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Clay Brick Floor and Self Leveling Compound vs Laminate Underlay

Postby Cottage-Renovator » Mon Jun 03, 2019 12:48 pm


First time posting so apologies if I'm in the wrong section - seemed the most appropriate here.

I'm renovating a cottage (1800) and the ground floor is currently old 1980's carpet.The rooms I'm looking at putting laminate down in two ground floor rooms (adjoined and level), and I have a query.

Both rooms have a substructure of red clay brick (I assume 100 years old at least), but appear in good level. Without ripping the carpet I cant really tell. I'm a big believer in trying to preserve heritage, even though its not the style we want it would be nice to keep it in case we / a future buyer wishes to reveal it again. One of the rooms is a simple carpet, underlay, brick. The other is a more annoying carpet, vinyl tile, bitumen, clay brick. I tested the tiles prior to doing any work and yep, it's asbestos so now I need to work out how to do this. Safe to say that I want this work to make sure that the risk of releasing any of the asbestos is low to none, so as far as I see it, I have two options:

Option 1 - safely remove tiles, leave bitumen and apply self leveling compound across both rooms to create new substructure to lay laminate. No risk of the bitumen coming up as it will encapsulated in the primer and then compound. This seems a shame because both original redbrick floors will be lost.

Option 2 - Self level only the room with asbestos tiles as the bitumen has effectively ruined the original flooring anyway. Now there will be at least a 3mm level difference between the 2 rooms now, which needs to be rectified otherwise laminate won't be able to deal with the level change. Most I've seen is +/- 2mm. I'm unsure whether I can pack this out with more underlay / board to make it all nice and flat but this feels like a challenge to try and save the redbrick in one room. The other issue is that should someone want to reveal this brick again in the future, there would be a level difference anyway now that one room has self levelling compound.

Has anyone got any advice or other thoughts how I could do this because it seems to be that the only option to make the flooring safe is to self level both, but this will result in losing decent original feature redbrick, which would be a shame.

Also, given the age I assume I'll need a DPM as none will be under the redbrick.

Thanks for any advice.
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Postby richardanthonyj » Sun Jul 07, 2019 10:12 am

I guess the first issue to point out is that putting down a DPM will form a moisture barrier and I can't see an immediate solution to the juncture with external masonry walls- i'm assuming they're 9" solid? The self levelling compound, given that it's latex based, would form a permanent barrier against moisture, protentially forcing it up the internal face of the walls and resulting in damp patches.

My immediate thought was forming a timber floor to the head of the clay bricks, with timbers set at 400 centres and new boarding over. However, moisture will probably rot them out in no time at all.

The more conservative solution would be to take up the bricks, set hardcore and a concrete slab with 75-100mm limecrete strip to the perimeter to protect the original fabric of the building. The correct way of forming a suitable floor is to set 400-500mm Clay aggregate, which doubles as the insultation and then form a 100-200mm limecrete slab over but I'm guessing cost is prohibitive? Besides, i'd expect footings to be nominal so that kind of work would undermine them and you'd have to batter the sides @ 45 degrees to prevent movement in the foundations.

Given all the above and assuming you have no other options, I'd suggest that the self levelling compound should be formed within shuttering, leaving a gap at the juncture with walls so that you could at least set a 100mm wide section of lime based screed (for want of a better description) up to the masonry.
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