Hi all I am intending to spray some expander foam under the plastic shower base in my Jayco Stirling to correct a sagging problem We have been experiencing water leaks and cracks because the shower seems to have never been supported properly when built Has anyone had a go at this and could give me some hints? I was thinking the best way to insert the nozzle and then foam would be to go just under the base by drilling a hole from floor level in the ensuite but looking for suggestions cheers Len

Whooh there, be very careful, the expander foam can do more than just fill gaps, it can completely wreck what you are doing. When it expands, it can exert quite a force and if you put in too much, now how much is too much? you will have problems.
Yes our Jayco has clearance under the shower pan, haven't decided how to fix it yet. maybe Sikaflex or something that does not expand.

Hi Dolly, when ever I have used expander foam I find that it seems to expand as soon as it comes out of the nozzle which is only 150 to 200mm long. Would it be an idea to fit a much longer length of plastic tube over the original nozzle ( tight fit ) and slide this longer length in under the shower base towards the rear and then retrieve it as you spray the foam. Assuming the foam will travel the length of such hose, as I have never tried it. The only other way I can think of, short of pulling your shower apart, would be to try drilling some holes from underneath through the ply floor and inserting the nozzle from there. You would need to use a spacer block on the drill bit so as to only leave enough drill bit protruding to drill through the thickness of the flooring and not into the bottom of the shower base. The holes could be filled with Sikaflex or similar to stop moisture penetration later.

Good Luck Rob.

Thanks everyone! Plenty to think about that's for sure We live in our van and rather than handing an otherwise well maintained van to a repairer for days on end we would prefer to do it ourselves So... the idea of going in from underneath sounds good ...will give it a go and report back!

Again I say be careful, I once used foam to block up holes in a window I installed in my old brick house, this was a 2 x 6 windowsill, the foam bent this wood up, jammed the window, its a wonder it didn't shatter the glass. If you find the floor of your shower could look like a raised cake top, I have warned you.
On the other hand I haven't used it on a flimsy Jayco shower base.

I've done a few IceBoxes etc for extra Insulation.

The trick is to drill multiple holes so you can insert nozzle and fill till it shows at next holes
and go progressivly across area.
VERY hard to do Properly.

and don't forget.
Expanded foam is brittle (normally) after mixing.
and will, over time break down and you're left with sagging effect again
after walking in/out on it for a while

If you that concerned.
Get a sheet of thicker plastic. Fibreglass.
and overlay over the floor of shower. with hole drilled for drain.
then seal around to stop water.

Easiest thing is to either forget it and carry on.
or lose some weight (chuckle)

There is a way from underneath,
But involves a larger hole underneath, in floor of van
coupla steel plates and a threaded screwbolt to adjust.
with larger timber flooring put back Inside. screwed in place
Screwbolt adjusted to suit from outside\underneath the floor itself..

Dolly, just another thought. Instead of using expanded foam, how would using a few tubes of silicon, Sikaflex or similar go. Drill holes from underneath and pump it in. Selleys , sold in the sausage packaging is less inclined to slump as much as the other two, but is also harder to squeeze out. Sold in the paint section of the big green h'ware shop. This of course all
depends on how much gap there is between top of floor and underneath face of shower base. Too much gap and it would take more than one application to allow for slump.

Cheers Rob.