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  1.  
    We'd like to use reclaimed floorboards on our upper floors. No UFH, though some kind of sound deadening material would be good as they'll be laid on OSB (Smartply) which is on top of metal web joists. We were thinking of getting t&g to minimise problems with movement and to minimise dirt getting trapped.

    On the ground floor we have a lime slab with UFH, so I guess we'll have to go with some kind of engineered board. The slab is a bit uneven, and we'd prefer to keep it somewhat breathable if possible.

    Does anybody have any experience with this kind of thing who would be happy to offer advice?

    Compliments of the season to everybody!
    • CommentAuthortony
    • CommentTimeDec 26th 2017
     
    Upstairs I would not bother with t&g, sound deadening, you should have rock wool between the ceiling and floor 9building regs requirement) after that a thin butyl membrane might help reduce impact noises. Seal,all gaps in the OSB holes edges, joined, indeed I would use t&g OSB and foam the edges, foaming glue the joins.

    Downstairs, are you sure? If you are I would buy a humidity monitor and leave it a couple years.
  2.  
    Thanks @tony. We already have wood fibre between floors and the sound deadening is quite good, but you can hear the impact. I was thinking some kind of membrane must help. I also thought t&g would help with fitting.

    Why avoid engineered board on the ground floor?

    Thanks for your advice.
    • CommentAuthortony
    • CommentTimeDec 26th 2017
     
    anything on the g/f made of wood needs to wait a good while before being installed, need to wait for all moisture to go and settle down, living in it with heating will help, monitor to be certain, a mistake would be expensive and heartbreaking.
    •  
      CommentAuthordjh
    • CommentTimeDec 27th 2017
     
    Posted By: ComeOnPilgrimOn the ground floor we have a lime slab with UFH, so I guess we'll have to go with some kind of engineered board. The slab is a bit uneven, and we'd prefer to keep it somewhat breathable if possible.

    We went with packers & battens with a caberdeck top over our concrete slab. The alternative was a screed and I wanted to avoid wet trades as much as possible. We have bamboo glued to the chipboard in most areas, carpet in others and some vinyl. The slab had been down just over a year before we laid the flooring.

    A very good way to avoid impact noise from upstairs is to use a soft finish like carpet and underlay rather than boards. Underlays/membranes can help, also acoustic screedboards. Suspending the ceiling from resilient bars also helps. Not wearing hard footwear upstairs is also good.
  3.  
    Posted By: djh
    Posted By: ComeOnPilgrimOn the ground floor we have a lime slab with UFH, so I guess we'll have to go with some kind of engineered board. The slab is a bit uneven, and we'd prefer to keep it somewhat breathable if possible.

    We went with packers & battens with a caberdeck top over our concrete slab. The alternative was a screed and I wanted to avoid wet trades as much as possible. We have bamboo glued to the chipboard in most areas, carpet in others and some vinyl. The slab had been down just over a year before we laid the flooring.

    Thanks @djh, so you leveled the floor using shims essentially. Sounds like quite a lot of work?
    •  
      CommentAuthordjh
    • CommentTimeDec 31st 2017
     
    Posted By: ComeOnPilgrimThanks @djh, so you leveled the floor using shims essentially. Sounds like quite a lot of work?

    Didn't seem it at the time. I don't remember how long it took - a day or two I suppose. Two carpenters. The main complication was getting levels to match the external doors and the wetroom shower former and setting the subfloor levels in each room so the finished floors were level depending on the surface treatment (carpet, vinyl, bamboo).
  4.  
    I've been in contact with a few second hand timber floor suppliers. They've all said that I should glue the boards to sheets of ply. I'm a bit unhappy about that idea, both in terms of the glue, and the possibility of recycling them in the future. What do others think?
    • CommentAuthordelprado
    • CommentTimeJan 23rd 2018
     
    why cant you just nail them onto the ply?
    • CommentAuthorbogal2
    • CommentTimeJan 23rd 2018
     
    I put an old school gym birch floor down upstairs directly on the old quite damaged floorboards. Glued and wedged by the old very experienced joiner as he went along. Sitting on a cork underlay. Seems good. The odd creak and one gap appeared but generally fine.
  5.  
    Posted By: delpradowhy cant you just nail them onto the ply?

    I'm not sure. I had a chat with one of them yesterday and he said he would be worried about the boards lifting or the ply beneath them lifting.
    • CommentAuthorowlman
    • CommentTimeJan 25th 2018
     
    Screw the sub ply to the joists, proper plywood as opposed to OSB has better nail holding properties, but OSB is a decent second choice,- better than chipboard..
    Nailing wood flooring has traditionally been the preferred method as it allows subsequent movement better than adhesive.
    I've no idea what condition the boards are in or if their tongues will fit the nailer shoe correctly, but a floor-nailer will produce the best results.
  6.  
    For the ground floor, all we have is a lime slab. Not sure if it's safe to attach anything to it, particularly as it has UFH pipes in it (one of my biggest regrets). I was wondering if the ply could just float on it.

    On the upper floors, we have an OSB sub-floor. Presumably we can nail straight to that (with some sort of impact deadening material between them).

    I was wondering if we could improvise a T&G by just putting grooves in both sides of the boards (so as not to loose too much width) and using a small piece of timber to act as a 'tongue' in both sides?
  7.  
    A message this morning from a timber supplier said that they wouldn't generally recommend timber over UFH, but say that some have set timber battens in the screed so that the boards could be nailed to the battens. Obviously this is a bit late for us!
  8.  
    Generally engineered wood flooring is used over UFH as it is less prone to movement than 'real' wood. Also don't forget that any wood will act as a bit of an insulator for the UFH
    • CommentAuthorowlman
    • CommentTimeJan 26th 2018
     
    I was referring only to the upper floors. Floating a ply sub floor over the lime slab may be your only option. How does that sit with FFL.
    If you use loose tongues then using a floor nailer ( i.e. secret nailing ) would at best be very difficult. I assume you're considering that because the tongues may have suffered damage. You are then into surface nailing, and subsequent hole filling. This marring of the surface may not be a visual problem for you especially as you intend using reclaimed boards which may have flaws anyway. Only you can make that call.
    Putting a thin underlay between the T&G and the OSB seems OK, cork may be an option there.
    The advantage of using a secret nailer is that the action of nailing drives the boards close/tight together.
    • CommentAuthorTimSmall
    • CommentTimeJan 26th 2018
     
    I glued T+G oak directly to a thin screed with UFH in it. Works well, no distortion after several years. I keep the floor temp to under 40C, and use an MS Polymer glue to glue down the floor (and maximise heat transmission).

    I've previously used a rubber mat floating floor, topped with T+G chipboard, then oak flooring. Airbourne sound isolation was good, and impact noise reasonable. I know of people having used rubber crumb carpet underlay for this (approx £4 per m² e.g. "Duralay Treadmore").

    You could also consider acoustic joist caps (but check joist bracing requirements).

    If the ceilings aren't up already then it might be better to try and isolate the ceilings instead (e.g. resilient bars and/or separate ceiling joists).
    • CommentAuthorowlman
    • CommentTimeJan 26th 2018 edited
     
    Posted By: ComeOnPilgrim
    A message this morning from a timber supplier said that they wouldn't generally recommend timber over UFH, but say that some have set timber battens in the screed so that the boards could be nailed to the battens. Obviously this is a bit late for us!


    Why?
  9.  
    Posted By: owlmanI was referring only to the upper floors. Floating a ply sub floor over the lime slab may be your only option. How does that sit with FFL.

    That will probably be a problem for the finished floor levels. I had assumed that we would be using a finish directly on top of the screed.
  10.  
    Posted By: TimSmallI glued T+G oak directly to a thin screed with UFH in it. Works well, no distortion after several years. I keep the floor temp to under 40C, and use an MS Polymer glue to glue down the floor (and maximise heat transmission).

    This sounds like it may be our only option. Did you spread a complete layer of glue all over the floor, or is it sufficient to glue it in 'spots'? I'm thinking about maintaining the breathability of the slab and the cork insulation underneath.
  11.  
    Posted By: owlman
    Posted By: ComeOnPilgrim
    A message this morning from a timber supplier said that they wouldn't generally recommend timber over UFH, but say that some have set timber battens in the screed so that the boards could be nailed to the battens. Obviously this is a bit late for us!


    Why?

    Their exact message was: 'We wouldn’t normally recommend you put a solid timber floor over the top of underfloor heating... However some people have done it by laying timber battens in the screed so each plank can be nailed down.'
  12.  
    There are some options listed here: https://www.britishhardwoods.co.uk/blog/fitting-hardwood-floors-over-solid-subfloors/

    One looks like a sticky backed plastic! Quite interesting that it is only sticky on one side (i.e., the side that the wood attaches to). I would have thought that there was a danger of the plastic riding up.
  13.  
    Ah, but the above is only for floors WITHOUT underfloor heating.
    •  
      CommentAuthordjh
    • CommentTimeJan 28th 2018
     
    Posted By: ComeOnPilgrimDid you spread a complete layer of glue all over the floor, or is it sufficient to glue it in 'spots'? I'm thinking about maintaining the breathability of the slab and the cork insulation underneath.

    You normally spread the glue everywhere, but I can't imagine any problem with leaving some lines of open space at right angles to the boards so as to provide a path for vapour movement.
    • CommentAuthorowlman
    • CommentTimeJan 29th 2018
     
    Hi Pilgrim,
    When I asked "why" I was referring to your sentence "it's a bit late for us ". Is that because of FFL and inevitable floor height build up; or, because you've got UFH pipes to consider?
    • CommentAuthorTimSmall
    • CommentTimeJan 29th 2018 edited
     
    Posted By: ComeOnPilgrim
    Posted By: TimSmallI glued T+G oak directly to a thin screed with UFH in it. Works well, no distortion after several years. I keep the floor temp to under 40C, and use an MS Polymer glue to glue down the floor (and maximise heat transmission).

    This sounds like it may be our only option. Did you spread a complete layer of glue all over the floor, or is it sufficient to glue it in 'spots'? I'm thinking about maintaining the breathability of the slab and the cork insulation underneath.


    Complete layer for good thermal transmission. I can't remember how vapour open ms-polymer is, but I think it's pretty much closed... Acrylic glue might be better in that case?

    Where's the DPM?
    •  
      CommentAuthordjh
    • CommentTimeJan 29th 2018
     
    Posted By: owlmanHi Pilgrim,
    When I asked "why" I was referring to your sentence "it's a bit late for us ". Is that because of FFL and inevitable floor height build up; or, because you've got UFH pipes to consider?

    Because his slab is already laid and it is therefore difficult (near impossible) to embed battens in it?
  14.  
    Posted By: djh
    Posted By: owlmanHi Pilgrim,
    When I asked "why" I was referring to your sentence "it's a bit late for us ". Is that because of FFL and inevitable floor height build up; or, because you've got UFH pipes to consider?

    Because his slab is already laid and it is therefore difficult (near impossible) to embed battens in it?

    Sorry for the confusion - it's because I calculated the levels based on a 25-30 mm floor build up. If we go any higher we won't have a level threshold anymore, and we also won't be able to open the bi-folding doors.
  15.  
    It also means that we won't be able to embed anything in the floor due to the UFH, or even attach anything to it using mechanical fixings.
    •  
      CommentAuthordjh
    • CommentTimeJan 29th 2018
     
    Presuming you know where the UFH pipes are, or can find them again with a detector, you should be able to use mechanical fixings with care?
   
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