I’m asking this question on the behalf of someone else, so I might not have all the details right.
This person’s roof appears to be leaking. I say “appears to be” because it doesn’t drip when it rains. It only drips when it’s about 70 degrees outside with the sun beating down on it. We had a lot of rain in the past few weeks, enough where you would think we would have a flood, and not a drop fell. But the rain clouds went away, the sun came out and sure enough: drip, drip, drip. It drips in the afternoon and stops when the sun starts to set. It doesn’t drip in the winter.
Here are some details:
It is a rubber roof.
There is an air conditioner that goes through a hole in the roof.
“Hey, that’s where the leak is. Problem solved!” No, there is insulation in the hole, and it’s dry.
This person put a rubber (I think) tarp thing around the a.c. and is reasonably sure the he sealed any openings.
Not really! My guess is the condensate line off the AC unit. I’ll bet it only leaks/drips when the unit is running right? AC units draw a tremendous amount of moisture out of the air and it has to go somewhere after… condensing. Algae and other crud builds up in the lines very easily so check the condensate line and make sure it is…
I left out a vital piece of information. The a.c. hasn’t been turned on since last summer! It was dripping today and the unit wasn’t turned on. The theory we have now, and we have no way to prove it, is that water got trapped in the roof before we sealed it and the heat from the sun is causing the water move and begin leaking.
It’s possible it’s the condensation drain tube for the A/C unit.
If it’s plugged up, then it’s just holding water. The sun heats it enough to let it expand and then drip out. Not hot enough at night or in winter to get the water expanded enough. Clean out the tube.
That is just a WAG.
For a more educated guess, answer this: Is it a flat roof? What type of A/C? A window unit? Or central air? Why is their a “rubber tarp” around the A/C? Is there a drain line? What do mean by rubber roof? Is it a torch down product like Vitek? If it is a torch down, was the right backing (mesh) used? Or was it just slapped on?
The plywood under the roof needs to be vented. That is, the shingles are nailed into plywood. Between the plywood and whatever’s underneath, there needs to be air, circulating.
I know about this because the roof on top of an addition to my house is about to be replaced because, while it doesn’t leak, it does have condensation built up between the plywood and the cedar that is exposed as a cathedral ceiling. After the plywood comes styrofoam insulation, and after that, the cedar. No air was left between the styrofoam and the plywood, and so condensation built up and the plywood rotted. My new roof will have an air space between the plywood and the styrofoam, and a ridge along the top to vent the air out.
This is a common problem. In a normal roof with an attic underneath, if the attic doesn’t have air circulating, you could get the same condensation, obvious to the eye in that case because the plywood is right there above you. A couple of people I’ve talked to had this problem in rooves that had an attic underneath with the plywood exposed to the attic, and solved it simply by improving the air circulation in their attics.
Take it from me, if this is what’s happening, it could be very expensive to replace if the plywood has in fact rotted. It could cost up to twice the normal price for replacing a roof, because basically, if the problem is far enough advanced, they have to reconstruct the entire roof from scratch, just about. Very depressing, but true.