www.ultimatehandyman.co.uk

Hi everyone, this is my first post and would appreciate your advice.
I have a small conservatory (3mts * 2.25mts) with a tiled wooden floor. this has been bombproof for the last 9 years, then in july when those heavy rains where around, my garden could not cope and the conservatory which is just a snitch above the garden became awash with approx 25mm of water, resulting in a number of tiles lifting.

(suspect the treated timbers are bucking and dislodging the tiles.

My plan is to completely lift the old tiles/wooden floor, which will leave me with my sound original concrete base. Then I'm thinking to solve this problem I will lay approx 100mm of waterproofed concrete on top of the old base. the old base protrudes outside the conservatory, but the new base will be an internal slab. right!
My question is: how would you recommend creating an expansion joint to allow for movement, because the conservatory experiences extremes of temperature.
take in to account that the flood water came up into the conservatory it did not breach the doorways do you follow me.

Also would you advise putting another visqeen dp membrane on top of the older concrete, or just key the new concrete to the old. the old does have a dpm and as I say it's approx 9 years old.

so that is it for now, so advice sorely needed.