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We have a huge lounge in our new house (in the UK) and it is covered with parquet flooring which we dislike. The little wooden blocks are starting to work loose here and there, so I don't see it as too much of a problem to remove them.

However, I expect the layer of black tar/bitumen/glue underneath is going to be rather firmly attached to the concrete base. I don't fancy scraping it off by hand. The room is 29x12ft!

Since the room is always cold in winter, despite 2 wall-mounted radiators, I am thinking about installing underfloor heating (plastic pipe with hot water from the main boiler). The cost/effort of digging down an inch or two to make space for the pipes will absorb the problem of the black sticky stuff on top!

So the question is: How much do I need to dig out (how deep, and over what percentage of the floor area) or should I forget the underfloor pipe idea (because you know a better way to strip the tar off)?

  • I planned to post an answer, but it would be a weak one. @MerlinMags Do You consider just additional insulation instead of heating? If You will mount subfloor heating, it will be warmer, sure, but You will lose money for nothing, cuz, I guess, You got lousy floor insulation. How about that? – Marek Oleszczuk Jul 17 '15 at 10:45
  • The floor is concrete which, I assume, sits on the bare earth. The wall cavities are already insulated. What more can I do? – MerlinMags Jul 17 '15 at 13:29
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Alternative solution: use an underfloor heating type which goes over your existing floor. Polyplumb do one called Overlay, which was what we had installed. 18mm thick panels are laid on the floor, which have grooves for the pipes to run in.

Obviously you're either a) going to need to put this in every room downstairs, or b) have a level difference between this room and the rest of your downstairs.

  • You might be able to pull up the blocks, and then find a suitable self levelling compound and just cover up the uneven/old adhesive and then as you say, fit piped panels. Quite like that idea. Just need to double check on the Self levelling compounds properties etc. – handyman Jan 22 '16 at 11:14
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    @handyman - I had misunderstood - for some reason I thought the adhesive was going to be very thin and therefore not lumpy. But yep, self levelling compound before panels works - it's what we did to cover up the lumpy adhesive from the old floor tiles we lifted. – AndyT Jan 22 '16 at 11:33
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You don't mention the age of the 'new' house....

It depends on the floors construction. Standard is to have a 50 to 75mm screed on top of a 100mm ish concrete subfloor on top of 150mm crushed and compacted hardcore/stone. Insulation has only been added since the 1990's.

If so, you'd need to remove the whole screed and hope that it's not terribly bonded to the concrete subfloor (sometimes is, sometimes not).

But I'm worried about any house old enough to have original parquet flooring. It's possible that the little wooden blocks are glued straight on on top of a concrete subfloor. Then you're in trouble.

Removing or digging out as you say to a specific depth in concrete is difficult. It's usually easier to remove the thing and start over.

Also heating a floor without insulation underneath is pretty ineffective, again it's best to... Remove the floor, dig out, insulate, new membrane, new concrete, heating pipes set into a new screen. Floor covering of your choice.

A lot of work. However there are mechanical scraper devices for removing sticky substances/adhesives, but I'll not lie to you, whichever way you do it will be hard work and take a while. Depending on age I'd have some of the black adhesive tested for asbestos too, as it's possible.... (but don't panic, just don't create dust whilst working on the adhesive. Tests are cheap, £30 or so)

Re: new info/comment...

Yes, insulation stops the heat going the wrong way if you like. There's a couple of schools of thought, one is to insulate directly under the heat source, throwing all the heat upwards and some like to insulate under the 'mass' if you like, then the heat soaks into the mass (concrete slab say) which acts much like a storage heater, evening out heat fluctuations etc.

You'll struggle to dig out the middle because of sealing the membrane etc.

Thinnest/cheapest way IMHO is to (either follow what AndyT said) or glue back any loose blocks roughly, sand the whole thing flat (again roughly) and then fit a new laminate floor over a heating mat. Try to get both from the same company for best reassurance. Pergo 'quickheat' is as good as any.

You'd probably get it all in around 22mm or so.

  • House was built 1959, and the neighbours have the same parquet, so I do think it is original. I hadn't considered the need to insulate UNDER the underfloor heating. Maybe I can just dig up the middle of the floor, and ignore the 1m border around the edge? – MerlinMags Jan 21 '16 at 9:13
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I agree with Handyman, start over with a proper modern job since you really can't just shave-off concrete. However, another possible option is to raise the floor by a regular stair step or slightly less. In this case insulation, reflective barrier, heat tubing & finished floor can be optimized much cleaner, quicker & cheaper.

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