Cracks in bitumne or Synthaprufe floors

[Leftie]

We have a 25mm thick bitumen or Synthaprufe floor (according to the building regs. notes) in our lounge. It is a very hard, quite brittle floor (judging by the way bits came up with the nail when I pulled out the nails holding the carpet gripper rods).

During the recent floods we ended up with water running over the floor for 2 days and when we finally cleared it the bitumen floor had two large thin cracks, each about 1.2m long which oozed water when you trod near them. During the flood it felt as if there was a bit of 'give' in the area of the cracks.

Is it likely that this floor will need to be dug out and replaced or will they be able to fil the cracks successfully. We are thinking about laying parquet flooring on the floor with one of thye modern oil based adhesives, so would that be sufficient to deal with the cracks?

We are hoping the water won't be back for another 400 years!

 

[JohnD]

Synthaprufe and bitumen are waterproof coatings that you apply with a brush like thick paint. the floor is probably a screed made of a sort of concrete. It sounds like yours has cracked or separated from the sub floor. Does your floor look black (this will be the synthaprufe) or does it look like smooth grey concrete (this will be the screed)?

there is probably a concrete slab underneath.

Sounds like water has got between the slab and the screed.

The screed at least will have to come up

It may be necessary to take up the slab below if it is in poor condition

Have a careful look at your floor (and use a spirit level) and see if it is perfectly flat, or if it seems to be "domed" and bulging up in the middle

You need to fix the floor properly first or your new parquet will be spoiled and your money wasted.

If there are several houses in your area of similar age and construction, see if you can find out if anyone else has similar problems.

 

[Leftie]

Synthaprufe and bitumen are waterproof coatings that you apply with a brush like thick paint. the floor is probably a screed made of a sort of concrete. It sounds like yours has cracked or separated from the sub floor. Does your floor look black (this will be the synthaprufe) or does it look like smooth grey concrete (this will be the screed)?

there is probably a concrete slab underneath.

Sounds like water has got between the slab and the screed.

The screed at least will have to come up

It may be necessary to take up the slab below if it is in poor condition

Have a careful look at your floor (and use a spirit level) and see if it is perfectly flat, or if it seems to be "domed" and bulging up in the middle

You need to fix the floor properly first or your new parquet will be spoiled and your money wasted.

If there are several houses in your area of similar age and construction, see if you can find out if anyone else has similar problems.

It is a very black hard tar like material (so Synthaprufe?). Sounds like it may have to come up if only to check the concrete sub floor is Ok. I don't think it goes all the way under ths stairs ( will check) so I may be able to see how thick it is.

The house is pretty much a one off: rennovated and the new floors laid in the 1980's but dating sometime prior to 1780.

I am presuming now the water has been between the two it will continue to lift?

 

[JohnD]

does the top layer look like that fine tarmac sometimes used for pavements (rather than just being a coat painted onto concrete)?

 

[Leftie]

does the top layer look like that fine tarmac sometimes used for pavements (rather than just being a coat painted onto concrete)?

Yes, a very dense 'hard treacle toffee' like substance. No sign of any texture in it at al, it just looks like a set black smooth liquid.

 

[JohnD]

OK, then I think it is a bituen-based material, probably mixed with sand or ash, and probably laif hot over the sub floor. It ought to stick quite well, so either water has got under it, or the subfloor is cracked or breaking up

It may well have been laid that way because the subfloor was damp, a modern solution would be to dig it out and lay a concrete slab with damp Proof Membrane and insulation, which is much better.

My question about the doming floor was because this indicates expansion breaking up the subfloor.

Probably not a DIY job as it will need some digging out and relaying.

I've never seen one like that, but with luck someone wil be along who knows the problem.

 

[Leftie]

OK, then I think it is a bituen-based material, probably mixed with sand or ash, and probably laif hot over the sub floor. It ought to stick quite well, so either water has got under it, or the subfloor is cracked or breaking up

It may well have been laid that way because the subfloor was damp, a modern solution would be to dig it out and lay a concrete slab with damp Proof Membrane and insulation, which is much better.

My question about the doming floor was because this indicates expansion breaking up the subfloor.

Probably not a DIY job as it will need some digging out and relaying.

I've never seen one like that, but with luck someone wil be along who knows the problem.

Many thanks for that. The black floor runs under the staircase as well so they will have to take that out to do the floor unless they acro prop the main staircase and just take the first 2 steps out.

Lets hope it is the two separating and not the sub floor breaking up. The water was coming in through the back of the house and runing under the sirs into the lounge so I am hoping that this was the only source and it wasn't coming up through the lounge flor too. I did trace the source to a blocked culvert above the house, and it stoped once I had cleared it so lets hope that it only came in at that one point and not up through the floor too.

The subfloor was laid in the 1980s and originally the floor level was 2 fet higher. They dug down 600mm, laid the concrete flor and toped it with the bitumen floor, probably because the lounge is about 6 feet below ground level (the house is built into a hill).

 

[JohnD]

The bitumen floor is waterproof, so would lift up and crack if water pressure was underneath it (that's why a concrete slab is laid on top of the DPM, to hold it down) so I fear water was coming up through the floor, especially if it's below ground level.

sorry

 

[mattysupra]

sounds like the subfloor is a surface dpm. It also sounds like it has sheared from the base underneath. You insurance company will have to pay for the repair to the floor which will be to dig it up and lay new dpm, concrete etc.