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Carpets, Lino & Flooring

How to approach uneven stone floors (on earth)

Anonymous user 03/03/2024 - 3.23 PM

Hello everyone, a qyest I ripped up the existing floor leveling compound in a mid-terrace 19th century house I bought and am renovating (because half of the floor was previously jacked up from the cellar, making the floor uneven). Underneath are large, rough stone slabs approximately 128x64 cm sitting on soil. They appear to be solidly placed and I don't want to dig them up and remove them. The other half of the kitchen is above a cellar in which I am rebuilding the subfloor with a 18mm plywood base. On top of the stone, there appears to have been a 1-2mm base of leveling compound, then a layer of black fabric, then between 5mm to 40mm of self leveling compound. (Now we're down to just the limestone). The kitchen on one end is about 40 mm lower than the other side, and because of the stone, needs a new round of self leveling compound. I plan on covering the floor with 6mm Marmox board and tiling with porcelain tiles. I believe Mapei Ultraplan 3240 is the most suitable self leveling compound, correct? Once I have a level floor, then should I use a Durabase decoupling membrane (or similar), and if so, should it be under or over the Marmox boards? If I am using Marmox boards, do I need a DPM, and if so, at what layer should it go? There is definitely condensation from the cellar, and for purposes of this exercise, let's assume that the soil under the limestone has a low amount of moisture. I know, I know. Call in a professional... :)

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4 Answers

Club 360 Services ltd

Rating: 5 out of 5

Upper Edmonton, London

needs DPM, and is placed under the boards

Answered7 August 2019

PAUL BROWNLESS FLOORING SPECIALIST LTD

Rating: 5 out of 5

Gainsborough

Yes the previous answer is correct but the liquid damp proof membrane (DPM) is sandwiched between two layers of moisture tolerant latex (don’t get confused with self levelling compounds and smoothing compounds cos they are completely different materials, floor layers use smoothing compounds). The DPM is a two part material that is whisked to an even consistency trowelled with a specific notched trowel then rollered to a smooth finish, then allowed to dry and then the final layer of smoothing compound. Then it should be ok to put whatever finishings you wish.

Answered27 August 2019

Kieran Lee Flooring

Rating: 5 out of 5

Oldham

As one of the above answers states, a ‘DPM Sandwich’ would be recommended. Using a smoothing compound to even out subfloor somewhat then applying a correct dpm, followed by another coat of compound to leave a smooth finish. note- due to depth majority would need aggregate/fibres adding for strength

Answered27 August 2019

boots specialist timber flooring

No reviews yet

Nottingham

Ardex c1 then level with ardex na which is moister tolerant , really needs a new floor slab ,

Answered29 August 2019