Hi All, popping in to ask a floor raising question

[Craigl]

Hi All,

Firstly, thanks for a great forum, I've got loads of valuable advice just from browsing over time.

I'm stuck with a floor raising issue.

I'm wanting to tile and lay underfloor heating in my conservatory, which is currently carpeted. Under the carper is chip board, under that, about 3" polystyrene raising the floor level and then concrete.

I'll need to create a secure enough level about 3" + above the concrete to tile onto, what do you guys suggest is the best option? Essentially it's a floating floor I think, and the usual suggestion is to run, but the 'boss' is insisting on tiles and I'm not getting past her.

Would putting 18mm ply onto the chip board and screwing it down work? although this will raise the level further. Or, do I take it all up, put down beams and secure ply to this? If I do this, how do I secure the beams to the floor?

Any ideas appreciated, many thanks,

Craig

 

[DHTiling]

Hi Craig...

So below this concrete you have a DPM ye...?

If that is the case then use 150mm frame fixings and fix every 300mm and pull the floor down tight to the substrate to remove any deflection... then over board with a backer board and tile to that.. with Min S2 adhesive but you MUST remove deflection and only if you do not hinder the effect of the DPM..

Or as you say RUN!!!!!!!!!!!

 

[Craigl]

Thanks Dave.

To confirm, I fixed the 150mm beams to the floor, the chipboard or ply wood to the beams and then backer board on that? When you refer to deflection, what do you mean?

Thanks again.

 

[DHTiling]

Deflection = Bouncy bouncy

 

[Ajax123]

Remove chipboard, remove polystyrene, lay 3"battens on concrete on dpc. Screw battens down to concrete making sure the gap between the battens is 400mm. Buy 50mm polyurethane insulation boards and cut tightly between the battens. Lay hin polythene sheet over the whole lot then lay 15mm underfloor heting pipes between the joists and attach into you radiator system via a return temperature limiting valve. Fill the pipes with water and check for leaks. Mix a gypsum browning plaster with sand approx 1part sand to 1part plaster should do it. Mix with water to a semi pourable consistency and pour between the joists over the pipes. Making sure you finish it level with the top of the joists to provide a flat level surface. Overlay with 12mm ply screwed down to the joists at 300mm centres followed by 6mm hardibacker stuck down with flexible cement based adhesive and screwed down to the joists every 300mm between the screws in the ply. Then tile..........

Alternatively as Dave says......

I never like only one option

 

[Craigl]

Thanks again both. I'm thinking of going the easier route with electric heating. I essentially need to create a new suspended floor, ensure this is solid and tile that.

I think I've got it.

 

[Craigl]

Hi Craig...

So below this concrete you have a DPM ye...?

If that is the case then use 150mm frame fixings and fix every 300mm and pull the floor down tight to the substrate to remove any deflection... then over board with a backer board and tile to that.. with Min S2 adhesive but you MUST remove deflection and only if you do not hinder the effect of the DPM..

Or as you say RUN!!!!!!!!!!!

Dave, I'm slow, I've only just realised what you mean by using frame fixings to pull everything down. That's an excellent idea. I'm assuming that gluing the backer board could be only improve this?

Would ply screwed down to the chip board have any benefit over the backer board?

Thanks again

 

[Time's Ran Out]

Take up all the floating floor and put down a 75mm sand/cement screed.

 

[Craigl]

Take up all the floating floor and put down a 75mm sand/cement screed.

Agreed, that is likely to be the best option. Unfortunately I assume that it'll mean not using the area for 4-6 weeks and then only tiling?

It'll also probably be worth it in the long run.

 

[Time's Ran Out]

There are fast curing cements around (Ardurit make one) and Bal have a green screed adhesive.

 

[Craigl]

Mmm, I was keen until I checked out this calculator: Calculate and estimate Floor Screed Quantities

Recons I'll need 17 bags of cement and 51 of sand? It'll be easier to get a cube of ready mix and be done...

And then hurry up and wait.

 

[Craigl]

Hey all, just a quick update on how I got on.

So, after much deliberation, the chip board and polystyrene came up, I thought I'd do it properly. The concrete floor had a DPM, so I put joists down with 300mm centres, noggins, filled the gaps between the joists with the loose fill loft insulation and then boarded over with 18mm weather proof ply, screwed down every 30mm. The floor felt really secure and had no bounce.

It's amazing what piece of mind you get when you spend a little more time and money and do it the harder, longer way.

Thanks for the advice guys, much appreciated.

Craig

 

[DHTiling]

Well done.

 

[kilty55]

welcome