Basic insulation question

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steve yates

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I have a bunch of 5mm closed cell foam camping mats, with one side covered in alumium foil.
I'm going to stick them to the insides of the hull of my bradwell 18 for insulation, then they will be covered by pine cladding ( painted with bathroom paint) screwed to battens.
My 2 questions are;
Should the foil side face the cabin interior? Or face the hull ?
And, what can I use to stick the mats to the hull? It has a fine ugly brown felt like covering in most places, which will be the surface the mats have to bond to..
I'm hiding it rather than attempting to remove it :)
 
I think the material that you are using is similar to that used under laminate flooring, In which case, I would put the foil towards the inside of the boat & glue the foam to the hull. This is so that when the insulation is fixed you will not get foam de lamination falling in.You will have a clean surface to fix to that is less prone to denting. ( Although it is a soft material anyway) If you ever have to remove it you should be able to get it off easier as the foam will break down easier.
If there is a moistuer/vapour problem it would come from the warm air inside the boat meeting the cold surface of the hull.( or at least the insulated surface) The moisture produced should run down the foil face & not down the face of the foam, (if it were the other way round). I do not think that moisture would form between insulation & hull surface.
To glue it, I would experiment with something like "Sticks Like"or a quick tack drying builders mastic adhesive, gun applied, but a water resistent one - check the specs before buying
That is my theory- but I may well be wrong & others will come along and agree/disagree
 
I think the foil should face inwards.
The main consideration is condensation. Water vapour will be carried in the air until it meets a cold surface such as the hull, where it will condense. Ideally you would fix the insulation directly to the hull without any void between them, so that there is nowhere for condensation to form.
In the real world, however, this is very difficult to achieve unless using spray foam on a bare, stripped out hull. So you will have to consider what will happen to the condensation that will be forming on the cold hull behind the insulation.
 
Interesting issue. The foil is a vapour barrier, as DD describes. If it were a heated building (i.e, in which the interior air carried elevated moisture loads and the outer skin of the structure was usually cooler) the foil face should definitely be on the inside. Being a boat, thus having a relatively small volume, condensation from breathing, cooking etc , this is even more of an issue, probably whether there is heating or not. However, the outside temp is variable in un-house-like ways, since some is above the water line, and some not. On the other hand, the insulation is unusually thin. Then there's the...

Sod it. Put it on the inside ?
 
steve yates said:
Here you go Sandy, from webbies thread.

"The deal seems to have ended, but I bought ten of these at £1.50 each on Sunday, their cyber monday deal was still running.

Yellowstone Foam Camping Mat With Insulated Backing Blue

about £1.65 p sqm and 6mm thick.

No idea if any good but seemed worth a punt :)"
Click to expand...
Thanks Steve. That stuff looks ideal.

I don't need much, planning to insulate the forepeak and rear cabin as the original foam backed lining has lost its foam. Having attempted to do the last boat with stuff from Hawke House and failing miserably I want something that is easier to use, I am planning to reuse the vinyl as that is sound.
 
That product works out at about a fiver for a square metre if there is no special deal on.
How about this & you do not have to worry about the foil
Arbiton Comfort Laminate & Wood Flooring Underlay 10.8m2 | Wickes.co.uk

More info
"XPS foam is an insulation board manufactured of fully recyclable material. It is produced from foamed polystyrene, a material that does not deteriorate. When you lay XPS boards as an underlay any heat from your room or floor will be reflected back towards the floor surface. As you will not be wasting heat through your floor you will utilize your energy in an effective manner and thereby lower your energy consumption and carbon footprint. XPS boards not only take care of the heat, they are also an effective guard against the cold and damp. The cold will be held back by the non conducting characteristics of the foam and as XPS board is also water repellent it will not rot or go mouldy and will help hold back any damp from your floor. XPS boards are also resistant to cement, plaster, and most alkalis, however not against organic solvents. In addition the boards have an excellent sound insulating effect, which makes the floor quieter to walk on and an ideal product for use when you need to reduce sound transmission to the room below. "
 
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[QUOTE="
"XPS foam is an insulation board manufactured of fully recyclable material. It is produced from foamed polystyrene, a material that does not deteriorate......."
[/QUOTE]

I had a boat made of expanded polystyrene. When petrol was spilt on it, the polystyrene would dissolve.

Just saying!
 
Daydream believer said:
That product works out at about a fiver for a square metre if there is no special deal on.
How about this & you do not have to worry about the foil
Arbiton Comfort Laminate & Wood Flooring Underlay 10.8m2 | Wickes.co.uk

More info
"XPS foam is an insulation board manufactured of fully recyclable material. It is produced from foamed polystyrene, a material that does not deteriorate. When you lay XPS boards as an underlay any heat from your room or floor will be reflected back towards the floor surface. As you will not be wasting heat through your floor you will utilize your energy in an effective manner and thereby lower your energy consumption and carbon footprint. XPS boards not only take care of the heat, they are also an effective guard against the cold and damp. The cold will be held back by the non conducting characteristics of the foam and as XPS board is also water repellent it will not rot or go mouldy and will help hold back any damp from your floor. XPS boards are also resistant to cement, plaster, and most alkalis, however not against organic solvents. In addition the boards have an excellent sound insulating effect, which makes the floor quieter to walk on and an ideal product for use when you need to reduce sound transmission to the room below. "
Click to expand...
Its a solid board, Not easy to stick to a hull.
 
It's a closed cell foam so vapour or moisture transmission will not be a problem, the silver foil is going to be covered by wooden batons so will not be useful as a heat reflector but well may be a point for condensation.
So I would strip or peel the brown mat off the hull sides cleaning of as much residual glue as possible then with any proprietary vinyl adhesive even Evostick, stick the mat with the foil side towards the hull as it will probably give a better bond with less chance of the material being dissolved by the adhesive.
 
Before you commit to fixing it, cut off a small offcut and hold a lit cigarette lighter under it for a few seconds. I don't know if the mat you've chosen will burn or emit toxic smoke, but it would be good to know before fixing it.
 
Fr J Hackett said:
It's a closed cell foam so vapour or moisture transmission will not be a problem, the silver foil is going to be covered by wooden batons so will not be useful as a heat reflector but well may be a point for condensation.
So I would strip or peel the brown mat off the hull sides cleaning of as much residual glue as possible then with any proprietary vinyl adhesive even Evostick, stick the mat with the foil side towards the hull as it will probably give a better bond with less chance of the material being dissolved by the adhesive.
Click to expand...

+1

Foil usually goes to the cold side, which is the hull. If on the inside, condensation is pretty certain. Hawke House sell self adhesive closed cell foam and there's some on ebay.
 
Sandy said:
Thanks Steve. That stuff looks ideal.

I don't need much, planning to insulate the forepeak and rear cabin as the original foam backed lining has lost its foam. Having attempted to do the last boat with stuff from Hawke House and failing miserably I want something that is easier to use, I am planning to reuse the vinyl as that is sound.
Click to expand...

You can usually find similar ones for around £3 per mat Sandy
 
To work as insulation, shiny foil needs to be facing an air gap, doesn't matter if inside or out.
As a vapour barrier, it wants to be on the warm side.
Ifyou are covering with pine boarding, then you could use something like
Airtec Multipurpose Foil & Polyethylene Insulation Roll- 1200mm x 25m | Wickes.co.uk
Which is basically bubble wrap with a metallised coating, effective as both insulation and vapour barrier.
 
Just as a suggestion. once you've decided on the foam answer.
Have you considered using plastic cladding boards instead of pine. Lightweight, easy to cut. some very realistic woodgrains and colours available. All the edgings etc you may need are readily available. Doesn't need painting or varnishing, and cheap! What's not to like?
If I was doing the job it's what I would use if it fitted in with the inernal decor.
 
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