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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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    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
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
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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"


  9. #9
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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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    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 )
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  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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    Default Re: Ridge vent with spray foam insulation in rafters

    Just to make it confusing: I am building a 7700 sq ft new construction with a metal roof that is a fully encapsulated structure using open cell foam in walls, and attic (rafters and underside of roof deck). The roof is constructed in usual deck covered with Sharkskin Premium underlayment, but between the roof underlayment and the actual metal panels of the roof, there is a layer of entangled mesh (this stuff is really interesting as it seems to have a multitude of uses) that creates an air gap between the metal panels and the underlayment. There IS a vent at the ridge but it only ventilates the airspace between the Sharkskin underlayment and the metal roof panels. At the drip cap, hidden by the vertical drip edge is a 1/2 in spacer that has fenestrations that connect the airspace under the eaves to the entangled mesh. At the ridge, the vent does not ventilate the attic but does ventilate the to the airspace under the roof panel thus creating a passively ventilated undersurface of the metal roof panels. Removing or blocking the ridge vent would defeat the system in this case. The value of the entangled mesh air space is that it drops the temp at the roof decking about 20 degrees F during the summer months in TX which is a legitimate decrease in thermal load the AC has to compensate for. I can imagine a subsequent owner thinking the ridge vent is not useful because of the encapuslation, but blocking it in this case would be a real bonehead move. Additonally, if water did get through the vent during serious windblown storm, it would be trapped outside the Sharkskin and just evaporate without entering the attic unless there is a defect in the underlayment. (FYI if you are wondering about the posting time - I have to be at the airport for a 5:15 departure and I'm ready early, so just killing some time)


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    Default Re: Ridge vent with spray foam insulation in rafters

    Michael,

    Your installation sounds similar to roof venting (versus attic venting) I proposed to others around 25 years ago, except I was proposing it for shingle roofs.

    Roof sheathing on the roof framing (trusses or conventional rafters); underlayment; vertical 1x battens attached through the roof sheathing to the roof framing; some type mesh to allow air to flow through it but able to resist birds and small critters (your "entangled mesh") between the vertical battens; a second later of roof sheathing; second underlayment; shingles.

    That would provide a 3/4" ventilation space for the roof, and would also use a ridge vent at the top with similar eave venting as you describe.

    I never was able to get anyone to do it.

    I am curious about your metal roof panels and no vertical supports (to keep the vent space open) and no horizontal supports for the metal roof panels.

    Is your "entangled mesh" structural to support the metal roof panels?

    Jerry Peck, Construction / Litigation Consultant
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  19. #19
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    Default Re: Ridge vent with spray foam insulation in rafters

    And what is it like to walk on that roof. Is it "mushy"? How rigid is the entangled mesh?
    The concept sounds great. Is this something being commonly done in your area? And finally, what is the brand name of this system?

    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 Jerry Peck View Post
    Michael,

    Your installation sounds similar to roof venting (versus attic venting) I proposed to others around 25 years ago, except I was proposing it for shingle roofs.

    Roof sheathing on the roof framing (trusses or conventional rafters); underlayment; vertical 1x battens attached through the roof sheathing to the roof framing; some type mesh to allow air to flow through it but able to resist birds and small critters (your "entangled mesh") between the vertical battens; a second later of roof sheathing; second underlayment; shingles.

    That would provide a 3/4" ventilation space for the roof, and would also use a ridge vent at the top with similar eave venting as you describe.

    I never was able to get anyone to do it.

    I am curious about your metal roof panels and no vertical supports (to keep the vent space open) and no horizontal supports for the metal roof panels.

    Is your "entangled mesh" structural to support the metal roof panels?

    REPLY:
    Hi Jerry: I was interested in creating an airspace under a metal roof panel that would allow walking on the panel without ruining it. I came across a video by Matt Risinger (Austin video blogger who has developed a large following) that showed using an entangled mesh product called Enkamat under a metal roof. Can't recall what was used to keep vented space open at the fascia, but the fact it was being done on an obviously high end construction convinced me to investigate further. Turns out several others have this concept in their products, with one product using the entangled mesh as an integral part of a roof underlayment so that one product accomplishes both waterproofing the deck and creating the airspace. A little persistence and a couple of phone calls got me in touch with the builder who had been the GC on the job that the company had made about the product and he told me about using a Coravent product to create a uniform ventilation inlet at the fascia by tucking a cannulated PVC strip made by Coravent under the drip cap. Shopped around and found a roofing co. in Ohio who had gotten some supplier to package an entangled mesh product in rolls for them and they were selling it under their private label for about 50% of cost of Enkamat. Bought the mesh and the Coravent products and showed my roofer what to do, and it was easy. You can walk on it, but it would make me nervous if a guy who weighs 250+ were to get on the roof and stomp around. Up early for busy day so have to get moving - but happy to send pictures of roof and details about all products if you want it.


  21. #21
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    Default Re: Ridge vent with spray foam insulation in rafters

    Quote Originally Posted by Ernie Simpson View Post
    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.
    Morning, Ernie.
    Hope to find you well and in good spirits today.

    Please, as best as you can, due to the fact there is not image, describe the attic.
    Roof shape/s, Gable, HIP, Slat Box, Rafters, Trusses, Eave, and venting, so we can become more familiar with your present quandary.

    You state; "Inspected a house yesterday with spray foam insulation in the attic."
    Spray foam in attics has become an occurrence I run into on rare occasions. Mr. Holmes started this fade catch on in Canada much chagrin of inspectors like myself, that run into untested foolish applications, and to the chagrin home owners alike I suspect.
    Reasoning, its not easily removed. You can not observe material behind the spray foam. It traps water. It hides rot.

    You state, There is a ridge vent.
    I assume, poor way to work, the attic space had eave venting at of some point in time, or still does, that maybe functioning, or not.

    You worry about driven rain into the attic with ridge venting? Ridge vents with "Weather filter" impede weather related moisture.

    Read this article from/by Inspectopedia. Stop Ridge Vent Leaks
    Causes & fixes for windblown rain or storm leaks at roof ridge


    Your options to stop leaks at your roof's ridge vent during high wind and rain include:
    Add ridge vent closure foam that will reduce wind-blown rain entry through the vent openings
    Add a taller ridge vent flange along the entire ridge run so that wind blowing rain "up" the roof won't send water over the existing vent flange and into the ridge vent. I've done this with complete success on several homes.
    Replace the ridge vent with a model designed to resist wind-blown rain water entry such as the CobraVent, CoraVent, or CertatinTeed's 12" Filtered Ridge Vent that includes both a "weather filter" and external water-blocking baffles.
    Follow hurricane Ike, FEMA issued an advisory giving tips for avoiding wind-driven rain leaks into buildings through the roof venting system. For ridge vents - which is what I think you're discussing - FEMA offers more advice that we have adapted from their document and cited below:


    Hope that helps.
    Best regards.
    Robert Young,
    Robert Young's Montreal Home Inspection Services Inc. Putting information where you need it most, "In Your hands!"



    Robert Young's Montreal Home Inspection Services Inc.
    Call (514) 489-1887 or (514) 441-3732
    Our Motto; Putting information where you need it most, "In your hands.”

  22. #22

    Default Re: Ridge vent with spray foam insulation in rafters

    Thank you Robert. I'll look at the links in the next couple of days (finally busy after dead winter and early spring). It would be nice to time travel forward 25/50/100 years to see which of today's building innovations have proven to be a problem. Overall, I'm optimistic about the closed cell spray foams as long as people don't do stupid things (which they will, of course). Stupid things include: letting the roof or flashing age/wear out so leaks occur. (Spray foam roofs probably need a periodic IR inspection as this should pick up wet spots on or below the sheathing). #2 Keeping internal moisture levels too high. #3 the infinite range of ways homeowners and builders find to screw things up.


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