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Table of Contents

Introduction
This guide provides step-by-step instructions on how to patch a rubber roof. You can repair an EPDM rubber roof yourself. EPDM rubber is one of the easiest roofing materials to repair properly.
Always follow roofing safety guidelines when working on a roof.
It is extremely important that you clean the repair area. EPDM roofing develops a fine layer of black carbon dust on its surface over time as small amounts of the carbon black material used during the manufacture of EPDM migrates out of the membrane. You may not be able to see it, but it’s there, and it will prevent your patch from adhering properly unless you remove it. Follow the membrane cleaning instructions or your patch will fail.
Important: You should never use asphalt products on an EPDM roof. EPDM is completely incompatible with solvent-based asphaltic roofing materials, such as asphalt-based roof coatings and roof cement.
What You Will Need
Option 1
DIY EPDM Repair Kit: This is likely to be the easiest option, as these kits have everything you’ll need except for a caulk gun or scrub brush, and they have an appropriate amount of each material, so you don’t end up with a lot of something left over.
One or two holes: See this repair kit (yes, it will work on a roof).
For more extensive repairs: See this repair kit on Amazon.
Option 2
Tools
- Caulk Gun See on Amazon
- Cleaning Brush, Soft-Bristled See on Amazon
- Cotton Cleaning Rags
- Paint Brushes See on Amazon
- Scissors, Heavy-Duty See on Amazon
- Seam Roller, Hand-held See on Amazon
Materials
- EPDM Rubber Membrane, large enough to cut your patches from, and at least 0.060″ (60-mil) thick, see on Amazon. Alternatively, you can use a minimum 6-inch wide peel-and-stick EPDM patch, cover tape, patching tape, or flashing tape, see on Amazon. Do not use double-sided seam tape. Fully-cured or semi-cured material is preferred over uncured material for long-lasting repairs.
- Lap Sealant See on Amazon
- Splice Adhesive See on Amazon
- Splice Primer See on Amazon
- Weathered Membrane Cleaner if you can find it, or Rubber Roof Cleaner See on Amazon

How to Repair an EPDM Rubber Roof
This is the proper way to repair an EPDM rubber roof membrane puncture using a patch made of EPDM rubber or EPDM cover tape.
Step One: Prepare the Patch
The patch must be large enough to extend a minimum of 3 inches beyond the edge of the damaged membrane area in all directions.
Cut an appropriate-sized piece of EPDM membrane or EPDM tape.
Round all corners of the repair piece with scissors or shears. This helps prevent later delamination of the patch.
Note that even a pinhole-sized puncture will require at least a 6″ x 6″ patch.
Step Two: Clean the Membrane
If you’re dealing with a ballasted EPDM roof, you need to push back the ballast stone around the work area to give yourself room to kneel and work. Also, ballasted EPDM roofs get extremely dirty because the ballast traps dirt and allows it to settle on the surface of the membrane instead of being washed away when it rains. Be prepared to spend a lot of time cleaning.
When you repair an EPDM rubber roof membrane which has been in service for some time, it is absolutely vital that you remove the accumulated field dirt.
It is very common to see failed EPDM repairs, even when they were done by professional roofers, due to the old membrane not being cleaned or not being cleaned thoroughly enough.
Fine particles of carbon black continually migrate out of EPDM membranes as they age, so even a membrane that looks fairly clean will often have a layer of black soot-like material on its surface.
You should clean an area that extends at least a foot beyond the roof damage in all directions.
Proper membrane preparation is accomplished by first scrubbing the membrane with a soft-bristled scrub brush (do not use a brush with wire bristles) and warm soapy water (I recommend using Spic and Span), then rinsing with clear water.
Repeat this process until all of the dirt is gone, and then dry the area with a clean cotton rag.
Then clean the area again using weathered membrane cleaner. A second cleaning with weathered membrane cleaner is often necessary.
Check the cleaned area with your finger (or a clean rag) to make sure you got all the dirt.

Step Three: Install the EPDM Patch
Note: If you are using a self-adhering peel-and-stick EPDM patch or tape to repair your EPDM rubber roof, you should not apply primer or splice adhesive to the patch itself.
1. Apply Primer:
Using a paint brush (or paint roller for large areas), apply EPDM primer (also called splice primer) to the clean area and the patch and allow it to dry. This stuff dries quickly. The area where you apply the primer should extend 3 or 4 inches beyond where your patch will go in all directions.
2. Prepare the Splice Adhesive and Apply It:
Thoroughly stir the splice adhesive before and during use. Apply the splice adhesive using a 3-inch- or 4-inch-wide by 1/2-inch-thick solvent-resistant paint brush in a thick, even, smooth coat with long, painting-style strokes, so that the marks from the brush disappear, yielding a smooth, glossy adhesive surface. For larger areas, you can use a paint roller.
The area where you apply the adhesive should extend an inch or two in all directions beyond where your patch will go.
Apply splice adhesive to both mating surfaces (on the roof and on the patch) at about the same time, so as to allow approximately the same drying time. Again, if you are using tape or a peel-and-stick patch, do not apply the adhesive to the patch.
Do not use a circular motion to apply the splice adhesive. Do not use spray equipment to apply the splice adhesive!
3. Apply Extra Adhesive at Cross Seams:
If your patch intersects a field seam (where the original roof installers joined two sheets of EPDM) or a factory seam (where two pieces of EPDM were joined at the factory to create a single manufactured sheet), make one short back stroke at each seam your patch crosses to apply extra adhesive at the step-off.
4. Test Splice Adhesive for Readiness:
Allow the splice adhesive to flash off. In a few minutes, touch the adhesive surface in the middle of the area to be patched to be certain that the adhesive does not string or stick to your clean, dry finger.
As you are touching the adhesive, push lightly straight down to check for stringing, and also push forward on the adhesive at an angle. If either motion exposes wet or stringy adhesive when you lift your finger, then it is not yet ready for mating and needs more time.
Flash-off time will vary depending on the temperature and humidity of the ambient air, but usually takes several minutes.
5a. Set the Patch (Using Applied Adhesive):
Lightly position the patch over the prepared membrane area. Starting at one edge, allow the patch to fall slowly and loosely onto the area with a rolling motion, without stretching or wrinkling the patch.
5b. Set the Patch (Using a Peel-and-Stick Patch):
Place the patch onto the prepared area. Firmly hold one edge of the patch in place with one hand. With the other hand, starting from the edge that you are holding, slowly pull off the protective release film from the bottom of the patch, allowing the patch to settle loosely onto the prepared area as you go.

6. Roll the Patch for Proper Adhesion:
Apply pressure along the entire area of the patch by hand to completely mate the two surfaces. Using a handheld seam roller, roll the entire patch with firm, heavy pressure going from the center of the patch toward the outside edges of the patch.
This will force any trapped air out from under the patch, ensuring a complete bond.

Step Four: Apply Lap Sealant
7. Wait Before Applying Lap Sealant:
Wait to apply lap sealant at least 4 hours after applying the patch, unless rain is coming. If rain is likely, the lap sealant must be applied before the rain starts.
If weather is not an issue, the lap sealant must be applied no later than the end of the following day. Try to make the repair on a day when rain is not in the forecast.
8. Clean the Edge of the Patch:
Clean the edges of the patch a minimum of 1 inch on each side of the edge itself using clean cotton rags and weathered membrane cleaner.
Apply splice primer to this area and allow to dry.
9. Apply Lap Sealant:
Using a standard caulking gun, apply a thick, continuous bead of lap sealant around the entire patch, about 3/8-inch wide, centered on the exact edge of the patch. Smooth down the sides of the bead of lap sealant immediately, taking care to leave the sealant very thick directly over the lap edge.

That’s it, you’re done!