floor Questions

[StrawMount]

Hello,
We're completely new to this forum and wonder if anyone can help us. The context is a house in 3 parts, front part is early1800 stone built two storey, then there's a two storey flatroofed extension to the back wall (unsure of age but very substantial brick built), and then a single storey 30 year old extension from there.
Our problem is the ground floor in the oldest area. We've just taken up a ratty old carpet to find what appears to be a concrete floor with some kind of bitumen layer over the top. A cardboard under carpet layer has now stuck effectively to the bitumen as far as we can tell. However, all across the room there are lots bubbles in the bitumen, which a gentle scraping removes the black bitumen and reveals the top of the concrete breaking up into dust, so we gather that's damp coming up. The walls are not showing signs of damp (although we think the external cladding is concrete and we know if it is that will have to go.) There is not a mould problem at the moment in this room.
The question is about the floor, we can't afford to have it completely removed and re-layed with something more appropriate at the moment. As there aren't any really obvious signs of damp in the walls, no mould etc. is there a quick temporary fix that would see us through a couple of years or so? Should we be taking up the cardboard and bitumen first?

Thanks for any thoughts!

 

[MatthewC]

Hi StrawMount

Welcome to the forum. Bad luck on the bitumen, but it has to go; the cardboard of course will always be damp, and the carpet was "ratty" for the same reason. I had bitumen on the quarries in my kitchen and found that it would come off quite easily when the tile was damp, but where it was dry it was almost impossible; hence your concrete is probably nice and damp!

It sounds as though they laid the concrete and after a while when it became damp they added the bitumen to try to sort it - typical poor effort to tackle the symptom of damp rather than the cause. If you can't replace the floor yet then I'd be looking for a cheap but breathable floor covering - some rug or carpet without an impervious backing; that would last longer than other modern stuff.

 

[malcolm]

About 100 years ago they used bitumen as an adhesive for parquet flooring. If that is the case you'll see the flooring pattern in the bitumen.

If the cardboard is not mouldy and a couple of years breathing space is all you need I'd be inclined just to bung another carpet on top of it. Or pull the cardboard up and throw some underlay down then a carpet. The trick with carpeting a floor that might get a little damp is to use breathable underlay and carpet. We've got ancient hessian underlay and carpet here and that seems to work with our iffy floors. Avoid anything with rubber in it as that traps the moisture and you get a mouldy floor.

 

[a twig]

We have a similar situation in our house, with some sort of black jack / bitumen style stuff lathered onto the concrete, newspaper on top of that, then underlay, then carpet. While it was largely dry, it still smelt a bit musty and the newspaper had gone mouldy in places!

We will be removing the black stuff and proceeding with breathable underlay/carpet. We're hopeful that should resolve things satisfactorily, but only time will tell!

 

[StrawMount]

Thanks all, think we'll get up what we can of the cardboard and bitumen and then look for breathable carpet and as 'a twig' says, time will tell. We won't be busting the bank on a carpet in case we're tipping it in a couple of years! Grateful for the input 8)

 

[Ebenezer]

We have a screed laid over our original(?) floor. It has blown in a couple of places but doesn't feel or look damp. I think our carpet helps, not sure if is designed specifically to be breathable but it must be allowing evaporation.

Ideally id like a limecrete floor put down but don't have the time it money currently unfortunately.

 

[Penners]

If you need a breathing space of two years before you are able to do the job properly, speaking for myself I definitely would not remove the bitumen and cardboard for the time being. It's apparently been there for a long time and is still largely intact except for a few bubbles. And it doesn't seem to have caused problems with the building. So I would just cover it with a cheap carpet and leave it as it is for those two years. There's no point in laying a breathable floorcovering over it, because it won't be breathing anyway.

Then, when you have the funds available, that's the time to consider removing the cardboard, bitumen and concrete, and substituting a limecrete or - better still - a suspended wood floor.

 

[Zebra]

No no! You must take it all up, and live with no floor at all, just bare earth, stepping between pipes, for at least two years. It is the way things are done. :wink:
Seriously, I think it depends. I would be tempted to poke and scrape and see what comes off, see what's underneath, and take it from there. You may even make different decisions based on what's underneath. Who knows, there might even be an original flagstone floor down there! But then, I really would be prepared to live with whatever was underneath in the meantime. If you need some semblance of a normal floor for now, then I'd leave it alone as Penners says until you're ready to tackle it.

 

[Penners]

Zebra has proposed some good black and white alternatives there. :wink:

 

[Tony.]

Maybe wise to get a definite reading for damp.
A decent moisture meter would give an indication of this.
I have one with 2 pins for taking readings it also has some clever electronics inside to detect readings approx 20mm from the surface.

Working in a 4" grid pattern record the readings on paper and from there work out where the highest readings are.
Do they match with exterior down pipes, radiator pipes you see where I am going with this.

 

[StrawMount]

Well we've gone for getting the cardboard up and seeing how much of the black stuff comes up too..... as Zebra has said. (No shades of grey?!)
Quite a lot of bubbles, more than we realised until we started scraping. We're going to give it a few weeks now, make sure there's not lots of damp coming up. We've of course set our hearts on finding an old flagstone floor now :wink: However, as there's a step down from the hallway into this room a suspended wooden floor would be good if there's not lots of moisture coming up.

 

[Penners]

a suspended wooden floor would be good if there's not lots of moisture coming up.

A suspended floor can deal with that. You need to make sure that there is crossflow ventilation of the air-gap beneath the floor by setting air-bricks into the external walls, at sub-floor level. Also be sure to use pressure-treated joists as the floor supports and insulate underneath the boards.