Ads re this. Is speay ok and cost.

NM

Is there actually any reliable science behind this? Been thinking about posting, as the commercials are all over tv. Color me skeptical.

If you're asking about insulating foam sprayed to the underside of your roof decking, I can attest that it definitely reduces attic temps. My main concern would be that it traps the heat in the decking, possibly shortening its life in hot climates like TX.

Very confusing post.

Retro-ing spray in an existing roof is a bit tricky. You need to cover all surfaces, seal the attic space, change over ac equipment (if necessary), make sure all venting is accounted for.

Not all homes have the access to properly do a retro spray foam application

So far as trapping heat in the decking- im not sure what that means.

Who?mikejones! said:

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Very confusing post.

Retro-ing spray in an existing roof is a bit tricky. You need to cover all surfaces, seal the attic space, change over ac equipment (if necessary), make sure all venting is accounted for.

Not all homes have the access to properly do a retro spray foam application

So far as trapping heat in the decking- im not sure what that means.

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Most homes use attic ventilation to remove heat from the underside of the roof decking. Sealing it with foam traps that heat in the decking, raising its internal temperature. More extreme temperature cycling can't be good for the lifespan of any material.

How does it "trap" it in?

Im not trying to be an ass, fwiw. I build homes for a living. I feel like im pretty in tune with the literature on foam insulation, its benefits and drawbacks and so forth.

I haven't seen anything on trapping heat in the decking and, if its an issue, im generally curious to learn about it. I haven't seen any ill effects that could be attributed to that but if its there, id like to know

Who?mikejones! said:

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How does it "trap" it in?

Im not trying to be an ass, fwiw. I build homes for a living. I feel like im pretty in tune with the literature on foam insulation, its benefits and drawbacks and so forth.

I haven't seen anything on trapping heat in the decking and, if its an issue, im generally curious to learn about it. I haven't seen any ill effects that could be attributed to that but if its there, id like to know

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They have issues with the roofs in Arizona and Texas with the heat between the roof and the foam. When we installed a roof on our home with spray foam, we had to find a roofing material that could handle 180 degrees.

I wish I had more information about what the OP is asking, but if we are talking about spray foam insulation, I still don't have adequate 'first hand' experience to tell you if it affects the shingles. My suspicion from an engineering minded person like myself is that it does not make a difference. In most parts of the country, shingles don't last past 15 years anyway.

That said, here is the warranty document directly from Certainteed, one of the leading shingle manufacturers in the world...

Quote:

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Inadequately Ventilated and Non-Ventilated Decks

Any shingles applied to inadequately ventilated or non-ventilated decks, other than the shingles and deck systems described in the section titled "Insulated Decks and Radiant Barriers," are subject to a reduced limited warranty period of ten (10) years and do not qualify for SureStart Protection. SureStart Protection and the Warranty Period applicable to the shingle are available if CertainTeed determines that the shingle damage was caused exclusively by a manufacturing defect that is unrelated to the inadequate roof system ventilation.

Insulated Decks and Radiant Barriers

CertainTeed's Limited Warranty, including SureStart Protection, will remain in force when its fiberglass shingles are applied to roof deck assemblies where foam insulation is prefabricated into the roof deck system (often called "nailboard insulation"), where insulation is installed beneath an acceptable roof deck system, or where radiant barriers are installed, with or without ventilation, directly below the deck. Acceptable roof deck surfaces must consist of at least 3/8" thick plywood or 7/16" thick Oriented Strand Board (OSB) and slopes must be 2:12 or greater. If a different deck surface material will be utilized, please contact CertainTeed's Technical Services Department for assistance. (See the following important restrictions.) The design professional is responsible for ensuring: 1) the proper quality and application of the insulation and/or radiant barrier, 2) the provision of adequate structural ventilation and/or vapor ******ers as determined to be necessary, and 3) that all local codes are met (particularly taking into account local climate conditions). Special attention must be taken if cellular foam, fiberglass, cellulose insulation or other highly permeable insulation will be used in an unventilated system, or if the insulation/rafter or insulation/joist planes may create an air leak that could lead to moisture transmission and condensation problems. All these important factors and decisions, while not the responsibility of CertainTeed, are critical to assure proper deck system performance.

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If spray foam insulation actually damaged your shingles, you can bet your boots the shingle manufacturers would bake that into the warranty. This warranty clearly makes note that poor ventilation limits warranty, but directly foaming your deck does not. So, take that for what it's worth.

In case anyone cares, 80% of the 100+ roofs I install during any given year are under ventilated. There is never a roof that could not benefit from MORE ventilation if it is not an enclosed attic.

If you want to seriously impact your cooling, change your shingles to Energy Star rated WHITE color.

In what way?

In decades of using foam, remodeling homes with existing foam insulation, with shingle and metal roofs, ive never seen an issue caused by excessive roof temperatures.

There are some specs that suggest potential performance degradation at extremely high temps, or if installed improperly could have negative effects.

Generally speaking though, theres not a problem with using foam, especially open cell, in Texas. You can add baffles to the bottom of roof deck to keep an inch of space between the foam and decking.

You can get moisture issues, especially in colder climates, when using foam.

Heres how id advise anyone wanting to retrofit foam into a house

1. Is there access to every square in of the underside of the roof deck. If not, dont foam the attic.
2. Is it feasible to 100% seal the attic space. If not, dont foam the attic space
3. Is the hvac(water heater too if applicable)compatible with a sealed attic space or does it need to be changed
4. Is the rest of the house comparable in quality? A house is a system- if you have old windows, poor doors, fiberglass in the walls, old shingle roof, etc etc, i consider retro foaming an attic space as throwing good money at bad.
5. If its a cold climate, do you have the ability to put in vapor ports?

If you're building a new house:

The best system is one that gets the insulation outside the framing.

If you cant do that, foaming the attic is a good solution, especially when paired with high performance windows and doors and if you can get a vented metal roof system on top. You can add a dehumidifier for the attic space (but that produces hot air) or even "condition" the attic space to help with heat/moisture.

But again, the house is a system

Another key component of foam is the competency level of the installers. That really matters for this application


Fun topic.

How does closed cell spray foaming the underside of the roof deck not lead to moisture being trapped in a moisture barrier sandwich between the outside underlayment and the spray foam?

P.H. Dexippus said:

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How does closed cell spray foaming the underside of the roof deck not lead to moisture being trapped in a moisture barrier sandwich between the outside underlayment and the spray foam?

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Closed cell foam doesnt allow any vapor transfer at all, so you wont get any vapor from the bottom side. Any moisture/water vapor would be forced out the top side

Jason can answer this as I dont know the permeability of synthetic water barriers on the top side. I dont think its 0 permeability and you punch a bunch of holes in it. Something like ice and water shield or tpo is probably different but, again, ive never had an issue with open cell.

felt paper would naturally dry out.

The goal would to not have any moisture accumulation in the decking itself at all. I dont see closed cell on roof assemblies very often. I cant actually recall one ive done at the moment. Its not really needed because we typically have the depth to achieve a good R value without going the closed cell route.

The main issue with closed cell on roofs is that it neither lets vapor or water through. So, if you have a leak, you wouldnt know until its at a crisis stage.

I use closed cell on subfloors of pier and beam homes.

So, the roof will breathe and dry and all of that. Synthetic is a good product and in emergency situations, it has been roofed over wet with no issue at all because the decking stays dry. However, with closed cell, leaks can be very hard to locate if that's a concern for you. On a related note, if you have a leak that is regular and you have closed cell, there is a chance you'll never see if and the deck will just rot because it's perpetually wet. Most folks call me for leaks when drywall starts to stain or peel. That's the clue. If that doesn't happen , they may never know. Eventually the roof deck will give and you'll end up with a depression and you'll find it that way. You will have to rip out the bad decking and some of the foam will come with it but not much but it will be unbonded at the repair site.

Personally, if the house is designed properly and spray foam is done well, I wouldn't let any of the above be a deal breaker. If you have a metal roof, even better.

Ol' Ags BigJim

me thinks maybe your topic could also be this roof shingle "restore" spray that is heavily advertising on the radio and podcasts ala
The Money Pit www.moneypit.com whose supporter is
Roof Maxx sm.roofmaxx.com

What A.I. says https://rebrand.ly/22fd49
What one BBB has on file https://rebrand.ly/6c3efa

Sorry that we have no quotes nor client feedback on this.
Upon demand, we would refer them to a Schulte Roofing VP, even though any roofer might tend to counsel toward a New Roof ... as would we until more evidence comes in hand.

BTW the last time we got quotes in 2014, the galvalume was almost in cost reach compared to med.high grade shingles & flashing. Going this way might put all future concerns to bed. Wish I had but unknown medicals were percolating then.

Dogdoc said:

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Is that you, Vaughn?

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Welcome
The kinda dig my almost architect son (land.arch) gives me ... and deserved, never a poet or songwriter am I
but

Sad
Prayers for your MIL's cancer, please post all good news coming and always a 2-3rd opinion from these sometimes profiteers ..

Tips: those that care most
Methodist Hospitals
BCBS Ins. and never Medicare (for those older)
but this is from transplant experiences from actual for-profit Hell indeed
Blessings