Is this the right product for my roof?

We purchased a 4-unit investment property last fall. As part of the inspection, we were told that while there is no visible water damage in the units, the roof probably only has another year or two before it needs to be replaced. Here is some basic info on the roof (all pulled from the inspection report):

  • it is a low slope roof

  • material is modified bitumen and clay tiles

  • connections + penetrations in the roofing surface are sealed w/ sheet metal and mastic

  • roof drainage system is comprised of scuppers and downspouts

  • tile roof system is in “adequate” condition

  • there is surface granulation in several areas of the roof, with the inspection report noting that this indicates a general failure of the roofing material

  • the roofing material has ridges, ripples, or bubbles

  • There are areas where tar/sealant has been applied as a patch or repair.

My real estate agent recommended a liquid EPDM rubber coating that we can use to essentially re-coat our roof. It sounds great because we would be saving a lot of time and money, but we don’t know enough to know the risks of going this route. I know a few snippets from an inspection report isn’t enough to make a qualified judgment, but I would appreciate any feedback or suggestions from the roofing experts in this group on a) whether liquid EPDM coating is a good product; b) whether it makes sense in our situation; c) what you would do if you were in our position.

Thanks in advance for any thoughts.

What weather is in your part of the country? Repair coatings are always iffy, maintenance coatings are mandatory.


I couldn’t get past the part where you said “my real estate agent recommended “. Are you going to now ask your roofer for investment advice for buying properties?


We are in Los Angeles.

What do you mean by maintenance coating in this context?

Maintenance coating would be to protect your roof from uv which helps certain roofs have a longer life span. However if you wait until your roof is leaking you’ve waited too long for “maintenance” coatings and need a new roof or at the very least a proper repair.

Thanks Island. Thankfully it doesn’t seem to be leaking yet.

So is it maintenance coating and then then EPDM coating on top? EPDM coating and then maintenance on top? Or maintenance as in you apply the coating now and then again in X number of years?

Flat roofs and commercial roofing is a whole different ball game compared to shingles and residential.

First, if your roof is modified bitumen it most likely is supposed to be granulated. That is what provides the UV protection for the sheet.

Depending on what type of penetration you have sheet metal and mastic is what is supposed to be used on modified roofs. Lead, copper, or stainless pipe boots, and steel roof jacks and storm collars for flues.

Scuppers and downspouts are normal for flat roofs to drain.

Ridges and ripples are not necessarily a problem in modified roofing. Bubbles can be depending on whether they are blisters or water trapped between plies.

“Tar”, which is used by people when they don’t know what something is, is supposed to be used to patch modified roofing as it as an asphalt product and only asphalt products should be used to repair it.

Commercial roofs are warranted differently than residential roofs. See if the previous owner has the roof warranty or a record of who installed the roof and what manufacturer.

Modified roofs are typically warranted for 20 years although you can also do 10-30 years depending on exact scope and manufacturer.

A commercial roof should have a No Dollar Limit warranty which is transferrable from the previous owner for a nominal fee, usually a few hundred dollars. This warranty covers all leak repairs for warranted conditions for the entire warranty duration. If you roof does need replaced you should make sure you get this type of warranty with your new roof. Not available from most coatings.

Elastomeric coating and other “liquid EPDM” roof coatings are only as good as the substrate. However many are not compatible with asphalt roofs and they must be able to adhere. This can be very tricky on modified roofs. They also make any future repairs much more difficult since you must remove the coating to actually repair the roof then put new coating on.

If you coat the roof you are almost always better off using an asphalt based coating product of which there are many. Some of which you can get a warranty on that is actually worth something.

You should contact a local reputable Commercial roof contractor or a local Registered Roof Consultant if you are worried that the contractor will just try to sell you a roof. It is entirely possible that you have more life in your roof than you think, 25-30 years is not unusual for a good modified roof to last. If you do need it replaced or coated either should be able to point you in the right direction.


All coatings must be matched to the existing roof to adhere and have any service life. Sacrificial coatings are installed on a serviceable, non-leaking roof, as they wear down they must be re applied. Your best choice would be a modified asphalt coating. Also, you must match the perm rating of the substrate or vent it properly.

Pics of the roof please.

Thank you for these very thoughtful replies. I tried to add a few pics of the roof, hopefully this works. Is there an asphalt roofing product that you can recommend?

Honestly it is hard to tell just from these pics but the small ridges are called mole runs and they can happen. Usually not an issue.

You can have a roofer use SBS flashing and cold adhesive or torch and repair those areas with a membrane patch. That would be permanent.

Then the granulation isn’t that bad. You just need some UV protection so use and unfibered aluminum coating over the roof and you should get a few more years out of it.