Cutting out windows, skylights. Before or after insulation and boarding . . ?

[Polar Bear]

The irony of it is I did appreciate your irony!

 

[sparrks]

Epic fail at the first hurdle:
Drilled and injected all the structural box sections the walls and roof of my van with aerosol expanding foam.
Extremely messy job, so decided to seal off the holes with tape straight after application - to keep the foam inside.
Next day - all the foam in the cavity has shrunk back to liquid goo. Apparently I should have kept the spaces open to allow air to cure it.
Second attempt next day:
Left the holes open, so the foam could ooze out at will.
Next day - all the foam has shrunk back to liquid goo inside the cavities.
Has anyone succesfully used this stuff in their build? Anyone had the same disaster?
Manufacturers tech dept. says 'try spraying water inside first'. Do I really want my van walls pre-soaked with water?
Nyaaagh!

I did mine on a warm day with no problem

 

[Polar Bear]

Epic fail at the first hurdle:
Drilled and injected all the structural box sections the walls and roof of my van with aerosol expanding foam.
Extremely messy job, so decided to seal off the holes with tape straight after application - to keep the foam inside.
Next day - all the foam in the cavity has shrunk back to liquid goo. Apparently I should have kept the spaces open to allow air to cure it.
Second attempt next day:
Left the holes open, so the foam could ooze out at will.
Next day - all the foam has shrunk back to liquid goo inside the cavities.
Has anyone succesfully used this stuff in their build? Anyone had the same disaster?
Manufacturers tech dept. says 'try spraying water inside first'. Do I really want my van walls pre-soaked with water?
Nyaaagh!

I've used loads of expanding foam with no problems. Outside, inside, cavities, even in lunch boxes!

You shouldn't need to dampen this time of year. Is it a good brand you are using?

I would have thought if it works as well as it should then it will be pushing your boards off or at least bulging them!

 

[sparrks]

I've used loads of expanding foam with no problems. Outside, inside, cavities, even in lunch boxes!

You shouldn't need to dampen this time of year. Is it a good brand you are using?

I would have thought if it works as well as it should then it will be pushing your boards off or at least bulging them!

Do you need to 'pad out' your lunch box?

 

[hextal]

Epic fail at the first hurdle:
Drilled and injected all the structural box sections the walls and roof of my van with aerosol expanding foam.
Extremely messy job, so decided to seal off the holes with tape straight after application - to keep the foam inside.
Next day - all the foam in the cavity has shrunk back to liquid goo. Apparently I should have kept the spaces open to allow air to cure it.
Second attempt next day:
Left the holes open, so the foam could ooze out at will.
Next day - all the foam has shrunk back to liquid goo inside the cavities.
Has anyone succesfully used this stuff in their build? Anyone had the same disaster?
Manufacturers tech dept. says 'try spraying water inside first'. Do I really want my van walls pre-soaked with water?
Nyaaagh!

:lol-049:
I laugh cos I had the same experience with some. I'd basically sprayed behind the kingspan, but it created a slight vacuum once the stuff around the edges had cured and the rest of it dried into a flat gunk.

It needs air/moisture to cure so you have to do it in relatively thin layers or the inner stuff just won't cure.

For the rib/box sections I found the recycled plastic loft insulation a much better solution, just stuff it in.

 

[Polar Bear]

Do you need to 'pad out' your lunch box?

You only do it to cheeky boys boxes?

 

[blackbird100]

I agree with Hextal, cut the holes first, and then build the frames around them, did it this way on our self build, worked a treat, Had to make a couple of adjustments with the drill, much later in the build, and the insulation was a pain in the A** gets wrapped round the drill, and not good with a jig saw at all :cool1:

 

[Longboard]

:lol-049:
For the rib/box sections I found the recycled plastic loft insulation a much better solution, just stuff it in.

Hey, I like the idea of 'stuffing' box sections with fibre as suggested - a cheap substitute for foam in larger spaces!
I'd rather use non-flammable glass fibre myself though.
I used fire retardant spray foam too, btw. The water spray technique did the trick in the end.

 

[n brown]

I agree with Hextal, cut the holes first, and then build the frames around them, did it this way on our self build, worked a treat, Had to make a couple of adjustments with the drill, much later in the build, and the insulation was a pain in the A** gets wrapped round the drill, and not good with a jig saw at all :cool1:

the whole point of making the wooden frames and sticking them to the wall/ceiling first,is that no adjustments will be needed,no insulation is anywhere near a drill bit or blade,and after the corner holes are drilled, the inner panelling and ceiling can be fitted.
then on a nice day,cutting out and fitting the windows is a breeze !

 

[hextal]

Hey, I like the idea of 'stuffing' box sections with fibre as suggested - a cheap substitute for foam in larger spaces!
I'd rather use non-flammable glass fibre myself though.
I used fire retardant spray foam too, btw. The water spray technique did the trick in the end.

I took a big wad of it out into the garden and set about it with a lighter then a blowtorch, and it was fine. Just melted slowly at the heat source then stopped as soon as the heat was removed.

Given its intended use I'd be surprised if it didn't have to meet strict fire safety codes.