EPDM Flat Roofing Repair in Maryland and Delaware


Apex Construction was hired by a commercial business in Salisbury Maryland to fix a leaking EPDM flat roof.  We have included step by step instructions on how to repair your own flat roof.  The professionals at Apex Construction can repair, fix, remove, and do complete installations of Sarnafil and Dura-Last Flat roofing systems. Contact us for more details. 

Step 1 – find roof leak:

Generally, a field sheet of rubber roof will not leak, unless there is a hole in it, and you can typically see these holes when you remove all dirt and debris off the roof.  Therefore, look for leaks in other not so visible spots.

Most flat roof leaks occur in common spots – low spots on the roof, where water pools after rain.  If you have a seam running through one of these low spots, there is 95% chance that there is a leak.  Use a probe or even a nail, to test the seam for any voids / openings. Other spots include inside / outside corners, such as chimney / skylight curbs, or roof to wall connection or pipe flashing, etc.

Step 2 – prepare roof surface:

Once you locate the source of leak, remove all dirt and debris, and using EPDM cleaner (do not use gasoline), clean the surface area thoroughly.  Use a dish scouring pad if dirt does not come off easily, and pour a little more cleaner over the surface area to clean it better.  Once you clean the repair surface, use another clean rag and a little EPDM cleaner for the final thorough wipe of repair area.  Let the cleaner dry.

Step 3 – apply EPDM primer

By using a simple paint brush, apply a good (but not too thick) coat of EPDM primer, making sure it extends at least 2″ beyond the edges of the patch that you are going to apply.  Spread the primer evenly, so that you don’t have too much in one place and not enough in the other.  Make sure you don’t have thick “puddles” of primer, as it will not completely dry, and your patch will not properly adhere.

Once you apply the primer, let it dry for about two-three minutes, depending on the weather, temperature, and how thick of a coat you’ve applied.  Once you think the primer has dried – do a tack and pull test.

Touch the center of primer with a clean, dry finger, and pull your finger off.  If primer does not stick to your finger, it’s ready to apply the patch.  If you pull some primer with your finger, let it dry for another minute, and repeat the test.

Note: Primer must be dry before you apply the patch – otherwise it will fail to adhere properly!  Also, if you applied primer over old glue (which is visible on a rubber roof) or some other sort of adhesive or sealant, which you did not completely cleaned off the roof surface, the primer will dissolve this old sealant and it will take much longer to dry, before you can apply the patch.  Do not add more primer over this spot.  However, you might need to reapply the primer to the area around such spot, as the primer should not dry for too long.

Ideally, you should completely remove any such spots of old glue / sealant, and rubber surface should be completely free of any foreign materials for best patch adhesion.  You may use a plastic or metal scraper to scrape this old material off the rubber.  Use additional cleaner and the brush for better results.  Also be careful if you are using a metal scraper as not to tear / puncture the rubber membrane.

Step 4 – apply the patch to a flat area:

If you are applying a patch to a flat area (i.e. – no inside or outside corners or other imperfections), this process should be very easy.  Make your patch so that it stick about 2-3″ beyond the hole in the roof, and round off the corners with scissors.  Once you confirm that the primer is dry, remove the film / paper off the back of your patch and slowly apply the patch to the roof surface, making sure you do not trap any air, so that you don’t create any bubbles / air pockets between the patch and rubber membrane.  Work your way out from on edge of the patch to the other.  Once the patch has been placed down, roll it in with the silicone roller, with moderate pressure.  Make sure you roll in the edges of the patch especially well.

Applying patches to corners or transition areas requires more attention to detail and some practice.  Contact Apex Construction for more information and/or a project quote to help fix your commercial flat in Delaware or Maryland.