Identify my wall type?

sergeantash · 28 Apr 2010

I have a house built in 1927 in the Bristol area - having stripped down the walls upstairs and removed the plaster from them I'm down to the bare construction material which is rather odd, I'm seeking identification!!

Here's some features of these odd walls...

- They sit directly on the original floorboards
- They run the same way as the joists, not along a weight bearing wall
- They're constructed from large blocks about 2/3 times size of a breeze block
- They're a black airated material, similar to breeze block
- They're about 1.5 inch thick
- The material is hard but quite crumbly once you break it

Any ideas? Someone mentioned 'Ash Blocks' but I can't find anything on those?

Thanks for your help!

Static · 28 Apr 2010

Clinker blocks.. used industrial smelting waste as aggregate.. might go by another name cant remember..

sergeantash · 28 Apr 2010

Many thanks for your reply. They're quite impressive considering their age, almost perfectly flat and they seem very rigid - even my structural engineer hadn't seen blocks such as these before that were sat directly on floorboards!

Static · 28 Apr 2010

Whenever ive come across them in the past they have been similar size to normal blocks if not a little thinner.. my guess is based purely on the black material and the crumbling..

When you say 2 or 3 times the size of a normal block? so upto 1.3m x 0.7m or 0.7m x 0.5m?? thats some serious sized blocks! thats more panel than block..

Sitting non load bearing block walls onto floor boards in older buildings is fairly uncommon but happens, there are various posts on the forums here about them.. its a little lazy and not adviseable..

sergeantash · 28 Apr 2010

Thanks for your reply. I would say they're about twice the width of of a standard size breeze block, about 1.5x the height. Thickness wise they're not as thick as a breeze block.

The blocks are put together to form the wall in a brick style pattern, cemented together with some sort of dusty black morter.

I was tempted to knock down the wall and rebuild in stud but these walls are solid, fairly stable and seem structurely sound so didn't want to suffer the mess of taking them down!!

Static · 28 Apr 2010

Sorry but my knowledge on that type of blockwork is pretty limited.. but so long as the floor isnt showing any signs of distress, so no cracking in the ceiling below or the floor is very bouncy.. and that the wall is still vertical and not cracking up.. then no real reason to remove it..
Just bear in mind how its supported if you ever decide to pull up all the floor boards..

maltaron · 28 Apr 2010

They sound like breeze blocks, usually tongued and grooved. Used a lot just after the WW2 as they were cheaper and lighter than timber partitions. They are usually plastered just like a brick wall. Beware if you try to remove a door frame, they had a groove in the back for the block, in fact the door frames were fitted first, fixed to floor and ceilings and the blocks built up to them.

stuart45 · 28 Apr 2010

Coal ash blocks and mortar were quite common in South Wales and Avon in the early 1900's.

sergeantash · 29 Apr 2010

Thanks guys! Its nice to know a bit of history about the house! They're a good sound barrier so I guess replacing them with Plasterboard would have been a shame.

Thanks for the feedback!

ajrobb · 29 Apr 2010

Could some of the sound insulation be due to lime plaster rather than gypsum?

I grew up in a house with breeze block walls upstairs and noise through them was never a problem, most of it seemed to come through doors. I was astounded by noise transmission through stud partitions.

sergeantash · 29 Apr 2010

ajrobb said:
Could some of the sound insulation be due to lime plaster rather than gypsum?

I grew up in a house with breeze block walls upstairs and noise through them was never a problem, most of it seemed to come through doors. I was astounded by noise transmission through stud partitions.

I can imagine that stud's would prove useless against sound insulation - regarding the walls I have, covered in plaster or not the material itself is a really good sound insulator, I'll try and take some pics in the next few days!

noseall · 30 Apr 2010

Cinder blocks or fly ash blocks were commonly used as first floor partitioning.

These would typically be 3" thickness and be laid upon a timber sole plate. Later these blocks were t&g'd along the perps to alleviate the need for perp mortar.

If your structural engineer has never come across these then he is a very inexperienced s.e.

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Identify my wall type?

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