under floor polystyrene

[Tim Lamb]

I have whinged before about access and repair issues where a layer of sound reducing foam has been laid on top of original flooring.

In this particular case my daughter has a London flat with vinyl strip wood effect glued to chipboard over a 25mm layer of foam. Directly in front of the kitchen sink is a join in the chipboard which does not appear to be tongue and grooved. Needless to say, movement has caused the vinyl to crack badly.

We have spare vinyl but need to stop further movement to avoid a recurrence.

The foam is obviously compressible and 8 stone applied close to the flooring edge gives several mm of differential movement. There is only enough spare flooring to tackle 300mm or so. Prising up the chipboard for a proper job not practical within her budget.

Thoughts so far after taking off the damaged vinyl:-

prise up one board and slide a stiff steel sheet under. Problems with getting it back under the second sheet, some holes might help. Difficult to spread the load very far and the polystyrene will already be compacted at the fault.

cut a strip off the edge of one board and trim the foam away. Insert an inverted *T* shaped wood support to carry the load to the original floor. This could be assembled from two pieces on site so should be easy to do.

or? routing grooves or rebates is probably outside my skills.

regards

[adder1969]

What I did, and it probably not allowed or not good practice, was to cut out a section of chipboard, remove a slice of the polystyrene down to the (concrete) subfloor,insert a wooden batten (or two) and replace the section of chipboard so that that particular part of the floor was solid. I actually used ply instead of chipboard as I was going to tile over with ceramic tiles.

[Tony Bryer]

I had exactly the same thing on our church kitchen floor. The fix was to cut some narrow slots across the join with a router about 75mm long and

12mm deep. Then drop a suitable dowel (I just used plated wood screws) in each slot and fill with fibreglass resin. This effectively stitches the two ends together - no further movement.

[Tim Lamb]

Ah. This sounds the sort of lateral thinking I need.

regards

>

[The Natural Philosopher]

Stroke of genius that one.

Another possible way to prevent relative movement is to get a glass fibre repair kit and lay up some glass fibre tape over the join.and impregnate with epoxy or polyester resin.

You can keep this all very thin and flat by using a plastic sheet - polythene - over the join weighted down with old bibles and suchlike, to make sure its very flat.

[Tim Lamb]

In message , The Natural Philosopher writes

Yes:-)

Umm.. I'd worry about adhesion to cheapo chip though. Smell in a micro flat is going to be interesting as well.

I think I'll go with the *stitching* suggestion using plated stemming.

regards

[Stuart]

As an alternative how about a fix similar to what is used to join kitchen worktops ,you know the threaded rods which sit in a recess with the ends shaped to take the rounded sections .You'll again need a router for this and depends how much room you have to use the real joining parts but maybe you could adapt one (2) or just use threaded rod and a couple of washers to take the strain ..

Stuart

[The Natural Philosopher]

Don't. It works well. Smell is not too bad with epoxy. I rather like it.

As you will :-)

[Tim Lamb]

In message , Stuart writes

The only easily available router is just about capable of the slots. The job is planned for tomorrow pm so I'm trying to keep it simple.

There might be an issue over how wide a gap the vinyl will span without dimpling.

regards

>

[Tim Lamb]

In message , Tim Lamb writes

It worked!

At least it looked OK yesterday evening:-)

The dowels were 6mm plated roofing bolts with the heads removed.

Issues arising. Scattering saw dust on a sticky floor, failure to realise how much resin would be needed (old chipboard is like blotting paper) and not anticipating that resin is thin enough to flow through tiny cracks.

I look forward to some future make-over program unearthing this patch and discussing the parentage of the perpetrators:-)

Regards to all who contributed