Cavity wall or cavity block (photos)

Summer2020

hi,

I’m looking to get walls pumped and read on here to remove a wall vent and you should be able to tell. Would anyone know by looking at these photos is it likely cavity wall or block construction please ?

Mellor

Neither. There's no cavity in that wall. Neither cavity blocks nor a cavity between leafs.

Those are solid blocks on flat. And what appear to be insulated plasterboard.

Summer2020

https://www.boards.ie/discussion/comment/122141054#Comment_122141054

thanks, I assume that’s not great for insulation ? Ruling out pumping the walls anyway

Mellor

https://www.boards.ie/discussion/comment/122142668#Comment_122142668

The solid wall is more an issue for damp and water ingress.

Internal lining can provide a reasonably good level of insulation. It depends on the thickness of existing verses a potential upgrade. Cost vrs benefit type of thing

Victor

https://www.boards.ie/discussion/comment/122142668#Comment_122142668

That is not to say that material improvements can't be made to the insulation values and thermal stability of the property. While the property might have OK-ish insulation on the inner face of the walls, there are likely as least some 'cold bridges' (spots where the insulation is ineffective, e.g. where internal walls meet external walls) and poor thermal stability - the property will find it difficult to stay warm / cold depending on the time of year.

Comprehensive roof insulation; a review of the ventilation, windows and doors; and external insulation are probably the best avenues to explore. Additional internal insulation risks losing floor space and might not be as effective as external insulation. Also look at how the property is heated.

Summer2020

thanks. It’s a 1991 built property, which while no doubt was well constructed at the time will need updating to modern standards. Has suspended timber floors for instance

Sheedy234

Do not pump cavity wall. The space is there for a reason. Pumped walls are being linked with accelerating defective blocks due to holding moisture

Victor

https://www.boards.ie/discussion/comment/122147530#Comment_122147530

There is no cavity.

Dr.Tom

https://www.boards.ie/discussion/comment/122147530#Comment_122147530

Have you evidence to support this claim?

Yellow_Fern

https://www.boards.ie/discussion/comment/122147813#Comment_122147813

Different walls have different designs but in recent decades semi fill cavity walls are popular. These have a deliberate void in front of the insulation for drainage. Whether that can be filled is controversial. There are higher risks in areas of high amounts of driven rain like west of Ireland. I have heard horror stories from Wales and Dongeal of problems from filling it.

Victor

The cavity has a number of uses, including creating a thicker, less slender wall and creating a thermal break.

Mellor

https://www.boards.ie/discussion/comment/122149980#Comment_122149980

the cavity is there to prevent water ingress. That is well established. The claim was that filling the cavity causes defective. You’ve also reiterated that claim. Have you anything to back it up?

I’m not saying it’s true or untrue. But somebody down the pub claiming it was due to filling the cavity doesn’t actually mean it had anything to do with it.

FWIW, I’m not a fan of pumped cavities.

phormium

Were block on flat type houses being built in 1991? I'm no expert obviously but my own house was built in 1990/91 and it's the standard two wall with cavity and aeroboard stuff in the gap. Would houses like that not be much older? Why would anyone build that type in 1991, maybe there is an explanation I'm not aware of.

That said I still wouldn't pump whatever cavity I might have because I can't figure out how the stuff goes in properly when there is alread aeroboard in there, surely it wouldn't be a very successful job! A friend of mine who bought a new house maybe 8 yrs after me so similar sort of construction had her walls pumped, couldn't understand it myself at the time as felt there should even be better insulation in her house being newer, anyways never noticed any difference in house after it!

Yellow_Fern

https://www.boards.ie/discussion/comment/122152111#Comment_122152111

I dont know the scientific literature on this but there are tons of cases of people reporting that filling it causes a lot of problem, including from Donegal. Really easy to find these reports. Not saying they are valid reports but they are out there.

muffler

https://www.boards.ie/discussion/comment/122155964#Comment_122155964

Im in Donegal and have personal experience of issues after pumping the partially filled cavity wall. And it's not just me as I'm aware of a lot of other houses with the same problems.

Sheedy234

Never said it caused the defective block I said there were talks of it accelerating the deterioration. It was brought up in discussions in Oireachtas. My own family home has pyrite and walls were pumped ,shed was not pumped and very little showing of pyrite.

Furze99

https://www.boards.ie/discussion/2058351761/cavity-wall-or-cavity-block-photos

https://www.boards.ie/discussion/comment/122141054#Comment_122141054

I'd have thought it's possible it is cavity block construction which would be typical of the age but that solid blocks on the flat have been used to frame the ducts. They're the same basic shape after all.

I'd have thought you'd want to pick an exterior wall to the rear etc and drill a few test holes through from the outside, you'll need a longish bit, 200mm at least. You'll should find out then, as it'll be obvious if the bit breaks through into the cavity. There's always a chance you're going to hit a joint in the cavity blocks which will be solid, so try a few spots unless it's obvious after the first.

You'll need to make up a bit of mortar to plug the holes after.

Mellor

https://www.boards.ie/discussion/comment/122160384#Comment_122160384

A regular cavity wall is a different dimension to a block on flat wall. There’s no room to built two leafs and a cavity in that depth. If that were the case, you’d see another vertical solid in the vent.

standardg60

https://www.boards.ie/discussion/comment/122160384#Comment_122160384

Agreed, most likely cavity block unless they had money to burn and solids on the flat around the vents. They allowed for the vents during construction rather than core drilling afterwards. Anyway pumping looks like it's a no go.

Furze99

https://www.boards.ie/discussion/comment/122163279#Comment_122163279

Yes but I thought it could be a cavity block construction with solids to frame the vents. Cavity blocks are 9" wide and same as standard concrete blocks 9"?

standardg60

https://www.boards.ie/discussion/comment/122179433#Comment_122179433

I was very tempted to post that response for you 😁

standardg60

..

Mellor

https://www.boards.ie/discussion/comment/122179433#Comment_122179433

That’s possible. But then it still would be a cavity walk and pumping would mostly be a waste of time.

Furze99

https://www.boards.ie/discussion/comment/122180274#Comment_122180274

Possibly, I'm not sure - seems to be a recommended method for some structures? I'd imagine it's be very hard to fill all the cavities in a cavity block wall anyway.

The OP was wondering about nature of construction.