Lifting 120 year old floor and insulating - Bit lost...need help!

Yossari

Yossari

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Im in the process of lifting my floors and removing the slag/burnt rock insulation. There is a layer of whitish plaster which I assume is horsehair between the joists. Is this just to keep the slag in or is there some other reason. Ive also got a sickly sweet smell coming from the floor. I guess what Im saying is that I dont know what it should look like under my floor? Where I have removed it all I can see some wooden boards between the joists that have gaps and I can lift these. Do I put my rockwool bats on top of that? Floor is also uneven and sags in middle.
 
Ill post pics...But from the top...original floorboards...under that is rubble/slag....under that is what I think is horsehair plaster about 2cm thick....under that is adjacent boards with gaps inbetween...
 
when you say fix the floor you mean get all the boards lifted? Ive done about half the room so far but just not sure about this layer of either solidified dust or horsehair plaster.
 
Is this a ground floor floor with a cellar below?
It sounds like you are describing a lath and plaster ceiling viewed from above.
 
ok first pic is half and half...the left side is what is under the white plaster (Id already removed the slag/rubble) and the right picture shows a little rubble at the top and the white plaster stuff below. under all this is the gapped wood. I am going to life the rest of the floorboards this weekend and clean it all up. I'll be using the netting and rockwool batts to insulate. Any advice? PS this white plaster stuff seems to give off a sickly sweet smell, worse when its humid. The smell could also be some 100 year old vegetation/twigs and leafs that seems to be in the wall gaps
 

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The floor is a 1st floor flat, 120 year old red sandstone 4 in a block. The joists were packed to the brim with burnt rock/slag. That has been removed. There is a layer of 2cm white plaster beneath that. Beneath the plaster layer is wooden slats with gaps. Do I just clear it ALL out and lay my insulation on top of the wooden slats (suspended by netting obviously)?
 
The stuff you may have removed was probably soundproofing.
the strips of wood and plaster is the ceiling of the flat below.
ON NO circumstances do anything to that.

fiddling with what was possibly sound proofing isn’t a great idea.
You may well have breached the lease? Replace with sound deadening material.
 
Tigercub...yes it was soundproofing. I know that. The strips of wood are NOT the ceiling of the flat below (I can lift them out...they're just suspended...not attached to anything and they are not lath of the ceiling downstair. the wood is UNDER the white plaster. Not above it. As stated I am putting in rockwool batts so I guess you could say Im fiddling with soundproofing...by improving it. ALso...I own the place so not breaching any lease. Rockwool is sounddeadening material so yes, it will be replaced. You dont seem to get the problem...but thanks for trying. I need someone who understands what these floors should look like underneath?
 
They will have been to keep the soundproofing off the neighbour’s ceiling probably.
Their wiring may be under that?
 
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