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  1. #1

    Default Ridge vent with spray foam insulation in rafters

    Inspected a house yesterday with spray foam insulation in the attic. A ridge vent was still present. (Sorry photo did not come out). My thinking is that the ridge vent should be sealed or removed as wind-blown rain that enters has no place to go. Right? Looking for confimation.

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  2. #2
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    Default Re: Ridge vent with spray foam insulation in rafters

    If the spray foam insulation is on the underside of the roof sheathing (where I suspect it is), then the way that works is for the attic to be a "sealed attic", and, as you are thinking, "sealed attics" cannot be ventilated (the attic wouldn't be "sealed" if it had openings to the outdoors).

    Jerry Peck, Construction / Litigation Consultant
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    Default Re: Ridge vent with spray foam insulation in rafters

    = My thinking is that the ridge vent should be sealed or removed as wind-blown rain that enters has no place to go. Right? Looking for confimation.
    Sealed attic or not, wind-blown rain entering an open ridge vent never has anywhere to go but down. It never has anyplace "to go", as it shouldn't be in there at all, no matter what type of insulation is present.


  4. #4

    Default Re: Ridge vent with spray foam insulation in rafters

    Thank you Jerry and Dom. Due to northeaster's we get a lot of wind driven rain up here (make that everywhere nowadays?) Ridge vents aren't supposed to leak water - but they do. I recommended to my client that he find out if the owner who had this done (an engineer who did every detail in the home right) sealed the vent from the inside with the spray foam. I suspect he did, but that's for my client to research.


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    Default Re: Ridge vent with spray foam insulation in rafters

    There are some other variables that should be addressed before recommending that the ridge vent be removed. No insulation between the ceiling and the floor of the attic? Any soffit vents? Conditioned attic or non heated space? The foam may have been some ill conceived method of adding insulation to an existing house.

    Jim Robinson
    New Mexico, USA

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    Default Re: Ridge vent with spray foam insulation in rafters

    Quote Originally Posted by Jim Robinson View Post
    There are some other variables that should be addressed before recommending that the ridge vent be removed.
    The two variables which need to be addressed are:
    - 1) sealed attic
    - 2) vented attic

    If 1), then no ridge vent is permitted as it is an opening, and sealed attics do not have any openings.

    If 2), then why the insulation is even on the underside of the roof sheathing is the FIRST question which needs to be addressed.

    Jerry Peck, Construction / Litigation Consultant
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  7. #7

    Default Re: Ridge vent with spray foam insulation in rafters

    This was no longer a vented attic; the spray foam filled the rafter cavities and end walls. It appeared to be a nice installation. The (potential) problem is that formerly this was a vented attic. Leavingt the soffit vents can't do any harm but leaving a ridge on the roof could allow wind driven rain to accumulate in the small space above the foam but under the vent. There was no evidence this was occurring, but are there any specific requirments to remove ridge vents when spray foam is installed. It won't vent anything but I worry about water coming the other way and not being seen until the roof sheathing has delaminated (although I think in this case it may be a board sheathing).


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    Default Re: Ridge vent with spray foam insulation in rafters

    I would keep my recommendations regarding fixing to a minimum. Most fully encapsulated homes that are insulated with foam are so tight that they need an additional air source to keep the home and the occupants healthy. The ridge vent may be part of this. The several gallons of water vapor given off (daily) directly by the humans, plus that given off from cooking and bathing, needs to go somewhere.

    Certainly a ridge vent would defeat the purpose of a home that is insulated only under the roof deck. (I assume there is no insulation at the ceiling level).

    Homes that are retrofitted with foam usually will have problems. They really should be designed from the day the plans are drawn. Involves many aspects of the home as a system including a matched heating/ac system as well as a designed outside air source/exhaust system.

    And since you were able to "observe" the foam in the attic (without cutting an access hole) It most likely needs an "Ignition Barrier" scroll down to "Fire Performance"


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    Default Re: Ridge vent with spray foam insulation in rafters

    I inspected one in March that was a new build. Ridge vent present and foamed roof deck all the way to the ridge. I researched it and could not find an exclusion of this practice but I think it is a no brainer that there should be no vent specifically because of the wind driven rain. The builders response to my concerns in the report (according to the buyer) was that the foam sealed the ridge vent so it should not be a problem. My conclusion was the vent may let some water in, but also let it evaporate out. I would not build one this way, I would just put the cap shingles on the ridge with no vent if I were foaming.


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    Default Re: Ridge vent with spray foam insulation in rafters

    Quote Originally Posted by Ernie Simpson View Post
    This was no longer a vented attic;
    .
    .
    Leavingt the soffit vents can't do any harm
    ????

    If one leaves the soffit vents, then it IS still a vented attic.

    Leaving soffit vents means it IS NOT a sealed attic (it has soffit vent openings - a sealed attic does not have openings).

    Jerry Peck, Construction / Litigation Consultant
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    Default Re: Ridge vent with spray foam insulation in rafters

    Quote Originally Posted by Dave Elden View Post
    I inspected one in March that was a new build. Ridge vent present and foamed roof deck all the way to the ridge. I researched it and could not find an exclusion of this practice but I think it is a no brainer that there should be no vent specifically because of the wind driven rain.
    While wind driven rain is a reasonable reason not to 'install a soffit vent and then foam it closed on new construction, a better reason is that the soffit vent is not installed in accordance with the manufacturer's installation instructions, so remove the soffit vent or ventilate it (and ventilation for it would "unseal" a "sealed attic", which would then require proper vent openings).

    On existing houses ,that practice is done to avoid having the insulation contractor remove the ridge vent ... potentially making matters worse as they aren't roofing contractors.

    The spray foam insulation should expand up into the ridge vent on existing houses and fill the vent, plugging the openings which wind driven rain would have come in through. Not ideal, but should prevent leaks.

    But, for new construction? That reasoning is replaced with "the soffit vent is not installed in accordance with the manufacturer's installation instructions - remove it'.

    Jerry Peck, Construction / Litigation Consultant
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  12. #12
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    Default Re: Ridge vent with spray foam insulation in rafters

    I can't see the picture, but it seems like the simple answer to me is that you either have a conditioned attic or you have a ventilated attic. You can do the job properly either way, but you have to make a decision which way you want to do it. Polyurethane on the roof deck is a pretty expensive option that would be absolutely useless with a ventilated attic. I am guessing that you don't have anything in the way of soffit vents either. The catch here is whether or not you have enough insulation on the underside of the roof deck to prevent ice dams. If the insulation is inadequate and you wind up having a problem with ice dams, you can wind up with wet roof sheathing and the resulting rot.

    I don't know where you are, but here in the northern tier states, it takes a lot of insulation on the underside of the roof deck to have satisfactory performance in the conditioned attic. Your local building official may have some guidelines. For personal reference, the Corps of Engineers did a study many years ago on conditioned attics and they developed a chart for how much insulation was needed for satisfactory performance. I would be hesitant to quote that in an inspection report. The Journal of Light Construction also has a number of excellent articles on unvented cathedral ceilings and conditioned attics.

    Greg Brainerd
    Livingston, MT


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    Default Re: Ridge vent with spray foam insulation in rafters

    And this foam is not "water proof". Even closed cell foam isn't designed to keep water out. And, it could be informative, if not entertaining, to listen to the comments from the roofers when the shingles are replaced.

    If you choose not to decide, you still have made a choice.

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    Default Re: Ridge vent with spray foam insulation in rafters

    Quote Originally Posted by Lon Henderson View Post
    And this foam is not "water proof". Even closed cell foam isn't designed to keep water out. And, it could be informative, if not entertaining, to listen to the comments from the roofers when the shingles are replaced.
    Completely agree, that would be interesting to overhear.

    Jerry Peck, Construction / Litigation Consultant
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    Default Re: Ridge vent with spray foam insulation in rafters

    Quote Originally Posted by Greg Brainerd View Post
    ... it seems like the simple answer to me is that you either have a conditioned attic or you have a ventilated attic.
    Absolutely correct, it is an either/or choice.

    Perfect for check box reports:
    Vented attic: yes/no
    Sealed attic: yes/no

    The wrong answers would be two 'yes' or two 'no' answers.

    Some things have an in between answer: is it wet or is it dry ... it's damp.
    (I.e., how 'wet' is "wet" and how 'dry' is "dry".)

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  16. #16

    Default Re: Ridge vent with spray foam insulation in rafters

    Thanks all for input. I think a previous statement i made is causing confusion. While soffit vents are still present under the eaves they have been effectively foamed over. Its like they are not there. This is no longer a vented attic. The home was built in 1957 so it is not particularly tight (although with plastered walls and ceilings it is tighter than most homes from that period).
    Larry: I agree that homes with foam insulation should probably have a designed ventilation system. I think in this case they will be all right (no gas appliances, for instance) given the size (large) and age of the home. The former owner has even been using the fireplace extensively with no apparent back-drafting. What they should have is an ERV or HRV system to bring in fresh air.

    Another thought: the spray foam would seal the underside of the roof sheathing AND the exposed cut ends of the roof sheathing. (where any water would tend to cause delamination). So, leavign the ridge vent is not right, but (in my opinion) the risk factor is probably small. I will advise having cap shingles used in place of the ridge vent. Fortunately, the roof will be due for re-surfacing within five years.


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