Bulkhead foam injection.
Know what it can and cannot fix.

What can foam injection fix?

Most foam jobs start with a sinkhole behind the cap. The installer drills small holes, sets injection tubes and pumps in a resin that expands and hardens. The goal is to fill the empty space and block the path the sand was taking.

That can be the right call when the wall itself is sound. It is the wrong call when the void is a symptom of a failing wall. Start with a written assessment if no one has checked the wall’s structure.

How does polyurethane injection work?

The Army Corps grouting manual separates repair goals. Epoxy is often used to bond structural cracks, while urethane grouts are mainly used to stop water or fill space. USACE grouting manual

Polyurethane products are not all alike. Some react with water, and others mix two parts. How much they expand and how they cure depends on the formula and the conditions. Bureau of Reclamation guide

• Void filling: filling a confirmed empty space in the soil behind the wall.
• Leak sealing: closing an open joint or crack that lets sand out, while keeping planned drains open.
• Soil stabilization: binding loose sand behind the wall. One manufacturer describes a single-part polyurethane grout sold for this use behind seawalls. That is a product claim, not independent testing. ^[1]

Ask which of these goals the proposal is for. A quote that says only “foam injection” leaves that open.

When does foam fit, and when does it not?

Expanding foam pushes outward as it grows. Ask how the installer controls pressure against a weak panel or an old wall.

Will foam block my weep holes?

It can, and that matters. Weep holes are small openings that let rainwater drain from behind the wall. Drainage and filtration work together to relieve water pressure while holding soil back. Coastal engineering guidance

If injection seals every opening, water can build up behind the wall after heavy rain. Ask how the plan keeps intended drains working while it closes the leak.

• Which openings are leaks, and which are drains that must stay open?
• How will you keep foam out of weep holes and pipes?
• How will you check drainage after the work?

What happens to foam near the water?

Research gives good reasons to ask product questions. Bureau of Reclamation tests found that different polyurethane grouts performed differently underwater, and water temperature changed how they cured. USBR field research Some formulas floated or clouded the water during testing. USBR underwater observations

In Choctawhatchee Bay, seagrass grows on the shallow margins of the middle and western bay, which takes in the Destin side. FWC seagrass report Ask how escaped foam would be caught before it reaches the water.

• Which exact product will you use? Ask for the technical and safety data sheets.
• Is it rated for contact with salt or brackish water before it cures?
• What containment will be on site, and what would make you stop work?

Do I need a permit for foam injection?

Assume yes until the permit office says no. Destin requires a permit to repair bulkheads and seawalls. Destin permit rule Ask the Building Division at (850) 654-1119, option 2, how it treats injection. Destin Building Division

Okaloosa County’s October 2026 post-storm guide lists seawall repair among work that generally needs a permit. Okaloosa storm guide Niceville says Florida’s new under-$7,500 exemption does not cover structural work or homes in a special flood hazard area. Niceville HB 803 page

If any work reaches the water side of the wall, the state layer applies too. DEP, not the water management district, handles single-family shore protection here. DEP-NWFWMD agreement Its Northwest District office is at (850) 595-8300. DEP Northwest District

• List the product and the injection spots.
• Show how close the work is to the water.
• Say whether any drains or weep holes will change.

The permit guide lists every office, and the Okaloosa and Walton county guides cover local steps.

What to ask before you sign

• What void or leak are you treating, and how did you find it?
• How much material is included, and what does extra cost per unit?
• If the void is bigger than expected, who approves the extra?
• What will stay unrepaired: cap, panels, tiebacks or toe?
• What does the warranty cover, and does it exclude a moving wall?
• What is your license number, and are you registered where the permit is issued? In unincorporated Okaloosa, contractors need a county competency card; call (850) 651-7180 to check. Okaloosa contractor licensing

Use the cost guide to compare proposals on the same scope, and the contractor check guide to confirm licenses.

What proof should I get when the work is done?

• A marked plan of where foam went in.
• The product name and the amount used at each spot.
• Before and after photos.
• Notes on drainage checks and any foam that escaped.
• The final permit inspection, if a permit was pulled.
• The warranty in writing.

If a sinkhole comes back, compare it to this record before you agree to inject again. It may point to a cause the first job missed.

Where water drives the voids

Foam fills a void, but the water that made it decides whether it comes back. These areas show why.

• Joe's Bayou: one city outfall drains more than 200 lots, and yards sink when water runs behind the wall.
• Mary Esther: Hurricane Isaias dropped nearly 12 inches of rain near the city.
• Fort Walton Beach: the normal tide is only about half a foot, so rain and storms move the water more than the moon does.