Help!: Advice needed please....

[vovo]

Hi

First time DIY and currently doing the bathroom. Need some advise please..

Originally it had chipboard 25mm and carpet but it's molding. We are
thinking of putting on new floor board (plywood) install underfloor
heating and tile on top.

Which is better option?
1) layer from bottom:
- 18mm plywood on the joist about 40cm apart
- 6mm ekoboard/any insulating board
- underfloor heating matting
- ceramic tiles
(is 18mm sufficient as base?)

2)
-25mm plywood on joist 40cm apart
- underfloor heating matting
- ceramic tiles directly on plywood
(do I need ufh insulating board as it will increase the floor
thickness with 25mm plywood)

3)
- 25mm plywood on joist 40cm apart
- 6mm insulating layer
- underfloor heating matting
- ceramic tiles directly on plywood


Is Dunlop tile on wood adhesive suitabe for joining the layer between

1)plywood and insulating board?
2) tiling ceramic tiles with heating matting on insulating board?
3) tiling ceramic tiles with matting on plywood?
If it's not suitable can anyone pls recommend suitable adhesive for
all the 3 layers above?


Would appreciate your help/suggestions.

[jay]

a couplle of questions what room are you doing bathroom dinning kitchen how strong is the floor in reg ti deflection and why is it going moldy

[Paddyh2]

I have many times done the following

1. Replace old floor with 18mm weyroc (chipboard) screwed to beams.
2. 6mm WBP ply screwed every 200mm to flooring
3. prime ply with acrylic primer
4. Fit UFH matting/wire
5. Cover matting/wire with flexible self levelling compound
6. Tile using flexible adhesive compatible with UFH.
7. Flexible grout

So I reckon your option 1 is as good as....(probably better if a full board of 18mm ply)

Can't comment on the Dunlop....never used it

Good luck

[365drills]

this is something like what you would be looking at for the floor sandwich.



Obviously the UFH matting would be between the ply and tiles.

[Richardk]

I have many times done the following

1. Replace old floor with 18mm weyroc (chipboard) screwed to beams.
2. 6mm WBP ply screwed every 200mm to flooring
3. prime ply with acrylic primer
4. Fit UFH matting/wire
5. Cover matting/wire with flexible self levelling compound
6. Tile using flexible adhesive compatible with UFH.
7. Flexible grout

So I reckon your option 1 is as good as....(probably better if a full board of 18mm ply)

Can't comment on the Dunlop....never used it

Good luck

6mm insulation or Hardie backer board would be a better option imo. Fix with spf and screws.

[vovo]

a couplle of questions what room are you doing bathroom dinning kitchen how strong is the floor in reg ti deflection and why is it going moldy

Its for bathroom, moldy probably due to water leaking through.

I'm not sure what it means with "how strong is the floor in reg ti deflection" - there is no floor at the moment.. bathroom is upstairs, and only joists 40cm apart.

Is 18mm plywood sufficient as base directly on the joist, or should I go for 22/25mm plywood?

Thanks.

[Matt]

Its for bathroom, moldy probably due to water leaking through.

I'm not sure what it means with "how strong is the floor in reg ti deflection" - there is no floor at the moment.. bathroom is upstairs, and only joists 40cm apart.

Is 18mm plywood sufficient as base directly on the joist, or should I go for 22/25mm plywood?

Thanks.

25mm would be better and I would also add extra noggins so that there is no more than 300mm between screws. 400mm is alittle to far apart

Edit: Jay means is there any movement (Deflection) in the floor.

[vovo]

25mm would be better and I would also add extra noggins so that there is no more than 300mm between screws. 400mm is alittle to far apart

Thanks for quick reply - I'm just worried that if require an insulator board,and UFH on top the floor will be too thick.

The other question is Richardk was suggesting the following:

1. Replace old floor with 18mm weyroc (chipboard) screwed to beams.
2. 6mm WBP ply screwed every 200mm to flooring
3. prime ply with acrylic primer

Just wondering why do you need a 18mm weyroc + 6mm ply , why not a thicker layer of ply?

And what's the purpose of prime ply wiht arcylic primer? Is it for insulation purpose, if yes, can I just prime my 25mm ply, and not having the insulating board?

[vovo]

this is something like what you would be looking at for the floor sandwich.



Obviously the UFH matting would be between the ply and tiles.

I can see 2 layers of base ply in this picture, just wondering if I want a 18mm ply, would it be better if I have 2 pieces of 9mm on top of each other or 1 piece of 18mm?

How do you join the 2 ply together?

[Matt]

Thanks for quick reply - I'm just worried that if require an insulator board,and UFH on top the floor will be too thick.

The other question is Richardk was suggesting the following:

1. Replace old floor with 18mm weyroc (chipboard) screwed to beams.
2. 6mm WBP ply screwed every 200mm to flooring
3. prime ply with acrylic primer

Just wondering why do you need a 18mm weyroc + 6mm ply , why not a thicker layer of ply?

And what's the purpose of prime ply wiht arcylic primer? Is it for insulation purpose, if yes, can I just prime my 25mm ply, and not having the insulating board?

I personally wouldn't use chipboard and would just put 25mm WBP ply onto the joists (With noggins)

You don't need to prime the face of the ply. If you were using the ply as an overboard, you would prime the bottom and edges of it, but not the face.

You don't need insulations boards, but, they do what they say on the tin. It will be more economical in the long run. Ply isn't too bad for UFH. Uninsulated concrete is the worst and would definitely require insulation boards.

[vovo]

I personally wouldn't use chipboard and would just put 25mm WBP ply onto the joists (With noggins)

You don't need to prime the face of the ply. If you were using the ply as an overboard, you would prime the bottom and edges of it, but not the face.

You don't need insulations boards, but, they do what they say on the tin. It will be more economical in the long run. Ply isn't too bad for UFH. Uninsulated concrete is the worst and would definitely require insulation boards.

Thanks Matt - I'll skip the insulation board.

Can you recommend what kind of prime to buy/use? Is it for water resistance?

Also I need to find out how to make noggins..

Cheers.

[Matt]

Thanks Matt - I'll skip the insulation board.

Can you recommend what kind of prime to buy/use? Is it for water resistance?

Also I need to find out how to make noggins..

Cheers.

If you want to waterproof it, then a waterproofing membrane or paste would be better. The primer is just to help the adhesion between the ply and whatever is under it. (Because you are not overboarding, you don't need to prime).

[Paddyh2]

[QUOTE=matt257;277280]
You don't need to prime the face of the ply. If you were using the ply as an overboard, you would prime the bottom and edges of it, but not the face.QUOTE]

I always prime the top. If anything it helps the adhesion when sticking the mat down. Any dust and nothing sticks.

[Daz]

I think you should only use a heating element of max 100 watts if you set it on ply (Uheat will confirm or deny this), but you can use a 160 or 200 watt element if using insulation boards.

I think Aaron mentioned this to me when he was working there.

[vovo]

Can anyone recommend where to buy 25mm plywood please?
Have a quick look and they seem to be really expensive about £50 per sheet, and I need 2 for my small bathroom!

[kilty55]

if you have access to a builders merchants you will get it cheaper than that mate

[Matt]

I think you should only use a heating element of max 100 watts if you set it on ply (Uheat will confirm or deny this), but you can use a 160 or 200 watt element if using insulation boards.
I think Aaron mentioned this to me when he was working there.

Hmmmm, this is not something I have heard. I know our UFH supplier say that 150w mats are suitable for ply.

[vovo]

if you have access to a builders merchants you will get it cheaper than that mate

Which builders merchants do you guys normally go to? Do I need a tradecard for that?

I can see that Selco has the 25mm for £44.19 (excluding VAT) - is the price reasonable or where can I get them cheaper?

Thanks.

[Richardk]

Thanks for quick reply - I'm just worried that if require an insulator board,and UFH on top the floor will be too thick.


The other question is Richardk was suggesting the following:

1. Replace old floor with 18mm weyroc (chipboard) screwed to beams.
2. 6mm WBP ply screwed every 200mm to flooring
3. prime ply with acrylic primer

Just wondering why do you need a 18mm weyroc + 6mm ply , why not a thicker layer of ply?

And what's the purpose of prime ply wiht arcylic primer? Is it for insulation purpose, if yes, can I just prime my 25mm ply, and not having the insulating board?

It was another poster who suggested 6mm ply, I was suggesting backerboard. I prefer to keep wood out of the equation.

[vovo]

Just checking again if anyone could recommend where to get cheaper 25mm plywood? Tried looking online but not found anything thanks