Old Wooden Boat Insulation

[Gus94]

Hello, 

I’ve read everything I can find about different options for insulating, but would really appreciate it if anyone has any ideas particular to my situation.

 

I have a narrowboat with a wooden beam frame to which is attached planks of wood. Originally the outside was MDF which rotted away, and I replaced with buffalo board. Now I have a condensation problem, which may be because the buffalo board doesn’t breathe and may also act as a cold bridge (not really sure). 
 

I’m thinking maybe I could take off the buffalo board and put something insulating between the boards and the wooden plank interior, does anyone have any ideas for something thin that would be good?

 

my gunnels are also uninsulated and exposed on the inside, so need something to insulate those as huge amounts of condensation form on them.

 

Hull is uninsulated at the bottom - just wooden plank flooring, but sides of the hull have polystyrene and then thin wood panelling. Some areas not insulated (a section in middle of boat is just bare steel, and also the front which is where the water tank is - plenty of condensation there)… Hoping to leave the lower half of the sides as they are with the crappy polystyrene boards because I can’t afford to rip everything out.

 

Very, very grateful for anyone’s thoughts.

[Alan de Enfield]

23 minutes ago, Gus94 said:

Originally the outside was MDF which rotted away, and I replaced with buffalo board.

 

When you say 'outside' are you refering to the 'wet side' (in contact with the canal) ?

[ditchcrawler]

1 minute ago, Alan de Enfield said:

 

When you say 'outside' are you refering to the 'wet side' (in contact with the canal) ?

There is also mention of steel, Is this a steel hulled narrowboat with a wooden top?

[rusty69]

26 minutes ago, Gus94 said:

I’m thinking maybe I could take off the buffalo board and put something insulating between the boards and the wooden plank interior, does anyone have any ideas for something thin that would be good?

No expereince of using it but have you looked at 3m thinsulate, Kingspan or rockwool.

[dave moore]

This sounds as if it might be one of Malcolm Braine’s early boats, steel hull, wooden cabin?

[koukouvagia]

The rebuilt back cabin of our butty is lined with Thinsulate.  There is not the slightest hint of condensation.  I can thoroughly recommend it.

19 minutes ago, koukouvagia said:

The rebuilt back cabin of our butty is lined with Thinsulate.  There is not the slightest hint of condensation.  I can thoroughly recommend it.

The main cabin is insulated with slab fibre glass insulation - not the floppy Rockwool stuff.  Absolutely every nook and cranny has to be filled.  On top of this the cabin was completely swathed in a plastic sheeting vapour barrier.  Again every square inch has to be covered.  Below the gunwales I used tongue and groove timber - not the flimsy matchboard T&G.  Then, yes, I used MDF for the lining above the gunwales.  Before I get shouted at for using MDF, I can report that after twenty five years it still looks pristine with no condensation whatsoever.

 

 

[ditchcrawler]

49 minutes ago, koukouvagia said:

The rebuilt back cabin of our butty is lined with Thinsulate.  There is not the slightest hint of condensation.  

 

 

I tried to buy some recently, not for boat insulation but for something else and found there are now loads of van insulation for sale. I don't think it was genuine Thinsulate and I don't know how it compares in performance 

[Gus94]

21 hours ago, Alan de Enfield said:

 

When you say 'outside' are you refering to the 'wet side' (in contact with the canal) ?

 

 

21 hours ago, ditchcrawler said:

There is also mention of steel, Is this a steel hulled narrowboat with a wooden top?

Sorry, yes, it’s a steel hulled narrowboat with a wooden top.

 

21 hours ago, dave moore said:

This sounds as if it might be one of Malcolm Braine’s early boats, steel hull, wooden cabin?

 

I couldn’t say but would be interested to find out! Has been in the family since about the 1970s/80s, my father lived in it before and now I am.

The wooden cabin is lovely, so I am loath to start insulating from the inside, which is partly why I’m wondering whether I can insulate between the outer layer of board and the planks of the inside.

 

I am guessing the damp problem inside since changing MDF for buffalo board is that the MDF was somehow breathable. Honestly I’m not that keen on all the plastic and foamy insulation for making an airtight boat with no breathability, but perhaps I now have to go that way…

 

Thanks very much to all for the insulation recommendations.

Edited February 6 by Gus94

[David Mack]

On a 70s/80s boat the 'mdf' on the outside of the planking would probably have been masonite, which was (is?) A sort of heavy duty oil impregnated hardboard. When well maintained it provided a good weatherproof exterior layer to protect the tongue and groove planking, but if it it is allowed to deteriorate the rain gets in and it starts to decay. Not really surprising that 40 or 50 years on this has happened.

[Gus94]

Here’s an artistically profound drawing.

 

I just wonder how effective piecemeal insulation is going to be, I know everyone always says every nook and cranny has to be filled, which I can’t do without ripping out the inside, and probably covering the interior planking.

[Gus94]

1 hour ago, David Mack said:

On a 70s/80s boat the 'mdf' on the outside of the planking would probably have been masonite, which was (is?) A sort of heavy duty oil impregnated hardboard. When well maintained it provided a good weatherproof exterior layer to protect the tongue and groove planking, but if it it is allowed to deteriorate the rain gets in and it starts to decay. Not really surprising that 40 or 50 years on this has happened.

That’s interesting, could have been that. It was all swollen and decaying, replaced it 6 years ago. So people just lived with that stuff and then the tongue and groove planking, and no other insulation?! I suppose not intended as a live-aboard. 

 

[David Mack]

And inch of softwood planking plus about 3/8" of masonite probably provides a reasonable degree of insulation and condensation shouldn't be too much of a problem on the cabin sides as long as you have sufficient ventilation (especially for shower/drying clothes/cooking). 

In your situation I would concentrate on insulating the bare metal areas under the gunwales and anywhere else. Also fill any gaps between the polystyrene panels on the hull (sprayfoam in a can perhaps), then tape over all the joints with aluminium tape, including over the edge of the gunwale insulation onto the bottom of the cabin planking. I wouldn't worry about insulating the floor.

[alan_fincher]

I agree with the suggestion that the cabin was probably clad in "Masonite" - it is highly unlikely to actually have been MDF

 

In my experience it was quite normal to have a layer of heavy duty roofing felt between the Masonite outer and the tongue and grooved inner, usually with a bituminous product applied to all surfaces in the "sandwich".  I have certainly constructed a cabin that way.

 

It was not unusual to have no additional insulation

[magnetman]

Ventilation is the key. 

 

Boats need to breathe as much as people do. Think of the Boat as yourself. Would you be happy with no air? 

 

I know a lot of people think air movement through a Boat means a 'draught' but it isn't. In Boat terms the draught is how deep it is under the water. 

 

There is a balancing act with all this and of course the fire but yes Boats do need air. 

[jacko264]

Just a idea how about drilling holes in the outside panels and having polystyrene  ball’s sprayed in or foam 

then plug the holes in the panels

this is only my idea so ask around before doing it

[David Mack]

6 minutes ago, jacko264 said:

Just a idea how about drilling holes in the outside panels and having polystyrene  ball’s sprayed in or foam 

Into what? There's no void to be filled.

[jacko264]

So am I miss understanding I though there was wood planks  then framing  and buffalo board on the out side

[David Mack]

The OP can clarify what his boat has, but usually there are hardwood frames on the inside, then tongue & groove planking, then originally masonite sheet, which the OP has replaced with buffalo board.

[jacko264]

6 minutes ago, David Mack said:

The OP can clarify what his boat has, but usually there are hardwood frames on the inside, then tongue & groove planking, then originally masonite sheet, which the OP has replaced with buffalo board.

Ok I will leave it to people that know  as I said it was only my idea 👍

[Gus94]

15 hours ago, David Mack said:

The OP can clarify what his boat has, but usually there are hardwood frames on the inside, then tongue & groove planking, then originally masonite sheet, which the OP has replaced with buffalo board.

Yes exactly, no gap at all!

 

On 06/02/2024 at 14:53, David Mack said:

And inch of softwood planking plus about 3/8" of masonite probably provides a reasonable degree of insulation and condensation shouldn't be too much of a problem on the cabin sides as long as you have sufficient ventilation (especially for shower/drying clothes/cooking). 

In your situation I would concentrate on insulating the bare metal areas under the gunwales and anywhere else. Also fill any gaps between the polystyrene panels on the hull (sprayfoam in a can perhaps), then tape over all the joints with aluminium tape, including over the edge of the gunwale insulation onto the bottom of the cabin planking. I wouldn't worry about insulating the floor.

Thanks very much for this!

Sounds like a good plan, although unfortunately not certain I can touch up the polystyrene panels on the hull as it would mean ripping out the thin tongue and groove panelling that is nailed on.

 

On 06/02/2024 at 21:28, magnetman said:

Ventilation is the key. 

 

Boats need to breathe as much as people do. Think of the Boat as yourself. Would you be happy with no air? 

 

I know a lot of people think air movement through a Boat means a 'draught' but it isn't. In Boat terms the draught is how deep it is under the water. 

 

There is a balancing act with all this and of course the fire but yes Boats do need air. 

Yes, I have come to realise this through the medium of mould… I am ventilating more now (although it already had air vents) but the problem is that with this level of insulation one room heats up while the fire is going, but the heat never really reaches 2/3 of the boat. Before that I wore several layers of clothes and never bothered heating even when 0 degrees, which meant roughly the same temperature indoors as outside, but meant not much pf a condensation problem.

[magnetman]

2 fires can be a solution for this. 

 

Lots of narrow Boats have two fires. 

[Gus94]

On 05/02/2024 at 14:13, dave moore said:

This sounds as if it might be one of Malcolm Braine’s early boats, steel hull, wooden cabin?

Apparently Dennis Cooper of CTS

[dave moore]

Ah, the yard next door! I’ve worked with them for many years, known Denis Cooper, the founder, since the 60s. I’m due there soon for another lettering and trad decoration job. Top end builders!

[Bee]

Problem is that if you insulate the outside your gunnels will become so narrow as to be pretty much useless and also you have the problem of how to make it waterproof at the side/top join. Having put buffalo board on the sides it would be disheartening to pull it all off again. I think you might have to insulate the inside, I used to use wood fibre board for this and it worked well as well as having one fairly OK surface that would take paint/hessian/carpet or whatever. The bit under the gunnel really must be insulated and it is awkward but it will drip constantly if you don't do it. The hull sides that have the pink stuff need to have a good 3" or as much as you can fit and then some sort of cladding on top, really you are looking at a bit of a refit.

[blackrose]

On 09/02/2024 at 22:40, jacko264 said:

Just a idea how about drilling holes in the outside panels and having polystyrene  ball’s sprayed in or foam 

then plug the holes in the panels

 

Just for interest, I don't know of any DIY dry polystyrene bead spraying method into voids although it must be possible. The main issues that I see would be the potential for contact with PVC cable insulation and I'm not sure how effective the insulation would be with all the tiny voids between beads and settling off the beads over time.

 

Spraying wet PU foam into voids isn't as simple as it sounds because it expands spherically and will rip panels off walls unless you inject small amounts into holes say every 6".