Insulation: celotex + spray foam?

[anniewhere]

Hi all,

I discovered that a part of one of my cabin sides isn't insulated. Ideally I'd not rip out the built-in cupboard and ply walls... There's a large inspection hatch big enough to put in smaller cuts of Celotex board (about 20x50cm). So do you think it would work to put in multiple bits of Celotex, and then fill any gaps with spray foam? 

 

Thanks

Edited January 26, 2018 by anniewhere

[smileypete]

Could do... the foam does er expand, maybe use a bit sparingly and top up later if need be?

Worth a quick look for some tips on use:

https://www.google.co.uk/search?q=expanding+foam+tips

[Chewbacka]

Normal foam burns fast giving off lots of poisonous smoke, fire retardant foam will burn if forced but a lot slower giving you time to escape if the worst happens.  Something to think about when choosing......

[blackrose]

Cellotex and hand held cans of sprayfoam are both available in fire retardant grades.

Edited January 27, 2018 by blackrose

[Bugbugs]

If you can access the area through this hatch, then it might be better to just fill the area only with spray foam, as this would reduce the risk of gaps but do it a little at a time, allowing for full expansion of each burst (this would stop a pressure build up).

[Dr Bob]

How big is the area that needs insulation and how far away is the furthest point from where you would inject the foam? The sort of foam you might buy could set in seconds and not flow into parts a long way away. It could be tricky without the right kit.

[koukouvagia]

If you've got a sort of inspection hatch, would it be possible to pack the space with slab insulation?  It's rigid enough for the large areas and can be torn into small pieces which you might be able to stuff into any remaining voids.  I have certainly used this method to fill nooks and crannies when lining out my boats.

[Dr Bob]

4 minutes ago, koukouvagia said:

If you've got a sort of inspection hatch, would it be possible to pack the space with slab insulation?  It's rigid enough for the large areas and can be torn into small pieces which you might be able to stuff into any remaining voids.  I have certainly used this method to fill nooks and crannies when lining out my boats.

Or even just stuff it with glass fiber, the sort you get to do loft floors. That way you will not have any gaps. It is still a good way of providing insulation.

[anniewhere]

Hi all,

Thanks a lot for your feedback. Fire resistance is indeed something I hadn't really considered!

I have filled it all with slabs of celotex and also bought some spray foam, but it might not be necessary. I'll check again in a while to see if any condensation has occurred.

5 minutes ago, koukouvagia said:

 

[ditchcrawler]

2 hours ago, anniewhere said:

Hi all,

Thanks a lot for your feedback. Fire resistance is indeed something I hadn't really considered! 

Nor have I but I feel that if the plywood cladding is already alight I probably wont be in any state to worry about the insulation going up.

[Dr Bob]

5 hours ago, ditchcrawler said:

Nor have I but I feel that if the plywood cladding is already alight I probably wont be in any state to worry about the insulation going up.

I think I agree. If you are using Polyurethane foam, that will not melt and run down. It will burn but I am not sure it will be burning before you exit the boat ....smoke alarms, CO alarms etc. By the time the PU foam starts burning, I would think there would be enough wood burning for the boat to be a write off inside. I would hope the occupants are off the boat before the wood really catches light and the insulation takes part in the fire.

This is not true however of polystryrene foam which will melt and run down behind the wooden paneling and may 'escape' causing a much more violent fire.