Spray Foam Insulation - The Ugly Truth?

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Some years ago we added a bathroom in our 180 year old brick farmhouse. When it came to insulation we decided on using spray foam. The chief reason for doing so was the number of rodents in the attic and walls. We were concerned about another space that the mice would have free reign at hence the foam. I did all the spraying myself. I used large kits that came with a 2 part foam in 2 pressurized tanks of chemicals. I suited up in coveralls, gloves, hood, face shield and HALF FACE respirator. The spraying went quite well using 2 kits to complete the job. when I got to the end of the first kit of tanks it spewed gases out without any foam forming. I completed the job with a second kit. To my surprise the house was filled with a fog. Well as it turned out it was only in my corneas. With a trip to the ER I came home with foggy vision and told by the ER doctor to seek specialist help in the morning. To my delight the fog had disappeared and my vision restored. So my advice is to let professionals do the work or use FULL FACE respirators.

I actually experienced an unexpected bathroom issue, where after spray foam, the bathroom began to stink of sewer gas. It turned out that the seal in the house was so good, the vacuum effect you spoke about was in effect, but the bathroom fan was a bit overpowered and it would actually suck an occasional bubble out of the water trap in the toilet whenever the bathroom door was closed. We actually had to keep the bathroom door open to prevent that until we got a less powerful fan.

A well balanced presentation Roger, the biggest issue in our opinion, is when something does go wrong !! it is a nightmare to locate and assess the full extent.

I live in a very cold area (below freezing for many months at a time) and spray foam is very popular due to eliminating drafty gaps. It’s good in new builds with the correct ventilation system for it. Mortgage companies in my country are fine with spray foam, so that must vary by country.

An underrated aspect of closed cell foams is the rigidity and strength. Especially with the high density foams, it can be incredibly strong, in many cases stronger than the frame itself. Ultimately I think it just makes sense to combine structural and insulative components in things like SIP panels.

I worked for the man that invented this product. I'm glad you detailed the many possible drawbacks with this material. I was in the manufacturing side but was also required to understand the different applications which required different product mixes.
Personally I have always had concerns with long term degradation and off gassing. Everything breaks down over time.
Also, moisture build up or leaks can be a real problem. Running wires or piping after the initial construction is also a problem.
I think you covered it all quite well.
Btw, this material was discovered by accident. The company was called Flexible Products which specialized in flexable adhesives. The inventor and his brother were experimenting with a new formula for quite a while looking for a stronger, construction type adhesive. One morning they came back after a late night in the lab of what they thought was a failure and this huge foam blob was covering the table they had been using.
Years later, he sold out to DOW chemical and generously paid his long term employees large severance/ profit sharing checks and he retired.
Unfortunately, a short few months later, he passed away at a golf course on Tybee Island.
He was a good, kind, generous man and everytime I see this product, I think about him.
Thanks for your time.

As an electrician I also always see issues where original cabling hasn’t been designed to surrounded by that extend of thermal insulation, which can lead to over heating of cables and possibly fire.
Also I see it as a nightmare situation if you ever need to make a repair or alteration, to locate or even cut through all the foam to add cabling for new fixtures or fittings.
Personally I believe that of this kind of insulation os going to be used all services should be informed so that it can be taken into consideration during design so that cabling size and maybe a conduit system could be installed to address certain potential issues. All this just means greater cost elsewhere so for me I would always go for modular insulation.

I had spray foam applied directly to the underside of my slate roof years ago, but the wooden beams remain visible. It certainly works as insulation - when it snows the snow lingers on my roof much longer than it does on my neighbours’. As a bonus, the original builders had used a very sandy mortar to bind the slates and it was constantly shedding dirt on everything below. The foam sealed all this in so now I have a clean attic space for storage. Recently, however, I have considered installing solar panels but for slate roofs these require special brackets which, in turn, necessitate removal and replacement of the slates. With foam sticking them all down this will be a problem. If anybody is considering solar panels and foam, I’d suggest get the panels installed first!

I had spray foam installed when I had the house built ten years ago. I was aware that a roof leak could compound things a bit as the foam could retain some moisture. To add an extra measure of protection I specified that a premium quality synthetic roof underpayment be used instead of tar paper. I went with Titanium UDL-30. That’s the sort of thing that is used in Miami where hurricanes are common. This stuff is head and shoulders better than tar paper, but it costs the same price. You might lose all of your shingles in a storm, but your roof still won’t leak. It also does not tear or decay like tar paper. Having done that I did not have to worry about a roof leak with foam installed in my roof. I should also mention that with foam installed in your roof your entire attic space will only be about five degrees cooler or warmer than the ambient air in your home’s living space. That reduces the strain on your hearing and AC system located in your attic space.

I had to board out a loft because of this foam. As Roger said, the people buying the house, couldn’t get a mortgage until it had been removed. It was quite a small house , a simple up an over pitched roof. The foam removal company charged £2,500 and wouldn’t touch it until the loft space was boarded, which is understandable. That was another £800 so it can be an expensive business. Good video Roger.

I made walk in freezers and coolers for years and we never had any sort of water problems. In fact, the water would run off plus the foam was so tight on the metal skin there was no room for water. People also overlook how strong the foam is, having it inside a wall would make it much stronger than fiberglass in the same wall. If you had two walls one with spray in foam and one without, I bet the foam wall could support twice the weight. It's not all bad you just need to let it off-gas before covering it up.

Many homes are built using 2x6 walls.
One engineer that worked in home construction told me after they used the closed cell,
they come back and fill in with open cell and have had good results.
You could use any number of insulation products for the remaining 3 1/2".
Closed cell foam should be limited to 1 1/2 - 2" thick. It has R6 to 7 per inch.
There are many cases where this has not been heeded and there are odors that linger for months if not longer making a home unlivable. Another reason to use a trained professional.
Open cell has R3 to R4 per inch. 2" Closed cell-R14 plus 3 1/2" open cell-R14 provides R28 total. This is before external sheathings are considered.
I don't think I would consider anything else if building new.

Really interesting video, my concern is enclosing a property with a chemical based thermal envelope and ignoring any potential health issues arising from the vapours coming of these products. I remember the cavity wall insulation debacle some years ago where householders fell ill because of the toxic fumes/vapours building up in the cavities and entering the interior. Adverse health issues through the use of chemicals in a living space can sometimes take a long time to materialise and not fully understood by the purveyors of these products. The building industry is littered with products that have found to be harmful to health and posthumously withdrawn. I personally over past couple years have come to realise that plastic is not a mans best friend anymore.

As I said elsewhere, I have about 30 years experience as a timber framer using with SIPs and closed cell polyisocyanurate spray foam insulation systems. I am retired now but I lean more towards dense pack cellulose without an air or vapor barrier/retarder. Finding “craftsman” willing to do it my way is difficult. I am fortunate to have satisfied clients that let me observe what works (and what doesn’t). Some places had blower door tests and thermal imaging to help me monitor our quality control.
So at 66 my wife and I are going to do dense pack cellulose for my “last” place …..ourselves.

Love this video! You did an amazing job of explaining spray foam insulation and hashing through some of the issues associated with it. Thanks.

Roger, I always enjoy your videos, which are packed with information that the normal home owner would know nothing about.
You touch on the matter of the condition of roof rafters that could become saturated if roofing felt breaks down, and it's that which would steer me towards using Celotex or similar.
Now that you've told your viewers how YOU create a warm roof, that's a 100% steer for me!
Thank you. Keep up the good work!

I had spray foam professionally done after a rehab of a 115 year old home. I gutted the attic “apartment”, repaired the weighted window pulls, ran all the electrical and CAT-6, added a proper adjustable vent, then spray foam in the rafters and walls up there, drywall, carpet. It went from the most uncomfortable room in the house to where the kids and I spent most of our time. Also sprayed a barrier around the skirt of the house which was exposed and accessible above the sandstone blocks in the basement. This house is in the southeastern US, where it’s hot and miserable in the summers, and grey and damp in the winters. Spray foam is _the_ best investment in energy savings and comfort I’ve ever made!

You need to provide ventilation baffles between the roof decking and the foam or fiberglass insulation to provide a path for moisture to evaporate from under the roof. These baffles need to communicate airflow between the soffits and the roof vents on the roof peak.

Almost 30 years ago we spray foamed the slate roof of an old stone cottage (inside obviously). This was done directly to the slates. I was worried for a long time about what we had done but here we are 30 years later and it's been absolutely faultless. We haven't even lost a slate off the roof in all that time. Not one. The main roof timbers were left exposed for the cottage look and the foam was hidden with plasterboard so, to the casual observer, it looks like an original ceiling. The cottage is very warm too.

Just a thought, could you line each area you are going to spray foam into with plastic sheet such that once the foam set into a block it would be removable? That way you would still get the transport cost saving, avoid inaccurate insulation block sizing and be able to remove the insulation for ongoing structural assessment. Of course the extra labour cost may be cost prohibitive and the plastic sheet would have to be fire safe. I'd be interested in your thoughts.

I got spray foam installed in my new home ten years ago. It was the open cell type. It’s been great as my utility bills are lower and the house is quiet. Cost was $7000 more than regular blown in cellulose insulation..it has paid for itself and will be a selling point when I come to sell the house. Absolutely no bugs in the house as it is completely sealed. I would do it again with another house.

The use of "vapour barrier" or rather vapour retarder is recommended for certain climate zones. For attics you need a good ventilation. You have to make sure that moisture in the air is vented out.

Spray foam in a steel framed home works out nicely. We built 3 of them, with a wall cavity of 8 3/8" on the exterior walls, heating and cooling the homes was very low cost.

One benefit of spray foam which I didn't see/hear mentioned is that a thinner layer of spray foam provides a similar level of insulation to thicker fibreglass insulation.

This seems like a great idea in theory but a mixed blessing in practice. Another fear with some 2 part systems is that if they are improperly mixed, the uncured components will off-gas, releasing potentially harmful fumes. I've not heard of the mortgage problems you describe here in the USA (perhaps because slate and tile roofs are rare here), but I'd lean toward an open cell foam, so that at least you know early when a leak occurs. On the other hand it is claimed that closed cell foam adds a lot to the strength of the roof, for those in hurricane zones.

It's interesting hearing about insulation in other countries. Here in Sweden the norm is 25-40 cm insulation in walls and floor and about the double in the roof.

Definitely some issues with spray foam, but also some massive advantages. Like most products, its dependent on the climate you are designing the system to address. Makes perfect sense to me that the UK with the cooler but more humid environment would lead to totally different results than using it in the USA, where that climate is not preset outside a few small regions (Seattle area for example). Here in the US, I have seen it praised highly in a number of specific circumstances. Particularly: R-value per inch is almost impossible to beat. Retrofit in tight and confined spaces like crawlspaces is MUCH easier than trying to perfectly size things by hand. Man-hours required are far lower compared to trying to get a good tight batt insulation, and as soon as the initial off gassing is complete you are available to work again. More training is required for the installer by far, but that training is centralized in a few highly competent installers, instead of a larger number of lower skilled labor. Finally - and something that might have the largest impact here in the USA: New construction in much of the nation is now required to pass a blower door test to verify the airtightness of the home before certification of occupancy. Spray foam dramatically reduces the number of potential touchpoints that could be letting conditioned air escape, and is relatively cheap insurance to ensure that the house passes without potentially project-busting overage to try and open things back up and find where those few CFM are going.

As a general contractor I hated spray insulation and only used it if I could not convince the owner it was a bad idea. It makes a remodel job a nightmare.

Moved from a doorman building in NYC to Chicago and gut-rehab two adjacent buildings into a live/work space. We used spray foam throughout the project (7000sq ft). I'm continually amazed at how small our heating and cooling costs are. Here in the US there spray foam insulation is sought after.

This must be a UK issue. No mortgage company in the USA ever asks about spray foam.

Great video. I'm in exactly the situation you've mentioned. Selling my house. But previous owners had spray foam insulation. After our buyers mortgage survey, we lost our buyers. Now in the processes of removing foam, replacing felt, etc. Pretty much new roof.

I think spray foam can be great, but not applied directly to the underside of a roof. For one, it forms a watertight seal which will lead to roof rot long before a leak is detected. But I also wonder about it's role in ice damming as there will still be some loss of heat. Where I live (in central BC, Canada) we get over three feet of snow and the roof is snow covered for more than half the year. The ceiling is insulated, but not the underside of the roof. In a northern climate, if an attic is not well ventilated and the same temperature as the outside, ice damming will occur.

Here's 1 problem with spray foam in attics...If you have plumbing vents that go through the roof then you have a rubber boot around it on top of your roof to keep water from coming in. That boot usually dry rots, cracks & shrinks allowing a small amount of water to make inside the attic where the foam absorbs it. This grows a small amount of mold & algae. This will attract the outdoor roaches nicknamed "water bugs" or "palmetto bugs"...(they're roaches). The exterminator will not be able to stop the roach problem so if you've noticed this I recommend inspecting your rubber boots around the plumbing vents.

I've have only recently started researching ways to insulate in hopes of having my home built, and I must say that this video is beautiful. None of these concerns was mentioned even once in all my past month researching. Thank you good sir! You got a new subscriber!

Great video. Spray foam is fantastic for basement and crawlspace walls and IMO....that's it. Use rockwool bats done properly in the rest of the house. Use R 30 in your flat ceilings and make sure your attic is as close to the outside temp as possible by venting it properly.
Use baffles in your vaulted ceilings with soffit and ridge venting for air flow beneath the roof sheathing.
Some old style things are just better

Missing one thing in the video: health and safety.
There have been several cases where the contractor didn't do the mixing correctly and the spray foam kept on releasing chemicals into the air. The residents became hyper sensitive to urethane and their houses had to be demolished and replaced by a completely new house. Recycling of sprayed building materials is a nightmare as well.

Used spray foam as standard on our builds in the US/Canada for a long time but it's better left for specialists. Open cell is cheaper but requires a larger depth for same insulation value as Closed cell. Closed cell works as an air tight water/air/vapor barrier but open cell doesn't. Both are flammable, both help stiffen the structure to a degree and both if mixed incorrectly can cause smell and sickness during off gassing which arguably is a more immediate risk than covering up the rot.
In the states it's been around long enough that the benefits are known and it suits the structure type (predominately wood) but back in the UK I wouldn't recommend it. Also roof windows, why the hell aren't UK windows flanged for wooden structures.

Very interesting. I also think that spraying foam over electrical lines would make it much more difficult to alter or fix electrical problems later on. The electrician would have to cut through foam or remove some foam to get at the lines, rather than cut rolled insulation.

They have preformed foam vent inserts that go in before the spray. It allows for a half inch gap between the roof and the insulation. It vents open on the top and the bottom and allows for borescope inspection with the foam in place.

Thanks, you did a complete and clear presentation. This was mostly new information to me as I have not heard of a mtg company being concerned about foam unless it is backed on the other side by plastic and no air/vapor can escape. Today it is 109F or about 43C outside and the air temp in my attic is abt 150F, or 65 C. Moisture vapor does not stand a chance in Texas. I am considering spraying the underside of the roof, it might help.

Never heard of spray foam used under the roof like that. We built our house in 04 insulated by spray foam in the walls and it has worked out great. Heating and A/C stays in just fine. Ceilings have that blow in / loose fill insulation that also has been great.

A very fair and balanced explanation of both the pro's and con's

The obsession with "saving through efficiency" is perfectly summed up by the use of spray foam on the underside of the roof structure. Personally, I'm happy to sacrifice a little R-value up here in the Adirondack mountains for peace of mind knowing that my rafters and beams aren't being eaten away by unseen collected moisture which could lead to a huge replacement bill down the road. A cold roof with soffits and insulation on the floor instead of the ceiling is the most cost-effective and nearly equally efficient setup where I live.

I had my attic and crawl space open cell spray foam. It would be 30 degrees outside and my home inside was 60 without using heat. I love it!

When they did our house, the attic was sprayed foamed directly on to the ceiling drywall and rafters, hence the attic isn't insulated, only the ceiling and walls of the structure. Is working great 11 years in. There is a slight wave in our ceilings but it is unique and it is waves! Likely caused by moisture in the spray foam at application.

A note about moisture. It's not moisture until it condenses. Otherwise, it's humidity. A humid home is a warm home. Reduce the humidity in the air and the house is cooler. So you want humidity in the cold seasons and not in the warm seasons. Luckily, in the warm seasons, you either open a window or put on the ac to take the humidity from the air.

I used Icynene in south florida and the insulation properties were amazing. I paid $7500 but I absolutely loved it. During construction, in the south florida summer with the house fully closed and NO air conditioning you could walk inside the house and be cool when you walked in. Sure, you would sweat after 20 minutes inside the house but in a home with no spray foam you could not even walk in! It is simple amazing.

Seems in the past few years professional installations have been shown in many cases to have shrunk away from the framing members. Closed cell as well of course as open cell (which really is to be avoided at all costs). Also any savings from shipping are way more than compensated for by the high cost of product and installation when using foam. I think the real lesson to be learned here is not to disparage the DIY'er as they can often do as good or better than the professional. Often the installer in rural or small town areas if available at all will not be doing foam full time and the expertise can vary drastically. Not many professional installers 'play with the formula' they just apply whatever is sent them and move on to the next job. If they can get a better price on a batch of foam and up their profit margin most will unquestionably accept the product. Again the point that is made is that any high tech material that is stringent in its application with little or no latitude for error or sloppiness is just not going to work on the real world construction site. Moisture and temperature parameters are going to be violated to get the job done where time is money, would be one example. A poorly trained and or motivated work force is also going to be a problem. There are so many things that effect the quality and performance of a building that it is foolish to add more complications. Narrow application limits should be avoided if at all possible.

True honest facts there Roger, a friend of mine actually has a company removing and inspecting this stuff and I’ve occasionally had to go in and construct a Entire new roof due to rot, which 9/10 times the tiles have fouled causing a leak which has gone undetected due to the foam, I’ve also noticed that the elderly seemed to get targeted for this stuff. You and the team keep up the good work 👍💪🏼

I have open cell spay foam which is totally superior to fiberglass insulation. I have vaulted ceilings and vented each space properly. The house is 3000 sqft in total with 3 floors at 1000 per floor. It holds the heat and hold the cold. With all the windows and skylites the air moves well. This insulation was the best thing I ever did in all the years of construction. Mortgage companies just want to extort money in any way they can.

Very informative, thanks. It's interesting how this stuff is different around the world - I came across this via Matt Risinger's Build channel and gather it's very common in the USA, possibly even the preferred approach. It's a fascinating thing to watch a pro do it. And ludicrous the main reason against it here is insurers/lenders who as you point out don't ever come and look at your roof anyway in many cases, let alone check behind a bit of plasterboard. I'm assuming this stuff is totally non recyclable, non-degradable if you do remove it?

I would call this a very thoughtful and honest presentation on the spray foam I always thought it to be good for maybe doing the underside of a house. Maybe in a crawl space..(understanding one doesn't loose heat through their floors of course.)

I live in hot, humid Florida. I built the house myself, and it's very airtight. I have spray foam (walls and roof) and insulated impacted windows and doors. I added an energy recovery unit for outside air, a high efficient two-speed AC, and a hybrid high-efficiency water heater with a hot water return. My electric bill is around $140 cheaper than my neighbors and their house is a little smaller.

If you put your wires in conduit and your plumbing pex pipe inside a poly pipe they are very easy to change out if you have problems if they are encased in concrete, insulation foam or even the ground. Works best if all fixtures are individually plumbed. You can also put all communication cables inside conduit for easy change out.

As a rule of thumb do you cut the rigid foam for an exact squeeze fit or do you leave an 8/10mm gap for the gun to get a solid squirt in around the borders? Thanks Roger.

Excellent video. One other issue with spray foam as I see it if you want / need to run additional wiring in a wall with it you might as well forget it. Just rip off the drywall and remove it.

Fiberglass batt insulation is not free of issues, either. It soaks up moisture, is the perfect medium for growing mold after it gets wet, loses its R-value when wet, and can slump down inside the wall cavity making large un-insulated voids that will end up costing you an arm and a leg in energy bills if not discovered for long periods of time.

I bought a house that had a sort of sunroom put on as an addition, over a crawlspace. I wanted to convert it into living space by adding a minisplit heat pump, but the floor was cold and drafty. Spraying foam on the underside of the floor solved both problems, keeping it warmer and sealing out all the drafts. I bought a tank of foam spray and it worked very well. You must wear eye protection and have very good ventilation--I had a box fan running on its highest setting blowing in from the entrance of the crawl space the whole time--there's no such thing as too much fresh air.

I have been using spray foam for a 100 years on valves and flanges etc but used it only once in a residential environment. All I would say (through harsh experience), ensure that your substrate, wooden structure is totally 100% dry and moisture free and does not hint of rot/mould or anything. My solum was compromised, thus increased moisture levels in the atmosphere and then by the time I got to it, I had x1 purling and x15 wooden beams to replace in my basement. Cost me thousands to resolve as I had to remove all the contaminated wood, new engineered flooring etc. The foam likely exacerbated the situation but the solum was the primary issue, so not really the foam to blame.
Another lesson learned - a sore one.

As always, very clear and cogent arguments for and against. Many thanks, Roger

This is a very important video and hope this gets many many more views .... I've had a terrible time remodeling with spray foam and it's a disaster for plumbers and electricians and refinishers ...

Had my house sprayed a couple years ago. No problem. My utility bill dropped, it's a lot warmer and didn't have to run furnace as much and it's quiet inside 👍

In the humid south of the US, we put the moisture barrier on the outside, under the siding rather than over the studs inside. A popular way to insulate here is called flash & batt. We lightly spray foam to close the air gaps and then fill the cavity with rockwool batts. Very effective

Great video - was really interesting ,
You described how you would fit the insulation yourself.
Could you please make a video showing this step by step procedure.
I want to know how it's done right.
Many thanks

The only thing bad I've ever heard about the spray form is if the chemicals aren't mixed properly it can leave a nasty smell some people say it smells like rotten fish and some people have had elergic reactions to it.

I was a deputy fire chief in my city in South Louisiana (USA). The highest Carbon Monoxide Level issue I had ever come across, was in a renovation house. The house was elevated on piers (about 18", common practice in wet Louisiana), new windows, new doors, spay foam, new sheet rock. Furnace and water heater were not replaced. Fortunately the owners had an alarm system that included a CO detector and the alarm company made contact with the FD. The reading was over 225 ppm on our meter (33 ppm over 8 hours sets an alarm for work environment). Fortunately, no long term effects were had by the occupants. The occupants said "everything was new, had to be a faulty detector". After investigation, it was determined that the renovations were done so well, that a house that was designed, and needed to breath, no longer could. The house was initially built in the mid 1800s. This incident has always stuck in my head, and will never add such measures in a renovation. Just my 2 cents.

In defense of the closed cell. There are some places where it is excellent. We sprayed the crawl space bottom of our floor joists. We had them spray ALL exposed wood (even a thin layer on cheeks and bottom of joists/sill plates) to seal from dirt floor moisture. This saved us doing the laborious encapsulation.... We will always know if there are issues of moisture from above (unlike a roof) .... I should also mention at the same time we did and ABSOLUTE meticulous job of French draining/sealing block from the outside, digging all the way below the footer. Also used 2" foam board from footer all the way up to the sill outside. The exterior block foundation cannot wick from the outside to sill. This killed any moisture migration from the dirt crawl space. I would be leery of doing a roof for ALL of the mentioned reasons.

We have closed cell foam insulation in our 2200 sq ft two story home. We have Anderson 400 series window with tinted glass. Our house was designed and built to be air tight. The HVAC contractor studied the plants and in concert with the architect they designed a system that includes fresh air make up system that tempers the incoming air by using the exhaust air. All of the parts and materials were available and none had to be “special” ordered of fabricated. Having worked in the home construction industry for most of my life, I believe that spray foam is the best bang for your buck if you look at the entire house holistically and systems vs individual pieces of the system. We heat with natural gas and have central air. We live in the northeast U.S. and we have never paid over $100 per month for our gas and or electric service. While we paid more to build the home, our ROI is occurring within the first six years of our completed date. Thank you.

3:03 - Presumably you have the impermeable membrane on the _outside_ (I assume that's what you mean by "the other side of the roof". So open cell lets the wood's moisture equalise with the _inside_ of your house through evaporation, which is exactly what you want. If you use closed cell, that's basically like having a second impermeable membrane on the inside, but the outer one will crack / fail first, so any water that gets in will have nowhere to go (water gets in through cracks much faster than it can evaporate back out through the same crack), and will just saturate the wood

Best main application for spray foam is to run spirals of wire nailed to the rafters over the roof sheeting then foam-cap the whole place and lay on membranes. The problem is that once the foam starts to burn, the house is a goner. It WILL burn.
Next application for the spray foam is poofing it in bags that compression fit cavities. Sprayfoam doesn't sag when wet like fiber.

The solution to moisture coming through the roof into the attic space is a product called Zip Sheating. The zip system if installed correctly creates a water and air barrier on the outside of the roof, all the joints are sealed with a specially formulated tape that is warranted for 30 years. The roofing and wall product is manufactured with the air and water barrier at the factory during manufacturing. It has been around in the US for about a decade and close/open cell foam can be applied directly to the underside. If your applying a new roof this system is worth a serious look, if your building new, it’s a must have.

I did some 'damp repair jobs last year on a couple of period properties here in Aberdeen, Scotland, one being around 120 years old, granite facing with traditional timber framing, lath and plaster finish on the inside. They had the spray foam pumped into the wall cavities (and the roof), but a couple of years later damp patches appeared in quite a few spots. Turned out the pointing around some of the granite blocks became defective and started letting water in. This wouldn't normally be too much of an issue if the cavity wasn't filled with foam as it would evaporate on the inside, but the foam began to absorb the moisture over time, or cause a bridging affect (carried the moisture through to the inside walls), and damp patches appeared on the internal walls.
Would I recommend it on an old property like this...no. Would I recommend it on a new build...possibly, but that would depend on it's design, as air still needs to circulate the structure

I remember back in the family house, the attic was so cold compared to the rest of the house. It only had insulation between the rafters that made the ceilings of the upper floor. The rest was pretty bare and the whole house could get really cold in winter.

We live in central Florida. Love to have more insulation against heat. But we have two issues to worry about. 1) moisture, 2) insects. I shudder of the thought of palmetto bug infestation or mold formation behind the insulation. I think I will stay with the trees around my house. They are a nuisance but at least I can see what is going on.
Thanks for the warning.

As someone who has been in the foam insulation industry for 15 years, I see all these problems all the time. I do not even touch remodels if the HVAC is not being adjusted properly to figure for proper ventilation. I love foam, but a house needs to be built for foam. I do not typically like using it for remodels, and where we live remodelers are not typically intelligent enough to understand air tightness and moisture control and most foam companies are just as bad. They just know how to paint walls, cabinetry, and flooring. Spraying foam directly against the roof with close cell to water proof is the most ignorant thing I've seen other companies do. The roof is incredibly difficult to remove like you said. I believe that 70% of the foam insulation companies have no idea what they are doing and do not properly get their guys trained. They rely on equipment sensors to tell them if the foam is correct which is often too late. An applicator should be able to see it on the wall instantly and know. I also believe foam is sprayed half as thick as it should be. I sprayed my personal house to and R-42 in foam which was about 11.5 inches. I can run my house on an ERV for over half the year in Texas. I only kick on my air conditioning in the summers and winters at the extreme points.

I had a customer who had an upscale house which had a fire. The fire could have easily been localized and contained if there were no foam sprayed. The foam retained the heat from the fire throughout the entire 4000 square foot house. Every window blow out from the intense heat and the entire house was destroyed from smoke damage.
Nice stuff

When I decided to tackle a DIY project with spray foam insulation, I had no idea it would become a comedy of errors. As soon as I pressed the trigger, the foam sprayed out with such force that it seemed determined to decorate everything in sight. My attempts to control it turned into a slapstick routine as I struggled to aim and direct the expanding foam, inadvertently covering myself in a foamy mess. The foam seemed to have a mischievous mind of its own, sticking to my clothes, hair, and even my pet, who looked more like a fluffy foam creature than a dog. In the end, I had a well-insulated project and a hilarious memory of my foam-filled escapade that still brings laughter to this day.

We had it done (slate roof, good condition 1950s, closed cell) 1996 and sold in 2018 with no problem - and the roof space was great (no 45C in summer, -10C in winter).
Had the new family home done in 2019 (membrane + concrete tiles, 1980s 'Barret" build, closed cell) done in 2019. No problems since.....the roofers didn't comment / complain when they needed to re-channel the interface into the extension (~1985).
But then we used proper ventilation (open a window occasionally) and bathroom extractor fans.

One of your best videos Roger. I never knew about the mortgage problem and a couple of my customers have looked at having it done and asked me what I thought. I can give them a better opinion now.
I wonder what long term research has been done about rotting timber? Was it just a rogue case which has spooked the mortgage companies.?

Your correct observation about impermeable membranes is the reason I do not place plastic insulation on the exterior of dwellings. Cold bridging also allows condensation to occur within the un insulated gap behind the plasterboard, which leads to mold growth. Now do a flat roof structure.

The other thing it helps with are ants roaches etc. as it doesn’t allow them space to get in. I have seen those bathroom fans vent to the outside as well and A/C would remove the humidity first before cooling the house. Yes it would mean you would have to run the a/c all the time or at worse have a whole house dehumidifier placed on the venting to remove the humidity from the house. I believe most of those have settings for what percentage you want. Could a plastic barrier be placed between the roof and joists. I know this would be for new houses or those with total roof replacement with a channel to le humidity to escape outside?

I used closed cell in my exterior walls, then batt behind it. Low utility bills. 28 years later still no issues. I'll use it again in my next house.

HVAC guy in the US and I spend a lot of time in sometimes very tight attics/lofts that have spray foam. One more thing to consider is if your air handler/furnace is up there, the spray foam guys need to be real careful about making sure they prep/cover the HVAC unit carefully and don't spray and entomb anything I need access to. Often service disconnects are attached to rafters and get sprayed shut- then I have to destroy the insulation to dig it out. Also if you have ducts or machinery tight against the rafters they may not spray behind it and lay thin or entirely miss large areas. I didn't consider the acoustic changes! Good video, boss.

Very important information and a lot to think about. I have never heard anything about mortgage companies refusing a mortgage because of the foam. Many things to think about building or repairing a home. Thanks!

You need a heat recovery extractor unit . This brings in outside air and warms it slightly with the extracted air

Potentially another reason UK mortgage companies might not like spray foam is the flammability. Compared to other insulations it burns pretty quickly and very hot.

Nice video! Thanks. Definitely a renovation nightmare. Go with rock wool insulation everyday.

Clear pros and cons. Great advice, helpful to make informed decisions.

Use to use two part foam, at a fiberglass company. We had three options on the second part. Each one was of a different density. A built-in boat cooler would have one density for thermodynamics, while a sailboard would need strength and lightness.

Roger. Totally agree with you. I have a letter in the "professional Builder" February 2020 copy which prompted a discussion that generated support to your conclusion. As a lifetime Carpenter & Joiner I am amazed that people fall for this concept. Fire could be a problem with over heated cables. Electricians I know are not happy with tightly packed insulation, which, even to a non-electrician is blindingly obvious! Another topic Roger you may like to discuss:, the obsession with washing roofs. I won't spoil your thunder!!!

Can you imagine trying to trace back a dry-rot outbreak in a house where that had been fitted? The mess would be the stuff of nightmares!

Thank you for finally explaining that. I first heard about this and could not find a clear reasoning for why the banks would have a problem with a more energy efficient structure.

ADVANAGE: INSECT BARRIER. I had closed-cell spray foam installed in an outbuilding with board and batten walls. I knew that as the boards shrank and warped, ants and other insects would enter but with the foam I have no insects entering through that path, have a water barrier and a much sturdier building. I covered my insulation with cedar paneling. In the US, it must be covered in a living area, but that's not required elsewhere. I did notice it is not UV resistant as evidenced by the green color's fading to white. Whether this is just the dye deteriorating or the product itself I don't know.

very well explained video. thats why you hire the right guys who know what they are doing. been doing it for 16 years and glad i took all the courses and have all my tickets because you can have someone destroy your home if not done properly..... dont cheap out guys

Best use of spray foam is to glue around the edges of rigid foam then slap it in place to make a rigid bond with the wood. If there's a problem you can easily cut the block out with a knife, it's not glued/foamed on the back (so it doesn't push out). Moisture may collect there but not against the wood necessarily so it has time to get out.

Had a “nontoxic” closed cell foam installed about 6 years ago. I traced the USA SDS sheet to the patent holder which did not list ingredients. For 2 weeks after install the house air quality was so toxic we moved out. After week 3 we moved back in and no odor since. Closed cell product shrank 5% a year later. All in all it was worth it.

My in-laws did icynene in their walls during a major remodeling about 10 years ago. They did in only in part of the house that had the drywall exposed. It turned out great. There is tremendous difference in comfort between the new and old. They wished they had done more of the house. If you have water entering the structure, foam won’t fix that. You are right you want to get qualified professionals to do this. Do your due diligence and check their past jobs. Done right, this is great.

I once had a house with a graduated tile roof so considered using spray foam to make sure the tiles never moved. But I decided against it thank goodness as that was often the first question asked by potential buyers. I simply put a very deep thickness of insulation on the floor of the loft as it was never used for storage.

I had the closed cell spray foam, but I used Double Bubble wrap on the ceiling and it is perfect,closed cell is the best,bugs won't eat it either, it was about a half inch thick