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Housing - Renovation: laying an 18mm T+G OSB3 sheets onto suspended timber joists

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  1.  
    • CommentAuthorthebeacon
    • CommentTimeJul 22nd 2019
     
    Hello,

    I’m going to be laying an 18mm T+G OSB3 sheets onto suspended timber joists with solid oak floorboards glued on top of the sheets.

    I will screw them down using: floor-Tite Screws 4.2 x 45mm https://www.screwfix.com/p/floor-tite-screws-4-2-x-45mm-200-pack/52936?tc=CA9&ds_kid=92700024762948872&ds_rl=1249481&ds_rl=1245250&gclid=CjwKCAjwtvnbBRA5EiwAcRvnpnwZ929X3nemgMAlDJ1PfZVF0Kfq7-c1Y6eUsiGNyQhh0C2B70fqARoCU-MQAvD_BwE&gclsrc=aw.ds&dclid=CPeMzYrmgt0CFYSnUQodkD8BYg

    Should I be gluing the boards in the T+G? I am laying them onto a VLC that’s running over the joists so cant glue them to them joists.

    The joists are about 300mm apart, what’s the recommended distance between screws running along the joist?

    Should I treat the edges of the OSB, as I read that it can swell?

    And should there be a space left for overall expansion?


    Thanks for the advice.
    • CommentAuthortony
    • CommentTimeJul 22nd 2019
     
    Approx 300mm cc for screws, yes glue joins, I like foaming wood glue, 10mm gap at all edges, can be foamed, it will expand
    • CommentAuthorowlman
    • CommentTimeJul 22nd 2019
     
    The boards will have seasonal movement and the adhesive works against that. What is wrong in this instance with nailing the boards with a T&G flooring nailer. It's quick, and it ensures a tight joint, but with movement allowance. I've done loads of flooring jobs using that method with no problem. Although OSB doesn't have the best nail holding capacity compare to softwood T&G or plywood it's much better than chipboard and acceptable for a nailed floor.
    • CommentAuthorrevor
    • CommentTimeJul 22nd 2019
     
    Do not quite understand the issue. Is this at ground level? You have a VCL under the OSB so seemingly are concerned about moisture. So what about the protection of the joists? Ideally you should glue and screw the osb to the joists using a D4 adhesive or similar alternative designed for flooring otherwise you are in grave danger of ending up with squeaking floors. I acknowledge that being over a VCL will give a separation between the joist and OSB and allow for decoupling but I do not know what the result will be.

    I would not glue down solid oak floorboards they will expand and contract and you will end up with splits in the boards in particular in areas near windows where the sun shines through. There will be a differential in the expansion and contraction between the OSB and flooring which will be problematic. You will have a better result with engineered flooring but I still would be reluctant to even glue this down but use the very thin floor tite screws designed for screwing through the tongue of the boards.

    Have a look here to see if this gives you some ideas.

    https://www.norbord.co.uk/resources/help-advice/installation-instructions/
    • CommentAuthorthebeacon
    • CommentTimeJul 23rd 2019
     
    Thanks for the feedback,

    Posted By: tonyApprox 300mm cc for screws, yes glue joins, I like foaming wood glue, 10mm gap at all edges, can be foamed, it will expand


    Thanks, will pick up some polyurethane glue for the OSB T+G.

    Posted By: owlmanThe boards will have seasonal movement and the adhesive works against that. What is wrong in this instance with nailing the boards with a T&G flooring nailer. It's quick, and it ensures a tight joint, but with movement allowance. I've done loads of flooring jobs using that method with no problem. Although OSB doesn't have the best nail holding capacity compare to softwood T&G or plywood it's much better than chipboard and acceptable for a nailed floor.


    It was more to with the nails finding the joists through the OSB, and also not puncturing the VLC. I was looking into using an adhesive with flexible tenancies such as Sikabond: https://russwood.co.uk/shop/flooring/flooring-installation/sikabond-ms-flexible-wood-flooring-adhesive/ It would allow for the expansion and compression of the floor.


    Posted By: revorDo not quite understand the issue. Is this at ground level? You have a VCL under the OSB so seemingly are concerned about moisture. So what about the protection of the joists? Ideally you should glue and screw the osb to the joists using a D4 adhesive or similar alternative designed for flooring otherwise you are in grave danger of ending up with squeaking floors. I acknowledge that being over a VCL will give a separation between the joist and OSB and allow for decoupling but I do not know what the result will be.


    Not so much an issue, more about trying to find out best practice. Yes its at ground level. I'm insulating between the joists with 200mm of rockwool. I just cant see the result being worthwhile if i glue between the VLC and OSB or joist and VLC.
  6.  
    I have recently laid 22mm T&G chipboard flooring in a bedroom.

    I laid wool joist strips along the joist and stapled them down. I'm hoping this provides an element of soundproofing from both the impact of walking and to prevent/reduce any squeaking if the screws ever loosen. I then laid the 22mm boards on top and glued the T&G with PVA glue. I then used Spax Chipboard Flooring Screws to hold them down, evenly spaced across the board (I think I used either 5 or 6 screws per joist).

    The original floors in our house are 22mm chipboard that were screwed down with a similar number of screws, and every single one squeaks like mad after being down for 20 years and having the screws work loose. I'm hoping the combination of wool joist strips and gluing the T&G helps to prevent this happening again over the next 20 years.
    • CommentAuthorowlman
    • CommentTimeJul 23rd 2019 edited
     
    <blockquote><cite>Posted By: thebeacon</cite>Thanks for the feedback,

    It was more to with the nails finding the joists through the OSB, and also not puncturing the VLC. I was looking into using an adhesive with flexible tenancies such as Sikabond: https://russwood.co.uk/shop/flooring/flooring-installation/sikabond-ms-flexible-wood-flooring-adhesive/ It would allow for the expansion and compression of the floor.


    Flooring nailers, nail at 45 degrees and the nails come in different sizes so you can choose one that won't penetrate through the substrate.
    • CommentAuthorandyman99
    • CommentTimeJul 24th 2019
     
    +1 for foaming glue and Spax screws - I prefer the torx head of these screw. You have to be fairly quick to get the first couple of screws in to prevent the OSB being forced apart.

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