ROOF LEAKING???? | Ask Mason Knowles - SPF Consultant | Spray Foam Technical Questions and Answers | SprayFoam Magazine Q&A Forums

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Craig Maturi Posted: Dec 20, 2007 04:18 PM	ROOF LEAKING???? i got called back to a job where we put 6" closed cell onto the underside of the roof deck in a vaulted ceiling new construction home. before we sprayed a vent system was installed using the styrofoam vents, from soffit to ridge vent in every cavity.well the problem is that he found a puddle of water on the floor and he claimes it came through the foam. there is a hole in the foam that only seems to be 2' deep. this is about 10' up the roof from the soffit. how can moisture be forming there when there is through vents? is this possible? i do live in northern minnesota where the temps have been -10 the last few weeks. please help with some answers.
mason Posted: Dec 21, 2007 09:17 AM	The SPF industry recommends unvented attics and cathedral ceilings when installing SPF to the underside of the roof deck. Using vents with SPF complicates the situation. Without vents, the SPF separates the interior and the exterior environments effectively so condensation on the underside of the roof deck does not occur (presuming a sufficient thickness of SPF). It is also easy to see where the foam is installed and where it is not. I don't know if the water comes from a roof leak or from condensation. But unless the foam was sprayed off ratio it did not go through the foam. But with the vents it is difficult to check on roof leaks. Water vapor may have formed on the surface of the foam if the thickness was light in that area. A rule of thumb is to keep the surface of the foam at 45 degrees F or above. You mention that you found a hole in the foam about 2 inches deep. The cold weather may have dropped the surface temperature of the foam to the dewpoint in that spot. You could check it out with a surface thermometer and also check out the humidity level in the attic. Another thing to check are your penetrations through the attic ceiling and roof deck. Has the SPF sealed them effectively? Are they insulated to prevent condensation? I have a condensation leak like this in my bathroom that requires taking down the gypsum board and insulating my vent. (can't get to it from the attic). Hope this helps, any other ideas?
Dave Strnad Posted: Dec 21, 2007 03:26 PM	I would really dig into this and see if it is a reoccuring problem. I notice that when I spray like you mentioned The foam and blue board will cup slightly in the middle. This would cause the water to run down the middle of each joist space. If you did have a leak and there was a crack all the way through it could leak through. Also we have similar weather here and building in the snow is a pain, it always gets in somewhere and then melts causing water. Remember other insulation holds alot of water before becoming noticable, Closed cell does not asorb it so even a little leak or snow that got in and melted would drip down if there is a crack all the way through. Was the roof and soffits completely finished before you started? I have seen snow drifts inside of attics that did not have the soffits on yet after a bad storm. Snow can blow through some ridge vents in bad conditions. What type of ridge vent did they use? Also has the house been continuosly heated or was it allowed to cool and then they used propane or kerosene heaters to warm it up quickly. If so it could just be condinsation and those types of heaters add alot of water to the air. Anyway a couple of thoughts I really doubt it has anything to do with the foam, but it is always the first to be blamed.
mason Posted: Dec 22, 2007 12:58 PM	Dave, Good info, appreciate your input.

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Craig Maturi

Posted: Dec 20, 2007 04:18 PM

ROOF LEAKING????

i got called back to a job where we put 6" closed cell onto the underside of the roof deck in a vaulted ceiling new construction home. before we sprayed a vent system was installed using the styrofoam vents, from soffit to ridge vent in every cavity.well the problem is that he found a puddle of water on the floor and he claimes it came through the foam. there is a hole in the foam that only seems to be 2' deep. this is about 10' up the roof from the soffit. how can moisture be forming there when there is through vents? is this possible? i do live in northern minnesota where the temps have been -10 the last few weeks. please help with some answers.

mason

Posted: Dec 21, 2007 09:17 AM

The SPF industry recommends unvented attics and cathedral ceilings when installing SPF to the underside of the roof deck. Using vents with SPF complicates the situation. Without vents, the SPF separates the interior and the exterior environments effectively so condensation on the underside of the roof deck does not occur (presuming a sufficient thickness of SPF). It is also easy to see where the foam is installed and where it is not.

I don't know if the water comes from a roof leak or from condensation. But unless the foam was sprayed off ratio it did not go through the foam. But with the vents it is difficult to check on roof leaks.

Water vapor may have formed on the surface of the foam if the thickness was light in that area. A rule of thumb is to keep the surface of the foam at 45 degrees F or above. You mention that you found a hole in the foam about 2 inches deep. The cold weather may have dropped the surface temperature of the foam to the dewpoint in that spot. You could check it out with a surface thermometer and also check out the humidity level in the attic.

Another thing to check are your penetrations through the attic ceiling and roof deck.
Has the SPF sealed them effectively? Are they insulated to prevent condensation? I have a condensation leak like this in my bathroom that requires taking down the gypsum board and insulating my vent. (can't get to it from the attic).

Hope this helps, any other ideas?

Dave Strnad

Posted: Dec 21, 2007 03:26 PM

I would really dig into this and see if it is a reoccuring problem. I notice that when I spray like you mentioned The foam and blue board will cup slightly in the middle. This would cause the water to run down the middle of each joist space. If you did have a leak and there was a crack all the way through it could leak through. Also we have similar weather here and building in the snow is a pain, it always gets in somewhere and then melts causing water. Remember other insulation holds alot of water before becoming noticable, Closed cell does not asorb it so even a little leak or snow that got in and melted would drip down if there is a crack all the way through. Was the roof and soffits completely finished before you started? I have seen snow drifts inside of attics that did not have the soffits on yet after a bad storm. Snow can blow through some ridge vents in bad conditions. What type of ridge vent did they use? Also has the house been continuosly heated or was it allowed to cool and then they used propane or kerosene heaters to warm it up quickly. If so it could just be condinsation and those types of heaters add alot of water to the air. Anyway a couple of thoughts I really doubt it has anything to do with the foam, but it is always the first to be blamed.

mason

Posted: Dec 22, 2007 12:58 PM

Dave, Good info, appreciate your input.

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