Fix for roof with no ventilation


Old 07-17-13, 08:32 PM
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Post Fix for roof with no ventilation

I am getting water running down the inside of one of my exterior walls and the wall has mold and the subfloor below is rotting and I think that it is because of a design problem with the roof.

I own a 1905 house that had a major renovation in 1990. They added a lean-to type of addition on one side. The roof from the interior out consists of drywall, double layer of vapour barrier, 8 inches of pink insulation, roof sheathing, and metal roof. There are no vents in the soffit and there are no vents in the roof. There is no space for ventilation inside the roof. I've opened up the fascia and checked the top of the exterior wall, and parts of it are wet. I think that I am getting condensation on the inside of the vapour barrier and it is running down the wall.

My problem is how to fix it. The house is very old and isn't worth major repairs. I would like to prevent this from happening over a two to three year period. One of the ideas is to put heat tape over the roof. Another that sounds more work but would be a more permanent fix is to put baffles up each of the spaces between the joists. This will compress the insulation but will provide ventilation if I put in vents at the top and in the soffits.

Does anyone have any other ideas and would the heat tape work in the short-term?
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Old 07-18-13, 03:09 AM
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Welcome to the forums! Basically you have a water sandwich. Having the insulation encapsulated without a means of air movement over it is a prime water condensation creator. We may have some ideas as to how it can be fixed, but would really like to see what we are working on. Could you post a few pictures of the inside and outside of the addition? That way we can see what you see.
Old 07-18-13, 04:15 AM
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Could any number of things in addition to what Chandler suggested.
If they did not install standing seam roof so there's no exposed fasteners the fasteners could be leaking.
A really common place for roofs like that to leak is where the new and old roof where tied in.
No drip edges, not enough overhang, using nails not screws to attach the roof.
Often times a low slope roof can be vented on the walls instead of the roof it's self.
Put without a picture it's anyone guess.
Old 07-18-13, 06:13 AM
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Post pictures of roof

Thanks for the help. I've taken these pictures. The houses roof is basically a pyramid with a porch type roof attached about 8 inches down the side of the house. I haven't been able to find any water staining inside the addition, just the mold and rot inside the outside window wall. Sorry I couldn't get the bottom picture to rotate. Name:  IMG_2262.jpg
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Old 07-29-13, 01:10 PM
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I am not sure of cost I would consider doing a ridge vent for the roof . This should allow the air to move between the metal and the old roof as well as the inside of the attic
I would install a couple of vents along the side of the house that you have open as well as the other three sides this would or should let the attic vent better
Last it looks like the metal may have been cut to short. You could get metal bent into a L shape, slide it under the roof metal and drop down along and past the side or eve/facia
Another likely leak is down the side of the dormer

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