Spray foam insulation to the roof deck - Does it cost more to heat this way?

[@marcfournier823]

As a retired math and science teacher i can attest that your back of the envelope modeling is remarkably accurate. For the math and science teachers out there, this would be a fabulous authentic learning and higher order questioning opportunity for your students. For the English and media teachers out there this video would server as an exemplar of cross curicular transmediation. Great job and well explained.

[@SprayJones]

Thank You!

[@daveray6335]

I got 6,666.667 cubic ft for the attic space volume. (0.5 x 40 x 8.3333 x 40)--"one-half base times height (of the gable) times length of the ridge" where 8.3333ft is the height of the gable, assuming a 5/12 roof pitch. Regardless, Spray Jones presents well.

[@Golf_Cart_Customization]

Would it make more sense to look at it from a surface area standpoint? Once you heat or cool the volume it doesn't affect the ongoing heat loss because it is only affected by the surface of the building.

[@John-tq4bf]

I never fail to learn something new Mike; keep up the good work.

[@SprayJones]

Thanks, will do!

[@steven7650]

It will likely be in the next IBC but the standard will be spray foamed if possible, but hen 4-6 inches of eps on top of the roof and then a vented batten layer. If you vent under the roof material it increases it's life and reduces the condensation against the sheathing material.

[@MegsCarpentry-lovedogs]

Subscribed yesterday 🇨🇦🍁as the algo sent me here due to lots of views on YT with building channels. Yuppie for algo's eh!👍💯. The fact that you pull out reports and read them as well as clarifying with a summary about them is extremely helpful. Yes, I have cathedral attics that are projects. Your channel is priceless🙏

[@SprayJones]

Welcome aboard!

[@larsonhomeinspection9932]

Have you had any experience with the breathable shingle underlayments? Products like GAF Tigerpaw and Deck-Armor are breathable and marketed for spray foam/hot roofs. From my research though, asphalt shingles have such a low perm rating that the underlayment breathability doesn't really matter anyway.

[@SprayJones]

No we don't get into any of that.

[@chadhartman1040]

I like the idea of spraying foam directly to the back of the metal siding vs against the house wrap in a pole barn type structure. Lots of benefits...increased structural strength, added dent resistance and excellent air sealing... but what about the inevitable water penetration around doors and windows? Seems like moisture would get stuck behind the metal with no way to dry. But spraying it against the hanging house wrap seems like a wasted opportunity.

[@SprayJones]

I agree with you on spraying direct to metal. Just far less to go wrong. Architects draw buildings for longevity NOT what is easier to take apart when damaged....

[@chadhartman1040]

@@SprayJones Any idea on how one would address the water that would possibly get behind the metal and into the wall system? Have you sprayed directly to metal around windows and doors in a pole barn? If water somehow did get in the wall I would assume it will become trapped as it would have a vapor barrier on each side (foam/metal) and no possible way to dry. But then again the foam sprayed in place -should- fill any void a water would possibly get into in the first place.

[@DigitalBenny]

I've been watching a bunch of your videos and I haven't found any where you address a concern that I have with a design idea I have for a potential home. Climate zone 3A, warm humid subtropical (cooling dominated area) 1800 square feet building footprint (30x60) single story on slab on grade. 2x6 exterior walls 24"OC, Zip-R3 sheathing, metal siding. Cavities sprayed with closed cell before being fully filled with open cell. Truss roof with a slight raised heel and no eaves, Zip-R3 running continuous from walls to roof deck and back (Yes, Zip-R as roof sheathing) Metal roofing. Similar treatment to underside of roof deck: closed cell followed by open cell, except open cell to a greater thickness than the walls. So, basically the entire envelope has the same control layers on all surfaces. Here's my big question though: Should I be cutting a slot at the ridge of the roof and installing a vapor-open (or some sort of "smart" one-way) membrane? Through stack effect and inward solar vapor drive, I can't help but think that vapor, no matter how little, will congregate at the peak of the roof and put an unnecessary burden on the HVAC What are your thoughts?

[@SprayJones]

Whomever you plan to hire to do your install should be coaching you along and answering your questions. Also look at energy wise structures in Arlington Texas. energywisestructures.com/ They answer these types of questions and help with HVAC loading.... for a fee.

[@DigitalBenny]

@@SprayJones Thanks for the suggestion. However, their post about not needing an air exchanger OR make up air in an ICF home because "the windows will leak enough" has me scratching my head with one hand and facepalming with the other 🤔🤦‍♂️

[@ericvando]

Down in the south US we use techshield or a radiant barrier for our roofing. How can we incorporate closed cell foam with this radiant barrier?

[@SprayJones]

Why do you need to? Take hot vessel tanks in the oil and gas industry. Do they use reflectives? No but 2 or 3 inches of closed cell SPF rated for 275 F....

[@where578]

Have you a talk on using spray foam to replace the fiberglass on the attic floor? Seems you would enjoy the sealing effect of the foam, plus the heat stoppage. Let the attic vent in a normal way with ridge vents, gable vents, etc. and enjoy the foam properties of far less heat transfer and air sealing!

[@SprayJones]

I do "Spraying down onto drywall, should this be done?"

[@hickorydragon8114]

Oh ,that's what that means. I get it now.

[@davidlampe4153]

Mike, I’m new to the spray Jones channel, this is a great example for spray foam, if the technology has been out there since the 50’s-60’s why wasn’t the technology more widely used? I remember my parents building a new home in the mid seventies and the building should have been as tight as ever with the technology for glass batts and vapor barrier plastic sheeting. The heating bill wiped out any savings in less than 10 years. What’s the overall problem for the country in not adopting the artic hot roof system before mid 90’s?

[@SprayJones]

The fibrous industry has huge lobby and pull with codes. So bureaucratic control along with universities that teach architects and engineers wrong factually outdated data create a non-stop flow of brain washed people that have a say on building design and use for 30 years.... that is your reason why foam stays where it has.

[@Monkey_Snot]

Informative for sure, I'm about to have a shop built in the spring, and I was contemplating whether I should use foam or fiberglass, but I think foam is much more expensive, but I'm not sure yet. Thanks for the info.

[@SprayJones]

Only up front. You pay on op costs with fibrous forever.

[@spikechampkart55]

Doing a post frame or steel frame building, steel deck all roof, 90 %of the walls. Will use zip on that 10, with options. Planning on foaming it, closed envelop, I should have no eaves? needed for ventilation is a savings, correct? 4/12 or a continuous roof still deciding. Any preference? 40x60x10 heated floor slab. My local guy thinks we should shoot the ceiling 1 inch closed, then go back with about 5 open Same on my walls, 1 and 4. Shop area all closed?? Sound like a good plan? SC heat, mild winters, retired, can build anything! Thanks for all the great info!!!

[@SprayJones]

You have a lot of questions there. Too many for me to be of assistance. Closed and open celled: pick one and stick with it. That is m opinion. I know that mixing is popular in some states. It isn't where we are. We use closed cell almost exclusively.

[@nickhourd]

Does it make sense to retrofit a hot roof onto a house insulated with batt? What would be required to maximize the benefits without having to re-insulate the rest of the home at the same time?

[@SprayJones]

Hard to do. Need a enough room or a major retro-fit to accomplish it safely.

[@nickhourd]

@@SprayJones Is the difficulty around access to the work, sealing the building effectively, or something else?

[@SprayJones]

@@nickhourd Correct. Watch the Playlist for vaulted roofs and in there is one about spraying inside an enclosed attic.

[@jjleda7324]

I've been trying to find out if spray foam affects the lifespan of asphalt shingles? Wouldn't this cause the shingles to heat up more, retain the heat longer, and then cause the shingles to need replacement sooner?

[@SprayJones]

Watch the video on shingle life and SPF ....

[@deanhuff4100]

What is the effect on asphalt shingles with close cell insulation?

[@SprayJones]

Watch the shingle life and spray foam video I made. Lots of good info.

[@markstorhaug9989]

If a guy spray foams the under side of the roof deck and keep an open ceiling (in a garage), is it prudent to spray the walls i.e. way less advantageous to batt the walls?

[@SprayJones]

I believe in spraying everything. Once you take the red pill on R value and see how slanted things are SPF is a no-brain needed decision.

[@billwinch7043]

What about comparing spray foaming the attic floor to foaming the roof deck? Other than attic stairs, wouldn't the air leakage go away with foam? it seems like your changing more than one variable in the comparison.

[@SprayJones]

No thanks, got some more interesting video ideas coming up that appeal to a wider range audience.

[@mikelutz6411]

Keeping your HVAC unit in conditioned space is much more efficient for it. Imagine in winter the amount of energy needed to warm up the duct work that is in your freezing cold attic. If the attic is warm it takes much less energy. Cheaper to keep it warm than to try and warm it up over and over.

[@bartmcgee4669]

Is attic venting required with spray foam under the roof sheeting ? The attic walls are sprayed with foam also. All closed cell spray foam. My entire house is insulated with closed cell spray foam. I'm just asking about the attic venting at top of attic walls. I was told not to vent them. Is this correct ? What about shingle life if so... Some shingle manufacturers​ mention attic venting.. I'm confused...

[@SprayJones]

No venting is needed with closed cell SPF. Please go to the YT channel and watch the playlist on vaulted ceilings.

[@bahopik]

This hot attic design clearly shows exterior insulation so that's going to yeld better results that cavity insulation any day. Like you said those are just lab results, I follow a Canadian KZbinr, and when he took tin for remodeling purposes off of his purple spray foamed garage, spray foam pulled away from wood allowing direct heat transfer and air leakage. Just like one can get a bad fiberglass install, just as much, if not more can go wrong with spray foam install. So until structures live in the real world for a couple decades and then get remodeled so we can seen how spray foam is holding up, it shouldn't be sold it as the best way to go.

[@SprayJones]

Learn something would you! The foam has been in the National building code since 1990. The first building done in SPF in Canada was 1969. The foam is specified in government and institutional building all the time. The studies are DONE. The code approves it and we have the most extensive testing and approvals of ANY insulation with ULC standards.

[@turboflush]

So.. Question is.. As the public and as the contractors.. What can we do to get the rules and regs changed? Get the r value system revaluated.

[@SprayJones]

Nothing. I don't think it'll ever change in my lifetime. 70 years of the industry going in the wrong direction. Maybe when you have a whole generation of younger engineers... maybe. But I have seen young people just as stupid as ever and worse in some cases. All of academia is skewed.

[@chrisarnone7896]

One question I have, would the said R-value for code still be the same when using spray foam? I know its better in every way but when getting it's inspected, will they be looking for a r-30 to r-40 (whatever code is in your area) even though 3 (R-18) inches is superior to ~18inches of batts? I'm in the south and my code is R30 in ceiling. Is there a difference for code when insulating the roof vs ceiling? We typically use a 2x6 rafters so would we need all 5" to meet code? or does the inspector take that it is spray foam into consideration and allow for ~3" be enough? Maybe you can't speak for the south but as a comparison, does the so called R-value need to be equivalent? Another point to make for insulating the rafters/roof is, since i live in the south, most people put their HVAC units in the attic, since we don't typically have basements. This puts a lot of temperature differences on the Ac or heater. Since is the Summer the attic is hot, this heats up the unit and the duct work and the unit will have to cool those down before cooling down the house. this is the opposite for the heater. I read an article saying that there is a 20-30% loss of energy by using this method. A conditioned attic will easily cancel out the heating or cooling of that attic area.

[@SprayJones]

I think it is best to wait for the Roof and Vaulted ceilings 4 part series as the question you have will be addressed in length within that series.

[@turboflush]

Great vid. Link The documents in your description.

[@markhindman9005]

I enjoy your videos and learn a lot. I'm building a 4 bay garage with an in-law suite above. Traditional shingle roof and would love to incorporate a conditioned attic. Do you have any contacts in the Pittsburgh PA area you would share for me to talk with for spray foam?

[@SprayJones]

No. Speak with BASF for your state and inquire of them as to who applies their product around there. Be blessed !

[@ratoneJR]

What happens when you need replace water damaged roof sheeting at re-shingling? Respray? Spray foam against roof sheeting could trap any moisture in the sheeting. Maybe causing accelerated rot. Hard to get to the edge of roof if it needs localized respray. Easy to do before drywall, near impossible to do evenly after occupancy. I feel the respray idea sucks. Could you apply a house wrap over roof rafters before sheeting? That idea still sucks, if you ask me. I love spray foam but I have concerns.

[@SprayJones]

In 15 years of business of all the roofs I have done, 2 had damage to the roof sheeting because of water getting past the shingles. In each case it was small, localized and they cut the plywood out, patched up the foam with a DIY kit, put the new sheeting down and repaired the roof. No problems at all.

[@giocondobianchi6557]

Spray Jones it seems like ppl are looking for any holes that they can expose and blow it out of proportion, failing to understand the true benefits of spraying roof decks. I have had this done in my home and I can tell you it works ! Night and day performances!

[@robertlamb161]

Yes

[@SprayJones]

Yes

[@rgloeschner]

I heard this argument many times as I was researching my spray foam project and I used a different route to my decision. After having a fire in my house and having to deal with the insurance company regarding all of the water damage I would prefer to have the roof sheathing rot in place and still have a water tight vapor membrane (closed cell foam) between me (my interior home structure and personal items) and the failed and leaking roofing system. My spray foam contractor assured me if that day ever occurred he could bring the truck back out and repair the foam for less than 600.00. That's way less than my homeowner's deductible and the time and frustration of dealing with the insurance company. BTW, I do actively heat and cool my unfinished attic space because of the amount of natural air movement between the attic and the finished space. With quality windows and doors and a highly efficient heat pump there is absolutely zero additional cost to my energy bill. I hope this helps.

[@crabkilla]

The other important benefit to a conditioned attic space is having all your ducts and mechanicals in a conditions space. This radically improves the efficiency of HVAC.

[@laoxshousebuildingtidbits7760]

The only downside beside the upfront cost is that it would be hard to detect roof leak before it's too late.

[@SprayJones]

Watch my video on closed cell vs open cell for unvented roofs

[@harrymiller1398]

Pop a

[@Zorlig]

If you spray the roof deck like that then you need another solution for venting otherwise your ice damning will be crazy. You need exterior air against the bottom of the roof sheathing otherwise the snow will insulate from the top and the sheathing will be warm and melt snow.

[@SprayJones]

Wrong. Go watch the 4 part series on non vented roofs.

[@safffff1000]

Why would anybody build a highly steeped roof without utilizing the space underneath for living space?

[@hickorydragon8114]

Ok , but what if you spray foam the ceiling???

[@PayneFamily]

I would like to know the same. If you spray foam the ceiling are you even more efficient?

[@KD-gu2mb]

I would like to add if I could. That air quality in the house goes up tremendously. I can go 6 month’s without changing the filter. In my others houses I have to charge the air filter every 30-45 days and the filter is nasty. And in the houses that get spray foamed there cleaner behind the appliances. Huge difference. Has anyone else noticed?

[@SprayJones]

Great feedback.

[@blindtomdiy5918]

Why not spray attic floor and not ceiling?

[@SprayJones]

Go watch our video on "spraying down onto drywall."

[@TomofAllTrades]

Another great educational video 👍🏼. What is the lowest outdoor/ ambient temperature can a contractor apply spray foam? Thanks.

[@SprayJones]

We spray Walltite by BASF and they have cold temp foam called CT that can be applied to -10 C. I however always want our clients to have things above freezing.

[@sibosifraiscompagny]

What ever the outside temperature. It's the temperature of the substrate that need to be over the minimum and like Spray Jones says it depend on who is the manufacture of the product. I shoot SWD and it's -5°C with the summer product. But on the same time free of ice. So more the substrate temperature is high better the bond will be, better the density will be and it's will be more homogene so it's more like the manufacture want. I love you're video we need more contractor like you!

[@Guy4UnderDog]

"Cubic feet of area" is making me crazy. Shouldn't it be square feet of area? Or cubic feet of volume?

[@SprayJones]

Yah yah. Clickon an ad..

[@mattlikesbikes]

Thank you for this. Building a metal barndo. Not arctic, but Central TX so nice and hot. We are focused on vapor barrier, so CCF but only 1.5in on the roof deck. Once we drywall the ceiling, does it makes sense to also blow in come insulation up there as well. It's truss, so no space for an attic anyway. This is a weekend place, so the apartment will get maintenance conditioning all the time (humidity control) but only run for real heat and AC on the weekends we are home.

[@SprayJones]

You have similar issues as the arctic only reversed. Heat outside trying to get inside. Is 1.5 inches all you are doing of CCF?

[@mattlikesbikes]

@@SprayJones looking at 1.5-2 ccf on the roof deck. Then for the corner of the building with an apartment 2" on the walls. For the rest of the walls just 1". Then I may throw some glass in the walls between the ccf and drywall.

[@mattlikesbikes]

Just watched your video on how to evaluate a contractor. Lots of guys throwing $/sf at me. But one is focused on our goals and wants to walk the project once the building is built. His first thought though was the suggested 1.5-2 roof and 2 in apartment walls/1 in others. All subject to change.

[@ItsCreated]

I’m debating on what to do. I’m having my walls, and crawl space insulated with foam. But im not convinced that a conditioned attic is the most efficient or cost effective way to go. I feel as if I have the attic floor (the ceiling of our living space) spray foamed and air sealed. Then leave the roof deck alone, with the attic still open air. That will be most cost effective. Not requiring as much spray foam, and I should not have leaking air into the attic. What are your thoughts about trying this, as opposed to going full conditioned attic? I live in southern hot climate where we rarely see any snow. Thanks!

[@SprayJones]

If duct work is in the attic, then foam to the roof is the only way to go. Please watch video on : "Should we spray down" for all the other issues associated with this.

[@jgren4048]

I was just hoping someone would mention the air ducts in the attic. There is so little if any insulation around the duct itself that a hot attic is making the ac or heat work way harder than it should. This cost is direct to your wallet

[@CoasterChaser4500]

Since all buildings move from wind load as well as ground movement spray foam would not settle like loose or even batts would so after seeing this I would if building spend the extra to give myself the best possible outcome. I am in the process of finishing my barn that dad I built making a shop space where I can have some heat and save my tools from rust,seeing this I now want to go with a spray foam roof your sample garage is almost the size of mine 40 x44 8 foot side walls mostly open ceilings with no ceiling joists,it’s no a clear span as most pole barn as we have a 12 foot outer bay and a 16 center bay all rough lumber roof rafters and scraping now over 38 years old. Should I be asking any specific questions to the spray foam company? Thanks for teaching us on layman terms?

[@SprayJones]

This sounds bad..... watch more of the videos I already have made...

[@larsonhomeinspection9932]

Great video, thanks! Spray foam is the best of all worlds.

[@SprayJones]

It sure is!

[@Mostviews111]

I think spray foaming the decking and trusses would be a horrible idea. If you have a small leak it has no where to go but soak into the wood.

[@SprayJones]

Go watch the 4 part series on non-vented roofs. We cover all that...

[@Mostviews111]

@@SprayJones I've seen it but the problem is if I peeled a shingle off and let the sheeting obsorb all the water with it sprayed you would never see the water from the attic or worse going through the ceiling. At least with the backside not sealed it would leak through and be visible if you are proactive on attic inspections.

[@michaelleuth7557]

Foam is 2.6 times more efficient. The fiberglass is 38.5% effective. The real world will have more wind and cold. We need real world testing, but who would buy fiberglass at an r-7. We just have to spread the word.