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Could plastic bottle insulation combust in summer heat if used to insulate roof?

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Gueyog8a7

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Would the temps get high enough to go on fire or not?

I saw that it is flammable under a naked flame but not sure if sun heating the bare metal roof behind it would melt it and possibly cause it to catch fire.

I ask because I already bought some for another section of the van and have some leftover and the rockwool (which does have high heat resistance) is expensive and also can't be bought in small sections which I would want just for the headliner section.
 
What product?

There should be pertinent data about flammability available for the product. I would consult some sort of data sheet about a product before deciding if it is appropriate for the intended purpose.
 
Gueyog8a7 said:
Would the temps get high enough to go on fire or not?

I saw that it is flammable under a naked flame but not sure if sun heating the bare metal roof behind it would melt it and possibly cause it to catch fire.

I ask because I already bought some for another section of the van and have some leftover and the rockwool (which does have high heat resistance) is expensive and also can't be bought in small sections which I would want just for the headliner section.
Click to expand...
It's fire resistant in the fact it won't ignite so won't burn on its own but it's only a ease of use product, it's thermal rating is 66% or lower compared to rockwool/fibreglass insulation and no real price difference. Personally I'd suit up and go down the itchy non-flamable better insulation route.
 
Heat rises so I'd want the best thermal rating possible in the headliner, also polyester insulation is 4x the price compared to rockwool per volume. Don't get confused by their sneaky marketing the only thing that's truthful is it's claim to be non itchy.
 
ThaiTaffy said:
It's fire resistant in the fact it won't ignite so won't burn on its own but it's only a ease of use product, it's thermal rating is 66% or lower compared to rockwool/fibreglass insulation and no real price difference. Personally I'd suit up and go down the itchy non-flamable better insulation route.
Click to expand...
Yes but regardless you can buy the plastic stuff for 27 quid but the rockwool the cheapest is 60-80.

I agree with your sentiment of the roof being the biggest leak/get the best. I just calculated it wrong, or rather didn't factor in insulating the headliner at the time!

Plus I bought this stuff already so wanted to make use of it.

I already paid 100 quid for 30mm closed cell foam stuff I never ended up using because not only did it stink something awful, which never seems to go down even after months, it would trap moisture behind it as no way I could find to completely make it flush with the metal to get rid of trapped air.

I ended just giving that away as it was just taking up room in the shed.
 
Last edited:
Gueyog8a7 said:
Yes but regardless you can buy the plastic stuff for 27 quid but the rockwool the cheapest is 60-80.
Click to expand...
Same B&Q site you shared
Screenshot_20240802-152546.png
Gueyog8a7 said:
I agree with your sentiment of the roof being the biggest leak/get the best. I just calculated it wrong, or rather didn't factor in insulating the healiner at the time!

Plus I bought this stuff already so wanted to make use of it.

I already paid 100 quid for 30mm closed cell foam stuff I never ended up using because not only did it stink something awful, which never seems to go down even after months, it would trap moisture behind it as no way I could find to completely make it flush with the metal to get rid of trapped air.
Click to expand...
Personally I would have cut the closed cell as close as possible then filled any gaps and stuck it with a can of low expanding pu foam
Gueyog8a7 said:
My van is mostly corked, which I love. 20mm on walls and most of the roof. I also have used rockwool behind most of that but ran out coming to the roof and lack of understanding at the time that the roof should be insulated most. I just bought the plastic due to lower price to entry for the outstanding bits.
Click to expand...
Shop around and do your research the polyester insulation seems to be extremely expensive compared to rockwool, don't let the very small roll fool you into thinking it's cheaper when you consider actual area it's atleast double the price if not more.
Also bear in mind polyester absorbs smells so anything from a hot sweaty night to a light bit of cooking will linger if your cladding isn't airtight.
 
ThaiTaffy said:
Same B&Q site you shared
View attachment 233239

Personally I would have cut the closed cell as close as possible then filled any gaps and stuck it with a can of low expanding pu foam

Shop around and do your research the polyester insulation seems to be extremely expensive compared to rockwool, don't let the very small roll fool you into thinking it's cheaper when you consider actual area it's atleast double the price if not more.
Also bear in mind polyester absorbs smells so anything from a hot sweaty night to a light bit of cooking will linger if your cladding isn't airtight.
Click to expand...
That stuff is glasswool not rockwool.
 
Gueyog8a7 said:
That stuff is glasswool not rockwool.
Click to expand...
Sorry I stand corrected I had no idea there was a difference as most knauf insulation is classed as glass mineral also and basalt can be considered volcanic glass. so polyester has less than half the r-value of rockwool as rockwool is considered 33% higher than normal fibreglass.
 
No, your van roof won't get so hot that polyester fiber would catch on fire or melt inside the van.

Otherwise paint on the van roof would also catch on fire and I don't see that happen very often. Common sense I'd hope.
 
ThaiTaffy said:
It's fire resistant in the fact it won't ignite so won't burn on its own but it's only a ease of use product, it's thermal rating is 66% or lower compared to rockwool/fibreglass insulation and no real price difference. Personally I'd suit up and go down the itchy non-flamable better insulation route.
Click to expand...
Here, Rockwool is advertised as not being itchy. Thinking out loud ... wonder if some individuals are more susceptible to itch than others?
 
ThaiTaffy said:
Shop around and do your research the polyester insulation seems to be extremely expensive compared to rockwool, don't let the very small roll fool you into thinking it's cheaper when you consider actual area it's atleast double the price if not more.
Also bear in mind polyester absorbs smells so anything from a hot sweaty night to a light bit of cooking will linger if your cladding isn't airtight.
Click to expand...
Polyester insulation seem to be suprisingly cheap (at least in UK)
100mm Diall 11.8GBP/m2
100mm Rockwool RW5 here in Finland 7 GBP/m2
100mm RW5 if bough by truckload: 24 GBP/m2
100mm Rockwool flexi-batt 11.8 GBP/m2
insulation4less.co.uk

Rockwool RW5 Acoustic Insulation Slab 1200mm x 600mm (All Sizes)

The RW5 are the best quality resin bonded Slabs designed for full fill cavity insulation applications and is an effective cavity wall insulation material.
insulation4less.co.uk insulation4less.co.uk
insulation4less.co.uk

Buy Rockwool Flexi Slab Insulation Online - Shop Now

The Rockwool Flexi-slab is a high value slab ideal for multipurpose applications. It features a flexible edge that allows it to put between joists.
insulation4less.co.uk insulation4less.co.uk

Performance-wise Diall polyester batts seem to be about same level as average rockwool.
 
Kornbread said:
Here, Rockwool is advertised as not being itchy. Thinking out loud ... wonder if some individuals are more susceptible to itch than others?
Click to expand...
It all depends what is the comparision point.
Old school glass fiber from seventies (I wish I would die-itch) vs. Rockwool (I feel like I have lint stuck under my shirt) 😆
 
MattiFin said:
Polyester insulation seem to be suprisingly cheap (at least in UK)
100mm Diall 11.8GBP/m2
100mm Rockwool RW5 here in Finland 7 GBP/m2
100mm RW5 if bough by truckload: 24 GBP/m2
100mm Rockwool flexi-batt 11.8 GBP/m2
insulation4less.co.uk

Rockwool RW5 Acoustic Insulation Slab 1200mm x 600mm (All Sizes)

The RW5 are the best quality resin bonded Slabs designed for full fill cavity insulation applications and is an effective cavity wall insulation material.
insulation4less.co.uk insulation4less.co.uk
insulation4less.co.uk

Buy Rockwool Flexi Slab Insulation Online - Shop Now

The Rockwool Flexi-slab is a high value slab ideal for multipurpose applications. It features a flexible edge that allows it to put between joists.
insulation4less.co.uk insulation4less.co.uk

Performance-wise Diall polyester batts seem to be about same level as average rockwool.
Click to expand...
What is missing from that equation is the it costs £50 for postage.

I remember looking at that site looking for the best price for rockwool but apart from picking up in store, which I couldn't be bothered at the time, the postage costs were really high.

Diy.com had the batts for reasonable postage but were out of stock for the nearest shop that is why, I now remember, I didn't get them and opted for the plastic instead as could not be bothered to wait.

Ironically I have ended up not even using the bottle yet so the perceived time constraint was moot! Such is life :D.
 
MattiFin said:
It all depends what is the comparision point.
Old school glass fiber from seventies (I wish I would die-itch) vs. Rockwool (I feel like I have lint stuck under my shirt) 😆
Click to expand...
I don't remember it being advertised as non-itchy and would not have bought or not bought on that basis.

From watching reviews of people who had installed I remember them saying it was itchy.

I had put on rubber gloves and goggles. Despite that the stuff still easily got into the gloves after a couple of hours.

I would say it was worse than itching. More like little needle pricks. Also it got onto my bedding and took a week or two to wear off.
 
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