DIY blown cavity insulation

[ElliotP]

Hi all,

 

Please bear with me, it's going to sound stupid, but needs must.   Current house is a 1930's standard brick build, 100mm cavity, no insulation.  We're knocking it down in a couple of years and building new, but right now it's absolutely freezing. I work from home and run up £10 in gas yesterday and was still sat here at 18 degrees.  Loft has been insulated properly at least, and we're double glazed.  I've gone round with foam to make it airtight as possible, silicon around the skirtings etc.  We're on a hill open to the elements, so we get battered by the wind.

 

Quotes have come in at £3k+ for cavity insulation, I'll never get my money back if we knock it down in 2 years, so pointless.

 

My plan (as others have done before) is to use a leaf vac, 100mm hose on the output side, reduced down to an empty tube of silicon with cut off nozzle at circa 20mm to inject the insulation.  Will inject into holes drilled through the external masonry at circa 1m intervals.

 

My issue is with materials, finding the best in terms of cost / suitability / availably.   Volume requirement is about 12m3

 

1) EPS Bead  - I know typically that it's injected with a binding agent to set solid.   I could possibly rig something up to do this - such as slightly diluted PVA pumped into the nozzle on the way through.  This is coming out quite cheap at about £400 for the materials, but i've gone for 'furniture grade' (fire resistant) beads, not anything specialist - will this work or will they be too small? And could I avoid the hassle of a binding agent.

 

2) Something like Thermofloc (although I don't believe this is strictly for use in external cavity), this is coming out more expensive - £1000 for materials.

 

As mentioned this is only a temporary solution, so i'd like to be as little as possible on the material cost, but not something that is just going to be pointless.  It seems to be that loose fill cavity wall insulation isn't generally available to the public as i'm finding it difficult to find suppliers.  Judging by my google time today, In the US it seems pretty normal to be able to rent a blower and get on with it.  In the UK, near impossible.

 

Would gladly take any advice on the above, especially potential materials and suppliers.

 

Thanks,

 

Elliot

Edited November 22, 2022 by ElliotP

[markc]

Is it the whole house that feels cold or just downstairs? Reason I ask is that a couple of years ago my soon to be mother in law constantly complained her house was freezing and it was the kitchen floor sucking heat away, the house was actually ok but you felt cold because your feet were cold. Dug floor up, insulated and relayed and the house has been completely different since.

if the loft is well insulated chucking that much heat in should have the upstairs fairly hot.

my house has no cavity, I like 18 degrees when I’m home but I don’t use much gas at all, but I don’t work from home.

[Mr Punter]

If it is being demolished in two years it seems a real waste to fill the cavities only to send it to landfill.

 

You could just heat a smaller room and wear extra clothing.

[Gone West]

37 minutes ago, ElliotP said:

Would gladly take any advice on the above, especially potential materials and suppliers.

We had an old timber frame, timber clad bungalow, 100mm cavity, filled with blown mineral fibre. It made a huge difference to our oil usage, reducing it by 30% to 40%. We lived in it while building our self build in the garden. It took us eight years to build the house, although the plan was only two or three years. You never know how things will turn out, so I would install the insulation, as cheaply as possible, and be more comfortable while living there.

[ADLIan]

You will not find a DIY option here as its notifiable work under the Building Regs. Injected cavity wall insulation must be certified/approved (BBA or similar) and be installed by an approved contractor.

[ElliotP]

Thanks for your replies.

 

The upstairs is as cold as the downstairs - although the radiators are off in the bedrooms given the anticipated convection, which never seems to materialise.     Floor is freezing throughout but we can't do much about it without ripping it all up.  In my last renovation I had every floor up, 100mm PIR and UFH on top - was wonderful.

 

I have a 16kBTU portable air con/heat pump which is running 12 hours a day from the solar/battery storage, that's just about keeping it above 17 degrees at the moment.  Got some heated blankets last week also, that's nice.

 

My Wife is at home also, and the kids back from school early afternoon - the whole of the downstairs is generally in use all day every day, so heating just 1 room doesn't work. I'm sat here in a big fleece but still can't feel my fingers

 

Landfill and waste  - yes I have considered this, it will be a shame, but 2 winters of this, and the potentially rising gas prices next year, I feel i need to do something.  Possibly if i go for loose cellulose i could recover it to some degree, even if it was used to insulate a garden room in the future.

 

I didn't realise it was notifiable, this explains why I'm struggling to source materials and equipment hire. 

 

 

[Gone West]

2 hours ago, ElliotP said:

I didn't realise it was notifiable, this explains why I'm struggling to source materials and equipment hire. 

We did our bungalow back in 2008 and were able to get a 50% grant so it was certainly worth it. I don't know if you could find an appropriate grant as they don't have to know it will be demolished sometime.

[Radian]

41 minutes ago, Gone West said:

We did our bungalow back in 2008 and were able to get a 50% grant so it was certainly worth it. I don't know if you could find an appropriate grant as they don't have to know it will be demolished sometime.

+1. How old are the kids? Anyone on any benefits? Call your local authority to see if can be done under the Energy Company Obligation

[ElliotP]

4 and 9 year old.  Child benefit, just about - but we're both relatively high income, so any grants /schemes i've looked at don't apply.  Besides the fact I feel bad given we don't really need the grant, it could go to someone else, and even worse if we're knocking it down in a couple years.

 

I've got a reasonable quote for EPS beads now, so I'm going to attempt this - it may end up being a disaster, but worth a go I think!

[Roger440]

10 hours ago, ElliotP said:

4 and 9 year old.  Child benefit, just about - but we're both relatively high income, so any grants /schemes i've looked at don't apply.  Besides the fact I feel bad given we don't really need the grant, it could go to someone else, and even worse if we're knocking it down in a couple years.

 

I've got a reasonable quote for EPS beads now, so I'm going to attempt this - it may end up being a disaster, but worth a go I think!

 

Can i ask who the quote was from please?

[ElliotP]

Just wanted to post a little update incase anyone else finds this and is thinking of it.  It worked rather well.  We've injected just under 10m3 into the cavities of the house, and it's already a lot more comfortable.

 

I think probably what was worse than the lack of wall insulation was that the air bricks were not funnelled into the sub floor - it looks like some time in the past the floor has been replaced (i'm guessing it was circa the 80's) and all they simply knocked a hole through the inner skin into the subfloor, but the air bricks were letting freezing cold air all through the cavity.  We installed 100mm pipes and foamed around the the inner skin to seal it up (to stop the EPS beads going under the floor), then mortar and (eventually) some vents over the exterior skinny to tidy it up.  I've gone for closable vents on the outside so we can block off cold air to the sub floor during the freezing months.  You can actually walk on the floor now and be comfortable - obviously yes there is a concern with rot of the timber, so i'll open them occasionally to air the sub floor out.

 

The machine itself I made up in a couple of hours out of a piece of mdf base, an old compost bin i had laying around, and the £50 3kw leaf blower from Screwfix.    I also made a PVA glue hopper out of an old pump and bits i had spare also.  We watered down the PVA 3 to 1 and injected this near the nozzle so it coated the balls on the way through.

 

Initially we were removing bricks as our nozzle was 50mm, any smaller and the machine would clog up.  However i realised that if we blocked off the leaf blower inlet to 20mm, we could have a 20mm outlet and it worked perfectly, just a bit slower.  So we did that, and used a short bit of 22mm copper pipe as our nozzle to inject through.  However it meant we could drill 25mm holes with an SDS bit - much nicer than removing bricks.  The main hose was a standard 100mm duct.  The eps beads flew in with some serious pressure - worked great.

 

We did have a little issue in the cavity wall not being closed in a small loft space above the utility room - bit of PIR and foam took care of that.  I did take half a day having to get the beads back in the bags however to go again, however I did have to laugh when i popped my head through the loft hatch to see a giant pile of beads not where they were supposed to be.

 

The jury is still out on the PVA - difficult to know if the mix was right, and if it was being pumped in quick enough to make any real difference.

 

All in all, total cost of £500 for some beads and £100 on materials.  £50 of which is the leaf blower which is fully useable again to actually blow leaves...

 

I do plan to suck it back out the walls and re-use it whenever we come to demolish the house in the near future, save the landfill and a few quid!

 

 

 

 

 

 

[ElliotP]

The beads! 

[Carrerahill]

On 22/11/2022 at 13:04, ADLIan said:

You will not find a DIY option here as its notifiable work under the Building Regs. Injected cavity wall insulation must be certified/approved (BBA or similar) and be installed by an approved contractor.

Nonsense. 

 

What happened to pragmatism. Guy is doing a temp job on a house that is getting demoed.

 

Approved contractor? Go over to the EV Charger thread just now and read the contempt for "approved" and "certified" "clubs" - you will get some poorly trained muppet with a pipe shooting beads into your wall regardless. I guarantee you that the majority of this forums members (clearly not all), would be more knowledgeable and competent than most of the people who come to install it and will understand how a building goes together far better. Most of us on this forum build buildings, all in compliance with regs and building standards, of course someone can buy the approved material and blast it into a cavity.

 

 

[Carrerahill]

10 minutes ago, ElliotP said:

Just wanted to post a little update incase anyone else finds this and is thinking of it.  It worked rather well.  We've injected just under 10m3 into the cavities of the house, and it's already a lot more comfortable.

 

I think probably what was worse than the lack of wall insulation was that the air bricks were not funnelled into the sub floor - it looks like some time in the past the floor has been replaced (i'm guessing it was circa the 80's) and all they simply knocked a hole through the inner skin into the subfloor, but the air bricks were letting freezing cold air all through the cavity.  We installed 100mm pipes and foamed around the the inner skin to seal it up (to stop the EPS beads going under the floor), then mortar and (eventually) some vents over the exterior skinny to tidy it up.  I've gone for closable vents on the outside so we can block off cold air to the sub floor during the freezing months.  You can actually walk on the floor now and be comfortable - obviously yes there is a concern with rot of the timber, so i'll open them occasionally to air the sub floor out.

 

The machine itself I made up in a couple of hours out of a piece of mdf base, an old compost bin i had laying around, and the £50 3kw leaf blower from Screwfix.    I also made a PVA glue hopper out of an old pump and bits i had spare also.  We watered down the PVA 3 to 1 and injected this near the nozzle so it coated the balls on the way through.

 

Initially we were removing bricks as our nozzle was 50mm, any smaller and the machine would clog up.  However i realised that if we blocked off the leaf blower inlet to 20mm, we could have a 20mm outlet and it worked perfectly, just a bit slower.  So we did that, and used a short bit of 22mm copper pipe as our nozzle to inject through.  However it meant we could drill 25mm holes with an SDS bit - much nicer than removing bricks.  The main hose was a standard 100mm duct.  The eps beads flew in with some serious pressure - worked great.

 

We did have a little issue in the cavity wall not being closed in a small loft space above the utility room - bit of PIR and foam took care of that.  I did take half a day having to get the beads back in the bags however to go again, however I did have to laugh when i popped my head through the loft hatch to see a giant pile of beads not where they were supposed to be.

 

The jury is still out on the PVA - difficult to know if the mix was right, and if it was being pumped in quick enough to make any real difference.

 

All in all, total cost of £500 for some beads and £100 on materials.  £50 of which is the leaf blower which is fully useable again to actually blow leaves...

 

I do plan to suck it back out the walls and re-use it whenever we come to demolish the house in the near future, save the landfill and a few quid!

 

 

 

 

 

 

Bravo! I doff my cap! 

[Radian]

1 hour ago, ElliotP said:

We've injected just under 10m3 into the cavities of the house

I bet that looked like a lot when it was delivered! Curious to see the nozzle you ended up using.

[ElliotP]

Had a few pm's asking about nozzle etc.  Attached photos and a bit more info.  Really pleased to share this info as i couldn't find much online after hours of Googling - and i think the more people that can do this the better, both for the environment and your wallet.  Would I do this if i wasn't planning on knocking the place down? Probably not, I'd get it done properly - however would it be done properly? We spent a lot of time sorting those sub floor vents out - i don't think anyone else would.  As far as i can see my cavities are full of EPS beads and the house is much more comfortable - and I saved £2k.

 

So the first photo was v1, which was 100mm to 50mm reducer, and a bit of ply just bigger than the size of a brick to stop any 'splash back'.  This worked great and filled the wall stupidly quick, but taking bricks out is not easy.

 

The photo, is v2, this is a 50mm to 22mm waste bung (from Toolstation/Screwfix i think), then a bit of 22mm copper shoved in it.   This worked great, but you do need to block off the 'suck' end of the leaf blower with a bit of ply or plastic, and cut a 22mm hole in it, so the leaf blower can't suck up too much too fast as it just blocks the tube up.   This caught me out, hence i went with the brick removal solution - wish i figured it out first instead of having to remove bricks.

 

For the intake, the leaf vacuum from Screwfix was great, seriously powerful.  The vacuum lance comes in 3 pieces, but for safety you have to assemble the enter length of the vacuum otherwise it won't start, so i unscrewed the last piece, slid out the contact joiner (i assume it's just a bit of metal, maybe a resistor) and used that -this way i didn't need to use the full length of the lance so it made it a bit more compact.  

 

If you have a drum you could simply sit the vacuum in the top i think, it would still work just as well, no need to cut holes out the bottom really.  My compost bin already had a hole here for compost removal, so it made sense to put the leaf blower lower down.

 

Video of v1 nozzle in action: 

 

https://www.dropbox.com/s/vfdpo8oz1uc30m8/IMG_0087.MOV?dl=0

 

I'm not sure if I can link out to other sites here but a rough parts list was:

 

For the bead blower: 

 

100mm x 6m fan duct from Toolstation - £6

100mm to 50mm reducer from Amazon - £6

50mm to 22mm bung - already owned

Little Copper pipe - already owned

Container - already owned (compost bin)

Leaf blower - Screwfix - £50

Plenty of gaffa tape / cable ties.

 

For the pva pump:

12v dc pump - already owned

12v power supply - already owned

6mm silicone tube (£8 ebay)

1/2 bsp to 6mm brass fitting (£5 ebay)

Ikea container - already owned

 

Also attached the drawing i used for rough idea of hole frequency/position.

 

[Radian]

Another trick they sometimes use on a corner is to inject just over a brick width in from the edge to get into the cavity of the return wall - should access to the side be an issue. They even use lance extensions to get further into the wall. Sods law says you'll end up on a wall tie though.

[ADLIan]

7 hours ago, Carrerahill said:

Nonsense. 

 

What happened to pragmatism. Guy is doing a temp job on a house that is getting demoed.

 

Approved contractor? Go over to the EV Charger thread just now and read the contempt for "approved" and "certified" "clubs" - you will get some poorly trained muppet with a pipe shooting beads into your wall regardless. I guarantee you that the majority of this forums members (clearly not all), would be more knowledgeable and competent than most of the people who come to install it and will understand how a building goes together far better. Most of us on this forum build buildings, all in compliance with regs and building standards, of course someone can buy the approved material and blast it into a cavity.

 

 

 I was merely pointing out why DIY systems are not available. Not my gift to be pragmatic as that's a decision for the OP - its his house!.

 

The approval scheme (BBA normally) for injected cavity wall insulation has been around for many years and is well documented covering manufacturer, system designer through to the installer. Approved Document C specifically covers this requirement. The installer does not have to understand how a building goes together just how to install the product correctly. Joe Public cannot purchase the 'approved materials' as they are only available as part of the 'approved' package.

[Roger440]

1 hour ago, ADLIan said:

 I was merely pointing out why DIY systems are not available. Not my gift to be pragmatic as that's a decision for the OP - its his house!.

 

The approval scheme (BBA normally) for injected cavity wall insulation has been around for many years and is well documented covering manufacturer, system designer through to the installer. Approved Document C specifically covers this requirement. The installer does not have to understand how a building goes together just how to install the product correctly. Joe Public cannot purchase the 'approved materials' as they are only available as part of the 'approved' package.

 

Like so many of these things, its just a protection racket. 

 

If i want to put beads in my wall i will. As it happens i cant, because its full of cables

 

Top marks to the OP for actually finding a way. Had i been going ahead, id be building a replica. Still might do for house. Not demolishing it either.

[Radian]

2 hours ago, ADLIan said:

The approval scheme (BBA normally) for injected cavity wall insulation has been around for many years and is well documented covering manufacturer, system designer through to the installer.

 

I think the approvals schemes are still unfit for purpose. The "Cavity Wall Insulation Victims Alliance" was set up in response to CIGA's indifference. CIGA is still the nexus for all the nonsense there's been in the industry.

 

"whilst we continue to promote the BBA as an effective offer from an established provider it is pleasing that CIGA can now build on this with our agreement with KIWA BDA"

[Sparrowhawk]

On 15/12/2022 at 22:08, Roger440 said:

If i want to put beads in my wall i will. As it happens i cant, because its full of cables

Same here. Prime candidate for cavity fill but they rewired by dropping everything via cavities, including an 80A cable to the 2nd fuseboard/electric cooker in the extension on the other side of the house.

 

I have an email from a technical manager at an insulation company saying it's not a problem because the cables inside a wall don't move once it's filled with insulation, so if the sheath becomes brittle it doesn't matter... That's one I've joined this forum to discuss in more detail - once I land on the correct section to post on.

[Roger440]

10 hours ago, Sparrowhawk said:

Same here. Prime candidate for cavity fill but they rewired by dropping everything via cavities, including an 80A cable to the 2nd fuseboard/electric cooker in the extension on the other side of the house.

 

I have an email from a technical manager at an insulation company saying it's not a problem because the cables inside a wall don't move once it's filled with insulation, so if the sheath becomes brittle it doesn't matter... That's one I've joined this forum to discuss in more detail - once I land on the correct section to post on.

 

Been discussed on 2 seperate threads in the last couple of weeks.

[Iceverge]

On 15/12/2022 at 12:52, ElliotP said:

to stop the EPS beads going under the floor

 

I commend you on your ingenuity. Bravo. 

 

As the place is being demoed have you considered doing the void under the floor. It would be a tremendous energy saver and suspect would confirm my suspicion that timbers on the warm side of insulation will not rot. 

[andyscotland]

@ElliotP brilliant achievement!

 

Would you be happy to share where you sourced the beads - were they just generic "packing" beads or something more specific?

[Andehh]

Outstanding work OP. I want to build a cavity just to give that all a go myself!!