Complex kitchen floor tiling repair job. uneven floor. what should I do?

Jack_Bauer

Hi,

My kitchen floor is not level as can be seen here.

• Floorboard to white kitchen leg towards the back, it is 28mm in height.

• Floorboard to white kitchen leg by oven on the left-hand side, it is 21mm.

• Floorboard to hallway door, it is 17mm in height.

That means, from one end to the other, there is a difference of 11mm in height. The kitchen has been built on top of the existing tiled floor and cannot be removed for my job.
In the exposed area, the previous tiles and adhesive have been taken up leaving Plywood with failed latex. These will need to be removed and they are included in the height considerations above.

Previous tilers laid 6mm Plywood and 10mm tiles. To overcome the height issues and level the floor, they tiled with only 1mm tile adhesive by the hallway, 5mm adhesive by the left hand side leg and across the whole middle area, and 12mm of adhesive towards the rear end leg area to make the floor level.
They used dot and dab, and didn't properly secure the plywood to the floorboards resulting in the tiles failing.
I need to get it redone but not sure what the best approach is. I have purchased replacement 10mm 600x600 porcelain tiles.

I am considering options of going with or without UFH. My assumed calculations are:

1. Using UFH. Floor height:

• Adhesive (3mm)
  
• Insulation board (6mm)
  
• Adhesive (3mm)
  
• Membrane with UFH cable (5.5mm)
  
• SLC (3mm)
  
• Adhesive (3mm)
  
• Tile (10mm)

Total height is 33.5mm

If a tiler went ahead with this option, with the gaps available at the 3 points, this will create a height difference of 16.5mm with the hallway floor, eat into 12.5mm of the left hand side leg and eat into 5.5mm at the rear end leg.
I am guessing this means that the tiles would have to be cut around them, and the kick boards would have to be cut to fit the reduced height. At the hallway end, the floor height difference between the hallway and the kitchen would be 16.5mm and a door transition will need to be used and part of the door cut. The floor would still not be level and I am not sure how discernible this would be.

2. No UFH heating

Floor height:

• Thinset (3mm)
• Hardiebacker (6mm) 
• Tile Adhesive (3mm) 
• Tile (10mm)

Total height therefore is 19mm

I am thinking if I got a tiler to go ahead with this option, this will add a mere 2mm to the hallway side, leave a gap of 2mm at the left hand size leg size and leave a gap of 9mm at the rear end leg. I'm assuming gaps can be filled with more tile adhesive in those areas when tiling which can then make the floor level.

Are my assumptions correct? I would absolutely love to get UFH on my floor as this Kitchen is arctic. It gets super cold being surrounded by Windows and with only a little paltry radiator but I am thinking that the easiest/best option is to retile the floor without it and go with option 2? Or is option 1 possible?

Are there any expert tilers here tell me what they would do to tackle this? What is feasible? What would you recommend your client? If I went with option 1, will the un-level floor look obvious considering it is only 11mm between the ends? Do I have no choice but to go with option 2? Are there any other options?

I have tilers quoting me £2500-£3000 for option 1 and £1500 or so for option 2 FYI but not sure what the best approach is.

Thanks

grumbler

What is the plywood sitting on? Joists?

Personally, I hate even tiling around units, let alone 33mm UHF. For UHF I'd remove the existing plywood where possible an put the insulation between the joists.

Jack_Bauer

grumbler said:

What the plywood is sitting on? Joists?

Personally, I hate even tiling around units, let alone 33mm UHF. For UHF I'd remove the existing plywood where possible an put the insulation between the joists.

Hi grumbler,

The Plywood is sitting on floorboards.

So you're saying to just insulate the floor under the floorboards and forgo the electric UFH system?

grumbler

No. IMO it's still worth having insulation under UFH and you can have more than 6mm between the joist.

Most likely the boards go along the kitchen and the joists across it. If so, I think, both the plywood and the boards can be removed partly, then insulation added, even under the units where the boards,and the plywood remain. Then, I think, 12mm plywood will be sufficient without any boards, possibly even 10mm with thicker hardback.

Jack_Bauer

grumbler said:

No. IMO it's still worth having insulation under UFH and you can have more than 6mm between the joist.

Most likely the boards go along the kitchen and the joists across it. If so, I think, both the plywood and the boards can be removed partly, then insulation added, even under the units where the boards,and the plywood remain. Then, I think, 12mm plywood will be sufficient without any boards, possibly even 10mm with thicker hardback.

That sounds like a much bigger job.

If I am understanding this correctly, your suggestion helps two solve issues:

1. More insulation to make the kitchen warmer

2. Reduces the height

Is that correct?

grumbler

Yes, but beware, I am a perfectionist.

FreeBear

Jack_Bauer said:

grumbler said:

No. IMO it's still worth having insulation under UFH and you can have more than 6mm between the joist.

Most likely the boards go along the kitchen and the joists across it. If so, I think, both the plywood and the boards can be removed partly, then insulation added, even under the units where the boards,and the plywood remain. Then, I think, 12mm plywood will be sufficient without any boards, possibly even 10mm with thicker hardback.

That sounds like a much bigger job.

If I am understanding this correctly, your suggestion helps two solve issues:

Also gives you opportunity to fix a third issue - The change in height across the floor.

Once the plywood and original boards are up, the joists can be jacked up and packing shims inserted so that you end up with a level floor. Yes, a bigger job, but adding insulation under the floor will pay dividends in terms of keeping the room warm.

Jack_Bauer

grumbler said:

Yes, but beware, I am a perfectionist.

I'll be honest, I see how that helps with insulation but I don't see how that helps the height of the floor issue. My assumption always was that I would start from the floorboards, after removing the existing 6mm ply and failed latex. The height measurements I have given at the 3 Kitchen points assumes this. Not sure in case I'm getting confused so apologies if so but for clarity I have added them again below and they assume there is no plywood and latex

• Floorboard to white kitchen leg towards the back, it is 28mm in height.

• Floorboard to white kitchen leg by oven on the left-hand side, it is 21mm.

• Floorboard to hallway door, it is 17mm in height.

You mention then adding 12mm plywood as being sufficient without boards. This would add 6mm to the height of the UFH floor, assuming you mean using the 12mm ply instead of the 6mm insulation board on my UFH stack? Or are you suggesting to just use the 12mm ply and forgo the UFH system once the underfloor has been insulated. I'll be honest, that won't help to heat the room much as there are very large window everywhere.

Jack_Bauer

FreeBear said:

Jack_Bauer said:

grumbler said:

No. IMO it's still worth having insulation under UFH and you can have more than 6mm between the joist.

Most likely the boards go along the kitchen and the joists across it. If so, I think, both the plywood and the boards can be removed partly, then insulation added, even under the units where the boards,and the plywood remain. Then, I think, 12mm plywood will be sufficient without any boards, possibly even 10mm with thicker hardback.

That sounds like a much bigger job.

If I am understanding this correctly, your suggestion helps two solve issues:

Also gives you opportunity to fix a third issue - The change in height across the floor.

Once the plywood and original boards are up, the joists can be jacked up and packing shims inserted so that you end up with a level floor. Yes, a bigger job, but adding insulation under the floor will pay dividends in terms of keeping the room warm.

Can this be done with the kitchen still in place?

At what height point would I be attempted to level the floor at?

grumbler

Jack_Bauer said:

grumbler said:

Yes, but beware, I am a perfectionist.

I'll be honest, I see how that helps with insulation but I don't see how that helps the height of the floor issue....

This helps if you need to insulate the floor. IMO 6mm is inadequate insulation for a cold ground floor.

You mention then adding 12mm plywood as being sufficient without boards. This would add 6mm to the height of the UFH floor, assuming you mean using the 12mm ply instead of the 6mm insulation board on my UFH stack? Or are you suggesting to just use the 12mm ply and forgo the UFH system once the underfloor has been insulated. I'll be honest, that won't help to heat the room much as there are very large window everywhere.

boards+plywood+ins.board ~ 20+6+6=32mm

12mm plywood +10mm backer = 22mm. Hard foam nsulation is under the plywood, between the joists.

Jack_Bauer

grumbler said:

Jack_Bauer said:

grumbler said:

Yes, but beware, I am a perfectionist.

I'll be honest, I see how that helps with insulation but I don't see how that helps the height of the floor issue....

This helps if you need to insulate the floor. IMO 6mm is inadequate insulation for a cold ground floor.

You mention then adding 12mm plywood as being sufficient without boards. This would add 6mm to the height of the UFH floor, assuming you mean using the 12mm ply instead of the 6mm insulation board on my UFH stack? Or are you suggesting to just use the 12mm ply and forgo the UFH system once the underfloor has been insulated. I'll be honest, that won't help to heat the room much as there are very large window everywhere.

boards+plywood+ins.board ~ 20+6+6=32mm

12mm plywood +10mm backer = 22mm. Hard foam insulation is under the plywood, between the joists.

It should be boards + ins.board ~ 26mm. The insulation board, replaces my Ply under my original scenario.

So based on the above, I would gain 4mm effectively if I did this? I don't think it is worth the effort.