Spray Foam Insulation — The Ugly Truth?

[Music] hello i'm roger bisbee from the skill builder channel and today in this little rant i'd like to talk to you about spray foam insulation now you've probably all seen those cans of foam that you get but this is an industrial process a professional coming in and spraying the inside of your loft or even the space in your walls with some kind of spray foam so spray foam what's not to like about spray foam it saves you all that cutting it saves all that laborious process and it produces a lovely airtight seal you don't get those draught gaps like you might get if you were trying to put in pir or pur ball something like celetex or kingspan and you don't cut it that accurately and then you get little gaps and of course the air gets through and as the air gets through the heat gets through so spray foam is sort of 100 seal because it fills in all those tiny gaps the biggest problem with spray foam is that mortgage companies don't like it if you go to sell your house and they say you've got spray foam in the loft they're very likely to say to the person who's going to buy your house we won't give you a mortgage on this property they can't see the roof structure because it's been covered in all this lovely spray foam they can no longer see the condition of the roof that means that the timbers could be rotting they would know nothing about it but i would say that's a little bit of a strange thing because if you think of something like a loft conversion for example you could have as our friend reg the other week found out in his house you could have damp building up inside that roof space rotting those timbers and you would know absolutely nothing about it because they don't go around with a little camera checking what's happening behind the insulation even if they could get there they don't do it so they assume that a loft conversion has been built to standards and that ventilation is in there or if it's not needed then it's a warm roof and therefore it's perfectly sound but when it comes to spray foam they assume that all kinds of horrors are taking place behind that spray foam they assume that damp is building up there and it's rotting the timbers now we have two types we've got closed cell and we've got open cell now the closed cell means that all those lovely little bubbles are all kind of closed up and the moisture the airborne moisture the steam the vapor can't get through because the closed cell stops any transfer of moisture through the material the open cell allows that moisture to go through now you might think okay if it's open cell that means in those words it can breathe as they say and it means that any moisture that's trapped inside your loft or somewhere else or your walls even because we're also talking about stud walls here it means that that moisture can permeate through and it can escape the other side and therein lies the rub because can it escape the other side if you've got an impermeable membrane on the other side of the roof the moisture is going to get through that open cell foam and it's going to sit there trapped behind the open cell foam and the impermeable membrane under tile slating that you've got there so very important that you look first of all at whether you've got that situation you have got that situation if you've got an impermeable membrane that you might like to say let's go for the closed cell and that means that the moisture is stuck it's almost like a vapor barrier well in fact it is a vapor barrier and it means that that moisture can't get through which then means that it's hanging around inside your loft which is you know if it's warm inside the loft because you've basically created a heated space then you could say that moisture is going to escape like all other moisture it's going to disappear through the vents or anything else that you've got in the loft would very often have this spray foam in conjunction with a loft conversion so you've got the spray foam that's been put in then you've got maybe an air gap and then you've got the plasterboard going in there and that's got a vapor barrier on it maybe and then you've got some kind of trickle ventilators in the loft or some kind of extractor fan which takes that moisture away out into the open air but if you haven't got that and that moisture is hanging around it could start to build up mould now another thing to observe about spray foam is that it's very rarely put in that thick in other words when you get something like you know celitex kinsman or any of those products they tend to be sort of a hundred mil 120 ml that kind of thing and so you've got quite a bit of mass there through which the uh heat can't travel but with spray foam they might put it into a depth of maybe 25 millimeters 50 millimeters something like that and then they rely on having that lovely sealed air gap on the inside between the spray foam and the plasterboard you've got a sealed air gap there which is basically a heated space and that stops a lot of the heat transfer because it's very difficult for heat to travel across a dead air airspace but of course you've still got your rafters here you've still got all those other areas where they're directly in contact with the outside so you've got a bit of cold bridging and you will see on some days you can actually see the pattern emerging on the inside of the plasterboard where you've got a difference between what's insulated and what isn't insulated so in those cases very often people put a layer of celitex or something like that across the underside 25 mil to just give some insulation onto those rafters so it could well be that you end up with a combination of the two you end up with a spray foam and you end up with some more conventional cut insulation if you like that you're going to put in those are the things to consider first of all if you're selling your house it could be a problem having said that i know a builder that uses spray foam all the time he gets the pros in they spray the house in one go and it's all done he hasn't got to pay people to cut up insulation and if you consider that this stuff arrives in a couple of small canisters that's a huge saving in terms of transportation cost because a lot of the time when you're transporting insulation material around the country the big cost there is of course the lore is full up with this insulation you know so it arrives on site with a carbon footprint before you even start with the spray foam it comes in two cans it's mixed together on site and it expands and forms the installation it's a lovely idea and there are diy kits available to do this semi-detached three-bedroom house probably about 750 quid to do that you get the two canisters you get a little gun and you spray the stuff in yourself don't try it it is absolutely probably the worst thing you can do it's not a diy product you need to know what you're doing because if you don't get that mix right and it does vary with temperature what you need in the summer is different to what you need in the winter so these guys spend weeks and weeks training so that they know how to apply that material and if you apply it yourself it can shrink back from all around the joists and things like that especially if you've got any moisture or oil in them and then you get the air gaps coming through so even if you've got a closed cell spray foam you end up with air and of course moisture percolating through so i would say it's not a diy job if you're going to have it done have it done by the professionals and check that they give you some decent guarantee having said that some mortgage companies don't like it there are people who say well i can't sell my house then can i so i'm going to have all that spray foam taken out and there are now companies that specialize in spray foam removal yeah hell of a job but they do it they take all that spray foam out so that your house can get a mortgage absolutely crazy probably the same companies who are putting the stuff in so what else can we say about spray foam well it cuts down all those air gaps it cuts down on airborne noises so that's a very nice thing if you're living near a motorway or you're living near a railway line or something or even an airport and you've got airplanes flying overhead it's absolutely lovely to have that continuous barrier if you like to stop sound coming through but it's not as easy as that it stops airborne sound coming through but if any sound gets onto the structure in other words if there's a vibration on a structure you find that that extra rigidity that's got and the fact that it's stuck to the actual building structure itself means that it actually transmits sound so you get a very peculiar thing you get more resonance in the house because you've got this solid structure you find that the whole acoustics of a house can change dramatically when you put in spray foam now i'm not scared muggle in here i'm not saying don't have it done all i'm saying is be aware that it may sound proof for your house in one way but it may enhance noises or peculiar resonance in the house that you've never experienced before so the other thing it does is a lot of spray foam has been sold in the past because people have had roofs which are on their last legs they're suffering from what we call nail sickness which is normally where the nails rust away and the slate start to slip off nothing wrong with the slates at all it's just the fact that they're not secure to the batons any longer so these guys come in and they say we don't need to renew your roof leave the slates they're perfectly okay we stick this spray foam on the inside it sticks all the slates together it sticks all the battens together and it kind of gives you a lovely insulation at the same time so you think oh that's a miracle that's a marvelous solution saved me five thousand pounds of having a new slate roof and it's only cost me two thousand pound to have a spray phone put in and they're telling me i'm gonna get a payback period because it's insulation that is probably paid for itself in five years or something like that so you think that's a great idea as i say great idea until it comes to the point when you try to sell your house then they want to hack the whole off and then you end up having to have a new roof anyway because it's very difficult to get that spray foam off and leave all those battens intact and all those slates intact they all start falling off and it really can be a little bit of a nightmare so it's one of those where i'm sitting on the fence at one point you're saying what are you saying roger are you saying spray foam's a good thing or you're saying it's a bad thing more importantly would you have it in your own house no i wouldn't but that's because i'm perfectly capable and willing to cut in that insulation spray around the edges of the insulation with the fixer foam tape over the joints put up the vapor barrier put up the silver foil plaster board and make a decent job of it that way i've been doing that for very many years on loft conversions and all that's a laborious job nobody likes doing it once it's done you can just forget it the problem is with that installation as we know that very often because it's a horrible job it's left to the labourer to do and they don't always make such a great job of it when you look at it as a low-skilled job they just come along with a saw and they kind of measure up roughly and they cut it in and it goes in as a few gaps i mean i've seen some horrendous ones and if you get a thermal imaging camera and you go around a loft and you just look at it you can see all kinds of places where the insulation hasn't been done very well and there's cold bridging going on at those points now isn't just a question of you losing heat out of the house the cold bridging can mean that it's an ideal spot for airborne moisture in the house to condense on so you will find that you start to get mold particularly around things like roof windows where very often that detail is not done particularly well there's an insulation gap there and we've spoken about key light roof windows which have that expanding foam collar that goes all the way around when you fitted the window you just pull the tape an expanding foam collar takes care of all those little air gaps and makes a nice snug fit but a lot of people are putting in roof windows other roof windows don't necessarily put any kind of insulation around that edge and of course that becomes another cold bridging place whereas if you've got spray foam you put the windows in you're all ready and you go over the spray foam and all around the edges of the window are sealed so one more thing i'd like to say about spray foam is that when people have this foam sprayed in the loft all around here and the whole thing is sealed up tight they find that it cuts down on all those draughts warms the house up quite a lot but what they then notice is that their extractor fan in the bathroom and maybe their cooker hood in the kitchen are not working as well as they were and the reason for that is that there's no air being replaced when that air is being sucked out and if you don't get that you do it doesn't vacuum the house cause a collapse of the house all it does is just makes those fans not work efficiently because they're not powerful enough to suck on that vacuum if you like so what we find is that unless you put some trickle vents in there you open some trickle vents on the windows if you've got double glazing got nice sealed windows draught proofing all around the house and you've got this spray foam especially if you've got a timber frame house and you've got a spray foam in all the walls and so on so you've got a continuous vapor barrier around there and you've got a continuous draft proofing you will find under those circumstances that it will mean that you're not getting enough replenishment air into the house and of course what that also means is that when the house is warmer and you're not getting the ventilation that the humidity in the house is also building up and it could well be that you start to get damp problems in the house where you didn't have those damp problems before you'd be nice and warm but it'll be foggy and of course that can also cause problems for people like dust mites and allergies and all the rest of it so again it comes back down to this thing of getting airtight houses still need to be ventilated you know seal it right but ventilate it right that kind of thing seal it tight but ventilate right any of those phrases you like just remember that you still need to breathe you still need air in the house so if you're going for this option make sure that you still allow a little bit of replacement air to come in so what i'm really saying i suppose is that spray foam is a good idea it could be done well it would solve a problem of having to transport all that massive insulation all over the country so i think in a way it would be a great thing for cutting down our co2 if you like but the mortgage companies really need to love it because if the mortgage companies don't love it it's game over nobody wants to be in that situation where they can't sell their home so i'm roger bisbee i hope you found that useful do come back and see us soon because we will have more coming up on skill builder more rants more how to's more everything really

Channel: Skill Builder

Views: 1,461,664

Keywords: spray foam, spray foam insulation, spray insulation, foam insulation, spray foam insulation problems, closed cell foam, energy efficiency, spray foam insulation cost, attic insulation, spray foam insulation diy, spray foam insulation metal building, spray foam insulation attic, spray foam insulation business, spray foam kit

Id: jYNufQVIFfA

Length: 14min 51sec (891 seconds)

Published: Tue Jan 25 2022