Shed roof leaking

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  #1  
Old 04-09-17, 06:09 AM
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Shed roof leaking

I've had 2 or 3 areas on the roof leaking in the shed from rain water and snow melt.
I think this is happening by capillary action where water comes over the edge of the concrete and into the gap between the roofing and the concrete.
It is then getting under the roofing material somehow and dripping down the rafters on the inside of the shed roof and onto the floor.
Do you think adding flashing between the concrete and roof will solve this?
1st picture shows the bannister on top of the concrete balcony hidden behind it and the metal roof material going underneath.
2nd picture shows the snow melt on top but even if I clear this it doesn't stop rain water coming in.
3rd picture shows the inside of shed roof where the drops come in in the connection between concrete and metal (+ a type of sealant).
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  #2  
Old 04-10-17, 05:46 AM
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A end view photo of the deck and shed roof would be helpful to see where the shed roof starts and the deck ends. In your photo 1, it looks like the collar board for attaching the bottom of the railings is in line with some of the metal roof attaching screws. How are the screw holes in the metal roof sealed after the screws are tight? These locations could be could be a source of the water leaks.
 
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Old 04-10-17, 06:54 AM
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They are special roofing screws so they have a kind of rubber o ring/gasket on them that does the seal.
I discovered a negative slope on the underside. Seems someone painted some rough/stucco type material on the flat concrete and they jammed their brush in the gap, meaning when the water comes over the edge of the concrete instead of going onto the metal and down, it goes backwards

I thought flashing from concrete to metal would work but unsure how to attach it.
I could also just jam silicone in the gaps.
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Old 04-11-17, 05:54 PM
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I thought flashing from concrete to metal would work but unsure how to attach it.
I could also just jam silicone in the gaps?
 
  #5  
Old 04-12-17, 04:23 AM
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Caulking is usually only a temporary fix but like you I'm unsure as to how to install the flashing as it's kind of an unique situation.
 
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Old 04-12-17, 04:50 AM
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I think it is more ice dam type of thing where snow on the roof prevents melt from the slab from running off and it backs up under the the edge of the roof and gets behind the flashing. Removing the snow should get rid of the problem. Capillary action is not likely as you can see that there is a groove cut in the under side of the concrete which prevents the water from wicking further down down the slab. Water after all can not travel up hill so when it hits the groove it drips at that point.
 
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Old 04-12-17, 07:25 AM
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There's a negative slope on the underside of the concrete. I can see the water flowing backwards...
Can't clear the snow on the roof as it is a property that we are not always at so it ends up on top. It's a non heated room.
There's no ice dam there right now and it's leaking though I agree, ice in winter probably does build up as well.
 

Last edited by qwertyjjj; 04-12-17 at 07:54 AM.
  #8  
Old 04-12-17, 08:17 AM
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Originally Posted by qwertyjjj
There's a negative slope on the underside of the concrete. I can see the water flowing backwards...
Seems that you just need to establish a drip line



If the stucco-concrete is in good condition, (e.g. not weathered or crumbly),
I would clean it off, and cut a drip line with a Dremel and small masonry wheel-

Short term, an easier solution is to clean the stucco-concrete and draw a thick line with a junkyard grease pencil, instant drip line.
 
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Old 04-12-17, 09:12 AM
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Really an awkward space to work in but can try.
If there is a negative slopw on the underside, won't a drip line just continue to flow backwards?
 
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Old 04-12-17, 06:47 PM
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Is there a way to attach flashing to concrete in case that is 1 of my options including repairing the drip line.
 
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Old 04-14-17, 09:09 PM
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Is there a wheel you can attach to a drill? I've used dremels before and the masonry cutters don't last long. Also, a drip line has to be at least a few millimeters thick and dremel masonry bits are not. There is no existing drip line there - i rechecked it today.
 
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Old 04-15-17, 05:41 AM
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attach flashing to concrete
Generally you would cut a line in the concrete up high, say about 1/2" deep with a saw using a concrete blade. Custom bend your flashing so there is 1/2" at the top, a 90 degree bend downward and finish with whatever flare you need at the bottom to accommodate your slope. Insert the flashing in the groove and silicone it in and on top. This creates a continuity of water flow over the top of the flashing without the possibility of it backwashing.

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Old 04-15-17, 06:58 AM
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They also make what is know as termination bar, for rubber roofs. Its just basically a piece that gets anchored to the wall, giving you a good solid ledge for sealant. You could do something similar...

Foam closure that matches the profile of your metal roof... a wall flashing that covers the foam closure and extends vertically onto the edge concrete. A square piece of wood or metal on top of the flashing (acts as a counterflashing once sealed) anchored to the concrete, then sealant to seal the top edge of that, sealing it to the concrete.
 
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Old 05-02-17, 02:00 PM
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2 questions about the approach.
I have a wood 1x8 in the way attaching to the balcony so putting anything in the side of the concrete means cutting this away.

1/ If a termination bar can be used and sealed, couldn't I put up some angled flashing, attach it to the underside and silicone it as well?

2/ If I cut a drip edge into the bottom of the concrete, I need to use a dremel with a diamond wheel. Am I likely to go through a lot of wheels or will 1 wheel do a section of around 10feet easily?
 
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Old 05-02-17, 02:39 PM
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Sorry if I am missing something, but you mentioned having an angle grinder in another post, so why would you not use that instead of a Dremel?
 
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Old 05-02-17, 05:00 PM
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Maybe, but if you do that, you will be trapping water behind the 1x8. Its a real cluster. I don't know that you can do this properly without removing the 2x8.

Looks to me like you don't have any room to cut a drip edge into the bottom of the concrete, I don't think that idea will go far. A kerf with a Dremmel diamond blade would be so thin that it would do absolutely nothing. The kerf needs to be wider than a raindrop is in order for that to work.
 
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Old 05-02-17, 05:46 PM
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Hmm. How about cutting off 1" of the 1x8 and then how to secure the flashing into the concrete. I guess I cut horizontally into the concrete then. Not sure a termination bar would fit in the space...

Say the roof is 10ft wide. I need to cut into concrete with angle grinder or circular saw. Do I need to cut some extra wood off at either end to allow for the circular saw plate?

...in fact, a circular saw won't even fit there sideways unless I can somehow clamp a straight edge sideways and put it on a deeper cut but only to cut 0.5" into the concrete.
 

Last edited by qwertyjjj; 05-02-17 at 06:07 PM.
 

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