Black concrete floor in 200 year old cottage with huge “lump”

[Beanbag]

Hi, I am hoping that someone will have come across something similar to myself and be able to give me some information and help. I live in a 200 year old stone cottage in North Yorkshire. The ground floor (which presumably was originally just compacted earth), has a hard black concrete floor. I am wanting to put laminate flooring down, but there is a large area (approximately 3 foot by 3 1/2 feet) that is raised. I need to flatten this in order to lay the flooring.

I have two concerns here…..what is it beneath the concrete, and what is in the concrete itself!?

The floor is very hard and very black. I can’t see any brush strokes in it. The bump is uneven, the deepest areas seem to be around one inch higher than the rest of the floor. I have coloured the lump in chalk marks….the pink areas being the highest.

I am at a loss as what to do. The floor has previously had a raised area to accommodate the lump, but it makes the room very small.

Can anyone help me please?

 

[stuart45]

It's possible that the floor has suffered a sulphate attack.

 

[Beanbag]

It's possible that the floor has suffered a sulphate attack.

A sulphate attack? What is that exactly? There are no cracks in the top, it’s still smooth. Does this mean I would be able to chisel this area out or get it ground down?

 

[Beanbag]

I have just had someone look at my floor, and confirmed that it is not in fact concrete. It is rock asphalt. It is absolutely dry with no sign of cracking, so I can only assume that there is something under it that whoever did the floor, couldn’t or wouldn’t remove. I am tempted to get it dug up, but I would love to know if anyone has a good idea of what it is underneath.

 

[Toby Newell]

Bitumen was often used as an adhesive to fix wooden blocks to the floor, sometimes it was used as a waterproof sealant.

 

[malcolm]

I was wondering how the floor works. When you have a concrete or lime floor you tend to get a little moisture coming through which needs to go somewhere. If you put a plastic wood-effect floor on top it will trap that water and the wood it is sitting on is going to be wet and rot away.

There are a couple of ways it might be made to work: Wood floors tended to be suspended floors where there was a gap between the joists and the floor which was ventilated to the outside. Other option used with parquet was placing the wood on a waterproof surface (bitumen) and letting the wood itself breathe to the room above.

Worth bearing those things in mind when deciding on what to do. I would be inclined to dig it up and replace it with concrete with a waterproof coat on top to get the levels right. The care point will be that the waterproof coating and what's happening around it may not be perfectly waterproof and there might be moisture getting in there over time. Suppose that's no worse than what you have already.

 

[stuart45]

Asphalt floors were normally about 3/4 inch thick on top of a concrete slab. It's really good at stopping moisture getting through. Can't you adjust the timber to get the floor level?

 

[Beanbag]

Asphalt floors were normally about 3/4 inch thick on top of a concrete slab. It's really good at stopping moisture getting through. Can't you adjust the timber to get the floor level?

Raising the rest of the floor did cross my mind…but the ceiling height is already very low! Also I would have to do the kitchen floor as well. The door leading into the kitchen is extremely low. Bit of a problem these old houses, aren’t they!?

 

[Beanbag]

I was wondering how the floor works. When you have a concrete or lime floor you tend to get a little moisture coming through which needs to go somewhere. If you put a plastic wood-effect floor on top it will trap that water and the wood it is sitting on is going to be wet and rot away.

There are a couple of ways it might be made to work: Wood floors tended to be suspended floors where there was a gap between the joists and the floor which was ventilated to the outside. Other option used with parquet was placing the wood on a waterproof surface (bitumen) and letting the wood itself breathe to the room above.

Worth bearing those things in mind when deciding on what to do. I would be inclined to dig it up and replace it with concrete with a waterproof coat on top to get the levels right. The care point will be that the waterproof coating and what's happening around it may not be perfectly waterproof and there might be moisture getting in there over time. Suppose that's no worse than what you have already.

You have a point about laminate trapping moisture in. I suppose I had better go for a wood type flooring. Still baffles me that whatever is underneath the lump, was not removed at the time it was laid.

 

[a twig]

Might have been old footings for something that they decided was too much effort to remove, maybe an old hearth or something, perhaps an ancient tomb - who knows

 

[stuart45]

That's the beauty of old buildings, there's always a mystery that people haven't seen before.

 

[Toby Newell]

Asphalt floors were normally about 3/4 inch thick on top of a concrete slab. It's really good at stopping moisture getting through. Can't you adjust the timber to get the floor level?

Another thing I did not know, never seen an asphalt floor!

 

[stuart45]

Another thing I did not know, never seen an asphalt floor!

It was used quite a lot on the older council houses. Asphalting is a bit of a dying trade now. Floors and roofs are quite difficult, but vertical on walls is a lot harder than plastering a wall. I went to the Crystal Palace years ago to watch a mate of mine get the silver in the apprentices competitions. He was a really good asphalter, shame his career was cut short through drink.

 

[Beanbag]

I am learning a lot too! I have decided to get someone to dig the lump up for me. It may be a few weeks before I can get it done (everyone is so busy), but when I have achieved my aim, I will upload a picture to this forum. Thanks for your help everyone.

 

[Toby Newell]

It was used quite a lot on the older council houses. Asphalting is a bit of a dying trade now. Floors and roofs are quite difficult, but vertical on walls is a lot harder than plastering a wall. I went to the Crystal Palace years ago to watch a mate of mine get the silver in the apprentices competitions. He was a really good asphalter, shame his career was cut short through drink.

You mean asphalt as in bituminous concrete right? Ie with aggregate? Like roads. I've never seen it in over 1,000 period floors so v curious. The only bitumen / coal tar I see is either thin coating at edges or as adhesive under wood block, where it's either sticky and gooey or brittle. I cannot imagine pure tar or bitumen either not flowing viscoelastically or cracking up. If it's pure bitumen, how they get it on the wall without flowing to the bottom!

And I know the score, polishers are no 1 in the alcoholics list, I guess they got free meths... my Great Grandfather (polisher) was a terrible alcoholic.

 

[Kearn]

Might have been old footings for something that they decided was too much effort to remove, maybe an old hearth or something, perhaps an ancient tomb - who knows

Georgian Hot Tub Time Machine??! what is this...

right, I am at this stage resigned for this to remain a mystery, but thought it would be an interesting one to throw out there for thoughts now that I've finally dug out my laptop and can upload photos... Context: - house is late 1500s/early 1600s - timber framed, built with some wealth...

www.periodproperty.co.uk

Sometimes you just never get an answer…!!

 

[stuart45]

You mean asphalt as in bituminous concrete right? Ie with aggregate? Like roads. I've never seen it in over 1,000 period floors so v curious. The only bitumen / coal tar I see is either thin coating at edges or as adhesive under wood block, where it's either sticky and gooey or brittle. I cannot imagine pure tar or bitumen either not flowing viscoelastically or cracking up. If it's pure bitumen, how they get it on the wall without flowing to the bottom!

And I know the score, polishers are no 1 in the alcoholics list, I guess they got free meths... my Great Grandfather (polisher) was a terrible alcoholic.

This gives a rough idea of the work involved on a floor. Vertical is another matter.

 

[Toby Newell]

This gives a rough idea of the work involved on a floor. Vertical is another matter.

Ah, that makes sense, biuminous concrete, still never seen it. I guess Under Floor Heating is out then...