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Roof / drain / gutter question

S

slackerinabox

Lifer
Odd question but, since I'm between jobs and have free time, I'd like to self diagnose before calling in the expensive pros - if possible.

Noticed a slight leak every time we get heavy rainfall in our top floor guest bedroom. I went up on the roof (flat) and saw a pool of water building up. Dried the area up and saw no damage/tears (and the roof is less than 2 years old) but did notice that,instead of your typical gutter there's instead a PVC pipe that had some standing water in about 8 inches down.

Could this be the cause of the problem and is there a simple solution to unclog it? I'm wondering why there wasn't a grate on it at all, perhaps it fell off or perhaps it's a weird exhaust pipe and has nothing to do with roof (flat) drainage. Again, the roof still looks and smell brand new and I don't see any tears or damage. I'm sure there's a warranty on the roof but it's been hellish getting things taken care of by the contractor (new construction, really shitty builder)
 
If the pipe is higher than the roof. IE sticking up 2 to 8 inches above the level of the roof decking it is most likely a plumbing vent. If it is level or flush with the roof decking it may be a drain.
 
weadjust said:
If the pipe is higher than the roof. IE sticking up 2 to 8 inches above the level of the roof decking it is most likely a plumbing vent. If it is level or flush with the roof decking it may be a drain.
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It's flush with the roof. I found the discarded slotted cover (damn contractor didn't screw it on) and I'm guessing this clogging is causing the puddles/leak. There's no visible roof damage so I'm guessing the standing water weight is causing the water to squeeze through. Thinking unclogging this will be the solution, any suggestions?
 
It shouldn't be leaking into the home regardless of how much water is on the roof, that indicates you either have a leak in the piping or a leak in the roof. Fixing the drain issue will help but you need to find that other leak point because it will continue to leak, just less water, and eventually will cause mold and mildew problems inside.

Bad news is that if it has been doing this for any length of time you probably already got mildew on the back of the drywall where the leak occurred.
 
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Not necessarily. You should never have standing water on a flat roof. If you look at the photo of the similar roof drain. You can see that the roofing membrane is folded over and into the drain pipe. Once the water collects in the pipe and on the roof water can seep underneath the membranes edge. With the pipe draining properly the water flows down the membrane and out the pipe.
 
Modelworks said:
It shouldn't be leaking into the home regardless of how much water is on the roof, that indicates you either have a leak in the piping or a leak in the roof. Fixing the drain issue will help but you need to find that other leak point because it will continue to leak, just less water, and eventually will cause mold and mildew problems inside.

Bad news is that if it has been doing this for any length of time you probably already got mildew on the back of the drywall where the leak occurred.
Click to expand...

I kinda see what's going on. The pipe is recessed and there' a gap around the pipe, shoddy workmanship for sure. I'm going to get an auger and some sealant and (recommend a type?) for a quick fix. I'll check if home depot has a snug fitting plate as well. As for mildew - as mention, I have a lot of free time so I'll replace drywall where I see any obvious problems and look at what sprays they have at the home depot. Problem wasn't around all that long so I hope the damage isn't that great.
 
bleach should work for remediation. replacing the drywall is a good idea. If the there is a gap you may want to get some roofing membrane and patch it into that area. if there is no gap a bucket of roofing tar should do the trick.
 
Might want to see where that drain empties to before pushing the debris farther down the pipe.
Does it flow out somewhere you can see or go underground?
 
100% silicone caulk (sticks to rubber roofing and corroded iron and anything else)
or
Rubber roofing cement (holds rubber roofing together, but may not stick well to corroded iron, probably will though)
 
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If you have access to the spout on the underside, the pressure washer idea works better from the bottom up, instead of from the top down, as the build up of water will start to "protect" the clog. I have a flat roof and was able to clear a clog in this manner. I did have to take off the bottom 1/2 of the drain spout though to do this, not sure if you can. In my case, I had also used the rubber roofing cement with some roofer's fabric.

Also, be careful of augers, some of them will damage the thin metal of the runoff drainage pipes.

And on the topic of leaking, you can have leaks if there is pooling water because it will work over the flaps. A flat roof is still graded, even if it is less than 1%. And most roofs are built as overlapping flaps of whatever roofing material, where they are not technically water proof like a container, rather re-direct water more like a raincoat. If water comes in at the wrong direction, you get the leaking.
 
This summer I tried a auger, pressure washer and also backfeeding water into the whole system, didn't work. I eventually just had to get a ladder and clean it out manually.

The downtube was the worst of the problem it was completely clogged as a result of me using using this on the gutters:

31eah8pkjaL._SL500_AA300_.jpg

Basically this just washed all of the big stuff into the downtube, and I had to take it completely apart and reassemble it. It sucked. I'm just going to pay from now on, it's not worth the time IMO. It only costs $150 to have it done, I spent hours on it.
 
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