Black coal like stuff

[stamas01]

Hi all,

So there is a layer of something between my ground and first floor. It seams that it is lime mortar and some black stuff. The black stuff is powder but also comes in small pieces that really looks like coal to me. Can someone just advise me what can this be? Also what is the purpose of this lawyer? Is it meant to be insulation?

Thanks,

Tamas

 

[Toby Newell]

Looks like clinker. Could be insulation.

 

[stamas01]

Looks like clinker. Could be insulation.

Thanks for your reply. That is reassuring! At least it is then not very harmful

 

[Toby Newell]

Not unless you break it up and inhale it.

 

[stuart45]

Sand plugging was sometimes used between the joists for sound insulation.

 

[fernicarry]

Known as ash deafening. For sound insulation rather than heat insulation. Imagine someone upstairs clumping around on the bare floorboards.

Ash deafening

Ash deafening - Designing Buildings - Share your construction industry knowledge. Ash deafening, or 'pugging' (occasionally mistakenly referred to as ‘deadening’) was traditionally used in the construction of buildings in Scotland to provide sound insulation in timber separating floors (floors...

www.designingbuildings.co.uk

Mine seems to be mainly fire ash or sand and is very fine and dusty. There are sea shells and small bits of unburned coal in it. You'll often find that tradespeople have disturbed the boards it sits on so there are great heaps of it on the back of the ceiling below.

 

[Toby Newell]

My guess was correct then. Ash = clinker.

Otherwise called slag. Basically porous high temp. fused glass / metals from impurities in coal. They used it in everything! Actually they still do, in tarmac and concrete.

Hence 'cinder block'. Also hence why they, your cheap black bin bags / cheap rubber products / wheelspinning tyres smell slightly burnt and slightly sulphurous.

It contains some not good for you chemicals but they use it in everything. If it's consolidated clinker then they did sometimes add asbestos, another thing that had a thousand uses. Just wear a mask. Any building over 100 years old probably contains some asbestos containing products somewhere. As in a previous thread, mask, ventillate, vacuum all dusts, old or new. In general your lungs do not like particles of any size, shape or composition. Which is why I have four dust extractors.

Nowadays they use Vermiculite, which is similar but less toxic. After it's been checked for asbestos...

Clinker is essentially waste whereas Vermiculite is mined and treated which is why it is so much more expensive.

They probably still use it like this in some countries.

You actually also find it a lot in old fire hearths.

Fly ash and sand mix would be more desnse for use as a sound deadener (packing ratio) this clinker is actually less dense than that because of all the holes, so probably much better as a heat insulator. It helps with both.

 

[fernicarry]

It won't do anything for heat insulation because there is an air gap above and below it.

Yes, face mask and vacuum up the spillage whenever you have to interact with it. I've removed it from under the rooms where I've installed UFH to fit proper insulation. Was not a pleasant job, v. dusty and weighs a ton to hump it downstairs. Imagine the load on the upstairs floor joists from it...

 

[Toby Newell]

It won't do anything for heat insulation because there is an air gap above and below it.

Yes, face mask and vacuum up the spillage whenever you have to interact with it. I've removed it from under the rooms where I've installed UFH to fit proper insulation. Was not a pleasant job, v. dusty and weighs a ton to hump it downstairs. Imagine the load on the upstairs floor joists from it...

insulation doesnt need to fill the entire void, in fact very bad to do that on ground floor. It is horribly dirty.

 

[stamas01]

Thanks for all the help and answer!

I mean when it comes to balancing between hearing a few footsteps and loading the first floor with a few tons of s***... I don't think I would personally go with the second one. I decided to leave it there as we live upstairs it the house as I renovate the ground floor. I tried removing it but the dust!!! It is unbelievable.

 

[Toby Newell]

Best option! Always amazes me how much dead load these old floors can take.

 

[philpjuk100]

Could it be lime/ash? We have a lime/ash attic floor and I believe that the poor quality lime (we are near a lime kiln) and coal ash (there is a "gas house" just down the road that supplied the local "big house") was just spread on laths or as we are near a river reeds in a dry state and absorbs moisture from the atmosphere causing it to set in our case a bit "patchy" there are areas which have clinker visible the pic shows the reeds supporting thr lime/ash (now plastered) The only pic I could find of the lime/ash from above (this is about the best bit of the floor) near the edges/chimneys it is loose and I have added some lime which seems to have consolidated it) even the "good" bits have cracked. When we had a survey done before purchasing the surveyor pointed out the lime/ash was between nine inches and a foot thick and the inch and a half thick cosywrap added nothing to the insulation..so to make the space more useable we removed it..

 

[philpjuk100]

History[edit]​

A malthouse in Yorkshire, England, that uses lime-ash floors
Lime-ash is the residue found at the bottom of a wood-fired lime kiln, consisting of waste lime and wood ash.[2] These kilns became common in the early 15th century and continued to be used until newer technology replaced them in the late 19th century. Lime-ash could also be made in coal-fired kilns. In areas where gypsum was common they were known as plaster floors.[1] Lime ash was used on the upper floors of yeomen's houses and in great houses such as Hardwick Hall in Derbyshire, where the upper surface would be buffed to a fine finish using a mixture of egg-white, curdled milk and fish-gelatine.[2] The underside could be left bare or smoothed with a lime-plaster. Alternatively the floor joist could be concealed with a conventional lath and plaster ceiling

 

[fernicarry]

The deafening doesn't form the floor surface, the floor above is conventional floorboards.

If you look at the first pic in the middle bay you can see the back of some of the floorboards where the deafening boards have been removed. You can also see the batons nailed to the sides of the joist that the boards would have sat on and the edge of the deafening layer on the first remaining board. The deafening is usually only a few inches deep and doesn't fill all the way to the underside of the floor boards (hence no thermal properties).

The boards are just any old left over rubbish. You can often see how adjacent boards have been split off the same larger piece. Not intended to take any point load.

I don't think anything was done to deliberately make the deafening 'set', but its often pretty solid probably due to absorbing moisture from the air and forming a sort of conglomerate. Sometimes you get lucky and can lift the boards out with the deafening largely intact avoiding the horrible dusty mess.

I have quite a few more to remove under the new shower room so that I can put in proper insulation for the UFH. Joy...