Support for Kitchen Floor joists

[digitalfm]

Hi, can you please help.

My Kitchen was extended to which half the floor is concrete, the other half (the extension) is a suspended floor with 6 inch joists every 35cm.

The floor feels a tad spongy which was fine for laminate but I'm going to tile the floor so have been advised to stiffen it a little.

Under the floating floor is a drop of about 1 meter with a concrete base underneath. Think of it as a mini cellar underneath.

I'm thinking of simply wedging some upright wooden struts between the concrete base and the joist. I've done this on one and the joist feels a lot more firmer as a result. The strut is 2inch squared in thickness.

My question is : will expansion of the strut push the joist up enough to pop the tiles above? Anything I can do to stop expansion of the strut? ... or am I over thinking?

Your help is appreciated.

[ALDA]

D,

IDEALY, A VENTED DWARF WALL SHOULD BE BUILT TO SUPPORT JOISTS.

YOU CERTAINLY WON'T BE THE FIRST OR THE LAST PERSON TO ADD EXTRA SUPPORT TO THE FLOOR IN THE WAY IN WHICH YOU DESCRIBE AS IN A TIMBER FLOOR ONLY THIS WOULD ACHIEVE THE DESIRED EFFECT BUT BECAUSE YOU WANT TO TILE THE FLOOR, YOUR CONCERNS OVER THE EXPANSION PROBLEMS ARE VALID ONES.

ALSO, ANY TIMBER RESTING ON CONCRETE SHOULD HAVE A DPM INSERTED INBETWEEN AND THE TIMBERS FIXED INTO POSITION RATHER THAN JUST BEING WEDGED.

A.

[digitalfm]

Thanks for the reply.

I've seen Wickes does treated Kiln dried timber. Would this be the best bet for minimizing expansion. The area below the floor is protected from the weather, exposed to the moisture in the air only.

Any one else got recomendations? The Water proof membrane was a good suggestion. Should have thought about that. :-)

[stevenc1603]

I've done the prop with wood method myself. In my case it was to stop the washing machine from shaking the house to bits when it went into spin cycle.

Chances are the concrete base will be below the DPM level so you will need s small bit of membrane to prevent moisture from traveling up the way.

Not sure how best to prevent expansion problems as our floor is wood so its not an issue for me.