I used a wall paper scraper. Once you get it behind the poly it will separate easy without fear of damage to the skin as the angle of attack is so shallow.
I found I had to remove the poly as even though it was stuck firmly it was very wet between the skin and poly. Once the water works it's way in there is no way for it to evaporate away.
No point doing a repair and trapping water in there.
When replacing the foam I used a combination of solvent free grab and PU adheisive. Not together but when I ran out of PU I got some grab from local DIY centre. In my experience the PU was better in low temps as it is moisture curing. Solvent free grab dries by evaporation so this time of year it takes a long time.
Quote: Originally posted by jayc001 on 10/12/2013
I found I had to remove the poly as even though it was stuck firmly it was very wet between the skin and poly. Once the water works it's way in there is no way for it to evaporate away.
No point doing a repair and trapping water in there.
Strange! I have found that the foam always dries out. It isn't waterproof, so water will evaporate through it. Some gentle heat from a fan heater blowing on the outside ally skin would have helped dry it.
I had a large dehumidifier running 24/7 in mine for a month after removing all the wallboard. When scraping the foam off the walls it was dripping in water still.
This time of year a 3kw fan heater is going to have no affect on a tin snail unless it's already inside a heated workshop.
Sounds like you still had a leak somewhere. The stuff absorbs water as it isn't waterproof, but dries fairly quickly for the same reason. Closed cell foam like Styrofoam doesn't absorb water at all.
From a building construction manual (EPS = Expanded Polystyrene, XPS = Extruded Polystyrene);
"EPS water permeability
EPS breathes better than XPS
EPS is less waterproof than XPS, but only because XPS typically comes with a thin polyethylene film bonded on each side. In wall design it is actually rather important that walls can dry out so it is actually a benefit that EPS is "less waterproof" because it does allow some water vapor to permeate through to dry the inner wall."
we put a dehumidifier in front of the polystyrene wall for a few days, its sucked out several litres and is now bone dry, in fact if we had have known this to start with we wouldnt have stripped any of it out!