Filled in concrete floor in 1900's house

[haystack]

So we moved into our house two years ago its a victorian end of terrace 1900 ish. We knew when we moved in that the downstairs floor had been filled in with concrete. When we arnt sure but I'm guessing around the 50's or 60's. I say this as we have asbestos vinyl tiles underneath the carpet. The floor is high and wont take any other flooring but a thin carpet. I think the vinyl tiles are also the damp proof barrier and they have been stuck down with what is now a brittle bitumen type of stuff. Without it I think we would see damp through the floor.

My heart wants me to dig the whole lot out and reinstate the floorboards. Although my head says .... er really, put some new carpet down and be done with it. We have stepped footings so if we dug it out we would risk some movement in the existing structure.
I believe the concrete bridges with the next door neighbours house and they have damp issues because of it in places on on the party wall. We are the only house of five in the terrace that have had the floor filled in.

Has anyone dug up a floor like this? My thoughts are to dig down a bit and seal, put a framework and insulated then floorboard on top we would have to dig down 200mm or so. Its only a small house I guess the floor area is about 40m2.

We cant be the only house that is in this predicament?

I would be keen to your thoughts.

 

[Tony.]

I would go with a suspended timber floor.
Introduce air bricks to vent under the floorboards.

If the house wasn't designed for concrete originally how does the DPM link into the wall?
Damp will probably be pushed to places it shouldn't be.

Carpets or any floor covering will mask the problem.

 

[MatthewC]

We have stepped footings so if we dug it out we would risk some movement in the existing structure... We are the only house of five in the terrace that have had the floor filled in.

Why do you think removal would risk some movement? It sounds as though the house was designed to have no filled floor, so nothing should move if you took it away, surely. It would also be a huge improvement vis-a-vis damp.

 

[livias]

Don't dig too close to the walls, allow a 45 degree footing to support them
Good luck. It is a particularly arduous job so they say, producing lots of concrete waste which has to be shipped away somewhow. I shall be doing it myself later in the summer to remove a concrete floor which should never have been put there.
Heyho

 

[haystack]

HI all thanks for the responses. I agree that we should reinstate the suspended floor but at what cost?

My comments on the movement would be that allow designed to be without the concrete as soon as you start to use any equipment to dig out a massive slab close to the walls there is surely some additional loading from the vibration? If any support was provided by the slab removing it will shift the loading suddenly. Livias your comment about digging at a 45 degree to provide support during the removal would mitigate this as much as possible. How much concrete (m2) are you removing do you know what depth it goes down too? Im not sure what a typical depth of concrete was poured during this time period. In my head it goes down miles.....

I have read online that someone dig remove a concrete floor and took it to a local farm to sure up an entrance to some of the fields for there vehicles. Worth a try if you are trying to get rid of it perhaps and it could be a sustainable re-use?

 

[MatthewC]

The floor should/can not have been supporting the walls; loads are transferred down quite close to the vertical - think of the slope of railway embankments.

The gap under the original suspended floor might have been three inches or three feet - my suspended living room floor has about ten inches of space. Can you ask your neighbours what they still have under theirs? However, it would have been very wasteful and tiring to lay concrete deeper than it needs to be, so I would hope that you have a sensible 4 inches of concrete on lots of compacted hardcore. Can you try drilling it to see? If it's "only" 4 inches, I would use a sledgehammer, not a pneumatic drill - better exercise and you don't get vibration finger.

Getting rid of hardcore is not fun - if you have more than one skipful, I suggest finding a "grab lorry" - much better value and easier, so long as you have room for a pile that he can reach. I did 9 loads with an 18 ton lorry!

Matthew

 

[livias]

I have dug a couple of trial holes and it seems to be just a couple of inches of concrete on top of hardcore, but my house is a 1620s farmhouse so the original floor would have been rammed earth

Matthew - Will take your advice about a grab lorry thanks

 

[haystack]

The gap under the original suspended floor might have been three inches or three feet - my suspended living room floor has about ten inches of space. Can you ask your neighbours what they still have under theirs? However, it would have been very wasteful and tiring to lay concrete deeper than it needs to be, so I would hope that you have a sensible 4 inches of concrete on lots of compacted hardcore. Can you try drilling it to see? If it's "only" 4 inches, I would use a sledgehammer, not a pneumatic drill - better exercise and you don't get vibration finger.

HIya Ive spoken with the neighbours and they say the cavity is approximately 400mm, they have broken up some of the concrete in their kitchen floor and it was 150-200mm thick, so like you said more possible than I had initially thought! I will post some figures if i can get someone to quote. I searched for a long time with no luck so maybe it will help someone else with this process.