Flat-roof failure--help!

Hi guys,

Last year my wife and I hired someone to replace our home’s tar-and-gravel flat roof. The roofer we contacted used a high-tech system consisting of a tar undercoat and a white polymer topcoat. The topcoat was supposed to last longer than a conventional roof, have great insulating qualities, etc. He had a large website with convincing-looking technical explanations.

After a couple of months, the topcoat began to come off. Large areas of it are now missing, and other areas are loose and waiting to detach.

The roofer says the failure occurred because his tar supplier changed the tar’s composition without telling him, and the polymer wasn’t formulated to stick to it. He claims that all the tar that’s available is now this substandard type. (Does that make any sense?) He’s refused to give us a refund, claiming he has no money.

Now we’re faced with either having another roofer completely remove this roof and start over, or trying to somehow repair the roof we have.

Here’s my question: As far as I know, the tar undercoat is fine. (They used a lot of tar; I watched.) Could we just add another coating, or even gravel, to what’s there? We could remove the rest of the white topcoat easily enough, if that was important. Structurally, the roof is solid with no sagging areas.

We’d sure like to avoid the expense of a complete new (i.e. torch-on) roof in addition to the money we’ve already lost. Thanks for your advice!

First of all, you don’t just mop down a lot of tar and apply a coating over it and call it a roof. You were taken by the first guy posing as a roofer. Tear it all off and start over with a reputable roofer that uses reputable products. If you use a tailgate roofer, you can expect your warranty to last as long as you can see the tailgate of his truck when he drives away.

Sorry to be the bearer of bad news, but this is one of those life-lessons you hear about.

You need pics.

The failure of the roof coating could be for a number of reasons. What specific failures are you experiencing? Seperation of the top coat from the base coat (blisters)? wash away of the top coat to expose the base?

Acrylics on ponding water won’t work. You could potentially add another coating, assuming the new coating will stick to the old coating and assuming that the new coating is formulated for your roof type. There is some very very cheap coating on the market that is nothing more than paint.

Did he tear off the old roof or just mop over it? What type of coating was used and at what application rate and at what rated dry mill thickness?

If you do choose a new roof torch down is only one option. In addition if he did tear off the old roof you may be able to build a new roof assembly over this existing roof, depending on the code and condition of the existing.

If you want to recoat it, first I would suggest doing some test patches to ensure the new coating will adhere to the existing coating. I say this because if you coat the new roof and it does not adhere it will seperate and blister. Definetly a washing with a low pressure powerwasha nd detergents will be necessary.

Again you need to post some pics.

I would suggest starting from scratch and tearing off anything your last contractor applied if you want to stay with a tar and gravel system. Otherwise you should look into a single-ply system as a go-over option. If you apply another t+g system to the one that has already failed then you will be in for more headaches. But a fully adhered single ply system done correctly will be quick and effective. EPDM OR PVC are your best options, EPDM being the cheaper of the two.

a coating “paint job” is not a roof.

I agree, but a good quality roof coating can be built up in a number of layers, with our without reinforcement to be easily 30 dry mills thick.

You’re right a paint job is not a roof and alot of people out there putting down coatings wrong give coatings a bad name. I have successfully stopped major leakage and added years to several roofs with coating systems.

Painting it on like a silver coat at 5 squares per gallon will do nothing. You need no less than 3 gallons per square or often times more.

A TPO roof is absolutely the best route to take unlike torch down which has seams every 3 ft. Tpo you can get in 10ft wide rolls. If done properly the seams will never come apart. This roof will last a very long time. Most Tpo roofs are an energy star rated material. Asphalt is a thing of the past. Also some TPO membranes are at least 90% recyclable. So go green and watch who does your roof. This is a roofing Contractor serving Virginia Beach Norfolk Chesapeake Newport News and Hampton Virginia

Pretty easy to recycle when there is just scrim left after 10 yrs…

hey ax…

at least the tpo tearoff/haul away is EASY! just roll it up, and throw it away when you are done. lol


where are the pics?

TPO has no track record. There are a lot of TPO roofs going bad in just a few years. I still will install them but recomend PVC.

Easy there, tiger… no need to tell us on every post where you are working in the Eastern Seaboard areas of Virginia. After all, your ‘signature’ says it already.

I’ll defer to Cerebrus on this one, however I am a fan of Duro Last (single ply PVC).

OP, photos would be nice. How large an area are you?