How to Repair Tar and Gravel Flat Roof Leaks

Tar and gravel roof repair is relatively easy process, but is quite messy and smelly. When leaks on the ceiling point your way to your flat roof, get out your old clothes and get busy.

A built up roof of layers of paper and tar topped with gravel can last 10-20 years on ‘flat’ roofs. A ‘flat’ roof still has an almost imperceptible slope to it to handle drainage of rain and snow. Leaks happen where things penetrate the roof surface, on flat areas where water ponds, and when blisters crack open.

Unfortunately, since many of these roofs are on apartment buildings or commercial buildings, someone always seems to find their way up there. “Is that the door to the roof? Let’s go sunbathing, or watch fireworks, or how about a moonlit party?” As the roof ages, blisters can form, and foot traffic can crack them, leading to leaks.

For blister repair, you’ll need tar, a roll of fiber cloth (rag), a trowel, a utility knife, roofing nails and a hammer. Be careful, tar is contagious, spreading everywhere quickly. Plan to toss your clothes away afterwards.   Brush the gravel off the blister, then cut an ‘X’ into the blister. Open them up to dry out, trowel in some tar, and nail down the flaps of the ‘X’. Put a medium coat of tar over the ‘X’ extending about 6” around it, then cut and place rag over the tarred area, using the trowel to push it till the tar squishes through. Cover with another thin layer of tar, smoothing out the edges to nothing. Brush gravel back over the top of the repair. Clean your tools with gasoline and a rag. Tar and gravel roof repair can be done but is a smelly, sticky experience best left to the pros.

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