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 silicone 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.

 

[Stewart]

Prep floor with suitable primer for adhesive
Install Marmox boards using SPF adhesive
Tape joints and install heat mat
Encase mat in a layer of flexible self levelling compound suitable for heated floors
Optional decoupling membrane (Ditra or New Dural CI) fixed with SPF adhesive
Install tile with SPF adhesive and seal and grout to finish

 

[davemul]

Thank you again guys. I feel much more confident now. This is a great forum.. I think i'll go buy a few pens!

Is it recommended to use a decoupling membrane? will it lessen the effect of the UFH?

oh and any reccomendations on best place to get SPF adhesive? is it specialist or avail in most big tile places?

 

[Stewart]

Thank you again guys. I feel much more confident now. This is a great forum.. I think i'll go buy a few pens!

Is it recommended to use a decoupling membrane? will it lessen the effect of the UFH?

oh and any reccomendations on best place to get SPF adhesive? is it specialist or avail in most big tile places?

You can get Mapie adhesive at Tile Giant. If you go on their website, you can find your closest one. You can also get Marmox boards from PHG who are a forum sponsor and you may even get discount for being a member.... I always tend to use a decoupler with heated floors, but make sure you only use Ditra or the new Dural CI and follow the fixing instructions to the letter. The use of the decoupler does not affect the heat mat efficiency in any way..... If you don't want to use a decoupler, you could use a two part adhesive to give increased performance.

 

[davemul]

Brill stuff Stewart, just spoke to the tiler he will be using a 2 part adhesive for the tiles.

ill go grab some of this from tile giant then (£30 for 20kg)

Keraflex Maxi White 20kg Flexible Floor Tile Adhesive - Floor - Adhesive - Adhesive / Grout

and will speak to PHG

 

[mikethetile]

hope it all goes well and welccome to the forum Dave

 

[DHTiling]

Yep PHG do sell the Marmox boards ... Waterproof Insulation Boards - PHG Wetrooms

they are infact stronger than ply IMO.. the New Marmox boards are very hard faced.. much better improvement..

 

[davemul]

Hi Mike, thanks

Here are some pics...


Conservatory with the poorly installed foam/chipboard being taken up. Take a gander at the gap between the concrete base and the door frame. should it be that much? shall I fill a portion of it in with concrete? otherwise any overhang of marmox board may result in some bounce when stood on!?

view in to kitchen

this is the gap between the kitchen and conserv... two rows of brick, gap in the middle and some form of damp course strip over the bricks, that will need replacing as it is shot at

and another (excuse my leg!)

 

[davemul]

hey guys, the base is pretty dusty.. whats best to seal it ready for adhesive?

BAL PRIME APD ?

or this http://www.tilegiant.co.uk/primer-g-1kg.html ??

 

[Colour Republic]

If using Mapei adhesive then use the Primer G, give the floor a good sweep and hoover first.

You'll need to incorporate an expansion joint across that door way BTW

 

[davemul]

If using Mapei adhesive then use the Primer G, give the floor a good sweep and hoover first.

You'll need to incorporate an expansion joint across that door way BTW

Okey doke.. Please pardon my ignorance ( i have done a bit of digging around) when you say expansion joint... you mean when tiles are being laid.. not the actual base on which I am sorting as per this thread.

In which case i'll let the tiler sort

Oooh wooden worktops arrive on Friday, new oven and dishwasher aswell...

I quite like this DIY lark!

 

[davemul]

Marmox boards are here! Now down to tile giant to get some sealer and adhesive!

 

[davemul]

Bit of an update.. boards down. Underfloor heating down, latex self leveling down, 1000 kg of limestone 20mm tiles... nearly all down!

 

[DHTiling]

Nice !!! tiling.

 

[Stewart]

Looking good and a job to be proud of.....

 

[Ian]

That looks great, I'm particularly impressed with the setting out, as we all know opus can be a bit of a pain, but that looks brill.