Sealing gaps between floorboards

Discussion in 'Builders' Talk' started by MrBoy, Feb 22, 2018.

  1. MrBoy

    MrBoy New Member

    My office has a Victorian painted floor which we sanded back and varnished. The planks are beautiful but have quite a lot of gaps; we just dropped the ceiling into the cellar underneath to prepare for a conversion and it's amazing how many places you can now see light between the boards!

    We will be putting a new ceiling underneath with insulation but I just don't like the idea of all those cracks... draughts, dust, noise, etc. Also we need to spray under the floor with anti-rot treatment so I'd rather it didn't flood my office - and when they start stripping the walls the amount of dust that would come up through the gaps will be crazy.

    I'm thinking some kind of sealant might be good for flexibility. However general purpose sealants all seem badly suited for porous materials like wood, and other products are all pale in colour and I want to retain the look of the 'cracks', definitely not have pale lines. Trying to colour-match with varnish after would be difficult and risk looking awful.

    What products and techniques would people recommend? I can access from above or below which I figure might be useful in terms of taping and so on.

    Thankyou!
     
  2. MrBoy

    MrBoy New Member

  3. KIAB

    KIAB Super Member

    Lumberjack Triple action wood treatment, from competitor, superb product, use garden sprayer to apply from below, & wear mask & eye protection.
     
  4. MrBoy

    MrBoy New Member

    I'm more asking about filling the gaps but since you recommend that - if sprayed below will it penetrate all the way through the boards? We have a couple of suspected spots of rot on the tops of boards (might just be damage) which are now varnished - would spraying the underneath make sure this doesn't spread?
     
  5. DIYDave.

    DIYDave. Screwfix Select

    Best / most natural / time :(:(consuming / expensive / way to fill gaps would have been whilst prepping floor, prior to sanding down and getting ready to stain / varnish, is to fill gaps with suitable size strips of similiar timber, cut tight and wacked in with some glue

    Once sanded down, lovely job and ready to stain / varnish

    Trouble with a lot of sealants / gap fillers is that most wont take a stain so unless you can get a colour your happy with, will actually highlight the gaps

    Fillers that say ‘stainable’ are likely to come out a differant colour to floorboard and again stand out, even using same product as used on floor

    Even timber strips can stain up a differant colour, depends on timber used, age, and loads of other things !

    But, once sanded, along with complete floor, would have looked a lot more natural :(

    No idea what to now suggest. How big are these gaps ? Photos will help :)
     
  6. MrBoy

    MrBoy New Member

    The gaps large enough to be packed mostly are. Since the gaps look very dark now - which I quite like - my thought was to use brown or black sealant to keep the same sort of look but I'm dubious and also the only brown/black sealants I find are bathroom ones which don't appear suitable for wood?

    I could pre-stain some narrow strips but I think some gaps will remain... hence thinking about a clear grab-adhesive. If I fill the gaps it might look ok.
    I'm debating whether to so it from above, or tape all the cracks on top and get into the cellar with the gun to 'backfill' .
     
  7. KIAB

    KIAB Super Member

    MrBoy likes this.
  8. MrBoy

    MrBoy New Member

  9. Did someone buy you shares in Everbuild?
     
    KIAB likes this.
  10. rogerk101

    rogerk101 Screwfix Select

    I had exactly the same problem as you described in the original post, and after much trial and error, I came up with t great solution.
    I sanded my pine plank floors, then oiled them with a few coats of Danish oil.
    I then used Screfix's No Nonsense oak coloured sealant to fill the gaps. (https://www.screwfix.com/p/no-nonse...lantsadhesives-_-oaksealant&_requestid=533766)
    You squeeze it into the gap, but before it gets a skin on it from drying, you sponge off any excess, treating it almost like a tile grout. Large gaps might need a few passes, but when it dried, it's almost the colour of the oiled pine floor, and the whole effect is great.
    It's important to oil (or varnish) the floor first though because if you do the sealant first, when you sponge it off to be level with the planks, it 'seals' the wood, and doesn't allow the oil to penetrate the wood. You'll then be able to see where the wood was 'natural' and where the wood was sponged.
    Give it a try in an area that is likely to be under furniture, and get good at it before you do the rest of the floor.
     
    MrBoy likes this.
  11. MrBoy

    MrBoy New Member

    What age are your boards? Mine are pine -we think but a much richer, less yellow colour than "antique pine" varnish... In fact treating new boards we used "Georgian oak" dye to get a closer colour.
     
  12. fillyboy

    fillyboy Screwfix Select

    I did a job last year, pine floor boards, stained and varnished, the owner wanted black silicon in between each joint. I must admit, it looked pretty good.
    Bearing in mind the gaps aren't consistent, the trick part is cutting the nozzle on the tube to the ideal size, then getting a good depth of silicon into the joint without overdoing it, then very gently fingering the joint although if you achieve a flush finish that would be better, then clean up either side of the joint with everbuild wonder wipes, or wonder wipe fluid.
     
  13. MrBoy

    MrBoy New Member

    Interesting...I was considering black but scared it would be too extreme.
     
  14. fillyboy

    fillyboy Screwfix Select

    The owner wanted an oak stain and the black was a good contrast. Google some pictures of teak yacht decks, they always have a black sealant between the deck planks. To be fair, I'm not sure any other colour would work as aesthetically well.
     
  15. KIAB

    KIAB Super Member

    Everbuild 825 isn't overpaintable.:(
     
  16. KIAB

    KIAB Super Member

    Those wonderwipes are brilliant,clean oil,bitumen off my hands, use them for cleaning halogen hob,a 1001 uses, want to try some Deleted member 11267...:p
    And Wonder Wipes Spray is good,with some kitchen paper or blue roll, tend to use that more, as Wonderwipes dry out if you don't pop lid on properly, available from competitor.
     
    Jord86 and fillyboy like this.
  17. fillyboy

    fillyboy Screwfix Select

    A gentleman can never have enough wonder wipes in his van.
     
  18. 2shortplanks

    2shortplanks Active Member

    sikaflex ebt would be a good choice, paintable flexible tough and sticks well. A customer had sealed the gaps in his victorian pine floor with dark brown sealant - contrasted with the boards, but looked good to me.
     
  19. matejko

    matejko New Member

    some horrible advices here. silicon is always bad idea, for many reasons, when used in not appropriate places. middle of the floor where it will be subjected to constant mechanical contact is one of them.
    1: if you have to fill gaps after painting , material would have to be wearable to go along with natural wear of the floor. silicon looks good initially but after some time it will detach on the edges and to still look good would had to be applied very neatly at the beginning, which is unlikely as its generally messy job even with experience.
    2: obviously it is much better to fill the gaps before painting, so the floor can become one solid surface and is sealed properly( by the paint)
    for that silicon is useless in long term , as it is not paintable,paint peels off after some time because its too flexible and it does not bond with most types of paint generally.

    saw dust mix with floor joint filler covers smaller gaps(works well with dyes or colours applied after), bigger gaps can be filled with pine slivers (designated wooden wedge stripes which will fit in to the gaps then excess can be chiseled and sanded).
    there is flexible floor gap filler avaiable as well which can be sanded and painted
     
  20. Phil_a

    Phil_a New Member

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