Sprayfoam + Vapor Barrier on newbuild WB

[Batainte]

The newbuild 70x12 will be ready in a few weeks time and after going through the forum, been concerned about taking extra steps to minimise condensation buildup as well as loss of heat. The shell will come sprayfoamed throughout and as per the concerns of humidity and heat-loss had started to investigate about various options in order to improve on future repair headaches and "potential" issues with insulation that other boaters have described on this forum (this includes sprayfoam insulation on its own as well).

 

So as per the title of this thread... In order to avoid any costly repairs in future why not add a separate layer of vapor barrier between sprayfoam and wall/ ceiling linings? Has anyone had any experience or troubles fitting this? Any known products? Or perhaps for some reason would suggest to steer away from such a thought?

 

The idea comes from reading about other boater experiences on using kingspan and/or celotext as their insulation on boat refits, where they explicitly explained the benefits of vapor barrier. Both insulation products have their foily barrier already embedded onto them as per manufacturing standard, but it would be interesting to know about anyone's opinion on sticking another layer on top of the sprayfoam itself.

 

Although its half a decade old, but so far managed to find only one user posting about this method (albeit its slab insulation + vapor barrier) on the post linked below, nevertheless looks neat and definitely must have worked its magic in the long run.

@koukouvagia if you are reading this, would you care to share how its served you so far?

 

 

 

Edited March 3, 2020 by Batainte

[ditchcrawler]

Make sure you have a good thick coating of spray foam, I have seen it applied like a coat of paint

 

[LadyG]

journey with jono had some issues with foam, he also put extra foil on ceiling, I think, but he did try a few ideas, on different episodes [youtube]. He adjusted his battening, at least twice!

Colin jaques only used thinsulate.

 

Edited March 3, 2020 by LadyG

[Bee]

In my opinion spray foam does not need a vapour barrier. The snag with slabs of foam is that there are always small voids, e.g. behind angle iron frames, in awkward nooks and crannies and other odd corners. These are where condensation forms and it does so 24 hours a day and can be hard to eliminate. Spray foam gets everywhere and if it is thick enough its pretty much unbeatable.

[peterboat]

I have thinsulite in the front half of my boat and spray foam in the rear.  The thinsulite was on the hull and the reverse of the wood panels, I would say that they are both very good, but the foam if correctly applied has the edge. Now this is just my opinion and has no scientific evidence behind it 

[Phoenix_V]

Correctly applied sprayfoam should not need any vapour barrier as it is a closed cell foam ie impermeable and is also stuck firmly to the superstructure. Make sure you are getting the thickness you have paid for 25mm is just OK 50 or more is better depending how much room there is.

The only weak point where condensation can get in then would be the frames. Wooden battens should be K (use treated timber such as roofing battens) but metal to lining contact might need thinking about, perhaps a small airgap? or strip of thin material.

[koukouvagia]

18 hours ago, Batainte said:

Although its half a decade old, but so far managed to find only one user posting about this method (albeit its slab insulation + vapor barrier) on the post linked below, nevertheless looks neat and definitely must have worked its magic in the long run.

@koukouvagia if you are reading this, would you care to share how its served you so far?

 

It has worked perfectly - not a trace of condensation anywhere.  ?

 

[nicknorman]

As said, no need for vapour barrier. You put vapour barrier on the warm side of insulation in a house, so that the cold side (interior of cavity wall or whatever) doesn’t suffer from condensation. But to get condensation you need an air gap / space for the condensation to form. With the spray foam being in intimate contact with the steel, there is no-where for condensation to form between the foam and the hull.

[ditchcrawler]

An easy way to check the spray foam thickness is to drive a thin nail though a small square of plywood about 2" square to the required depth of spray foam and check the thickness before they pack up. I had to get them back to re do mine 

[blackrose]

22 hours ago, Bee said:

In my opinion spray foam does not need a vapour barrier. The snag with slabs of foam is that there are always small voids, e.g. behind angle iron frames, in awkward nooks and crannies and other odd corners. These are where condensation forms and it does so 24 hours a day and can be hard to eliminate. Spray foam gets everywhere and if it is thick enough its pretty much unbeatable.

 

That's correct. PU sprayfoam is a vapour barrier and doesn't need any additional barrier.

 

If using PU board like Kingspan and Cellotex it can be applied and stuck on with hand hald cans of sprayfoam or with a PU sealant/adhesive like Stixall. I agree that there will still be voids behind but those voids will be small in depth and more importantly finite in terms of volume (assuming the voids are sealed around their circumferences). How much water vapour would be held within the air in a sealed void? Very little, and therefore very little condensation can form. A lille bit of moisture isn't going to cause much of a problem and any corrosion behind the board will be finite because there's only a finite amount of moisture.

 

I think there is some confusion here because the voids that you don't want are those which are unsealed and open to the warm air of the cabin because then you have an infinite amount of water vapour, condensation and corrosion that can form behind the PU board over time.

Edited March 4, 2020 by blackrose

[Batainte]

23 hours ago, ditchcrawler said:

Make sure you have a good thick coating of spray foam, I have seen it applied like a coat of paint

 

Have read the horrors of other boaters on this forum talking about this exact matter. It appears that "cowboy" contractors try to get away or cut corners with the fact that if a person doesnt know or ask for details about the required job. For this reason its just done as quick as possible with any potential future failures inherited by whoever owns the boat. Its all about collecting the cash and hopping back into that white van and heading off to next job.

 

23 hours ago, LadyG said:

journey with jono had some issues with foam, he also put extra foil on ceiling, I think, but he did try a few ideas, on different episodes [youtube]. He adjusted his battening, at least twice!

Colin jaques only used thinsulate.

 

Will check some of his episodes out.

23 hours ago, Bee said:

In my opinion spray foam does not need a vapour barrier. The snag with slabs of foam is that there are always small voids, e.g. behind angle iron frames, in awkward nooks and crannies and other odd corners. These are where condensation forms and it does so 24 hours a day and can be hard to eliminate. Spray foam gets everywhere and if it is thick enough its pretty much unbeatable.

Would there be a way to know whether the foam has been applied as necessary before covering the sides with lining? Assuming if the job is overlooked by someone and not sprayed dense enough over the awkward bits as it was meant to. It being a foam, there is a potential in having some "blind spots" on the bottom layer and not having them covered on second layer?

 

21 hours ago, peterboat said:

I have thinsulite in the front half of my boat and spray foam in the rear.  The thinsulite was on the hull and the reverse of the wood panels, I would say that they are both very good, but the foam if correctly applied has the edge. Now this is just my opinion and has no scientific evidence behind it 

Isnt this where the science gets tested "Boat Building & Maintenance"

 

12 hours ago, Phoenix_V said:

Correctly applied sprayfoam should not need any vapour barrier as it is a closed cell foam ie impermeable and is also stuck firmly to the superstructure. Make sure you are getting the thickness you have paid for 25mm is just OK 50 or more is better depending how much room there is.

The only weak point where condensation can get in then would be the frames. Wooden battens should be K (use treated timber such as roofing battens) but metal to lining contact might need thinking about, perhaps a small airgap? or strip of thin material.

Was quoted 4k+ for the whole of inside cabin of 70x12 sprayed to 50mm (supposedly for a top job), however unsure of whether this an adequate price.

Marine ply was used for battens, but one idea was to apply a coat of bitumen to battens once the job has been done to increase their length of service- should work.

For lining to metal contact, perhaps to mitigate any impact due to condensation, another idea would be to use some galvanized brackets (or similar depending on the application) screwed onto the lining itself.

5 hours ago, koukouvagia said:

It has worked perfectly - not a trace of condensation anywhere.  ?

 

Would you have any suggestions or advice about how you would have done otherwise (if at all)?

 

4 hours ago, nicknorman said:

As said, no need for vapour barrier. You put vapour barrier on the warm side of insulation in a house, so that the cold side (interior of cavity wall or whatever) doesn’t suffer from condensation. But to get condensation you need an air gap / space for the condensation to form. With the spray foam being in intimate contact with the steel, there is no-where for condensation to form between the foam and the hull.

Kinda makes sense- as in the scenario of having vapor barrier throughout the interior of cabin it would only "protect" the sprayfoam itself which doesnt really need this at all. Presuming there are air gaps/ voids between shell and sprayfoam layers or sprayfoam and cabin interior, then the biggest question perhaps is how to make sure whether the sprayfoam has been applied evenly and correctly to create solid bond with steel shell? Is there a method of testing this?

 

4 hours ago, ditchcrawler said:

An easy way to check the spray foam thickness is to drive a thin nail though a small square of plywood about 2" square to the required depth of spray foam and check the thickness before they pack up. I had to get them back to re do mine 

Neat trick, would it mean youd repeat this action throughout the cabin to inspect this? What was the thickness you had it sprayed to?

 

2 hours ago, blackrose said:

I think there is some confusion here because the voids that you don't want are those which are unsealed and open to the warm air of the cabin because then you have an infinite amount of water vapour, condensation and corrosion that can form behind the PU board over time.

Exactly, was reading about other boater experiences with having uneven, thin layers of sprayfoam. These "voids" had been created by irresponsible contractors towards the cabin as well as between the steel and the foam, which were getting filled with warm cabin air and for this matter thought to entertain with this idea to at least be able to protect the gaps facing the cabin.

 

[peterboat]

5 minutes ago, Batainte said:

Have read the horrors of other boaters on this forum talking about this exact matter. It appears that "cowboy" contractors try to get away or cut corners with the fact that if a person doesnt know or ask for details about the required job. For this reason its just done as quick as possible with any potential future failures inherited by whoever owns the boat. Its all about collecting the cash and hopping back into that white van and heading off to next job.

 

Will check some of his episodes out.

Would there be a way to know whether the foam has been applied as necessary before covering the sides with lining? Assuming if the job is overlooked by someone and not sprayed dense enough over the awkward bits as it was meant to. It being a foam, there is a potential in having some "blind spots" on the bottom layer and not having them covered on second layer?

 

Isnt this where the science gets tested "Boat Building & Maintenance"

 

Was quoted 4k+ for the whole of inside cabin of 70x12 sprayed to 50mm (supposedly for a top job), however unsure of whether this an adequate price.

Marine ply was used for battens, but one idea was to apply a coat of bitumen to battens once the job has been done to increase their length of service- should work.

For lining to metal contact, perhaps to mitigate any impact due to condensation, another idea would be to use some galvanized brackets (or similar depending on the application) screwed onto the lining itself.

Would you have any suggestions or advice about how you would have done otherwise (if at all)?

 

Kinda makes sense- as in the scenario of having vapor barrier throughout the interior of cabin it would only "protect" the sprayfoam itself which doesnt really need this at all. Presuming there are air gaps/ voids between shell and sprayfoam layers or sprayfoam and cabin interior, then the biggest question perhaps is how to make sure whether the sprayfoam has been applied evenly and correctly to create solid bond with steel shell? Is there a method of testing this?

 

Neat trick, would it mean youd repeat this action throughout the cabin to inspect this? What was the thickness you had it sprayed to?

 

Exactly, was reading about other boater experiences with having uneven, thin layers of sprayfoam. These "voids" had been created by irresponsible contractors towards the cabin as well as between the steel and the foam, which were getting filled with warm cabin air and for this matter thought to entertain with this idea to at least be able to protect the gaps facing the cabin.

 

You are right but my boat warms up fast in both halfs so it's a difficult one to call

[ditchcrawler]

9 minutes ago, Batainte said:

 

Would there be a way to know whether the foam has been applied as necessary before covering the sides with lining? Assuming if the job is overlooked by someone and not sprayed dense enough over the awkward bits as it was meant to. It being a foam, there is a potential in having some "blind spots" on the bottom layer and not having them covered on second layer?

 

You need to check the foam  before the contractor leave site to make sure you are happy, once its lined out its too late

 

 

Neat trick, would it mean youd repeat this action throughout the cabin to inspect this? What was the thickness you had it sprayed to?

 

Yes, all panels in lots of places. When they redid mine it was well thick, proud of the battens and the boss rang up to make sure I was happy before the chap left Suffolk back to Wales. It left a lot of trimming back

 

 

[Phoenix_V]

9 minutes ago, Batainte said:

 

Was quoted 4k+ for the whole of inside cabin of 70x12 sprayed to 50mm (supposedly for a top job), however unsure of whether this an adequate price.

Marine ply was used for battens, but one idea was to apply a coat of bitumen to battens once the job has been done to increase their length of service- should work.

 

 

Price is in the right region, if the lining hasn't been fitted should be easy to check depth of foam just check visually for any bits that look thinner and test there with a small screwdriver, its probably not that they set out to con you just its very hard to get an even depth. The bitumen doesnt sound a bad idea. Its normal to tape over any parts that you do not want sprayed and it should specify in the contract whether they you (or the builder) are to do this.

[nb Innisfree]

After Innisfree had been sprayfoamed I spent a couple of days cutting back excess foam and in doing so found a few places where the foam hadn't managed to penetrate leaving very narrow holes leading to bare metal, always in awkward hard to get cavities round battening etc, I think it would be difficult if not impossible to totally avoid them, so I set to with aerosol foam and filled every one I could find (with a different colour foam as a guide) Being a bit obsessive it took me nearly two weeks before I was satisfied, even then after a couple of winters aboard rust marks appeared on the bathroom wall, I located a pinhole and injected some foam, job finished. 

 

I would say that even a first class spray foam will leave a fissure or three in the foam, nothing serous but they will eventually allow condensation to develop along with rust. 

 

 

[ditchcrawler]

5 minutes ago, nb Innisfree said:

After Innisfree had been sprayfoamed I spent a couple of days cutting back excess foam and in doing so found a few places where the foam hadn't managed to penetrate leaving very narrow holes leading to bare metal, always in awkward hard to get cavities round battening etc, I think it would be difficult if not impossible to totally avoid them, so I set to with aerosol foam and filled every one I could find (with a different colour foam as a guide) Being a bit obsessive it took me nearly two weeks before I was satisfied, even then after a couple of winters aboard rust marks appeared on the bathroom wall, I located a pinhole and injected some foam, job finished. 

 

I would say that even a first class spray foam will leave a fissure or three in the foam, nothing serous but they will eventually allow condensation to develop along with rust. 

 

 

I didnt have that problem as I effectively had two coats, a thin one that covered all the steel and because it was thin it went behind things, I then had a second coat on the top to full thickness

[cuthound]

11 hours ago, Batainte said:

Isnt this where the science gets tested "Boat Building & Maintenance"

 

 

My two shareboats had sprayfoam insulation and my present boat has 3M Thinsulate insulation.

 

Subjectively I would say there is not a lot of difference in performance. Thinsulate deadens noise better. I think sprayfoam might just provide better thermal insulation, but that might be because my current boat has bigger windows in the saloon area.

 

On balance I would get whatever is easiest for you.

[Batainte]

On 04/03/2020 at 21:16, ditchcrawler said:

 

Would there be a way to know whether the foam has been applied as necessary before covering the sides with lining? Assuming if the job is overlooked by someone and not sprayed dense enough over the awkward bits as it was meant to. It being a foam, there is a potential in having some "blind spots" on the bottom layer and not having them covered on second layer?

 

You need to check the foam  before the contractor leave site to make sure you are happy, once its lined out its too late

 

 

Neat trick, would it mean youd repeat this action throughout the cabin to inspect this? What was the thickness you had it sprayed to?

 

Yes, all panels in lots of places. When they redid mine it was well thick, proud of the battens and the boss rang up to make sure I was happy before the chap left Suffolk back to Wales. It left a lot of trimming back

Makes sense, in order to get the money's worth its essential to be onsite for different stages and always be ready to overlook with a suspicious eye. Same recipie for any contract type.

 

On 04/03/2020 at 21:17, Phoenix_V said:

Price is in the right region, if the lining hasn't been fitted should be easy to check depth of foam just check visually for any bits that look thinner and test there with a small screwdriver, its probably not that they set out to con you just its very hard to get an even depth. The bitumen doesnt sound a bad idea. Its normal to tape over any parts that you do not want sprayed and it should specify in the contract whether they you (or the builder) are to do this.

Actually received rather attractive quote by another boat insulation company and their figure was a little less than half of original 4k for 60mm throughout cabin. Unsure whether i am to share their details, in case am getting blocked for promotion? Thanks for explaining this, it makes sense that it may be rather hard to get into awkward bits of the boat and those may require more detailed attention afterwards.

Would anyone know how long does it take for sprayfoam to dry or is it like any other foam product... fully dried in less than 30 mins.

On 04/03/2020 at 21:31, nb Innisfree said:

After Innisfree had been sprayfoamed I spent a couple of days cutting back excess foam and in doing so found a few places where the foam hadn't managed to penetrate leaving very narrow holes leading to bare metal, always in awkward hard to get cavities round battening etc, I think it would be difficult if not impossible to totally avoid them, so I set to with aerosol foam and filled every one I could find (with a different colour foam as a guide) Being a bit obsessive it took me nearly two weeks before I was satisfied, even then after a couple of winters aboard rust marks appeared on the bathroom wall, I located a pinhole and injected some foam, job finished. 

 

I would say that even a first class spray foam will leave a fissure or three in the foam, nothing serous but they will eventually allow condensation to develop along with rust. 

 

 

Equally as you id practice obsession sparingly.. especially on a project of this magnitude. The company which provided the quote also include cutting back and disposing of rubbish so id assume anything "not" covered would be exposed and they would redo the part which got looked over :o

 

On 04/03/2020 at 21:38, ditchcrawler said:

I didnt have that problem as I effectively had two coats, a thin one that covered all the steel and because it was thin it went behind things, I then had a second coat on the top to full thickness

"Measure twice and cut once" could be paraphrased to "Spray twice and cut once". Sounds like the logical way to work with this. Did you sprayfoam everything yourself? Would like to have a go on a project that would be on a smaller scale and practice this... but believe its like with spray paint- required steady hand and even application.

 

On 05/03/2020 at 08:38, cuthound said:

 

 

My two shareboats had sprayfoam insulation and my present boat has 3M Thinsulate insulation.

 

Subjectively I would say there is not a lot of difference in performance. Thinsulate deadens noise better. I think sprayfoam might just provide better thermal insulation, but that might be because my current boat has bigger windows in the saloon area.

 

On balance I would get whatever is easiest for you.

How did you manage to put the boards throughout to sit tightly against the steelwork? Surely the cabin sides and not 90 degree, have curviture and whatnot...

Was under the impression that youd want to get your insulation boards as tight as possible to the surface of anything that protects you form outside.

[ditchcrawler]

9 minutes ago, Batainte said:

 

 

"Measure twice and cut once" could be paraphrased to "Spray twice and cut once". Sounds like the logical way to work with this. Did you sprayfoam everything yourself? Would like to have a go on a project that would be on a smaller scale and practice this... but believe its like with spray paint- required steady hand and even application.

 

 

No, the company paid the chaps piece work, the feller who did the first coat did several boats a day. The chap who did the second coat had to come all the way from Wales to Suffolk to redo it at the companies expense. It was only due to the support I got from the hull builder that it was sorted. ie the boss of the sprayfoam company ringing me and asking when they could come because the hull builder wouldn't have him back on site until it was sorted

[cuthound]

46 minutes ago, Batainte said:

How did you manage to put the boards throughout to sit tightly against the steelwork? Surely the cabin sides and not 90 degree, have curviture and whatnot...

Was under the impression that youd want to get your insulation boards as tight as possible to the surface of anything that protects you form outside.

 

Thinsulate is like a thick woven cloth, and is glued directly to the steelwork with a 3M contact adhesive.

 

https://www.ebay.co.uk/i/331464897104?chn=ps&norover=1&mkevt=1&mkrid=710-134428-41853-0&mkcid=2&itemid=331464897104&targetid=878160862233&device=t&mktype=pla&googleloc=1007147&poi=&campaignid=9446197402&mkgroupid=96107653375&rlsatarget=pla-878160862233&abcId=1140486&merchantid=101734723&gclid=Cj0KCQiAhojzBRC3ARIsAGtNtHXVipVpGE-P4fqMU3H4yS3LioklxBMRGkmEqC7wTUtkGNrDz-IUkUIaAlI-EALw_wcB

Edited March 6, 2020 by cuthound
To add link

[Batainte]

18 hours ago, ditchcrawler said:

No, the company paid the chaps piece work, the feller who did the first coat did several boats a day. The chap who did the second coat had to come all the way from Wales to Suffolk to redo it at the companies expense. It was only due to the support I got from the hull builder that it was sorted. ie the boss of the sprayfoam company ringing me and asking when they could come because the hull builder wouldn't have him back on site until it was sorted

This sort of attitude is what is definitely reassuring to learn that your boatbuilder protected your interests. To embark on a project of this scale one has to go through quite a journey of education, acquiring information (often conflicting) on all sorts of technicalities, details and nuances, surely sprayfoam is one of them. Happy to know it was all done well for your project. Nowadays trust is rather difficult to come by in any section of contracting/ construction industry.

 

18 hours ago, cuthound said:

 

Thinsulate is like a thick woven cloth, and is glued directly to the steelwork with a 3M contact adhesive.

 

https://www.ebay.co.uk/i/331464897104?chn=ps&norover=1&mkevt=1&mkrid=710-134428-41853-0&mkcid=2&itemid=331464897104&targetid=878160862233&device=t&mktype=pla&googleloc=1007147&poi=&campaignid=9446197402&mkgroupid=96107653375&rlsatarget=pla-878160862233&abcId=1140486&merchantid=101734723&gclid=Cj0KCQiAhojzBRC3ARIsAGtNtHXVipVpGE-P4fqMU3H4yS3LioklxBMRGkmEqC7wTUtkGNrDz-IUkUIaAlI-EALw_wcB

Looks like a good type of insulation and reasonably cheap in comparison to sprayfoam. Was so overwhelmed in learning about sprayfoam insulation and comparing it to kingspan etc... that completely overlooked these. Did you use just one layer of 35mm for this or added one on top of each other to make 70mm (if that would even be possible spacewise)?

[cuthound]

13 minutes ago, Batainte said:

This sort of attitude is what is definitely reassuring to learn that your boatbuilder protected your interests. To embark on a project of this scale one has to go through quite a journey of education, acquiring information (often conflicting) on all sorts of technicalities, details and nuances, surely sprayfoam is one of them. Happy to know it was all done well for your project. Nowadays trust is rather difficult to come by in any section of contracting/ construction industry.

 

Looks like a good type of insulation and reasonably cheap in comparison to sprayfoam. Was so overwhelmed in learning about sprayfoam insulation and comparing it to kingspan etc... that completely overlooked these. Did you use just one layer of 35mm for this or added one on top of each other to make 70mm (if that would even be possible spacewise)?

 

Mine is slightly different, but they only seem to stock it in the states now. It is black on one side, white on the other and about 50mm thick when not compressed. The stuff I linked to is used extensively when insulating camper vans, so more information might be had on a camper van forum.

 

I cannot see why you couldn't use two layers to improve the insulation.

[peterboat]

On 07/03/2020 at 09:46, cuthound said:

 

Mine is slightly different, but they only seem to stock it in the states now. It is black on one side, white on the other and about 50mm thick when not compressed. The stuff I linked to is used extensively when insulating camper vans, so more information might be had on a camper van forum.

 

I cannot see why you couldn't use two layers to improve the insulation.

Mine has a layer on the hull and a layer on the wood panels 

[Batainte]

On 07/03/2020 at 09:46, cuthound said:

 

Mine is slightly different, but they only seem to stock it in the states now. It is black on one side, white on the other and about 50mm thick when not compressed. The stuff I linked to is used extensively when insulating camper vans, so more information might be had on a camper van forum.

 

I cannot see why you couldn't use two layers to improve the insulation.

Actually it was on camper forums where people discussed having vapor barrier as an additional option for their insulation. Apparently 50mm is a decent thickness for a boat/ van (in contrast to onshore buildings which have 100mm as per standard in Europe).

 

On 08/03/2020 at 21:43, peterboat said:

Mine has a layer on the hull and a layer on the wood panels 

Did you insulate your floor? If so was it laid out on top of ballast and between the floor boards?

Wouldnt this reduce hull ventilation as boaters discussed on other threads about the fact that it is normal for condensation to remain there and the air between ballast would help it slowly evaporate?

[peterboat]

3 hours ago, Batainte said:

Actually it was on camper forums where people discussed having vapor barrier as an additional option for their insulation. Apparently 50mm is a decent thickness for a boat/ van (in contrast to onshore buildings which have 100mm as per standard in Europe).

 

Did you insulate your floor? If so was it laid out on top of ballast and between the floor boards?

Wouldnt this reduce hull ventilation as boaters discussed on other threads about the fact that it is normal for condensation to remain there and the air between ballast would help it slowly evaporate?

No insulation or the floor I have a Rayburn in the kitchen with full central heating, the bedroom has a large thick Chinese rug so it's warm enough.  If I was building from scratch I would install under floor heating in the ballast to get rid of the radiators