best floor bodge/kitchen floor stripping 2

[Pennyviz]

I've managed to remove the copious layers of tiles and cement screed using sds chisel and brick acid. Most of the floor is coming up well but there is a large patch of concrete, maybe max 2 m2 that I am getting up. it is about 2/3 cms in depth max and on stone/earth and the remains of an old wall, adjacent to blue vitreous bricks (which I am going to turn over). I have got some matching reclaimed quarry tiles but my problem is what to bed them on. The rest of the tiles are on lime ash mortar

Obviously the ideal thing would be to get the whole floor up and relay with limecrete but I have neither the time or money for that.I was thinking of NHl 5 and sharp sand mix, 1:3, but then I wondered about putting some concrete in the mix too to add strength, what does concrete actually do apart from reduce permeability?

At least there doesn't appear to be a well under there but it is quite damp.

Anybody tried anything similiar?

Penny

 

[Socksitis]

I don't know much, but what I would say is do not under-estimate the strength of NHL5 at 2:1 mix - we have done our floor with this, even my cement loving builders were amazed.

 

[plasticpigeon]

I agree NHL5 is pretty strong, I don't think you need any cement in there too if that is what you decide to use.

 

[Flyfisher]

I'd ask what the strength is actually for in this sort of application.

Obviously the floor slab should be solid so it can support normal foot traffic without subsiding over time (though how many of us have tiles laid directly on earth that are not entirely flat after a few hundred years? :wink: ) but after that why the need for anything 'super strong'? The tiles only need to be weakly held down as there are no great 'lifting' forces on them in normal use and they cannot migrate sideways because the walls keep them in place.

If the aim is to maximise breathability then surely NHL2 would be perfectly good enough? If not, then I may have made a mistake when laying a new fireplace slab using NHL2+LECA 'limecrete', although it shows no signs of problems after 4/5 years.

 

[plasticpigeon]

Your fireplace slab isn't lots of small tiles that gets walked on a lot!!!

 

[Flyfisher]

True, but what is it about a floor slab that needs so much 'strength' and what do we mean by this anyway?

All the forces acting on the floor are compressive and even lime putty mortar is strong enough in compression to support two storey buildings, or higher, so how much more 'strength' is needed for a floor? And providing the ground is solid enough and not subject to movement, tiles can be laid directly on the earth, with no slab at all, and they will not lift or move sideways, so I'm just wondering about this whole 'strength' thing and wonder if it's really so important - especially in cases where breathability is important because I understand NHL5 is less breathable than NHL2.

As strong as necessary certainly, but no stronger - so the real question must be what strength is actually required?

 

[Pennyviz]

I don't know much, but what I would say is do not under-estimate the strength of NHL5 at 2:1 mix - we have done our floor with this, even my cement loving builders were amazed.

I assume you mean 2 NHL5: 1 sharp sand? That's interesting, why did you choose that ratio? I had always assumed that it was a bit like a cake recipe with the optimum amounts for the best set.

The general advice is the ratio I suggested using NHL 5, from both googling it and asking Lime suppliers, but I wondered what others had done. Some internet advice on laying floor screed also suggests adding concrete so I wondered what properties concrete adds.


Thanks for comments so far


Penny

 

[MatthewC]

I don't know much, but what I would say is do not under-estimate the strength of NHL5 at 2:1 mix - we have done our floor with this, even my cement loving builders were amazed.

I assume you mean 2 NHL5: 1 sharp sand? That's interesting, why did you choose that ratio?

I'm only guessing but I'm sure that Socksitis meant Sand: NHL as 2:1, not the other way round. You'd use an awful lot of NHL and probably get a very bad mix! I normally use 3 sharp sand to 1 NHL.

I used NHL5 on my limecrete floor and a stone wall, but otherwise I have used NHL 3.5. If I want a slightly more yellow colour then I will add some building sand in one of the measures of sharp sand (possibly quarter to half a measure).

Matthew

 

[88v8]

The positive of cement is that it sets quickly and needs no aftercare. No damping no patting. The negative for many purposes is that it is too strong too brittle and impermeable. And an ugly grey.

Here, cement will shut down the permeability of the lime. Then the damp will go sideways until it finds an escape.

The tiles need only be evenly supported. Thoroughly tamp any disturbed earth, and after relaying do not walk on them for as long as possible - ideally a week - and then very gingerly while you do the (lime) pointing, which should be well consolidated and not just put in with a brush or, worse still, dry brushed.

Shame about that area of concrete, Your efforts to retrieve the floor appear to be going remarkably well.

Ivor