How flat is flat for click floorboards?!

Discussion in 'Carpenters' Talk' started by Danomite, Jan 3, 2019.

  1. Danomite

    Danomite New Member


    I am looking at buying 40m2 of click oak flooring but just need a bit of advice about laying it.

    I am laying it over a floor that is half concrete which then meets a chipboard floor (suspended timber floor), there was a dividing wall there that has now been removed.

    The joint is pretty good within 2-3mm, the chipboard floor is nice and flat. I am just a bit concerned about the concrete side, it is a rough poured concrete and where walls have now been removed the levels aren’t perfect and there are dips and rises that I have noticed.

    I just wanted to know what the tolerance is like on the flatness of a sub layer before laying click flooring? I am guessing it is worth trying to get it as flat as possible, are there any tricks/products for achieving this? (The underlay helps abit aswell I am told?)

    I dont think that using self levelling concrete to get the whole floor level and flat would be worthwhile?!(disruption and hassle? never used it before, we are living in the house and need access through the room).

    I did wornder about mixing some sharp sand and cement for the dips and fading it at the edges so there is no big steps?

    I guess I am hoping that a gently undulating floor that is not dead level or flat will be ok? Obviously, a totally flat concrete floor would be ideal, but.....I have found 'ideal' rarely happens during renovations!!

    The last thing I want is a floor that bounces or squeaks etc.

    Advice from people who have experience would be appreciated.

    Many thanks,

  2. KIAB

    KIAB Super Member

    Leveling compound is the best option even for the dips, as you can feather it.

    What underlay you using, if a fibre board underlay, then you might get away with leveling floor.
  3. Danomite

    Danomite New Member

    Thanks for the reply KIAB, I havn't decided on an underlay yet, any ideas?

  4. KIAB

    KIAB Super Member

    Fibre underlay can only accomodate so much uneveness,plus you might need to trim any doors,so if floor is bad, then I use leveling compound, & Sonic Gold underlay first choice or fibreboard underlay, see what others say about suitable underlay.
  5. DIYDave.

    DIYDave. Screwfix Select

    You can’t use sand/cement mix at 2-3mm and feather out, it will just crumble, and it’s too gritty to feather out

    So as above, self levelling compound made for the job, or Ardex Feather Edge, or even cement based floor tile adhesive (yee ha) :)

    Any of the above products, sweep/hoover and remove all loose material and dust then thined out coat of SBR 1-5 water to aid bonding

    Your spending a fair wedge on flooring so worth spending a bit more ££ and time on floor prep ;)

    Sack of Mapei Self Leveler from SF £20 I believe, not so bad eh :D
    retiredsparks likes this.
  6. rogerk101

    rogerk101 Screwfix Select

    I've never laid a click engineered floor that doesn't have at least some bouncy areas. If they end up being weighed down under furniture then it's no big deal, but you really don't want it bouncy in the passage areas. Self leveling screed would help, but for it to flow and work well, you need to use a fair bit of water, which will take a long time to dry in the dead of winter.
  7. goldenboy

    goldenboy Super Member

    Wickes High Performance levelling is good for this kind of thing.

    Its got a fibre mix in it. And its mixed thinner than a lot of levellers so flows great

    Just make sure you use the correct primer for the floor. Not pva!

    Get a long straight edge and mark in sharpies on the floor where its low.

    Prime the floor 4-1 with the primer.

    Use lukewarm water to mix and it will dry a lot quicker

    Mix and pour out in the marked areas

    Smooth it out with a boat shaped flooring trowel.

    Let it go off for about 30mins.

    Then when its green you can scrape off any high spots.

    Let it go off for another couple of hours and smooth with a sander.

    But I would advocate ditching the oak engineered and going with Quickstep Livyn click vinyl in an oak effect. Look the business and is great to lay.

    Leave it for a day or so and lay the engineered over it.
    WillyEckerslike likes this.
  8. JustPhil

    JustPhil Active Member

    I think In the long term there’s no such thing as too level, but there is definitely the opposite :)
    I used self leveller to take out the worst of my concrete subfloor before diy fitting 25m2 of engineered, and whilst I’m happy with it, if I did it again I’d spend more time getting it dead flat.
    I don’t think leveller is as difficult to use or as disruptive as you might be thinking. It’s gonna be easiest to level the whole floor (forget about feathering) use a spiked roller, and if you choose the right leveller it can be walked on in a few hours, or at least the next day if you do it in the evening. It will be worth it, trust me on that.
  9. goldenboy

    goldenboy Super Member

    This is true. However level you get it you wish you had got it more!

    Have to strike a balance. I do loads of floors often on very old places and if you got it pancake flat sometimes you would have to raise the floor height by miles at doorways etc.

    Worst I have ever done was a 15th/16th/17th century school/pub/shop.

    The upper floors were some kind of a horse hair, clay, manure and some kind of aggregrate mix poured onto thick laths laid into rebates in the beams. They had worn and sagged so much that the centre of the floor in a 4m x 3m room was 150mm lower than the perimeter.

    The first guy there to look at the floors suggested using levelling compound! A quick calculation worked out that 3000kgs were required just for the first little room alone.

    I ended up doing it and put 11mm ribs of osb scribed to the curve as "joists" then filled all the voids with expanding foam to fix it and to insulate it both thermally and for sound. then fixed an 11mm floor over the top and then laid a 14mm engineered on that.

    Unusual job, but about the only way to put a super lightweight level floor in that I could think of.
  10. KIAB

    KIAB Super Member

  11. Danomite

    Danomite New Member

    Thanks so much for everybodys replies, I guess I will get down to wickes for some leveling compound! I wish I had leveled it before I put down the suspended timber chipboard floor now as the level will probably change now, HERE WE GO AGAIN!

    Many thanks
  12. KIAB

    KIAB Super Member

    Can do it with a notched trowle if area isn't too large.:)
    Most leveling compound can be walk on in around 3 hours,but needs 24 hours to throughly dry.

    Did floor here,laid leveling compound at night,solved problem of through traffic.:D
  13. retiredsparks

    retiredsparks Super Member

    Use a long level to assess the entire floor.
    It will be the large shallow areas that cause problems.(bouncing)... not a rough surface.
    Never liked supposedly self level compounds altho they may be better these days.
    I might be inclined to look at SBR site for tech info on thin screeds and feathering.
    SBR gives superb adhesion to sunstrates and waterproofing and gives cementitious mixes an almost unbelievably flexibility.
  14. KIAB

    KIAB Super Member

    SBR bonded screed minimum thickness around 10mm, add in underlay & flooring, will most likely end up needing to trim any doors.

    Nothing wrong with leveling compound, most problems is lack of preparation when using it.
    Last edited: Jan 4, 2019
    goldenboy likes this.
  15. goldenboy

    goldenboy Super Member

    Right product and right preparation.
    KIAB likes this.

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice