Floor make up questions and options

[ProDave]

We have suspended floors downstairs made of JJI joists at 400mm centres.  Insulated between and overlaid with 11mm OSB

 

Original plan was lay 25 by 50 battens on top of OSB following the joists. Lay UFH pipes in the void created by the battens, fill with biscuit mix and overlay with structural flooring, most likely an engineered board with a lacquered Oak finish.

 

The total make up thickness of that option is 47mm and that is the height at which the door thresholds should have already been set, so cannot now be changed though as it happens the thresholds are a little higher than I had expected so we could probably stretch that to a total makeup thickness of 52mm

 

First question:  Is a lacquered finished oak board going to be a success in a room that is partly the kitchen?

 

Now regardless of the answer to that, the hallway will be some form of tile, probably slate. So we need a robust floor make up that will give a solid surface for tiling, will incorporate the under floor heating pipes, and will provide a level transition from the wood to the tiled floor.

 

My thoughts:

 

Span across the joists with strips of 18mm chipboard. The gaps in the strips will be where the UFH pipes run, using aluminium spreader plates that lay on top of the chipboard.  Span over the whole lot with 15mm plywood glued and screwed to hell. Tile over the plywood.  Assuming 12mm tiles that will be about the right make up thickness. depending on the thickness of adhesive.

 

Here is a rough mock up of that idea:

 

 

I have used another layer of chipboard for that mockup but the top layer would be plywood.

 

The spreader plates (assuming I do use those) are 170mm wide and the UFH will be at 200mm centres so there won't be much gap between adjacent spreader plates.

 

Problems with this:

 

I have not yet found 15mm ply locally. Jewson can do 12mm (too thin I am sure) or 18mm.  The 18mm would be pushing the total make up thickness to over 50mm needing a very thin bed of adhesive to meet the door thresholds (could thicken up in other areas)

 

I have been quoted £62 per sheet for 18mm marine ply. More phoning to improve on that. Does it NEED to be marine ply?

 

Any other thoughts on alternative floor make up for this tiled section?

 

 

 

 

[PeterW]

Fermacell can be used for the top floating surface and takes tiles direct. You can also use one of the EPS track systems to keep the UFH in place and also improve on insulation. 

 

It doesn't have to be marine ply - you can also use HardieBacker which is plenty strong enough at the centres you are talking about. 

[Onoff]

You can get 15mm in WBP ply.

[HerbJ]

7 minutes ago, PeterW said:

Fermacell can be used for the top floating surface and takes tiles direct. You can also use one of the EPS track systems to keep the UFH in place and also improve on insulation. 

 This is essentially what I installed for my 1st Floor.  I used a relatively expensive system, with some focus on the sound proofing aspects,  but there are much cheaper systems available with different floor buildups.

 

i enclose the Firmacell flooring info and the integrated product I used

ECO-10U Pt E.pdf

Fermacell_Flooring_brochure_s_1109.pdf

[Construction Channel]

Def no to the marine ply. What BM’s have you got about. 15mm standard ply is fairly common around here. I assume it would be the replacement for old 5/8. 

 

Or if you really had to you could go 11mm OSB followed by 3.6mm ply which I’m sure would be close enough for tiling. 

[ProDave]

I need to move this on and make a decision.

 

So if I go for the tiled floor with an 18mm ply base layer, just what sort of plywood do I need?  We have agreed Marine ply is way over the top and too expensive.  The merchants are offering me a bewildering array of different types from shuttering ply at £21 per sheet, "grade 1" for £29.50 per sheet and "gold" at £37 per sheet.  I have no idea really what any of those are and which one is right.

 

Only TP and Jewson locally but many more in Inverness, I haven't tried them all yet.

 

But the more fundamental question is do we go for the tiled floor or the oak floor?

 

My concern is the logevity of tiles.  If we do choose tiles, SWMBO wants tiles that look like wood.  I am mindful of the tiles we had in our last kitchen which at 15 years old are looking tired and scratched, they are not proving to be the indestructable everlasting floor we had expected.  If there is any chance of the same happening to these wood effect tiles, I would rather go back to plan A and fit real wood.

 

 

[Onoff]

I believe that BS EN 636-3 ply uses the same glue as marine ply which is BS 1088 but that marine ply uses harder wood for durability. The 636 can use anything. 

[newhome]

Not a technical comment, just an observational one. I have tiles in the kitchen / family room, and the hall and they’ve been down since 2009. They are not scratched at all. I would say that engineered oak is much more easy to scratch as I have it everywhere else. A 6mm wear layer is pretty essential in high traffic areas I think. 

 

My friend has a kitchen family room and she has tiles in the kitchen area and wood in the family area and it looks pretty good as the join is done really well. The tiles are cream however so a complete contrast to the wood. As a different sort of option I had Karndean Da Vinci wood effect in my last house and it still looked amazing after 10 years. Again we went for the thickest wear layer as we have dogs. 

 

We looked at lots of engineered wood flooring and had loads of samples everywhere. In the end Jewson gave us a great price on an Atkinson and Kirby 22mm oak board so we went with that. 

 

 

 

 

Edited May 19, 2018 by newhome

[Nickfromwales]

Dave. 

Why the 11mm layer? To hold the biscuit mix ?

Q2, why the biscuit mix ?

Use the 11mm OSB to support proper plates ( not that plate shown in the pic above, never seen something so weird as that before TBH ) and then just plates over a 20mm batten and then your floor covering ( 22mm finished engineered board ). 

For areas where your tiling you'll need 18mm OSB or P5, overlaid with 9mm ply, then primer then adhesive then tile. 

Where is your 47-52 allowance taken from ? After the 11mm OSB ? If tight for height, lift the 11mm layer, batten the JJI's and drop the 11mm flush with the joist tops. 

[Ian]

@ProDave

if your’re worried about tile longevity choose a porcelain with a high PEI wear rating. Guide to ratings:

https://www.builddirect.com/learning-center/flooring/porcelain-tile-rated-hardness/

[ProDave]

51 minutes ago, Nickfromwales said:

Dave. 

Why the 11mm layer? To hold the biscuit mix ?

Q2, why the biscuit mix ?

Use the 11mm OSB to support proper plates ( not that plate shown in the pic above, never seen something so weird as that before TBH ) and then just plates over a 20mm batten and then your floor covering ( 22mm finished engineered board ). 

For areas where your tiling you'll need 18mm OSB or P5, overlaid with 9mm ply, then primer then adhesive then tile. 

Where is your 47-52 allowance taken from ? After the 11mm OSB ? If tight for height, lift the 11mm layer, batten the JJI's and drop the 11mm flush with the joist tops. 

Explain the plates you are thinking of.

 

The plates pictured are some I already have.  I will need more if I do the tiles floor, so will probably buy some of these https://www.ebay.co.uk/itm/Aluminium-UFH-Spreader-Plates-for-Water-Underfloor-Heating-Systems-Qty-40/261653810327?hash=item3cebc84c97:g:1kUAAOSwY3RXJmVp

 

So the idea is support those on 18mm chipbopard just with gaps for the pipe then ply over the top to take the tiles.

 

The only other option I can see is the sheets of PIR type insulation with channels cut in them for the UFH pipes, but that would make the whole lot a floating floor not fixed down?

 

In the case of fitting the spreader plates, ply then tiles, then the OSB layer that is there is doing nothing at all. But if I remove it I would have to built up more with something else otherwise my FFL will be too low, so it might as well remain.  The OSB layer was fitted originally to support the biscuit mix  if we go for the wooden floor.

 

The best option we have been offered for wooden flooring is a 190mm wide engineered wood with oak as the top layer, I forget the thickness of the actual wooden top layer. We are looking at one with a laquered finish, on the basis if it gets too tatty it can be sanded and laquered again.

 

If we choose tiles, then SWMBO wants tiles that look like wood. I can't see that working as the kitchen end tiles and the living room end wood, it would be too much the same, yet different. So if we choose tiles, it will be for that whole room.

 

 

[Nickfromwales]

These have far more surface contact against the deck above. Tried and tested. 

I'm not a fan of the one you've shown as it appears to favour emissivity to the down side. 

Use the 11mm layer to support rockwool strips. Use the rockwool to make the plates sit slightly distended so your deck squeezes them back down ensuring excellent surface to surface contact, essential for good heat transfer characteristics.

Just been to look at a job with the plates out of contact with the deck ( P5 ) and the entire flat refusing to achieve temp. Told them the floors all need to come back up and get a decent fitter back. Flow temp was set to 60oC when I arrived !!!

The insulated panels get bonded down with a spray on contact adhesive. They then need another layer bonded over that to accept tiles ( HDF iirc ) or the 400kpa aluminium which will take a tile DIRECTLY. 

Link

 

[newhome]

We went for a 22mm thick board as it was to be laid over joists upstairs but also because the 6mm wear layer meant it could be sanded down a few times if needed. A 2 or 3mm wear layer can be sanded too of course but probably less times than 6mm. If longevity is important I would choose a thicker wear layer otherwise you might be down to the ply if you sand it say 2 or 3 times. 

 

 But personally I would go for tiles but choose carefully. 

 

 

 

 

[ProDave]

1 hour ago, Nickfromwales said:

 or the 400kpa aluminium which will take a tile DIRECTLY. 

Link

 

That has turned all the options on their head.

 

I have looked at the link and watched the video. NOT enough detail (like even basic stiff like the sheet size so I know how many I need and can cost it)

 

So all I gleaned is they are a structural 20mm thick panel with grooves for the UFH pipe and I can tile straight on top.

 

That gives me another problem, not ENOUGH floor build up. the FFL would be too low. I would probably still need an chipboard or ply base layer to get the FFL correct.

 

I assume you have used them so what can you tell me about them? What are they made of? are they completely rigid or slightly flexible?  Can they really span 400mm joust centres and be tiles on top successfully with no other support? or as the video implies, they need to be laid on an already flat structural floor? Do you have any pictures better than on that link?

[PeterW]

10 minutes ago, ProDave said:

That has turned all the options on their head.

 

I have looked at the link and watched the video. NOT enough detail (like even basic stiff like the sheet size so I know how many I need and can cost it)

 

So all I gleaned is they are a structural 20mm thick panel with grooves for the UFH pipe and I can tile straight on top.

 

That gives me another problem, not ENOUGH floor build up. the FFL would be too low. I would probably still need an chipboard or ply base layer to get the FFL correct.

 

I assume you have used them so what can you tell me about them? What are they made of? are they completely rigid or slightly flexible?  Can they really span 400mm joust centres and be tiles on top successfully with no other support? or as the video implies, they need to be laid on an already flat structural floor? Do you have any pictures better than on that link?

 

Better link is here to the Data sheet

They are a 1200/600 board that goes over the existing floor. 

 

Made from EPS, you can always put another layer of 25mm EPS under them to make it thicker and better insulating but you do just get a very fast responding floor. 

[ProDave]

3 minutes ago, PeterW said:

 

Better link is here to the Data sheet

They are a 1200/600 board that goes over the existing floor. 

 

Made from EPS, you can always put another layer of 25mm EPS under them to make it thicker and better insulating but you do just get a very fast responding floor. 

Thanks

 

So for my room I would need 48 of those sheets at a shade over £400 and I would still need the 18mm ply first to give s structural flat floor for them to sit on.

[Nickfromwales]

5 minutes ago, ProDave said:

Thanks

 

So for my room I would need 48 of those sheets at a shade over £400 and I would still need the 18mm ply first to give s structural flat floor for them to sit on.

Yup 

Id just batten and plate as you don't need the extra insulation. In fact, do you need any insulation in this equation at all ?

Even with the data, I'll be honest, my gut is telling me to use 200kpa sheets and cover with 22mm P5 and 6mm plywood as a binder. 

 

Oh, and porcelain tiles should outlive you. We're your old tiles ceramic ?

[ProDave]

The old tiles were ceramic. But as I see it's not the substrate that was the issue, the glaze was too thin or too delicate, it has scratched and the tiles just now look dull and worn. It has not worn through to the substrate. As I see it that could happen regardless of the substrate so is down to the quality of the finish, something you can't easilly tell in a showroom.

 

I think we need another trip into town to make the decision tile or wood. Only then can we move forward with the floor make up option.

[Nickfromwales]

Good luck . 

[PeterW]

@ProDave I’m lost ...

 

Do you not have a floor down now..? Haven’t you got 22mm chipboard on the JJI Joists..?? 

[ProDave]

57 minutes ago, PeterW said:

@ProDave I’m lost ...

 

Do you not have a floor down now..? Haven’t you got 22mm chipboard on the JJI Joists..?? 

At the moment there is just 11mm OSB over the JJI's

 

If we go for the wood floor, 25mm by 50mm battens will be laid following the top of each joist  (400mm centres) to support a structural wooden floor, and the OSB will be there just to support the UFH pipes and biscuit mix as a heat spreader

 

This thread is about the alternatives if we choose a tiled floor.

[Nickfromwales]

Spreader plates vs biscuit mix. 

So.....

Plates give a super fast warm up, but also don't retain any heat. Not a problem if your not using the floor as a buffer. 

Biscuit mix has to be bought, mixed, bucketed around, laid and compacted, and won't be 100% in contact with the deck. Essentially your burying a storage heater. 

Why ? 

Plates = quick, clean, cheaper than shoplifting and at least as good as ( if not better ) an emitter. 

If it were alu plates filled with a biscuit core then I'd stop harping on, but c'mon dave, tell me why go for biscuit mix ? 

[ProDave]

The other side of the coin is I have plenty of sand and cement left over, and an electric mixer, so biscuit mix = £free but a bit of effort mixing barrowing and pouring.  Indeed if I don't use all this sand, it is "waste" to get rid of (though freecycle would take care of that)

 

The last house used biscuit mix and it worked fine.

[ProDave]

I forgot to come back and say we chose engineered Oak in the end for the whole room. In fact I collected it earlier in the week, all 700Kg of it a full trailer and car load but done in one trip.

 

Room is plastered and painted, UFH to go down soon, then we start flooring.

[ProDave]

Here are the long awaited photos of that floor.

 

Battens, UFH and start of the biscuit mix

 

 

And the oak flooring laid

 

 

More pictures on the blog, look for the entry "Under Floor Heating and Oak flooring"