What is Multifoil Insulation? - With Byron Lawson

[@Hew.Jarsol]

Hi I have an old external solid brick wall with plaster on the insides. It's cold. Should I remove the plaster, batten and rockwool it first, or just batten and insulate it on top of the plaster? Thanks.

[@greigmcdonald6018]

Prefer using SuperQuilt to SuperFoil, it's better quality and UK manufactured vs Chinese products! Used SuperQuilt first in my garden building then used it in my loft conversion. Great product will use again

[@johndufton9686]

I use SuperQuilt for the same reason.

[@xinleixu5244]

you didn't know Superquilt also bought chinese raw materials?

[@marksmout5289]

I have a cross wall constructed roof with 9inch purlin. I have a new roof tile above with a vapour barrier and 100mm of kingspan solid insulation between the purlin and plasterboard on the underside. I want to add insulation below to increase the thermal efficiency and bridge the cold spots what's the recommended options

[@beachhut95]

Have installed this in a property in Greece. Below a sloped timber tiled roof and also a Concteate flat roof to keep out the heat from the summer sun. I had a lot left over so added a second batten and additional foil layer. It works brilliantly and is easy to fit ,transport and handle on site. Would highly recommend

[@magzi113]

I moved into a 1960's bungalow. It's freezing cold in my living room because there's no insulation under the carpet, just the underlay put directly on the old vinyl tiles. Would this type of foil be any good to insulate the floor before putting underlay and the carpet? I'm worried about the damp that may set under the insulation causing the mould to appear.

[@GimbloBlimfby]

The problem I see with this stuff is the fire risk. How much exterior cladding has had to be removed following Grenfell? Does Skill Builder want to give some of these the blow torch test, given the material used inside them?

[@aibel99]

This vs pir insulation? Speaking from an energy saving perspective, which is warmer? I don't care about passing regs, I just want a cheaper heating bill...

[@gmangtr]

Installed Superfoil SF60 in the loft over very thin amount of fibre glass insulation and in conjunction with nice triple glazed windows ( old double glazed had blown) chopped our heating KW by 60%

[@nickgeorgie1957]

There’s a problem too: in the areas where you nail or screw it its R goes completely out. And given the low rigidity of this material these zero R areas become quite important.

[@Aindriuh]

You are meant to staple it, not use screws and nails.

[@johncowie3092]

Also wrong re screws it only flattens at that point but not to zero same as a staple

[@thepaintedsock]

Thanks. At 1930m into this video this is the most insightful regarding installing sf19 plus 45mm quilt on inner wall of old house. Though I am curious: Given that old solid walls need to breath to allow moisture to escape whether this quilt is 'breathable enough'? Also, if I used, as suggested, a 38mm X 50mm wooden batten, isn't that asking or trouble regarding wood deterioration against a moisture prone wall? I'm wondering why I couldn't cut a rigid pir or pf board to the equivalent thickness as a wood batten and mechanically fix those at 40 - 60cm centers instead. Since they are water impermeable, and add a little extra insulation, or is that idea problematic? Then I could install wood wool boards, and render over with lime, to protect any worry of damp growing on gypsum and maintain a breathable wall with maximum insulation. Any thoughts on this much appreciated. Thanks

[@benrichards1]

I've always used the superquilt make. From what I understand that's the better product. Happy to be corrected though.

[@eddjordan2399]

i have used ybs super quilt to great effect on new project its great for loft rooms and vaulted ceilings. cut it on a flat surface with a sharp Stanley blade with a heavy strait edge. use clouts to tack and use a good quality foil tape.

[@MartinSansone]

Re - floors - How does this compare to fitted Celotex 50mm between joists underneath 19mm flooring?

[@timjackson3954]

Some years ago when these products were first appearing I happened to do some work for a factory making a multilayer foil that was being advertised as having an R(si) value of about 6 despite being only about 2 cm thick. As a physicist, this raised my eyebrows. I also happened to have a guarded hotplate thermal resistance instrument, and tested a sample: it read 1.1 R value. I am pleased to see that standards appear to have improved since then.

[@AmirAlwan]

Great content as usual Roger! Thanks for keeping the conversation practical and relevant to all roles.

[@raybunn8895]

Roger, we have a 1950's built semi with 9 inch walls and solid concrete floor (I beleive with No insulation in it ). The stairs run up the end outside wall so, 1, best solution for insulating walls without eating into stair and room space ? 2, whats the best insulation for under underlay without raising floor height by too much because of stairs worktop height etc ? Tia

[@philipfox8797]

Have heard many stories about dry rot and moisture being caught by foils, how do you avoid this?

[@sandypatience]

As an architect I would say that it might work if the foil is next to an air gap and can act as a radiant heat reflector - but in all other circumstances I wouldn't touch it with a barge pole. The BRE took a dim view of it in testing.

[@jimosullivan1389]

You are correct. That is why they have the batten system. It's the air trapped behind the battens that give you the insulation. Everyone talks about vapour barriers but homes need to breath!

[@philiphurdwell3443]

Actis/ tri iso was only proven by manufacture tests only until quite recently and did not pass under independent tests. My real issue with the product is the installation method in so much that it is forever being sandwiched between batters etc which crushes it to less than 5mm thk . It's the installation method that I would like to learn about as I'm sure it works when installed correctly. Also 90 percent of loft conversions would not allow warm roof construction as this would raise roof height which is not compliant from a planning perspective and would look awful on a semi and so really looking for proven design details for cold roof insulation to u/s rafters with all condensation and air flow addressed. Great article, thanks

[@SkillBuilder]

Hi Phillip You are right, there is no way of achieving the required U value on new build with the multifoils but when you combine it with other insulation it can be done. Personally the squashing of the insulation over the rafters doesn't worry me because it reduces cold bridging a bit and dray timber is not that conductive. We can't achieve perfection in refurbs so this is a good compromise. We will do a lot more on this subject soon.

[@philiphurdwell3443]

@@SkillBuilder it's a very interesting topic and look forward to more, def a sign of things to come. I personally wont specify it on any of my projects just yet but I work for a few developers who spec it as a combo with slab insulation. If you know of any resources that offer definitive info on using it in combinaion I could really use the links, sadly, in today's world its who gets blamed if there is an issue, I can print spec sheets and u values from king span and celotex app for the saps assessors and building control and with that data can address all the issues inc air flow, cold bridging and of course u value..........I still have concerns about squeezing it between batters, it must compromise performance, and so although very installer friendly I'm not quite ready for it yet.........but that's just me and a humble opinion!

[@sandypatience]

@@philiphurdwell3443 You have to understand how it allegedly works. There are different forms of heat transference through a built-up envelope such as a wall or roof. The ONLY way that foil is likely to work is that it is installed adjacent to a void where heat is radiated across the void to be reflected from the foil. Any other type of installation is worse than useless. The foil industry needs to be brought to heel with their ridiculous science-free claims. Frankly, as an architect who lectures on the subject, I wouldn't touch it with a barge pole.

[@philiphurdwell3443]

@@sandypatience I would be very happy to learn more and would attend any seminars but currently remain very cynical and agree with you more so than the promoters of these products. The honest truth is that I dont know enough. A lot of my projects have post completion tests, if they fail it's very expensive which kind of comes back to my comment about performing when crushed between battens, the hot and cold spots are alarming to say the least.. if crushed at 400 c/cs only the central 50 mm will work at full capacity and if full capacity performance is in doubt then I have to agree with you that it's pretty hopeless.

[@rd6864]

These foil films are all very good but they are superbly effective at blocking radio waves. By the time you've wrapped your cosy new home with metallised foil insulation, topped it off with multifoil and fitted windows with nano reflective coatings you can say goodbye to DAB radio and mobile phone coverage indoors, and heaven help you if you use it in internal walls and floors because that'll stuff your wifi too. Still, you'll be nice and warm in your insulated (and isolated) tech free hideaway 😀

[@coop_coop007]

Sounds fantastic.

[@SkillBuilder]

Living in a Faraday cage No thief will clone your car keys

[@eliotmansfield]

Tin Foil hatters will be queuing up in their droves

[@jk28416]

that might be why my DAB radio never worked in the university hall new build!

[@mrfr87]

Will go brilliantly with my tin foil hat. No government or aliens will be able to scan my brain🧠….

[@michaelhorn5633]

when you screw your battens on , how can they remain straight going over the double thickness of the overlaps ?

[@richardgore2000]

Used the superquilt 19 product on the inside of a hottub, got the 1.2m width, folded it so its 2 layers and wrapped on the inside of the case. Seems to work well, saving a few kW a day

[@CONEHEADDK]

I don't get the panic over heating prices. "All" you need to do, is "become a polar bear". Probl solved.

[@Inkling777]

Foil itself works well, particularly given how easy it can be to install. My attic has attic foil (not multifoil) on top of blown-in cellulose. That's single-foil-only reflective aluminum with no insulating layer. By simply bouncing back the radiant heat in the attic, there's about a ten-degree (F) difference between the top of the foil and the surface of the cellulose underneath. That little bit does a lot.

[@mattyh4554]

I have YBS superquilt underneath my floors and in the kids ceilings. I also have actifoil hybrid in my loft conversion. They are so easy to fit and works just aswell as traditional insulation.

[@johnmcdonald9977]

Information wrapped up in an advert. No skill needed! Insulation is also resistance to cold! It is also depends on affordability, and these are too expensive!

[@andrewdowniephd]

Thanks for the presentation. I live in an old cottage and we have a fair bit of loft insulation which really needs to be added to however we'd also like to have storage space. There is limited head height to the roof ridge of about 5feet 5 inches. So in the area I want to use I thought of using LoftZone stilts and boards to the left and right on a central walkway. I wondered what you'd recommend as insulation material underfoot along the walkway? Sorry only an occasional DIYer so might not be explaining myself clear enough.

[@DesperateDan3231]

Thanks Roger, I've just used YBS Superquit to insulate the inside of my 9" soild walls. Double batten, quilt and plasterboard took around 95mm of floorspace. Good quality scissors are a must to cut this stuff.

[@WillNotBeBeat]

Installed superquilt in my loft early this year and is much easier to install than PIR insulation for awkward spaces and I am very happy with the performance.

[@scottvincent1810]

Is it cheaper than pir insulation?

[@johnf3326]

I got a HUGE roll of packing bubblewrap cheap. Be interesting to make this several layers thick to see how well it performs. Could even add some kitchen foil mid layers.

[@justmeEnglandUK]

I've been using this in combination with 25mm PIR on walls . First strip wall paper off if plaster is sounds leave on . Stick the PIR boards on to the wall with dabs at 400mm or 600mm centers . The dabs don't stick the PIR boards to the wall they provide a packer and level up any unevenness . The boards will come off if knocked tape the joints . Fix the battern to 400 or 600 centers on the same line as the dabs . Fix the screws through battern and PIR into the wall with 150mm screws and tighten up the batten to the foil board which will clamp PIR boards to the dryline adhesive packer blobs . .then staple multi foil to the battens then add another batten then add the plaster board . Used in combination with PIR can achieve higher values with smaller thickness . . In suspended floors l carefully remove floorboards fix batten to the joist fix PIR boards 60mm minimum drop onto the battens . If you leave the boards down 20mm from the top you can fix under floor heating to the PIR boards and fill with dry sand and refix floorboard it make a excellent heat sink for under floor heating . Foil tape pipe work and joints to the PIR , sand stays warm for hours no drafts no radiators required . The boiler flow eventually goes back to the boiler at virtually the same temperature .

[@Candisa]

I'm very sceptic about R-value claims in these kinds of products, simply because they consist of layers of heat conducting materials and layers of not-so-great insulating materials. Saying things like "we don't measure the speed of heat transfer but the resistance" is nonsense, one is the inverse of the other, that's like saying "we don't measure at which average speed you drive to the shop 5 miles down the road, we measure how much time it takes you". I would never rely solely on a product like this for heat insulation. HOWEVER, this doesn't mean it can't add a serious value to glasswool/rockwool/PUR/PIR: with energy bills going through the roof, people are rediscovering the value of radiant heat in which it isn't necessary to have air temperature in the room at 21°C to be comfortable as long as you and the surfaces you touch receive heat energy through radiation. Products like this can be very good at blocking and reflecting heat radiation, hence the subjectively ugly but effective foils that are being sold to stick behind radiators and mirrorlike foils and coatings that are put on southfacing windows to prevent overheating in the summer, and the bit of resistance to heat conductivity they offer could be enough to reduce the effect of thermal bridging. Instead of buying the thicker versions of this product or only putting in glasswool/rockwool/PUR/PIR, it could be a good idea to insulate with traditional materials between the rafters and use a thin version of this product as supplemental insulation and dampproofing sandwiched between the construction/insulation and the finishing. If there's a dampopen version of this it could even be a great idea to use this on the outside underneath the shingles to keep out the radiant heat in the summer before it builds up in the rafters and insulation.

[@acraftman2823]

Guy speaks like a true sales rep

[@mervynshute880]

I can't see, that you have done a film on vapour barriers, so I ask some questions here. it seems that vapour barriers go hand in hand with thermal installation. yet what is a vapour barrier, and how does it work? I wonder if this kind of barrier came out on the market, after goretex clothing. goretex is hydrophilic. but needs body heat as a vehicle to push vapour through the membrane. this is similar to the moisture vapour barrier. that it does not seem to work, if heat is not present, or is it on the basis. that heat rises and would carry any moisture with it. so what happens when moisture, say comes into contact with a vapour barrier, say underneath a roof: is the barrier breathable?

[@amazing451]

At point 30.00 on the video when Byron spoke about drapping the insulation in between the joists would this not cause a cold bridge at each joist centre ?

[@giotto4321]

Correct, that's the problem with any insulation that gets compressed at the point of connection, he conveniently ignores this issue. You've effectively got 1/8 of your floor area as a cold bridge, assuming 50mm wide joists at 400mm centres. I'm not convinced at all by this guy or his products!

[@DesperateDan3231]

Not quiet 100% accurate. I thought about this when trapping it between battens in the wall. But the wooden battens or floor joists would also act as form of insulation. I'd sooner have a warm floor with the odd cold bridge, than a cold floor.

[@WHATSUPWATSON]

The foil over the joist is surely better than no foil between the joist and floorboard, like if only pir is pressed in between the joists there will be more of a cold bridge.

[@legendaryirishgreats2427]

Does this superfoil offer the same important. insulation u-values as 100mm pir kingspan

[@newbeginnings8566]

Can it kill a family as effectively as Kingspan should a fire break out in the home?

[@haroon420]

@@newbeginnings8566 huh??

[@pauldavies5655]

slightly confused here !! so-- is it BETTER then normal insulation ?

[@legendaryirishgreats2427]

Good question, I am following.

[@MJWhelan1]

@Skill Builder any idea when you're going to take a look at the Superfoil in more detail? Very interested to see if it actually performs as claimed and is a viable alternative in refurbs to PIR on battens

[@MultifoilsDirect]

Great post guys! SuperQuilt Insulation Team

[@CRB81]

Can this product be used to insulate a garage floor without battens but completely seal with foil tape, then install MDF wood on top and then install top finished layer ? Same way as installing Airtec multipurpose foil straight on a flat floor

[@opelstu]

Any discount code for the website? Cheers.

[@christopherbyrne8611]

So for a 9inch solid wall foil insulation takes up 95mm. Plaster board bonded to P I R 100mm seems easier and cheaper to me.

[@theconsistentnoddy9851]

Roger I’m currently renovating my entire home and removing all ceilings and plaster from walls. The walls are all plastered directly over the brickwork, it’s an ex council house & I believe they came and blew those small polystyrene balls into the walls some 20 years ago. I was wondering would i be better off dot and dabbing the walls or would it be just as thermally efficient to re plaster of the bricks? Thanks👍

[@elfidge1]

I've just finished doing exactly this to my house, which is a 1960s build. The inside skin is all clinker blocks and rather than dot n dab I decided on hardwall everywhere. 2 reasons: 1) all the plaster had blown and sand n cement is prone to cracking so I wanted to ensure cracks wouldn't return after all the graft and money, 2) the spread had to build out the hardwall to get it flat anyway, and the he reckoned it'd offer a similar thermal insulation to dot n dab anyway. The one thing I would say is that with dot n dab you can use thermal plasterboards, but these are significantly more expensive and much thicker (37/42mm compared to 12mm). And dot n dab at least according to the spread I selected, and an architect, are more prone to cracking along the joints, and are also not coming off easily. Spreads love dot n dab as it's quick, easy and skimming is a much easier job than float and set. For my money the bigger ticket items will make more of a difference - good U-value windows fitted properly, doors kept closed to keep heat in, and lagging around pipes etc.

[@tanja8907]

If you can afford to, I would use insulated plasterboard which can be dot and dabed on the walls.

[@legendaryirishgreats2427]

@@tanja8907 is that because the insulated plasterboard would have better u-values ? I have 100mm kingspan between my roof rafters, on my valued ceiling , and I plan to stagger full size 8ft by 4ft (73mm) insulated plasterboards bringing the total to 160 of solid insulation with the 12.5mm plasterboard. It is cheap. But I want the best bang for my buck. I only want to do this job once : ) I appreciate your feedback

[@davidosalsero2519]

MULTIFOILs seem to need careful consideration. Maybe in the loft, laid over a traditional minimal fibreglass fleece. By the way, for my traditional 1970's brick-cavity-block-wetplaster walls I am thinking about using one of the QUITE THIN Erfurt Wallrock or Erfurt Redlabel wall lining products, not least because then the depth loss at skirting boards and door frames is less obtrusive. These come from just 1mm to 4mm thickness, the 1mm ones are a paper product and are naturally over-paintable, the 3mm and 4mm ones seem to be more polyester meaning more prep needed if one wishes to then over-paint. The products U values are stated in the specs and are obviously on the weak side, but I'm hoping will be enough bearing in mind the current 1970's spec cavity walls (which, by the way, do include retrospectively blown in insulation - which, I've heard, is not often of significant worth). My logic for thinking of going this wall lining route is that, almost by chance, I noticed ON AN INTERNAL WALL where one side is emulsioned and the other side is vinyl wall-papered, that (at an internal door), one hand placed on the wall this side, and the other hand placed on the common wall the other side, gave a noticeable tactile temperature difference! Try it. David Whyman.

[@steamsearcher]

Almost total transformation of our home using these foils. We live in Reading and have had the heating on 3 times so far. I currently have the inner wall down in the 1974 kitchen extension. And all the horrors of missing rockwoll and masses of damp bridging coming to light. I did the front top in 2017 and just did the bottom finishing off with bricks. Lovely tip of cutting a blanket size of the foil for your bed. Then you see it works. TOAST. David & Lily.

[@simongrice5788]

How have you used it David?

[@steamsearcher]

@@simongrice5788 In the cavities having taken out the inner bricks. Also in the roof and outer walls of the garage.

[@alax5953]

So where does all that rising moisture from your home go if you line your roof rafters in this foil and vapour seal it. It's just going to stay in your loft isn't it? The now warm loft is going to be so humid the stuff in your loft will be covered in mould?! Are we supposed to run a dehumidifier in the loft 24/7 eating up the savings we made on the heating bill? Am I missing something here?

[@SkillBuilder]

It will evaporate in the same way it does in a loft conversion. I would say that a couple of ridge vents or through tile vents will be needed.

[@alax5953]

Thanks for responding. I think i understand how vapour barriers and condensation etc works (thanks to your vids), but the vapour that rises through the ceilings in the house would surely get trapped inside the loft by the vapour barrier, causing a very humid loft?

[@Flat-Five]

@@alax5953 yes I was wondering the very same thing. If it was sealed there’s no where for it to escape to and unlike a loft conversion, no windows for ventilation. It’s on the warm side though so perhaps wouldn’t condense but I imagine the loft might get very humid and stuffy if it was air tight.

[@stephenhudson3496]

Roger love to see a video on using this in a truss roof on rafters maintaining existing air gap between under felt and bottom of 100mm rafters

[@SkillBuilder]

We will try and cover this in more detail soon

[@handle1196]

@@SkillBuilder I'd love to see this too

[@pedrocoentro2009]

I´m considering installing this foil in my great grandfather house, the roof is only tiles without any insulation, the structure is made of wood so weight is crucial.

[@khagendrasingaklimbu7910]

Hi Roger and Byron, very useful information about insulations. All touched, roof, walls and floors but the less solid floor as you raised it but later ended up with a suspended timber floor only. So please Byron, could you answer me what is the procedure for insulating a solid floor, can we directly put it on top of the floor or do need battens?

[@SisterAbdullahX]

Make some Superfoil slippers!

[@l0I0I0I0]

This is very helpful! Address so many issues in one short vid. Good stuff, TY!

[@margaretbegley9201]

Could I put this on an external wall of a bungalow wall which has an attached garage to it. Inside the bungalow the plastered wall is cold and on the garage side of the cavity wall it is finished in blockwork, so can I put it on the blockwork wall inside the garage which is the cold side of the wall. There is no existing cavity insulation, can foil be attached to the outside wall of the bungalow. Obviously there is no heating in the garage, I just want to improve the insulation of this wall inside the bungalow and just want to use to use the fixing space of the foil inside the garage. Any advise or comments would be greatly appreciated. Martin

[@grahampride4633]

Great topic and a useful update on multifoil. Your end comments on wooden ground floors with air bricks removing any heat from the house is equally as bad, or worse, with 'modern' block and beam floors that also require air bricks.

[@l0I0I0I0]

Just wondering, when foil is used in a crawl space, should a reflective foil itself be on the outside facing ground and not the inside? Secondly, can it be used on the ground as a vapor barrier as well as radiant barrier? I would think it would corrode if it touches the soil? TY!

[@andypandy1488]

Hi Roger what is your opinion of loft ceiling superquilt insulation as i have a very low ceiling in my loft and already have space blankets between th beams on the floor , also do you know of a product that will raise the blankets from the plaster boards 10mm to allow the reflective side of the blankets to be effective in radiating heat back down as they are currently flat against the plaster board ? Cheers in advance

[@SkillBuilder]

Hi Andy I think you can forget that air gap under the quilt, it isn't achievable due to sag and it probably won't add enough to make it worth the hassle. I wouldn't put more insulation on the underside of the rafters because the dew point will be on the insulation and it will drip all winter. If you have space blanket on the loft floor just add some more if you like but I would be happy with what you have and look elsewhere for improvements

[@andypandy1488]

many thanks for your reply & benefit of your experience , much appreciated 👍 @@SkillBuilder

[@thomaschapple4749]

Would you hack off plaster in solid wall, or leave existing plaster?

[@SkillBuilder]

Leave it, bare brick or block lets in a lot of air and you want that air gap sealed.

[@jbwentworthe6082]

Are these suitable for very humid climates such as a "tropical" ? The problem here is "mold" that grows any place dampness can form, such as behind a wall where circulation of air does not occur ? Keeping cool air in and 90 degree heat out ?

[@lostinspace480]

What foil would you recommend for a flat roof?

[@seanplatnauer7211]

hi roger, how do you stop the batons rotting between the foil and the wall? thx sean

[@SkillBuilder]

Make it airtight so the moisture can't get in.

[@seanplatnauer7211]

@@SkillBuilder OK just worried about the joists

[@rougeangler4535]

Can you batten over original wall paper and plaster board?

[@simonroberts9759]

Another very interesting video - thanks Roger. I am interested in improving the insulation of the solid walls (and floors!) in my 1870 ish cottage. Whilst adding 95mm or so to the internal face of external walls might be manageable (but not desirable), it would be good to see some practical solutions to how you work around windows, door frames, plumbing for radiators etc. I see these problems as more difficult than losing 95mm but depends on size of room. Given the massive price hike in electricity costs together with recent and likely upcoming Government legislation there is a serious need for a coherent set of tools to help owners of older properties at prices which are affordable. What can we learn from other countries?

[@Dave5843-d9m]

Dense Rockwool is the usual "go-to" for external insulation. It's hydrophobic and attached with metal mesh over the top that's mechanically fixed to the wall. Battens are hardly needed as the mesh is folded and pinned to the wall. Render over the top seals in the insulation and allows moisture to escape. Internal insulation needs battens to support the wallboards or a firm bonded insulation (e.g. Isocyanate foam) that can be "dot-dabbed" to the wall.

[@GabrielSimon]

WHERE are the tests on these foils ? I can't find any study/test to read on these Multi Layer foils Roger Bisby was right, how can we know it works/ how much better it is than a regular cheap Aluminum foil with 2,5cm gap ?

[@paguliukas]

ok guys what foil is best for solid concrete floors at ground level i want to put engineered wood flooring do you really need plywood ???

[@paulmanser6887]

Can you use super foil under a screed to reduce volume ? I have used celotex in the past I don’t have the depth to use this

[@SkillBuilder]

Not it is not the right product. Better to use what you can with closed cell PU boards.

[@kenkennedy5516]

What product would you recommend to insulate a corrugated garage/workshop roof, and how would I attach it? Good video.

[@mikewalker8655]

Spray foam

[@keithmatthews9043]

Would it be okay for conservatory roof insulation

[@stephenking7809]

Roger, i have a screeded floor with carpet on top, really cold, could multifoil be laid under the carpet. thanks.

[@SkillBuilder]

There are many foil baked underlays out there which improve the insulation. I don't think that multifoil without an air gap brings much more to the party in that instance. I could be wrong about that. Maybe we should try it and see the difference.

[@MrGarry128]

Hi Roger, Please do a video on aerogel Insulation products. Aerogel blankets are extremely thin Compared to other insulation products.

[@jamesbailand4311]

Can't drill though it though, is one of the issues, (for walls) creating the issue of how to fix it. So building a wall out by 92mm plus skim. And thats just to get one layer of insulation and doubling up CLS costs. For 77mm of wall space, and half the timber you could use 25mm foil backed insulation foam boards between the timbers and over the top. With super foil, you get the vapour barrier but on masonry that isn't necessarily a good thing, but not having to cut foam boards is a seriously good thing!! They work very well in lofts. Skill builder, would slaters lath be enough void space, (between the foil and the back side of the plaster board)??

[@chriswaldron9703]

I was very interested in this discussion as I am about to renovate a room of my house which is built of 9" solid brick walls and I want to take the opportunity of insulating the two external walls. I was almost sold on this product until I watched another video of someone doing a fire test on some different foil insulation products. In the test it ignited and supported the burning process rather than being flame retardant and that would seriously worry me.

[@DesperateDan3231]

I recently did a few 9" solid walls in my house. When installed this stuff is well sealed in within the wall between timber battens, behind plasterboard and plaster. My house would have to seriously burn for a long time before it reached this insulation layer. Most building supplies burn in isolation but rarely have the chance to burn in unrestricted open air

[@arniet1]

Fantastic! Thanks Roger. This is exactly what we need answers to! You should be up there with the likes of Martin Lewis for helping people

[@PreNeanderthal]

I have a 1930s built semi with a crawl space/basement (5' high). I want to insulate under the living-room floor above. The electrics run between between the joists. Can this foil be stapled directly to the bottom of the joists (does stapling it negate its effectiveness) or should it be installed between the joists (up against the floor boards) and held in place by net or thin timber battens?

[@SkillBuilder]

I would always staple it on the underside of the joists, provided you have the access. That way you don't have to touch the floorboards and you get a lovely air gap of 4inches that is sealed and has great insulation value in it's own right.

[@PreNeanderthal]

@@SkillBuilder Many thanks for your quick response Roger. There was mention in the video of sealing the edges. Is there a special tape or can something like duct tape be used?

[@allthegearuk]

@@PreNeanderthal foil tape

[@jacko4806]

I can understand why the multifoil requires an airgap on the warm side of the wall but why does it require one on the cold side as well? What would happen if it was installed in a following build-up: - 4inch External Brick Wall - Stud wall with PIR in between - multifoil SF19+ acting as VCL (no air gap between the foil and PIR) - 38mm battens - plasterboard

[@SkillBuilder]

You have the answer right there. The multifoil is on the warm side of the PIR so the air gap is insulating and stopping thermal conductivity between foil and PIR

[@jacko4806]

@@SkillBuilder would removing the gap between the two have any major impact on the performance of the foil as it’s supposed to resist thermal conductivity and reflect the heat in the first place meaning that amount of the heat transferred onto the cold side should be greatly reduced by the time it reaches the PIR? With just an air gap on the cold side of the foil and no PIR the residue heat is already lost and it wont be returned into the room?

[@alexscarbro796]

Could this multi-foil be used in buildings over 18m (eg 25m)?

[@susanfrombflo8368]

Is there a similar product available in the US?

[@congt9288]

Very interesting. I imagine that the air 'spaces' between the multi layers is the secret to efficiency.

[@purplemonkeydishwasher5269]

Whats the difference in sound insulation for dividing walls? My kids want seperate rooms so we are thinking of splitting their current large room in two. I want to sound proof the wall so thay when theu become teenagers we dont have stereo battles.

[@thomaschapple4749]

So when installing in roof across rafters, do you stretch across and leave an air gap?

[@SkillBuilder]

yes exactly that but overlap and tape all joints.

[@vinnysurti]

The foil was radiating so much heat Roger took his top off in one of the photos! 🥵

[@Giftedmike359]

Thought it was Robin for a moment

[@delwalker6336]

Before I saw this I bought the Aldi version what do you think Rodger?

[@delwalker6336]

Sorry spelling Roger!

[@laineybojaney]

Can you put this multifoil on inside wall, then use stick on wallpaper as a quick fix to insulate a wall in a bedroom?

[@aracknidd]

Metal is a heat sink, it cools hot things, it can cool a warm environment. I wonder if the metal feels cold to touch in a warm room would it be a condensation point?

[@SkillBuilder]

yes but in the end the metal would be the same temperature as the room, it is not intrinsically cold.

[@jobloggs6528]

Lots of talk about comparison to Rockwool, which is a tenth as effective as Kingspan. Why not compare with another foil and insulation product like cellotex/kingspan?

[@logik100.0]

Can SB talk to the like of Q-BOT about underfloor spraying. Removing all my floor boards is not an option (the internal walls are built on the floor!)

[@maxinerobb5942]

Can you paint over the foil? I🤔

[@janlesinski4719]

I used it in France and it really works

[@andrewhay8033]

Can you use this under floor joists instead of on top? I'm guessing you may need to fit insulation or foil up between the floor joists around all the external perimeter. To avoid cold getting in above the foil and below the floorboards. It would be a lot easier to fit than crawling in under floor fitting glasswool above your face or trying to cut and fit PIR.

[@SkillBuilder]

Yes, if you have the space then it is a great idea to staple it from below but still tape the joints

[@jacksmith8754]

Good thinking. It would have been good if they covered this scenario in the video. I have a cellar / crawl space that shallows from 1m at the entrance. I recently fitted Rockwool slab between the joists and covered in a breathable membrane on the underside. The rafters don’t run parallel in a lot of places so a different method might have been easier. I wonder if there is a limit on the joist depth for fitting foil on the underside of a suspended floor.

[@johnf3326]

This is what I don't get: Most heat will be lost through conduction, only a little by radiation. One layer of foil should stop radiation, then the rest would be down to a material which traps air in very small pockets to stop conduction. So why would multi layer improve on this? Surely just add a reflective layer and then take the best conductive insulating material in whatever thickness? I have an expensive roll of Airtec double. Supposed to be the equivalent of 50mm polystyrene BUT you have to install it with an air gap and of course the air gap itself is an insulation! I've often wondered if bubble wrap with kitchen foil would be a good and really cheap alternative! The ideal insulation would of course be a vacuum with a foil reflector. No loss of radiated, convected or conducted heat!

[@deeeirl]

Yeah but if you use a single layer of foil, although it would stop radiation of heat from the warm space to the cold space, it would now also be an excellent conductor of heat from the warm space and will dissipate this to the air in the cold space. Depending on its placement (pitched roof rafters for example) it could also cause convection currents to occur behind the rafters further increasing heat dissipation. The idea of the multilayer form is to progressively slow this process down by alternating density of materials sandwiched together.

[@yvonne3903]

Have you heard of self closing air bricks in situation where flooding is possible?

[@SkillBuilder]

Yes I fitted some years ago and they did no good at all

[@logik100.0]

Not sure if it relevant but, the test involves using a seal box and then the insulation inside (I think) but the very fact that your using a sealed box is actually the major insulation factor. Just placing a foil insulator somewhere without the box is not going to get the insulation value.

[@kathrynwhitby9799]

i had some installed when i had the roof re-felted, it's been a good improvement. Now considering it to reinsulate my vintage caravan.

[@st11gxavier71]

So 40mm of Superfoil would be equivalent to ? mm of eg fibreglass.

[@manc66]

How doe's it compare to Gutex?

[@CrashUK28]

Would this be any good in loft I have a combi boiler in the loft also would this cause damp

[@SkillBuilder]

I have built a small cupboard in a loft with studs and multifoil just to house the boiler and cylinder. If you are going to line the undersides of the rafters above and around the boiler then fine but if you line the whole roof you might need to remove some of the loft insulation to stop moisture condensing on the foil. I would seek more advice.

[@whu58]

Can these multifoils be used on underslung fresh & grey water tanks to stop them freezing on campervans?

[@SkillBuilder]

It will help but in the end the only thing that will stop it freezing is a tank heater. I have a camper and it might take a few days to freeze the tank but even with insulation it will freeze eventually.

[@johnbodnar3720]

Are your R values the same R value everywhere else? You talk about U values? Have not heard about this. Our gas and electricity prices are going up very often, so I want to over insulate the house. You talk about your different types of multi foil insulation but you did not give any R values to each amount of multifoil. You also say fit insulation tightly between the studs, rafters and joists, I intend to insulate the studs, rafters and joists aswell. Thanks for all the information, I pick up bits and pieces from everywhere.

[@zedman442]

Have also used this for the floor insulation for new builds where you don’t have the depth. It’s not cheap but it compares to PIR. Can also be coupled with PIR if you wish

[@td807]

Great chat guys, very informative and clear info about regs,

[@philippoundall3387]

Hi there , Didnt know that Superfoil was made in China ! Do you know how Superquilt compares in price with the Superfoil please as I would much prefer to use a British product if possible ? Phil .

[@robyndavis3043]

Thank you for sharing this information--I've saved this video post for future reference

[@ttfweb1]

Great technical discussion. Thanks!

[@steviebye1]

Hi Roger, I have a dormer, the builder fitted the quilt between the plaster board and studs, is this correct and if so is it the reason my dormer is the coldest room in the house?

[@SkillBuilder]

Did it have an air gap?

[@steviebye1]

@@SkillBuilder No. It is directly between the plaster board then studs, also the plaster is popping of where the nail heas are aswell.

[@brettwoollacott85]

it's a great product, but the biggest drawback (especially in loft conversions) is the sheer lack of sound insulation. I have seen several installations where this has been used to save space in a loft conversion, and it worked perfectly, but when it rains... the noise! great product under the right circumstances, but it has its limitations.

[@m.o.2085]

Good discussion and nice to see that it wasn't a sales pitch. Multi foil insulation very useful when retilling old roofs, especially with skillings that are even harder to insulate well. For solid walls however insulated plasterboard is a far better option.

[@nigelmagnay1453]

My BS Alarm went into overdrive when I hear things like "reflecting heat rather than insulating" as a justification for "selling on R value not lambda". R=d/λ !