Before you begin your rubber roof repair:

First – the following conditions should be met, to perform a rubber roof repair properly:

Ambient (outside) temperature MUST be 40 degrees F or higher – otherwise the primer will either freeze or the bond will not be as strong as it is intended to be, thus your patch will leak prematurely.

Repair surface MUST be dry when you apply primer and patch – otherwise patch will not hold.

Before applying patch, you must thoroughly clean the repair surface, remove any and all debris, dirt, any tar or other sealants / caulking that might have been applied.

It is recommended (but not necessary) in certain situations to also remove old lap caulk, before applying new patch.

Second – in this guide, we will cover most common types of rubber roof repairs / patch work. However, there might be situations (on your roof) that go beyond the scope of this DIY guide – let’s call them complicated repairs – we will provide a few sample photographs of such complicated repairs.

With all our experience with flat and rubber roofing, even we sometimes run into these unforeseen scenarios which take considerably more time and flashing materials that we initially anticipate, and basically test our skills in flat roof repair – and we fill that such cases are beyond the difficulty level of most roofers and even advanced DIY homeowners.

If you feel that your roof has one of these complicated cases, we would recommend that you do hire a professional to fix your rubber roof for you.

Here is what a rubber roof repair look like on a real roof – not in perfect factory conditions.

RUBBER ROOF REPAIR VIDEO: How to apply rubber roof patch to an outside corner on a REAL roof (10 minutes long):

DIY Rubber Roof Repair – step-by-step guide:

Below we will describe the process of locating roof leaks, preparing the roof surface for repair (cleaning / removing debris and foreign materials), applying EPDM primer, and lastly applying EPDM flashing membrane to complete your repair.

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 are thoroughly. Use dish brush 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

– 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 4.1 – apply the patch to a flat area:

If you are applying a patch to a flat are (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.

Step 4.2 – apply patch to an outside corner:

Outside corner flashing video #2 – filmed in studio by Rubber Roof Manufacturer

This is a more complicated / advanced technique and may require some practice, as well as redoing your first patch. Before performing this operation, watch included videos (above) several times to get a good idea of what you will have to do and in which order.

Once you applied the primer and let it dry thoroughly, take the 7×9″ corner patch (you may also cut a 6×8″ piece off the 10′ roll included in our rubber roof patching kit), fold it in half, and peel back half of the film (but do not remove it completely). Attach the patch to the vertical part of the outside corner, and wrap it around the corner, making sure that it’s tightly applied without any air bubbles. Now use your fingers to slowly roll the patch down into angle change from vertical wall onto horizontal roof deck. Do not stretch it there or the bridging (voids / gaps) will occur, and this flashing will not work.

It is very important that this transition has no voids or bubbles where roof goes from horizontal to vertical plane! – otherwise your patch will not work – make this transition as tight as possible. Then slowly start to apply the remaining flap to the horizontal plane. Use your fingers to lightly stretch the patch from the center out and keep rolling it in with your fingers. Continue the process until entire flap is attached to the roof.

Once the patch has been applied, roll it in with silicone roller, paying special attention to step-offs. Roll the edges tightly, and apply EPDM lap caulk along patch perimeter.

More advanced rubber roof repair techniques will be added soon.

Rubber Roof Repair part 2 – learn how to fix rubber roofs using older “black rubber glue” (EPDM splice adhesive).

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