Conservatory floor/base - Help please, its all coming up!

[davemul]

Hi guys. Long story short....

We moved in to our new house a while back with 3 year old conservatory. All floor tiles loose, grout all cracked. Pulled them all up pretty much by hand (we're having stone laid now)

Under the tiles is 20mm T&G chipboard boards on top of 25mm styrozone foam sheets (chipboard & foam is glued together) This is laid on a concrete base

this floor was as springy as you like, not firm hence causing the cracking/breaking tiles.

Ive taken up all of the chipboard and attached foam leaving a pretty sound concrete base 45 to 50mm lower than the kitchen floor that the conservatory is attached to.

My question is, what can I put down to replace this with so it is FIRM. I was thinking 25mm x 50mm treated timber batons screwed in to the concrete base with foam in between. Then screw down sheets of 20 or 25mm treated plywood to these batons. I need something that takes up about 50mm max that is firm, unlike the chipboard ive just removed!

Does that sound feasable? or does anyone have a better solution? I need a firm base in which to lay insulating boards, underfloor heating, flexible SLC and then the stone flooring.

many thanks guys and sorry for the waffle! I will add pics tomorrow as it is dark now and no lights in the conservatory (another remedy to make!)

Dave

 

[Colour Republic]

The stone going down is limestone right?

 

[Stewart]

Install 40mm marmox then heat mat then slc then tile....

 

[davemul]

Hi guys

The stone will more than likely be this stuff (same cost as limestone but easy to maintain/no sealing required)

Zeus Limestone Flooring

Hi Stewart, 40mm board is too thick as the conservatory joins to kitchen. From the concrete conservatory base I have about 50mm max before I lay the insulating boards for UFH and then the mats

 

[Stewart]

Hi guys

The stone will more than likely be this stuff (same cost as limestone but easy to maintain/no sealing required)

Zeus Limestone Flooring

Hi Stewart, 40mm board is too thick as the conservatory joins to kitchen. From the concrete conservatory base I have about 50mm max before I lay the insulating boards for UFH and then the mats

It comes in sizes of 6mm to to 50mm ......

 

[davemul]

aaaah just had a look on their website.

I could go this route with 50mm thick marmox (laid directly on to the concrete base with flex tile adhesive)

Marmox Board - CONCRETE FLOORS

or would I be better screwing batons down with hammer fixings and screwing on to these with a thinner marmox board?

Is marmox just as strong/rigid as plywood?

 

[mikethetile]

leave timber out of the construction and build up from your concrete base as described above

 

[akinsontiles]

If you install timber batons you could penetrate the damp proof membrane which will be under the screed you are drilling into causing more problems later. I would advise the use of the boards simply because they are rigid and offer an ideal background to tile onto.

So long as you allow for expansion around the perimeter of the floor which is filled with a flexible substance such as Silicon and the skirting board is placed over this joint then you will have a floor that is fit for life.

Use a spirit level when laying the marmox and use the re-inforcing strips to prevent any chance of movement later. The other route you may have considered could have been a screed to bring it up to level followed by a de-coupling membrane but if you are not experienced in this then it could go really wrong and the marmox boards are an easier solution.

 

[davemul]

Thank you so much guys. So just to recap...

The course of action is to clean the concrete base, remove any dust. Mix some powdered flexible tile adhesive (any reccomendations on brand?) and lay my desired thickness of marmox board in a staggered pattern. Taping the joins once the adhesive has set. Leaving say a 5mm perimeter aound the base for expansion?

And this will be strong / firm enough with no bounce (provided I lay a continuous layer of adhesive on the concrete base)

I will put pictures up of the progress... will make a start this eve

 

[akinsontiles]

Absolutely strong enough. If you are laying a heat mat onto this as well you can self level over it to protect the heat mat from damage. Using a plastic serator reduces the risk of damage to the electrics as well when laying your tiles.

Limestone can be a bit of a bugger to work with sometimes so make sure you set it out so that you have no fiddly little cuts into doorways etc that could cause you bother. If you get the prep level then you tiling should be an easy enjoyable experience so don't rush it.