Insulation top up advice

[maywillis]

We bought a lovely narrow boat and are doing it up slowly as we go. 

Pulled out the kitchen to build more 'purpose built' units and have found the previous owner has cut away some of the insulation and exposed bits of the steel. Under the gunnel.  This explains why there was damp in the old kitchen units. 

Can people suggest how best to 'patch this up'. It's not like this everywhere, just where you can see in the pictures. 

Is it worth me scrapping away sections so that I can put a long bit of rigid insulation in, or just use a spray expanding foam on the bits you can see? 

 

I have also got some hammerite to put onto the bits that he exposed. 

[nb Innisfree]

Form a trough from plywood or some such and fix temporarily around the area, then inject aerosol foam. Wrap the trough in clingfilm before injecting to ease its removal. When film is cured trim back with a knife, the odd void or two may need topping up. 

Edited February 24, 2017 by nb Innisfree

[David Mack]

I would be inclined to cut out the irregular shaped bits of spray foam and then fit some pieces of kingspan or celotex. Try to cut them to get a good fit and tape the joints. You can fill any gaps with the aerosol expanding foam, but only use very little at a time as it expands and might push the kingspan/celotex off.

For the small amounts of kingspan/celotex you need for a job like this you can probably blag some offcuts from a building site, or try your local freecycle or freegle group.

[Giant]

I would suggest you clean up the exposed steel before adding any new foam, as it looks like it has gone rusty. Then if you apply sprayfoam it can bond to good steel rather than to a layer of loose surface rust. Or if you decide to cut blocks of solid foam, paint the steel first.

Otherwise, you are leaving a space behind the insulation where condensation can form and corrode away the unprotected steel.

[WotEver]

3 hours ago, maywillis said:

I have also got some hammerite to put onto the bits that he exposed. 

 

15 minutes ago, Giant said:

I would suggest you clean up the exposed steel before adding any new foam, as it looks like it has gone rusty. Then if you apply sprayfoam it can bond to good steel rather than to a layer of loose surface rust. Or if you decide to cut blocks of solid foam, paint the steel first.

Otherwise, you are leaving a space behind the insulation where condensation can form and corrode away the unprotected steel.

 

Couldn't work out an easy way to swap those two quotes. 

[Giant]

Ah sorry, missed that line. Still, worth giving the steel a good scrape/brush down before putting it on. Hammerite is handy stuff but not magic!

[Murflynn]

11 hours ago, Giant said:

I would suggest you clean up the exposed steel before adding any new foam, as it looks like it has gone rusty. Then if you apply sprayfoam it can bond to good steel rather than to a layer of loose surface rust. Or if you decide to cut blocks of solid foam, paint the steel first.

Otherwise, you are leaving a space behind the insulation where condensation can form and corrode away the unprotected steel.

Not necessary unless you have water dripping onto the steel.

Poly foam will adhere more readily to rough rusty steel, believe me, and if it covers the steel there will be no more rusting.

Just make sure your poly foam gets into all the spaces around the steel.

 

......................  oh, and try to find out the source of the water, maybe it was a window?  of course it may be historical rust, the source of which has now been cured.