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jillemorgan
Joined: 07 Jan 2008
Posts: 3
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 Posted: Mon Jan 07, 2008 6:12 am Post subject: Roof Scuppers |
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My husband and i are in the process of building a house that is stick framed (parapet too) with a low slope roof and consequently thru wall scuppers. We are experiencing problems with condensation forming on the scuppers. we do not want to have long term problems with mold growth, maintinance and decay of our new home. does anyone have any details for dealing with this issue that they would be willing to share?
thank you in advance.
-Jill |
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phansford
Joined: 18 Apr 2004
Posts: 550
Location: SW Ohio
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| Posted: Mon Jan 07, 2008 8:50 am Post subject: |
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Can you provide some more information?
Your Location (city/state)? When does condensation occur - snow, rain, all the time?
Condensation does not necessarily mean you are going to have mold/mildew problems. Go look at the tank on your toilet - on certain days (indoor air temperature v. water temperature) - there will be condensation on the tank. I'm sure you don't have mold growing on your toilet tank.
Condensation on your scupper doesn't mean its getting into the house...... if they were installed/constructed properly. I get condensation on my gutters when its warm outside and I have cold water, snow or ice in the gutters. |
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jillemorgan
Joined: 07 Jan 2008
Posts: 3
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| Posted: Mon Jan 07, 2008 9:25 am Post subject: More information |
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We are building in Upstate NY. Our concern comes in that we are getting so much condensation that it is dripping onto our finish woodwork and onto the floors as well as soaking into the insulation that we have in our walls and starting to mildew and mold on the sheathing and framing where the water is captured. we are relatively confident that it is NOT a result of the roof or scuppers leaking but of the scuppers being cold and the interior air being warm and semi-humid (which we are working on controlling the humidity). i have seen and heard of horror stories where moisture is in the walls and creates huge messes.
-Jill |
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phansford
Joined: 18 Apr 2004
Posts: 550
Location: SW Ohio
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| Posted: Mon Jan 07, 2008 11:53 am Post subject: |
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What you are describing sounds like "ice damming". There are alot of issues that could be causing your problems. You need to have a design professional look at the problem first hand. They may bring a roofing contractor with them to help in their assessment.
Do you have a single roof or a single-ply membrane? Since you have a parapet, I am assuming a membrane, but if your slope is greater than 2.5:12, it could be shingles.
Some other questions -
Are the scuppers clear? Is there debris or snow/ice stuck in the scuppers?
Is this occuring at all of the scuppers or just one? (Is it an isolated condition or universal)
Is the house still under construction? Is this how you are seeing the wall insulation has been damaged?
Did you use an architect? If so, have you contacted them for assistance?
Has the Builder been notified? Are they providing any guidance? |
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jillemorgan
Joined: 07 Jan 2008
Posts: 3
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| Posted: Mon Jan 07, 2008 12:21 pm Post subject: |
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I almost hate to admit it, but i am an architect... i have specified and detailed successfully scuppers in masonry construction and never had issues with them...This is kind of an odd situation. Our house is single story and we we framed the exterior walls with an interior ledger for the roof framing (balloon framing) so that the exterior wall would be a continuous height all the way around and the interior ceilings would then slope as the roof slopes.
My husband being an engineer and i being an architect have taken on this building/learning experience of doing a self build. We made it successfully thru the foundations and the framing and electrical and the roofing (or so we thought) and now the insulating and plumbing... but we are having issues with these ever-loving scuppers.
We have a ballasted epdm roof. the scuppers are custom made brake metal. on a low slope roof that has a slope of on average 1/2:12. there is no ice built up in the scuppers. the primary issue is that they are sweating. we need to stop the sweating to stop the insulation and finish work. We insulated the heck out of the walls (r-31 - r21 in cavity and r-10 continuous) and the roof (r-52 cont). i had been hoping that i could find a simple detail to fix the problem, but i have not had any luck. I am thinking that i will call our roofing materials rep and see what his thoughts are but i wanted to see what i could find here first.
-Jill |
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phansford
Joined: 18 Apr 2004
Posts: 550
Location: SW Ohio
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| Posted: Mon Jan 07, 2008 2:25 pm Post subject: |
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I take it the construction is wood framed (walls and roof).
There is no reason for metal to sweat unless there is water, snow, or ice present and heated air underneath. My guess is somewhere you have created a problem in the thermal envelop that is allowing snow and ice to melt and then wick into the building somehow.
The scupper can "sweat" - the issue is water penetrating the envelop and my guess is the scupper is not properly flashed. You may have detailed it properly and it wasn't installed properly.
I'm not sure why you would use a ballasted system - most roofing contractors don't recommend them. We are specifing either fully-adhered or mechanically fastened systems. The ballast could actually be causing your problem. It can be trapping water near or against the scuppers. There is always a little ridge at that point.
Is the "attic" vented? There are vents that can be installed in the EPDM roof system - however the ballast would negate their use.
Can you post the wall detail? |
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birgco
Joined: 01 May 2007
Posts: 302
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| Posted: Mon Jan 07, 2008 4:00 pm Post subject: |
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Hi Jill,
need to know what is the metal the scuppers are made of. If they are copper, were they primed before the edpm was adhered to them? What was the sealant used and what method? However, without knowing more info, I think iit would be almost impossible for the "sweating" to be the source of all your "condensation". The detail work around a scupper on a very low slope roof is problematic at best. Unless the seal between the metal, wall and roof material is perfect, water will find a way into your home. |
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phansford
Joined: 18 Apr 2004
Posts: 550
Location: SW Ohio
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| Posted: Wed Jan 09, 2008 5:22 am Post subject: |
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| jillemorgan wrote: | | I am thinking that i will call our roofing materials rep and see what his thoughts are but i wanted to see what i could find here first. |
Hopefully you called the roof rep. What was his thoughts? Keep us informed of how this gets resolved. |
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JWmHarmon
Joined: 15 Apr 2004
Posts: 112
Location: Ohio
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| Posted: Sat Jan 12, 2008 6:34 am Post subject: slope of the scupper |
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Can you give us more info about the design of the scupper?
Does the scupper slope down towards the outside or is it releatively level where it goes through the wall? Can it be modified so that there is a greater slope so that any condensation will drip away from the house instead of onto the house?
"Bridge freezes before roadway" signs are posted on most bridges in northern areas. Likewise, water vapor condenses on metal before condensing on the wood trim or house siding or EPDM roofing material becasue of the latter's greater thermal mass.
Can the scuppers be redesigned to channel all the condensate farther away from the wall?
_________________
When building or manufacturing always ask, "How will we recycle that?" - JWmHarmon |
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modjohn
Joined: 07 Nov 2007
Posts: 38
Location: Kansas, USA
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| Posted: Mon Jan 14, 2008 9:25 pm Post subject: |
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Hi Jill,
I am assuming that you are heating the building to some extent since it is winter and you are in New York. I also have to assume that the warmer air in the building is having some contact with the scuppers and causing water vapor to condense at that point.
Could the solution be to use some closed cell expanding foam to isolate/insulate the scuppers from the warmer building air. This would move the dew point further away from the metal of the scuppers and should eliminate any condensation at this area.
Hope this helps,
John |
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