Sorry - concrete floor removal

[Bayliss]

Had a search and see that limecrete is one of the best sub-floors to replace a concrete floor with. Our cottage has a typical full width 1940's/50's single story extension, I would like to remove this at some point but at the moment its a good usable space for kitchen and bathroom. This extension has a floor level of about 12 inches below that of the cottage floors adjoining. We step down into our kitchen from our dining room. This is the room with the concrete floor. Damp is very evident on the kitchen wall, this being the original exterior cottage wall. We have stripped off the vinal paint back to the bare wall and painted this with a breathable emulsion.
So now I need to remove the concrete floor in the dining room, the old sill beams have long since been replaced with a concrete and brick sill and plastered over. If I remove the concrete floor to within about 12 inches from the walls and infill with limecrete I hope this will stop the damp seeping to the walls and allow the damp to escape through the floor.
Advise sought, how deep should the limecrete be, do I need anything over the limecrete and what floor finish will be suited? In other words help please

 

[Lime]

Bayliss perhaps I'm being thick but I don't understand the term "the old sill beams".

With regard to you leaving a 12" section of concrete floor next to the walls I think that will be a bad idea.
It will hold the damp in the wall (as it is now) and the wall will remain damp regardless of what you replace the rest of the floor with.

I assume the rest of the house has a suspended floor?
If this were my diningroom and I was going to all the trouble of removing a concrete floor I'd reinstall a suspended floor.
Relaying a wooden floor really isn't that difficult.
It requires sleeper walls to be built and the rest is simple woodwork.

 

[88v8]

If you contact Ty Mawr, for a nominal fee they will provide you a spec for the floor, and will waive the fee if you buy materials from them.

For myself, I would say it depends how deep the concrete is, but min 4" LECA, 4" limecrete, then you can either screed it in NHL 5/sharp sand or, if the limecrete is reasonably flat, lay the finish direct on that.
Floor finish, stone or unsealed quarries, laid and pointed in NHL 5/sharp. A finer finish to the pointing is imparted by using silver sand or stone dust in place of sharp sand.

Within 12" of the walls is where you want good breathing. Are you being cautious about undermining the walls? If the ground is solid, and you excavate and then lay without delay, you may be able to go right up to the walls. We did, indeed to get the minimum floor depth we went a bit below the keystones, but we are on very solid clay and our walls are over 24" thick, and we excavated one day and laid the next.

Ivor

 

[Bayliss]

Thank you for both replies, our cottage is a typical Suffolk timber framed home with thatch roof. Originally it would have had oak/elm timber sole plates, what I called sill beams which is likely wrong term. The timber studs would have been jointed into the sole plate. I fear the sole plates have long since rotted away and a concrete substitute put in place. Most likely bodged by cutting out the sole plate rot mixing some concrete and working this into place where the beam used to be.
My big concern is if I remove the concrete floor to the edge of the concrete sole plate I may bring down the whole thing on top of me.
I cannot afford to have people in to replace the oak/elm sole plate and rebuild the structure as I would like to do. I know if I embark on this course it may open a can of worms that I cannot deal with.

 

[Keithj]

Been there. We live in a Grade 2 listed house whose sole plates were starting to rot 20 years ago, and were therefore smothered in concrete. The only viable solution is to acro-prop the house, remove the concrete, and replace with oak sole plates.

See this litany for more details of ours. If your studs go into concrete, they need rescuing.

 

[robgil]

Not necessarily. What will be happening is the weight of the stud will simply be pressing down on concrete instead of wood. If the studs are kept dry then I cannot see a problem with this.I cant see how weight distribution will be effected too much. If you are unable to keep the studs dry then yes perhaps you should sort it. Do you have any photos?

I used a mix of lime to ballast 1/3 for my limecrete floor. Buy your lime by the pallet if using a lot, you should get a discount and you should certianly ask for it. Doing this yourself can be a bit of a nightmare. I was back and forth to the mixer like a fiddlers elbow, if you can get someone to man the mixer things get done twice as fast.
Dont be tempted to make too wet a mix especially the sub base, it will just take much longer to dry.

 

[LadyArowana]

OT, but good to see you back Mr Robgil, I was only just mentioning a few days ago that we hadn't heard from you. Hope all goes well.

 

[88v8]

Mixer?
Our floor isn't very large, just 12' x 15', and we only did 4" & 4" as I said, but it was 3 tons that went in.... BIG mixer, three conveyors, four blokes... £4,000.

Ivor

 

[worms]

we only did 4" & 4" ... but it was 3 tons that went in....

:shock:

 

[robgil]

OT, but good to see you back Mr Robgil, I was only just mentioning a few days ago that we hadn't heard from you. Hope all goes well.

Thank you LadyArowana, been busy with work and wotnot so I have not been doing much on the cottage, happy to say I am now unemployed again so I can now get on with it.


My floor space was 3 meters by 3.5 meters or there abouts, 100 mm deep or so and it took 1.5 ton of ballast and a fair amount of lime. Didnt cost 4k though, I would happily do a floor for someone for 4k , or less, much much less. Depending on how much has to come out and what insulating is going in if any at all it's only a couple of days work, if that. I only use a little mixer but the trick is to keep it running constantly.

 

[Bayliss]

Thank you, the good advise is always welcome