Screed over bitumen

Discussion in 'Builders' Talk' started by Lawrencez, Jan 7, 2021.

  1. Lawrencez

    Lawrencez Member

    I have removed some old woodblock flooring that was held in place with bitumen over a concrete subfloor.

    I want to screed the floor to the correct level and my question is can I sand and cement screed over the bituumen or does it need to be removed?
  2. Wayners

    Wayners Screwfix Select

    Mine was thin bitumim and been down 30+ years under those asbestos tiles. I was told to use 2 pack floor leveler vs powder and water.

    I tried to rough sand 40 grade and cleaned well then poured leveler.

    I don't know if this is correct but what I done. Been fine for 10+ years now
  3. DIYDave.

    DIYDave. Screwfix Select

    I'm only diy here but I would suggest a SBR Slurry coat over the bitumen would aid adhesion between the layers
    So that's dry cement whisked into neat SBR to form a thickish, but brushable mix
    Paint or roller this over your bitumen then screed away (follow mix/drying instructions on sbr tub)

    The bitumen certainly doesn't need to come up, is the good news :)
    Hans_25 likes this.
  4. Lawrencez

    Lawrencez Member

    That was my plan to use SBR/cement slurry as a primer/bonding agent..
  5. DIYDave.

    DIYDave. Screwfix Select

    What a coincident eh :) !
    That was also my plan also

    Great minds think alike ,,,,,, definitely the way to go in this situation

    Just don't go bellow minimum screed depth recommendations otherwise the bonding element will be futile
  6. Lawrencez

    Lawrencez Member

    What mix ratios would you use for the SBR/cement slurry?
  7. Lawrencez

    Lawrencez Member

  8. Astramax

    Astramax Screwfix Select

    1part SBR, 1 part water, 5 parts cement........or use Google for more information.
  9. jimoz

    jimoz Active Member

    I did same thing other year.
    Advice at the time was scrape loose bitu off. Re coat with water based bitu. I used bostick from screwys. Then ardex n/a over the top to seal in and get you back to a workable floor
  10. DIYDave.

    DIYDave. Screwfix Select

    Decide on your SBR brand and check the ‘recipe’ on the label / or look online at the data sheet - full details will be stated

    I’ve got a tub of Everbuild SBR in garage, it’s definitely got details on the label for creating SBR slurry

    Ratios may differ from brand to brand so best check with what you purchase and go with the ‘recipe’ :)

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