Redoing the insulation on 55" steel canal boat

[Redhawk106]

Hey all, been following the fantastic threads on this forum for a while now, and time to ask my own question.

 

Some background: Bought our first 55" by 10" canal boat a couple of months ago. All knowledge learnt is from the last year or so reading this forum and talking to people, so we're still very new! All tips welcome. The boat is currently out of the water in the boat yard, and will be going back in in the next 2 weeks once hull is blacked, so we will continue the wall and kitchen on the water, but Im hoping to paint the bottom inside of the bilges (Owatrol + Red Oxide) before it goes back into the water.

 

The insulation on our boat in the kitchen is very thin, just a cm or two of white polystyrene, so while we were ripping out the old kitchen and plumbing, we thought we might as well go further and do the insulation.

 

See photos of the walls below:

 

(Photo 1 of the horizontal frame sections of the wall)

 

(Photo 2 of the horizontal frame sections of the wall, my hand going behind it to show there is a hollow space where we would slide insulation behind)

 

My question is around how to do the vapour barrier between some of the steel frame and the plywood. The steel hull wall is a bit tricky to describe, so I've added the photos above to try to explain. It has 2 horizontal steel sections with a 80mm wide L shaped "face" that would be touching the plywood wall panels. So against the whole hull in between these sections we were thinking 50mm insulation board, and then also make sure to slide this behind that face, as the previous people had just left this 80mm steel section hollow behind it and the steel hull. We figured we sliding insulation behind this can only be a good thing!

 

The insulation im looking at is the IKO Enertherm Cavity Wall PIR Insulation Board, 50mm thick.

 

Example here: https://www.selcobw.com/iko-enertherm-cavity-wall-pir-insulation-board-1200-x-450mm?thickness=59066

 

Question 1

Is this the right board to use. Both type and thickness. We were recommended to do about 50mm thick but the space available in between those beams is 80mm deep btw. So that leaves another 30mm gap. Not sure what to do with that. Thicker insulation or just leave it as a gap.

 

Question 2

After putting the boards in, this still leaves two 80mm hight strips of steel going horizontally along the wall, what do we put in between here and the plywood? Some have suggested 75mm neoprene tape, but that gets very pricey when you add up the metres needed.

 

What if we put plastic sheeting over the insulation boards and the steel sections, or maybe that bubble wrap aluminium rolls stuff. I know the insulation boards will likely have a vapour barrier, and normally I read you would aluminium tape across the seems between them, but in this case, how do you deal with these steel bar sections?

 

Question 3

Also, another question is the fire rating on these boards. Some have several fire ratings where one of them say its quite fire resistant, and then the next fire rating on the same board says its extremely flammable....

 

Im thinking to avoid the issue around this by putting rockwood at the bottom section where the water line is, and then the rest can be the insulation board, so that any pit welding in future can be done without much fear? Unless the fire rating it important for things other than future welding.

 

For context, the current plan for the walls (below the tung and groove window sections) is:

1) Clean the rust and remove flaked rust with wire brushes/scrape etc.

2) Phosphoric acid rust converter (might skip this step due to the owatrol)

3) Owatrol mixed with red oxide, 2 coats.

4) Insulation board as above

5) Something to deal with the 2 horizontal steel beams.

6) 3mm hardboard, or maybe 10mm plywood boards.

7) White paint finish for the wall.

Edited February 6, 2023 by Redhawk106
clarifying questions

[Tom and Bex]

Don't use rock wool anywhere on the boat, horrible stuff! 

 

Insulation boards similar to what you linked to is what we used on our last boat. Fill any awkward gaps with fire resistant expanding foam. We then used thin (5mm?) laminate floor foam insulation cut into strips to bridge any remaining exposed steel, all sealed to insulation boards with foil tape. 

 

Use handheld gun with expanding foam canisters, instead of just the cans on their own. More controllable, and lasts longer.

[Tonka]

25 minutes ago, Redhawk106 said:

Hey all, been following the fantastic threads on this forum for a while now, and time to ask my own question.

 

Some background: Bought our first 55" by 10" canal boat a couple of months ago. All knowledge learnt is from the last year or so reading this forum and talking to people, so we're still very new! All tips welcome. The boat is currently out of the water in the boat yard, and will be going back in in the next 2 weeks once hull is blacked, so we will continue the wall and kitchen on the water, but Im hoping to paint the bottom inside of the bilges (Owatrol + Red Oxide) before it goes back into the water.

 

The insulation on our boat in the kitchen is very thin, just a cm or two of white polystyrene, so while we were ripping out the old kitchen and plumbing, we thought we might as well go further and do the insulation.

 

See photos of the walls below:

 

(Photo 1 of the horizontal frame sections of the wall)

 

(Photo 2 of the horizontal frame sections of the wall, my hand going behind it to show there is a hollow space where we would slide insulation behind)

 

My question is around how to do the vapour barrier between some of the steel frame and the plywood. The steel hull wall is a bit tricky to describe, so I've added the photos above to try to explain. It has 2 horizontal steel sections with a 80mm wide L shaped "face" that would be touching the plywood wall panels. So against the whole hull in between these sections we were thinking 50mm insulation board, and then also make sure to slide this behind that face, as the previous people had just left this 80mm steel section hollow behind it and the steel hull. We figured we sliding insulation behind this can only be a good thing!

 

The insulation im looking at is the IKO Enertherm Cavity Wall PIR Insulation Board, 50mm thick.

 

Example here: https://www.selcobw.com/iko-enertherm-cavity-wall-pir-insulation-board-1200-x-450mm?thickness=59066

 

Question 1

Is this the right board to use. Both type and thickness. We were recommended to do about 50mm thick but the space available in between those beams is 80mm deep btw. So that leaves another 30mm gap. Not sure what to do with that. Thicker insulation or just leave it as a gap.

 

Question 2

After putting the boards in, this still leaves two 80mm hight strips of steel going horizontally along the wall, what do we put in between here and the plywood? Some have suggested 75mm neoprene tape, but that gets very pricey when you add up the metres needed.

 

What if we put plastic sheeting over the insulation boards and the steel sections, or maybe that bubble wrap aluminium rolls stuff. I know the insulation boards will likely have a vapour barrier, and normally I read you would aluminium tape across the seems between them, but in this case, how do you deal with these steel bar sections?

 

Question 3

Also, another question is the fire rating on these boards. Some have several fire ratings where one of them say its quite fire resistant, and then the next fire rating on the same board says its extremely flammable....

 

Im thinking to avoid the issue around this by putting rockwood at the bottom section where the water line is, and then the rest can be the insulation board, so that any pit welding in future can be done without much fear? Unless the fire rating it important for things other than future welding.

 

For context, the current plan for the walls (below the tung and groove window sections) is:

1) Clean the rust and remove flaked rust with wire brushes/scrape etc.

2) Phosphoric acid rust converter (might skip this step due to the owatrol)

3) Owatrol mixed with red oxide, 2 coats.

4) Insulation board as above

5) Something to deal with the 2 horizontal steel beams.

6) 3mm hardboard, or maybe 10mm plywood boards.

7) White paint finish for the wall.

Can you trust the flammability reports for the insulation boards. Kingspan lied about their boards which was all found out after Grenfall. I thought Sheeps wool was better then Rockwool, something to do with moisture retention. Google insulation in older properties for more info. 

[Alan de Enfield]

3 minutes ago, Tonka said:

I thought Sheeps wool was better then Rockwool, something to do with moisture retention. Google insulation in older properties for more info. 

 

But you do need to leave a few access holes for feeding / watering and mucking out - apart from that they are ideal.

[Mike Tee]

Are you intending to remove all lining and completely re-insulate? If so, get it spray foamed professionally, it might cost a bit now, but you won’t regret it.

[Peanut]

Buy a can of gun cleaner to keep the foam gun clean

[Tonka]

1 minute ago, Alan de Enfield said:

 

But you do need to leave a few access holes for feeding / watering and mucking out - apart from that they are ideal.

No actually you need the correct one from Ireland. Don't use polyester in theirs and properly treated so don't get moths

[Alan de Enfield]

17 minutes ago, Tonka said:

No actually you need the correct one from Ireland. Don't use polyester in theirs and properly treated so don't get moths

 

We've never had moths in our sheep - foot rot and maggots, yes, but never moths !

[koukouvagia]

Have a look at this thread.  I've used slab insulation (the semi-rigid insulation - not Rockwool) and a plastic sheet stapled to the battens as a vapour barrier.

 

https://www.canalworld.net/forums/index.php?/topic/80379-sticking-battens-to-hull/&do=findComment&comment=1685245

 

[robtheplod]

1 hour ago, Peanut said:

Buy a can of gun cleaner to keep the foam gun clean

but how do you keep the gun cleaner, clean?  another can? 

[Puffling]

1 hour ago, robtheplod said:

but how do you keep the gun cleaner, clean?  another can? 

A well-trained earwig

[Peanut]

2 hours ago, robtheplod said:

But how do you keep the gun cleaner, clean?  Another can? 

Yep, just a can of gun cleaner, squirt it through the gun and that's it, clean gun.  No 4×2 or pull through needed.

[Redhawk106]

5 hours ago, Tom and Bex said:

Don't use rock wool anywhere on the boat, horrible stuff! 

 

Insulation boards similar to what you linked to is what we used on our last boat. Fill any awkward gaps with fire resistant expanding foam. We then used thin (5mm?) laminate floor foam insulation cut into strips to bridge any remaining exposed steel, all sealed to insulation boards with foil tape. 

 

Use handheld gun with expanding foam canisters, instead of just the cans on their own. More controllable, and lasts longer.

What's your reason for rockwool being horrible stuff? Would like to know in order to make informed decisions. Many others have said it's great if not using spray foam including high heat resistance, so it's hard to know who to listen to without more details / understanding on reasons.

[Feeby100]

Rockwool will absorb moisture that’s why

Kingspan or cell atecs  is the best stuff to use if you’re not going to go spray foam and vapour seal it all

Edited February 6, 2023 by Feeby100

[Redhawk106]

Thanks for responses on spray foam but I don't think it's cost effective for us, as we're only able to do below the windows right now, and it's mainly in one room (kitchen). We're currently living aboard so fumes from the spray foam would I think not be manageable. I think spray foam would really only be an option if we stripped everything out. Currently everything just had to be moved to one side of the room, then back again when we do the other side.

[Redhawk106]

5 minutes ago, Feeby100 said:

Kingspan or cell atecs  is the best stuff to use if you’re not going to go spray foam and vapour see little

 

Is it the best stuff even at the waterline with the possibility of pit welding? The rest will be the board I mentioned in the original post, which I imagine is similar to kingspan.

 

And yes, sadly the moisture is a concern with the rockwool. Trying to weigh up the pros and cons for that waterline section 😞

Edited February 6, 2023 by Redhawk106

[Tony Brooks]

14 minutes ago, Redhawk106 said:

 

Is it the best stuff even at the waterline with the possibility of pit welding? The rest will be the board I mentioned in the original post, which I imagine is similar to kingspan.

 

And yes, sadly the moisture is a concern with the rockwool. Trying to weigh up the pros and cons for that waterline section 😞

 

Only insulate the hull down to floor level, and make sure whatever insulation you use is prevented from slipping down into the bilge area.

[PCSB]

The kingspan type product (including the one you linked to) have better insulating properties. Typically around 0.02 W/mK whereas rockwool is in the resion of 0.3 W/mK - smaller values are better here.

 

iirc kingspan type products are also lighter than rockwool which may, or may not be relevant.

 

True rockwool is resistant to fire at greater than 1,000C I believe but I can't remember for kingspan type (it has been a very, very long time since I needed to know this).

 

I'd use kingspan type fwiw, you will also find it easier to keep from dropping into the bilge as Tony above advises.

[Tom and Bex]

2 hours ago, Redhawk106 said:

What's your reason for rockwool being horrible stuff? Would like to know in order to make informed decisions. Many others have said it's great if not using spray foam including high heat resistance, so it's hard to know who to listen to without more details / understanding on reasons.

 

As others have mentioned, rock wool will hold moisture against the hull promoting more rapid rusting, will be difficult to keep in place, and tends to get wet and sag down over time. Added to which is it's just not a nice product to work with, very itchy and dusty. Definitely best avoided at all times in a boat, but definitely in a partly fitted one. 

 

We used kingspan or celotex boards. We subsequent had some welding carried out on an area we'd previously insulated with no obvious problems (well the boat didn't go up in flames anyway!!!). When i mentioned sprayfoam, I was meaning the handheld cans (used with a gun) and using it to fill any gaps between the boards. This is much easier than accurately cutting the boards for a tight fit and manipulating them into position, there'll always be some gaps to fill!

Edited February 6, 2023 by Tom and Bex

[Redhawk106]

2 hours ago, Tony Brooks said:

 

Only insulate the hull down to floor level, and make sure whatever insulation you use is prevented from slipping down into the bilge area.

Yep only to floor level. Any tips on stopping the slippage? I have noticed old crumbs of poly going into the bilge during crane lifts etc. Maybe the boards won't be so bad though, but a tried and tested method would be welcome if anyone has some 

1 hour ago, Tom and Bex said:

 

As others have mentioned, rock wool will hold moisture against the hull promoting more rapid rusting, will be difficult to keep in place, and tends to get wet and sag down over time. Added to which is it's just not a nice product to work with, very itchy and dusty. Definitely best avoided at all times in a boat, but definitely in a partly fitted one. 

 

We used kingspan or celotex boards. We subsequent had some welding carried out on an area we'd previously insulated with no obvious problems (well the boat didn't go up in flames anyway!!!). When i mentioned sprayfoam, I was meaning the handheld cans (used with a gun) and using it to fill any gaps between the boards. This is much easier than accurately cutting the boards for a tight fit and manipulating them into position, there'll always be some gaps to fill!

Thanks for future explanation, especially on the mess and experience after welding (already knew about moisture). Will definitely steer away from the rockwool then.

 

Interesting on the spray foam from cans to fill gaps, aren't those mainly open cell ones? Any way to tell which are closed cell? I assume that's important if trying to fill gaps. Or should spray can foam be combined with the aluminum tape to seal gaps for moisture barrier.

[Tony Brooks]

6 minutes ago, Redhawk106 said:

Yep only to floor level. Any tips on stopping the slippage? I have noticed old crumbs of poly going into the bilge during crane lifts etc. Maybe the boards won't be so bad though, but a tried and tested method would be welcome if anyone has some 

 

It will probably involve screwing small pieces of wood to the underside of the floor at suitable centres to stop the insulation moving down, but much depends upon what you fined.

[Tom and Bex]

29 minutes ago, Redhawk106 said:

Yep only to floor level. Any tips on stopping the slippage? I have noticed old crumbs of poly going into the bilge during crane lifts etc. Maybe the boards won't be so bad though, but a tried and tested method would be welcome if anyone has some 

Thanks for future explanation, especially on the mess and experience after welding (already knew about moisture). Will definitely steer away from the rockwool then.

 

Interesting on the spray foam from cans to fill gaps, aren't those mainly open cell ones? Any way to tell which are closed cell? I assume that's important if trying to fill gaps. Or should spray can foam be combined with the aluminum tape to seal gaps for moisture barrier.

You'll find the insulation boards will generally stay in place once wedged in. I stuck most of ours on with a PU sealant though such as Sikaflex or Puraflex 40. 

 

As to the handheld spray foam I used, I think I assumed it was closed cell, but didn't really bother to look into it much. Its only gap filing after all. 

 

Definitely ended up with a much much better insulated boat than our current boat which has polystyrene insulation🥶

[roland elsdon]

Ive never found owatrol has any rust resistant properties . Tried it in red oxide and even with wirebrushing it re rusted in a year.

I used fertan 4 years ago on 80 year old steel outside and primed and top coated it with no problems to date.

 

if you dont mind mind altering effects waxoil on top of hull sides primer seems to assist.