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Repairing a Split in a Built-Up Roof
(A.K.A. Tar & Gravel Roof)

The tools used here were not the typical tools I would use to repair a split in a gravel-surfaced built-up (a.k.a. tar & gravel) roof. I flew in to the closest airport, about 4 hours away, to look at this roof. The roof is on a nursing home in a very small town and I had to buy the tools and materials to make the repairs at the local lumber yard. Because there wasn't a Lowe's or Home Depot around, much less a roofing supply place, I was pretty limited as to what I could use. But the repairs were very effective so everything worked out well.


This photo shows a split in a gravel-surfaced built-up roof that was causing some severe interior damage.

In order to make the proper repairs, a few materials are needed:
  1. 1 gallon of roofing cement.
  2. A rubber glove to spread the roofing cement.
  3. Reinforcement fabric (a.k.a. membrane, or web, or jute) - in this case, the store didn’t have the usual product so drywall repair fabric is being used; which is typically available in the painting department of any hardware store or Wal-Mart.
  4. A flat bar to scrape the gravel. In most cases, a roofer would use what’s called a “spud bar” but I flew on a plane to get here and couldn’t carry a spud bar with me.
  5. A utility knife.

Step 1 - scrape the gravel back with the flat bar, going 4 or more inches on either side of the split. This is not a simple task and takes a bit of finesse to keep from damaging the roofing membrane under the gravel.

This picture shows the scraping (actually called "spudding" in progress. Note the split is turning out to be longer than originally thought.

This picture shows that what originally appeared to be a split about 18 inches long, turned out to be over 3 feet in length. That is common and is why it’s so important to properly scrape the gravel back. What appears to be a simple fix can easily turn into a more time consuming project.
Step 2 - Once you find the end of the split, make a small horizontal cut through the membrane. This helps prevent the split from continuing on. This cut will also be sealed.

At this time, it would be ideal if you can nail down the roofing on either side of the split to “secure” the roofing membrane in place, plus it also helps the split from “spreading.” In this case, I was unable to because the decking underneath was rotten.

Step 3 - Clean the surface very well and then lay out the fabric reinforcement. It should extend 2 to 3 inches past the split. Pre-cut the fabric to save time and help prevent a mess.
Note: For those of you who don’t know, the purpose of the fabric reinforcement is to keep the roof cement from splitting and cracking. A proper 3-course repair can last for several years. If a reinforcing fabric is not used, then the repair will only last a few weeks, or months at best.
Step 4 - Put on the rubber glove. In this case, all I had was a left hand glove so I turned it inside out to make it a right hand glove.
Note: Some roofers like trowels, which will also work. I feel a better job can be done with gloves because I can work it in better.





Step 5 - Dip your gloved hand into the plastic cement and smear the plastic cement over the entire split, including the small cut you made to prevent further splitting. Rub the cement in good to ensure good adhesion. It needs to be about 7 inches wide, just wider than the fabric reinforcement. Extend beyond the split on all sides either end about 2 to 3 inches. The thickness of the roof cement should be about 1/8 to ¼ inch or so. You don’t want it too thick but you need it thick enough to fully cover the split, so use common sense.
Step 6 - Lay the pre-cut fabric reinforcement over the freshly applied roof cement. Use your gloved hand to lightly rub it in place.
Step 7 - Put a very thin layer of roof cement over the top of the fabric to embed it. I left the end exposed for clarification.
Here is the completed repair.
Step 8 - Cover the repair with gravel to keep UV rays off of it. UV rays are very damaging to asphalt products which is why shingles and cap sheet roll products are covered with colored granules.
Option: If the roof does not have a gravel surface and is instead smooth-surfaced <> or cap sheet surfaced <> then you can use aluminum coating. Typically you should wait about 60 days for the roof cement to “cure” before applying the aluminum. Be sure to mix the coating very well.



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