer than the wall height it crosses, so measure the crack itself, not straight up.

1. Find both ends

   Follow the crack to where it stops, including the hairline tail at the top. Foam only seals the part you port.

2. Measure each crack

   Run a tape along the crack and round up to the next half foot. Write each crack down separately.

3. Count separate cracks

   Each crack starts with its own port at the bottom, so four 2 foot cracks need more ports than one 8 foot crack.

4. Check the wall thickness

   Ports go about one wall thickness apart. If your wall is thicker than 8 inches, expect to use more foam per foot.

The 30 ft kit’s data sheet gives 10 to 21 ounces of foam per 8 foot crack in 8 to 10 inch walls. That wide range is why the calculator rounds up instead of cutting it close.

Do I need the epoxy paste or peel-off version?

Pick by how damp the wall is and whether it will stay exposed. Both versions cover the same length, so the choice doesn’t change how many kits you need.

• Epoxy paste cures with some moisture present, though the instructions still say not to put it on a wet surface. It stays on the wall and comes off with a grinder or chisel.
• Peel-off won’t cure on a damp surface, and the instructions say to keep the wall dry. It peels off after the foam sets, which leaves a cleaner finished wall.

The peel-off vs epoxy paste comparison goes through the trade-off in detail.

When is a refill the right buy?

When you already own the 30 ft kit’s gun. The 30 ft consumables kit has everything except the dual gun and tool box, so on its own it can’t dispense the foam.

For a 10 ft kit, its product page offers a consumables kit for about 10 more feet. Whatever you buy, check the shelf life: the foam lasts 1 year unopened, stored between 45°F and 95°F.

When should you skip the kit?

Skip it when the crack points to a wall that’s still moving. Foam injection seals water out, and the foam’s maker says it is not intended for structural cracks.

Get an engineer to look first if you see:

• A horizontal crack, or a wall bowing inward.
• A crack wider than 1/4 inch.
• One side of the crack sticking out farther than the other.
• Stair-step cracks in a block wall.

The U.S. Bureau of Reclamation’s repair guide puts it plainly: it’s better to leave most cracking unrepaired (opens in a new tab) than to do an inadequate or improper repair. The horizontal crack guide shows what the warning signs look like.

For a stable, leaking crack, the crack injection guide walks through the job step by step. The epoxy vs polyurethane comparison explains why foam is the usual pick, and the product chooser covers every other crack.