Ballpark Cost to Restore a Commercial Gravel Built-up Roof

Gravel built-up roofs (BUR) present unique restoration challenges — primarily the need to remove the gravel before any new system can be applied. Here's what to expect cost-wise.

Step 1: Gravel Removal

Gravel must be removed before spray foam can be applied. The most common method is hydro-vacuuming, which costs approximately $0.50–$1.00 per square foot depending on gravel depth and roof accessibility.

Spray Foam Restoration on BUR

After gravel removal, spray foam is applied directly to the existing BUR substrate. Total installed cost — including gravel removal, foam application, and silicone topcoat — typically runs $4.00–$7.00 per square foot depending on foam thickness and roof size.

Compared to BUR Replacement

A full tear-off and replacement of a gravel BUR roof typically costs $8–$14 per square foot. Restoration at roughly half that cost — while also avoiding the significant disruption of removing thousands of pounds of gravel and multiple plies of roofing — makes it the preferred approach for most BUR roofs in reasonable condition.

The Key Variable: Wet Insulation

As with all roof restorations, the extent of wet insulation is the critical cost variable. More wet insulation means more cut-and-replace work before foam can be applied, which increases cost. A core sample inspection is essential before finalizing a budget.