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What’s in my cavity?!?!


Gav_P

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.... what’s in my wall cavity, as in, what insulation? I have a small 1980’s block built 2 story extension, with the upstairs room ceiling under eaves, which gets quite cold (both upstairs and downstairs). I was wondering what the easiest way is to find out what insulation (if any) has been used in the cavity. I’m thinking I could upgrade with full fill beads. 

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Do you have any wall vents? E.g kitchen extractor? Pull the cowl off and you should be able to see in to the cavity. Ditto if you have a electric or gas meter box.

 

My money is on poorly installed 100mm of mineral wool. You don't be able to do anything about it. If you are in luck, the cavity will be empty and you'll be able to pump with beads.

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1 hour ago, Conor said:

Do you have any wall vents? E.g kitchen extractor? Pull the cowl off and you should be able to see in to the cavity. Ditto if you have a electric or gas meter box.

Unfortunately not... no openings other than windows. 
 

 

1 hour ago, Conor said:

My money is on poorly installed 100mm of mineral wool. You don't be able to do anything about it

Bugger, that’s was what I was afraid of but wasn’t sure if there was any possible fix. 

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1 hour ago, Gav_P said:

Unfortunately not... no openings other than windows. 
 

 

Bugger, that’s was what I was afraid of but wasn’t sure if there was any possible fix. 


There is but it’s not cheap and invasive. I’ve had quotes to have fibre removed and beads installed. They take bricks out on corners and use steel rods and a long vacuum cleaner nozzle to suck the old insulation from the cavity. Then blown beads installed. 
 

Got a couple of contacts for it. 

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I’ve just order myself an endoscope to connect to my phone and then I’ll be up the ladder to have a peak. 
 

Not sure that I fancy going down the route of removing structure to get at it all.... I don’t like the idea of the cost either ?

 

If it turns out to be some kind of mineral wool, I wonder if there is a diy way of removing it. 

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You can use the Elephant Technique.

 

Drill a hole at either end.

 

Connect your elephant at one end, then make it sneeze.

 

Sorted.

 

(You can do it the other way by squeezing its trunk with a clothes peg to prevent an intake of breath then connect it very quickly so that the insulation is sucked out. In this case you need to be fast runner as the elephant will be quite grumpy.)

 

 

Edited by Ferdinand
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  • 3 months later...

Has anyone done cavity wall insulation removal? It seems to be a process using high pressure airline and an industrial side vacuum. 
 

I am thinking about giving it a go to replace the crap 80s stuff with new full fill beads. 

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1 hour ago, Gav_P said:

Has anyone done cavity wall insulation removal? It seems to be a process using high pressure airline and an industrial side vacuum. 
 

I am thinking about giving it a go to replace the crap 80s stuff with new full fill beads. 

 

 

When getting a cavity wall insulation quote for my 2001 built house the assessor drilled a 10mm hole in the mortar bed at the corner of a brick. By looking for debris on the drill bit as it was removed he checked what was in the cavity. The cavity was empty as I thought.

 

Why not top up the current wall insulation with an extra internal layer of PIR lined plasterboard?

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46 minutes ago, epsilonGreedy said:

Why not top up the current wall insulation with an extra internal layer of PIR lined plasterboard?

I could also do this, although I’d rather not as that means completely redoing the rooms internally. 
 

The reason for removing the insulation is because it’s got wet and slumped in the cavity. So wet insulation at the bottom and nothing at the top. 

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38 minutes ago, Gav_P said:

I could also do this, although I’d rather not as that means completely redoing the rooms internally. 
 

The reason for removing the insulation is because it’s got wet and slumped in the cavity. So wet insulation at the bottom and nothing at the top. 

 

 

Ok that is a very different situation. So you want to know what insulation type has slumped to the bottom of the cavity that you suspect is wet due to other symptoms.

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How big is the cavity ..? Is it 100mm or less ..?

 

Depending on where you are in the UK, JJ Crump in Sheffield do this and they are very competitive on pricing. They do a couple of different bead types too. 

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3 hours ago, PeterW said:

How big is the cavity ..? Is it 100mm or less ..?

 

Depending on where you are in the UK, JJ Crump in Sheffield do this and they are very competitive on pricing. They do a couple of different bead types too. 

It’s less than 100 I would assume as the wall is 290 including plaster and render. 
 

Unfortunately I’m in Bristol area so don’t think Crump would be a viable option. 

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15 minutes ago, Gav_P said:

It’s less than 100 I would assume as the wall is 290 including plaster and render. 
 

Unfortunately I’m in Bristol area so don’t think Crump would be a viable option. 


Got an office in Newton Abbot and do cover the south west so may be worth a try 

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On 02/01/2021 at 19:43, Declan52 said:

Everything from a hp bottle to fruit according to a mate who works in A&E.

 

A chap came in with an apple up his arse when I worked in A&E. Wonder if it counted as one of his 5 a day?

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