Using expanding foam to support laminate

[leeturne]

I've put down a laminate floor in the kids playroom. The floor is mainly floorboards but at one end it is concrete leading onto old (+- 50 year old) tiles. It looks as though there was once an entrance hall there. The problem is that the concrete is about 5mm higher in some places than the floorboards. I tried to get support under the whole floor but for about 18 inches at it's most extreme height difference there is a lot of movement in the laminate. Is it possible to inject some foam under this (it's next to the skirting) and will the foam degrade?

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[Diyisfun]

Foam is not suitable for this type of application, it could also if not injected correctly push the floor up.
Sorry to be negative, I also cannot advise how to support it. But Im shure you will get some ideas soon.

 

[big-all]

heeelllooo leeturne and welcome

although 5mm will cause problems it sounds a bit like theres more causing the problem than just the 5mm discrepancy
possible causes a ridge as well as the hollow [rocking on the ridge]

have you got a clearence gap [about 6mm] all round the edges!!!!
have you got any underlay underneath!!!!

is it click type laminate or glue type!!!

 

[leeturne]

Big-all

It's click shi**, sorry type, there is underlay underneath (the board type), a constant expansion gap (7mm) and yes there is a ridge which I think is causing the problem. There is also a cellar underneath the room so I didn't want to start hacking into the concrete/tiles. At one end of the room the transition from wood to concrete is acceptable but it's just about 18inches where it's really noticeable.

 

[big-all]

at least with click type you have a chance of removal access and reassemble

is the ridge in a door way[ would cutting along the ridge help the floor settle]if its rocking on a ridge you wont cure the problem easily with packing
take a long strait edge[2m if pos] try it at a few points along the ridge also at positions accross the ridge

i personaly like the corrigated packaging the boards come in
my initial thought are remove boards at the edge [complete length]
and feed some corrigated cardboard into the hollows make shure its a mm or two thicker than the hollow to support it also a reasonable width

this will only work sucsesfully if the the hollow is about the 4mm mark and the boards arnt rocking on a ridge