Self-adhesive 'Class O' foam insulation - massive price difference, why?

[dankilb]

I knew Armaflex wasn't 'cheap', but have been perfectly happy with the total cost to insulate both our hot water pex pipe and heater ducting with their pipe insulation (between £3 and £15 ish per metre).

However, now I'm looking to source sheet insulation material (for under new cabin linings) and the equivalent product is £38 per m2 (Armaflex Flat Sheet Class O Black Nitrile Foam Insulation) compared to an eBay version that claims to have the same Class O rating at £13.50 pm (Self-adhesive Acoustic Soundproofing Fire Proof CLASS O FOAM in Various Sizes | eBay).

Does anyone have any insider knowledge and/or experience that might justify the extra cost? Over the whole boat (42') and with a plan of insulating all surfaces not behind cabinetry from the topsides up, inc. all headlinings (which require replacement anyway) it could really add up. We're not too worried about the adhesive failing, as all linings are 'hard' and fastened in place (going for new cedar strips on the topsides and replacing ply headlining) - not glued vinyl.

TIA!

 

[dankilb]

Think I might have partly answered my own question, in that the eBay foam above appears not to be 'closed cell'. A Google search suggests Armaflex is the only 'class O' closed cell sheet available.

However, another eBay supplier has closed cell adhesive foam claiming a different fire certification (FMVSS302) at around £12 per m2 (5m Camper Van Insulation 10mm Closed Cell Foam Sound Proofing Mat Roll 783101476676 | eBay).

 

[Elessar]

Closed cell is not nearly as effective at sound proofing.

 

[Plum]

I knew Armaflex wasn't 'cheap', but have been perfectly happy with the total cost to insulate both our hot water pex pipe and heater ducting with their pipe insulation (between £3 and £15 ish per metre).

However, now I'm looking to source sheet insulation material (for under new cabin linings) and the equivalent product is £38 per m2 (Armaflex Flat Sheet Class O Black Nitrile Foam Insulation) compared to an eBay version that claims to have the same Class O rating at £13.50 pm (Self-adhesive Acoustic Soundproofing Fire Proof CLASS O FOAM in Various Sizes | eBay).

Does anyone have any insider knowledge and/or experience that might justify the extra cost? Over the whole boat (42') and with a plan of insulating all surfaces not behind cabinetry from the topsides up, inc. all headlinings (which require replacement anyway) it could really add up. We're not too worried about the adhesive failing, as all linings are 'hard' and fastened in place (going for new cedar strips on the topsides and replacing ply headlining) - not glued vinyl.

TIA!

Suggest you ask for a small free sample of each type, say 100mm square, soak them in water then measure the volume of water you can squeeze out of each. Closed cell foam does not always mean 100% closed cell and could be as low as 50% of cells are closed.

Www.solocoastalsailing.co.uk

 

[dankilb]

Closed cell is not nearly as effective at sound proofing.

Wasn't concerned with sound as much as heat insulation (and avoiding condensation etc.). Because the boat has always had ply head/topsides lining affixed to batons, there is already a void there and so it seems to good an opportunity not to insulate with something. (I do need to replace the engine compartment sound deadening too, but happy to plump for the cost of the proper stuff for that).

Getting hold of a sample is a good idea. I already have some Armaflex/Armacell to compare against. It seems great stuff - it's just the cost that I'm not sure we can live with (easily into the thousands for the total square metreage for our 42' AWB).

I wonder if anyone has any recent experience with the eBay adhesive foams as cabin lining insulation?

 

[LoneHort]

stay away from the ebay crap.... do what I did and start buying up camping mats and yoga mats, both closed cell, you can get em online off folk or sometimes the german discounters carry them. Did a great job on mine.

 

[ianc1200]

In Building Regulation terms Class O was a measure of the surface spread of flame, it was the highest standard, but has been replaced by a euro standard. Many in the building control profession would still relate to Class O.

 

[Daverw]

We use armaflex for work insulating refrigeration vessels and pipework, it’s the only one that lasts and the level of insulation is high. The sheet has always been very more expensive than the tube, the plain sheet is cheaper than adhesive lined. Also used gym mats and they work very well and good price when Aldi or Lidl have them

 

[dankilb]

Thanks for the replies, all.

It does make sense that Armaflex is more expensive for this application, if only as there is so much more area of material required than for insulating the odd pipe/duct.

I know that camping/gym mats can work well. My only concern with that is knowing whether it is fire retardant. I try not to be too universally paranoid about these things, but 'just in case' I've tried to avoid materials that might be combustable in this refit. My rationale is that this boat is capable of getting is far enough away from help if we were to get into trouble as to justify a tad more 'concern', whereas I might feel/do differently with another type of boat. (Another recent example of this was looking for 'garden' type cushions for use in the cockpit but realising that, for outdoor use, they don't need to be fire retardant the same as indoor fabrics - when, in reality, they'll be stored inside the boat most of the time...)

It sounds like my choice is between Armaflex for the 'Type O' construction rating and it being a known quantity (quality?!) or one of the 'car builder' supposedly closed cell foams that is tested to the equivalent vehicle standard (FMVSS302). Both should offer the peace of mind I'm after, say if a wire shorts out or something else goes on fire nearby. The vehicle stuff is about a third of the price, so I've ordered a sample that I can compare next to the Armaflex pipe insulation I already have. I'll report back.

 

[Daverw]

You could very easily get a camping mat and do a fire test. i agree to you thoughts on looking at the fire issue but suggest that within a boat the insulation is only a small part, the furnishings, headlining, timber and coatings are significant and most not fire retardant at all. Cable is itself protected and can be protected further with conduit and much better correct fusing and installation. Electrical fires are most due to poor connections and chaffing cables I suspect

 

[geem]

I wouldn't use yoga mats. The density is far higher than you need. We insulated our last boat using 6mm closed cell foam sheet that came in 8ftx4ft sheets. We used 2 or 3 layers and high temperature contact adhesive. I wasn't worried about class O as it was all contained behind vinyl and timber.panels.
The benefit of multiple thin layers over one thick layer is the ability to make the foam go around corners or curved shapes. You may not need to do this but worth knowing.
I ran all the thermal insulation calcs through the computer at work at the time and concluded that 18mm on the roof would work and 12mm elsewhere. The boat was noticeably warmer in winter and cooler in summer.
The benefit of closed cell foam is that it is also a vapour barrier. You run the risk of condensation of any air can get to the cold internal hull surface. Seal all edges with sealant or aluminium tape joints. Good luck

 

[thinwater]

Learn more about insulation, condensation, and mold.

This is a job for closed cell insulation. If the open cell becomes damp you will get severe mold and want to sell the boat.