How should I fill a wall cavity from the loft?

[joeG]

Hello 

I have discovered that the previous owners of my house removed the chimneys and covered up the "bungaroosh" walls with plaster board but without any insulation.

This goes up two floors to a cold loft on one half of the house.

I can get access to about 150cm wide by 10 cm deep gap from the loft. and believe there is a void 3m wide 5m high 10cm deep. 0.1×3×5 = 1.5 meters3

I live in a 19th century mid terrace.

 

My questions are should I try and fill this void from the top with Vermiculite Micafil Loose Fill Insulation? eg https://www.amazon.co.uk/Vermiculite-Micafil-Loose-Insulation-100ltr/dp/B018NVZK7U/

I calculate I would need 15 bags @ £35 = £525! But I have no idea how well it will spread in the void.

Is there something better/cheaper?

Or should I not bother and just pack the top best I can with rockwool?

 

thanks a lot for any help

 

Joe G

 

 

[Iceverge]

blown bead?

[joeG]

Thanks but Id like to do it myself and save money.

Im guessing that Blown beads is not DIY?

[joeG]

I have looked into EPS insulation but it says this

"Expanded Polystyrene should not come into contact with any PVC cables. This is to avoid plasticizer migration which causes PVC cables to become brittle and fragile. Any PVC cables should be protected within a suitable conduit or with a suitable air gap."

 

I have some electric cables behind the wall which I can only assume are PVC as I have no idea.

 

 

 

[markc]

Yes that’s the standard cop out bumf. You also should allow cables to chaff on brickwork, mortar etc. which is much more likely in a cavity. 

[joeG]

So I can ignore this small print?

[markc]

8 minutes ago, joeG said:

So I can ignore this small print?

Not saying you can ignore it, but the chances of your cables being affected is very low. Cables and polystyrene is similar to copper and cement … never allow cementitious materials to come in contact with copper but loads of people have outside taps and even internal plumbing through walls and bunged up with mortar or pipes clipped to concrete walls etc. there are 1000’s or hundreds of thousands of buildings with cables surrounded by poly beads or through insulation boards 

[Radian]

Our rental property was built in 1986 and had EPS bead cavity fill. The PVC cabling went through it across a couple of cavity walls not least to get into the meter box outside. I've noticed a few tiny marks on the cables but nothing anywhere near causing problems. It's still like this today only there are loads more poly beads in the meter box. Nowadays they bond the beads with a PVA solution to stop them moving about and the better kind of beads have a graphite coating. This is primarily to enhance their R-value but I think it may also prevent contact migration of the plasticiser in PVC. We just had our empty cavities filled with graphite EPS and I asked the surveyor about cable issues and he said it's no longer an issue 🤷‍♂️

[Miek]

15 hours ago, joeG said:

I have looked into EPS insulation but it says this

"Expanded Polystyrene should not come into contact with any PVC cables. This is to avoid plasticizer migration which causes PVC cables to become brittle and fragile. Any PVC cables should be protected within a suitable conduit or with a suitable air gap."

 

I have some electric cables behind the wall which I can only assume are PVC as I have no idea.

 

 

 

If you insulate the wiring you need to downrate it or it could overheat. Cables within insulation need to be bigger to allow the same current through as they can't dissipate the heat so well, so a 2.5mm ring main might need to be a 4mm ring if its in insulation . 

 

I'm not a sparky

[joeG]

My only option is to pour something like eps beads from the loft down two stories.

I dont think rewiring the whole side of the house is a simple option.

 

Thanks to you all but thats a lot of quite conflicting information.

From "Its fine " to "downgrade the wiring to stop it overheating"

This doesn't seem to be a cheap or DIY project any more.

[Jasp]

Hey JoeG,

What did you decide to do in the end? I face the same issue at the moment.

Thanks :)