Flooring Experience/Advice Welcomed

[wrongfoot]

Hello everyone, My first plea for help...

From reading other posts I gather that some people like to have a context and others want questioners to get straight to the point. If you're the former please read the italics and if you're the latter skip them :wink:

I own 2 identical semi-detached 2 storey properties in Northumberland. They aren't listed or in an AONB or coservation area. They're primarily built with >0.5m walls comprising sandstone blocks internal and external (with a rubble fill also of sandstone) laid with lime mortar. The walls have been "repaired" and pointed with OPC in places which I will replace with lime mortar as it fails in due course. The walls show evidence of injected DPC on the inside behind the skirting. Not what I would prefer but you get what you get with old properties. I gather this injected "DPC" is unlikely to be effective on sandstone with a rubble fill but that's no bad thing since the walls should still breathe (if a little less than before) protecting the foundations. Inside the exterior walls a lot of the lime plaster on laths has been skimmed with gypsum or replaced with gypsum plasterboard and similarly skimmed. Stud partitions are all modern plasterboard with gypsum skim. Whatever the original ground floor once was it has been removed / replaced / overlaid with OPC slabs almost certainly without insulation or a DPM probably on a room by room basis. There must be plenty of properties which were victim to such "improvements".

There is a single storey modern-build flat-roof extension out the back with cavity walls / cavity insuation also on an OPC slab.

Despite all these changes there is no evidence (so far) of damp in the sandstone walls and only black mould from surface condensation in on the walls of the modern extension which houses the kitchen and bathroom. I hope to address that with better and more continuous heating (installed already) and ventilation.

So much for context. My problem is that I'm in a quandry about how to floor the older / main part of the property. There was a bamboo tongue and groove solid wood floor in place glued to the concrete but this had lifted in part on higher tread areas and when I lifted it I found some areas of black mould, some efflorescence and spalling of the slab / screed patches. Mostly at the furthest distance from the hearth but also visible along wear areas. It's difficult for me to determine whether these symptoms of damp are due to condensation from the room, wet carried in on feet or from dampness in the slab. I suspect mostly condensation from the room because the old Parkray wood boiler in the hearth was run very intermittently by the previous owners and the uninsulated slab and stone of the house will not have warmed, but obviously I can't be sure.

So what flooring do you recommend for a cash-strapped period property owner?
I'd prefer to install modern laminate flooring over the current OPC slab but I'm open to other flooring types if they are better suited. I'm concerned that if I install a laminate / wood / engineered wood over a vapour barrier sheet that may push moisture breathing from the slab to the walls and cause damp issues there? Or alternatively that if I install those floor types without a barrier sheet they may swell / blow.
Vinyl type floors / tiles seem to be vapour barriers themselves and may trap moisture and convey it to the walls just like a vapour barrier sheet.
Glazed tiles don't breathe at all, although I can ensure the adhesive / grout does. Is that likely to be enough breathing?
Terracotta parfits etc. wouldn’t be in keeping with the locale but might be the best option. Are there other breathable tile options that are affordable?
Flagstones might breathe depending on rock type, but, oh my, quarried rock tiles are expensive!
A timber floor above the concrete with an air gap would raise the floor too high and I’d be dealing with lower doors / ceilings and staircase issues.

I want to be reasonably sure that a floor type will work in the environment of my home. Am I missing a simple breathable floor solution? It looks like there are a lot of practical and knowledgeable people here, any advice welcome including any links to forum threads I haven’t had a lot of success searching this site.

Thank-you.

 

[Feltwell]

Replying more to bump your thread back to the top (new ones take a while to appear), but is carpet a complete no-no to you as you don't mention it?

I'd be tempted to put some cheap carpet down for a while and see how your new home behaves. Yes, a concrete floor is not ideal, but it won't necessarily be damp. A period of living in the home with it properly heated will tell you a lot. Carpet will provide a bit of insulation as well.

Personally, I don't like modern laminate in old buildings, but each to their own.

Another option - dry the room out for a period, no floor covering at all. Then put some plastic vapour barrier down for a while and see if you get condensation forming under it before you commit to laying new wood/laminate flooring.

 

[Penners]

Good advice from Feltwell above, with which I completely agree.

Have you checked to see whether there are any signs of the concrete slab having been laid over a damp-proof membrane? In such cases you can usually find edges of the plastic sheet visible between the edge of the concrete and the adjacent wall. If there is one, then I think this would tend to confirm your theory of condensation on the floor, rather than damp rising through the concrete.

If there's no DPM, and if there is damp coming out of the concrete, then I fear there is nothing you can do to prevent this (short of digging the whole lot out and fitting a suspended floor). If it were my problem, I think I would was the mouldy areas of the concrete with a bleach solution, to kill the mould. I would then leave the concrete uncovered for as long a period as possible, while heating and ventilating the room. This should dry it out. After that - as you've observed - you have two choices. You can lay an impermeable floor and expect to have problems within a few years, or a permeable one that will allow some degree of breathability for the floor. My choice would be to follow Feltwell's advice and lay inexpensive carpet. If you lay it on underlay, make sure it's not a plastic or rubber one.

 

[wrongfoot]

Thanks for the replies so far I've been reading through old topics and I'm very impressed with the practical matter of fact user produced content on this site. Pleasingly mature compared to some of the internet postings that can arise on forums.

Feltwell / Penners - We've discussed your suggestion and we're actually quite swayed by the carpet idea for the living room, it makes a lot of sense. Should be warm and a forgiving surface for kids to crawl around on too. Has anyone any recommendations for a suitable underlay material with a bit of depth?

Penners - There's no evidence of a DPM sheet at the margins of the concrete slabs and I've had all the skirtings off. I might be lucky with a low water table here though so there may not be much water to transpire through the slab and being old concrete it will have had a chance to dry for years after it's first cure. It looks as though a lot of self-levelling patches have spalled off with salts beneath / behind them. I presume I can re-level those areas with a float and OPC concrete using a mostly soft sand mix, but if there's anything like a "breathable" self-leveller I could do a good job across the whole floor. Has anyone any recomendations for something like that (obviously without latex)?

I still have to floor a porch and kitchen both of which are non-DPM concrete and a carpet isn't a great floor for areas like that. I'd like to tile there. Despite some research I can't determine whether modern unglazed ceramic tiles breathe appreciably or whether I should stick to teracotta type tiles? I have read that a lime mortar grout heavy on the lime with suitably fine sand can be a breathabe adhesive and grout. The grout to be sealed with linseed oil or some such. Has anyone done this or seen this on a blog / video?

 

[Penners]

if there's anything like a "breathable" self-leveller

Frankly, since the substrate will be OPC concrete anyway, I wouldn't worry about the breathability of a self-levelling compound. Just use the normal stuff.

As for your porch and kitchen, I can't confirm this from personal knowledge or experience, but I have heard that red quarry tiles are somewhat breathable.

 

[Feltwell]

I agree with Penners, but the same logic applies to your porch and kitchen - if it's a concrete floor then I wouldn't worry about breathability for tiling - it's already non-breathable.

At my first house, long before I knew much about old houses, I had a downstairs loo with a very damp floor. It was an unheated room off an unheated passageway to the back of the house, and had clearly been damp for a long time, someone had had a go at covering the floor with a bitumen compound to stop the damp. When we moved in lino was down and it was mouldy underneath.

Not knowing any better I cleaned up the floor as best I could, covered the very uneven floor with latex self-levelling compound, then tiled it with a cement-based tile adhesive with porcelain tiles, and grouted it with a cement based grout - so all about as non-breathable as you can get! It was fine though, at least for the 8 years we were there, no sign of damp ever returned.

I suspect if I hadn't used cement based powder adhesive - i.e. if I'd used the ready-mixed stuff - then I may have had problems.

I have original concrete floors here to half of the ground floor - the Victorians used concrete sometimes. The hallway is a suspended concrete floor over the cellar so won't have any damp issues. The kitchen has original quarry tiles and is fine, but most tellingly the downstairs loo has modern tiles over what I suspect is an original floor that's been screeded in recent times - not by me - and it's ok, no visible signs or smells of damp. The tiles look awful but that's a different matter!

And I wouldn't worry too much about the kids - my eldest crawled around in a fully carpeted house, but my two younger ones were fine here where we have no carpet at all downstairs, just a big thick rug in the lounge which they used to sit and play on. They coped just fine with a combination of floorboards and tiles in all the other downstairs rooms, even with all the steps we have between different rooms. Ride-on cars get pretty noisy on tiles though, and my youngest perfected the art of 4-wheel drifting his ride-on fire engine around a corner on our kitchen tiles!

 

[masochists-r-us]

Agree with Feltwell's advice to determine if the damp course under the concrete has failed or was ever installed. It could have been done with the 'Black Jack' paint-on latex which might explain why you can't see any plastic.
If it has failed then you will need to either dig it all out if you want breathable or re-do it if you don't.
I personally would not go for carpet on the ground floor as a permanent solution. We have installed reclaimed victorian quarry tiles in the kitchen (on top of a concrete floor), reclaimed stone flags ( on earth) in the dining room and a suspended wooden floor in the sitting room and they all work well.
Frankly, I'd re-do it if it has failed rather than dig out because if you then decide to lay either flags or quarries on top of earth and then apply any sealant to them, the floor will no longer be breathable anyway.

 

[wrongfoot]

Thanks for the continued advice.

Your replies have touched on something which is confusing me. If OPC concrete is so impervious that it can't transmit damp why does it need a DPM in in modern builds? This is somewhat at odds with advice that suggests that I needn't worry about impervious screeds because the OPC will be impervious anyway.

I have a period property specialist coming (hopefully before Xmas) who might be able to clarify this for me, but I'm grateful for and interested in the replies I'm getting here too. Thank-you.

 

[Penners]

OPC concrete is not completely impervious. It's just a hell of a lot more so than limecrete.