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How to use self levelling compound! For concrete!

Discussion in 'Floors, Stairs and Lofts' started by mattysupra, 18 Feb 2007.

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  1. mattysupra

    mattysupra

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    There are 4 basic levelling compounds on the market-

    latex - This can be used over most floors without showing any problem, but tends to be weak etc, used mainly by profesionals that dont know what there doing!

    acrylic - This is a very good levelling compound. dries hard. Downside is that it does not flow very well.

    waterbased - This is also very good. Flows very well and is really hard when dry. Downside is that it does not like moisture in subfloor base.

    fibre bonded (waterbased)- The same as water based but better! Designed to go over floors that flex. Even floor boards!

    You should start by finding out if you have a dpm and if your floor moisture content (if a new base) is within british standard of 75% relative humidity. This will make a big difference to the product you use. Water based being a big no no if above 75% rh and the same for most floor coverings, wood, amtico, karndean, lino etc. You also need to make sure the base your screeding over weather it be concrete, tiles, quarry etc is stable and sound.

    If below 75% or you have a working dpm-

    1st- Clean floor from contaminates (polish etc) next take a large straight edge and go over floor and mark out any major low or high spots. High spots should be grinded down (will save on compound) and low spots should be filled with 400 repair mortar, ( there will be a link at the end for where to get all products from) Try to get all repairs within 3mm per meter run out. Fill in any cracks/holes etc with mortar

    2- Prime with p131 neoprene primer. Neat on non absorbent floors and diluted with water (approx 1-3) on absorbent bases.

    3- Choose your screed. I would always say water based unless moister problem in base floor. Water based flows really well and cant go wrong putting it down.

    4- make sure you mix as the bag says. Stir with electric whisk until lump free and then tip out onto floor, then trowel as flat as you can. Your not trying to get it level here, just flat and smooth. Dont play with it to long and try to keep above 3mm deep. It will flow easier.

    5- make yourself a cup of tea grab a beer , whatever and put the t.v on!

    If you dont have a dpm or moister content is to high- READ -
    How to install a surface dpm and refer back to this where needed.

    If your levelling between wood and concrete or just over floorboards- READ- how to level a very uneven wooden subfloor.

    You need p131 neopreme primer
    Either - red bag (water based)
    - green bag with 55 acrylic or 114 latex liquid
    - 400 repair mortar
    - Maybe 700 flex. (for flexible bases)
     
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  3. Tozzy

    Tozzy

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    And in the meantime while you're watching TV, the cement on your trowel will be drying because you skipped cleaning up afterwards :LOL: lol.

    By the way, thank you very much for compiling this great tutorial! It will come in very useful in the future. The only thing, I'm not really sure where to get the exact materials from other than ordering them on online and paying for delivery. Not the same as nipping into your local homebase/ b&Q :(.
     
  4. Damo1176

    Damo1176

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    Now I'm scared

    I had carpet right into do my carpets, I had a slight drop from my dining room to my lounge of just under 2cm...and a shoddy finish previously. The young guy came in and use latex compound( stopgap 300) and he did not do a great job, nowehere enar as smoothj as I'd hoped he'd make it so you can still feel very slight deviations under the carpet. I just was not sure how good a job I could expect...to cap it off he moved some gripperods from where they'd been to further along as we'd removed a wood plinth from the floor, a tile obviously had broken up from the rod and so rather than point it out or repair it he just pulled the thin broken tile bits out and put the underlay and carpet down leaving a slight divet you can feel if you stand immediately on that part of the carpet....is this what we have to expect from some tradesmen, I am a perfectionist when i work but some people seemed determined to finish quickly.

    Any advice on what I can do or shall I jsut at some stage take back up the carpet and redo myself.
     
  5. flicktokick

    flicktokick

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    OK. A question from an idiot. :oops:

    I am going to lay some vinyl tiles in my kitchen and understand the need to put down a screed. The problem is that our units etc are in place and fixed to walls/plumbing etc. Is it possible to lay self-levelling compound up to the legs of the units, ie behind where the plinths are. Would I have to create a frame to act as a border, holding back the liquid screed? Would I use a similar temporary barrier at doorways?

    i know these probably seem ridiculous questions, but logic tells me that as the screed is a liquid, it would simply spread beyond the areas I want to cover (and by doing so thin out in the area i do want to level) if I dont use some form of dam.

    Right that's it. Chuckle if you like, but please help.
     
  6. mattysupra

    mattysupra

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    damo if you use firms like them you are going to get a low quality fitter. Reason they work so quick is because they get paid peanuts so have to do twice the work. Next time you want a good job done go to the nicf web page ( national institute of carpet and floor layers ). They have approved and master fitters in your area that work to a very high standard. And stick to the small shops.
     
  7. mattysupra

    mattysupra

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    flicktokick. Levelling compound only really runs over 3mm thick. If you are doing a deep screed then use plywood or something as a barrier.
     
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  9. Damo1176

    Damo1176

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    Hi Mattysupra

    You are a fountain of knowledge, so in my current predicament what would you recommend, is it worth pulling up the dining room part and trying to level it myself or get someone in. They're not hugely bad and I'm sure long term they won't damage the carpet either but I can see them. HOw easy is it to use a knee kicker and put 3 walls worth of carpet back properly, do I stanbd a chance in hell of doing half a good job?

    Alternatively how much should I expect to pay to get someone in to level the floor properly, make a good job of it and refit the carpet?
     
  10. mattysupra

    mattysupra

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    damo. with out seeing the job i cant answer your questions . All i can say is that if you want the job done perfect you need to consult a master fitter off the nicf website. If you use a master fitter you will get a proper job done but you will pay for it to. As a diy job you will not meet the same standard. I can talk you through how to do the job , but as i cant see it and as im not doing it you will not get a perfect job.
     
  11. Damo1176

    Damo1176

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    I understand and without pulling up the carpet it would be hard to show you as well. Suffice to say the best description I can give youis as follows, ignore me if you'd rather not have me babble.

    Lounge and dining room used to be separate rooms, there used to be a wall dividing the two and suffice to say they were on different levels with the floor slightly inclined near the doorway. The people rippe dout the wall and made good the trough that was formed with unlevel concrete and also looks like they placed some cable in plastic trunking an inach below the surface (wouldn't be legal to do it that way now). So before this guy came along wit the latex we had a trough round the plastic trunking and and some uneven concrete on the trough further along, the drop in total about 15mm. Rather than cover 2-3sq m to try and make the drop as subtle as possible he has tried to lose the 15mm in about 50-60cm, filling the trough with latex as well, I just remeber it being a bit uneven and not sanded to a smooth finish and the drop particularly towards one end is very noticeable.

    Its whether you rip up what he's put down or make good on top and try and extend the area covered to make the drop less subtle.

    As for the broken tiling I am guessing this will be jsut a case of laying a very fine layer of compound over it therefore achieving a flat finish (that bit I think even I could manage).

    Very frustrating as I am sure my other half would prefer we left it but I'd rather get it done properly. I jsut want to know before I start playing about how much I could expect to pay for someone to level it nicely over 4-5 sq metres and then relay carpet over an area of the dingin room and part of lounge which is about 3mx4m.

    Thanks
     
  12. mattysupra

    mattysupra

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    damo dont bother filling in where missing tiles. Take them up. Easy with large scraper. You should also not put levelling compound over them. It has a 90% chance it will fail in the future. If you want job done properly you need to level whole room. ( 2 coats). I would charge you about 350 to do this. (with out seeing it and including materials) But it would be perfect when i leave. You get what you pay for at the end of the day.
     
  13. markocosic

    markocosic

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    Q - Garage floor, substantial amount of concrete with something over the top that was laid and then had plastic sheeting stretched over when the house was built. Looks like cement, pretty smooth, DPM between concrete and the top layer.

    Used for 5 years or so, including oily work, then scrubbed with washign up liquid/water, allowed to dry, then painted with an epoxy floor paint.

    Has taken a battering in recent years, and with the spunky wall tiles looking good I'd like to level it and repaint it with epxoy floor paint.


    Will old oil or epoxy floor paint affect anything?
     
  14. mattysupra

    mattysupra

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    Yes oil can be a problem if not cleaned. But you will need to use correct levelling compound and primer to go over the top off the old epoxy.
     
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