Can I "Replace" my white foam cavity wall insulation

mickyduck

Hi I have a 1960s property that has "White polystyrene type" cavity wall insulation that must have been blown in at some time. Over the years modifications like running cables through the cavity has put some holes in this and to be honest when I last looked as few years ago it did not look like it was a very good job. As I have got older and a little greener I have been thinking about improving my homes insulation.

Do any of you know is there is a way to remove the old insulation (short of digging it out of the cavity manually) and replace it with a modern alternative?

Update : Checked the internet and it does seem to be possible... now awaiting callback.. I suspect it will be expensive.

Thanks
Mick

carly

I'd be interested to know how you get on with this. My own cavity walls were filled with beads in approx 1982. I've often wondered how many were left after extensions, alterations etc. I've never seen much evidence of loss in my own home but also never had too much difficulty running cables etc.

EricMears

mickyduck wrote: »

Do any of you know is there is a way to remove the old insulation ?

Update : Checked the internet and it does seem to be possible... now awaiting callback.. I suspect it will be expensive.

Thanks
Mick

I've absolutely no idea of the 'proper' answer but can't really see why it should be all that expensive. All a contractor would need to do would be to drill a series of holes at DPC level (just like they did originally and would have to do again to fill with an alternative) and suck the stuff out with a vacuum cleaner.

If the same contractor gets job of sucking out old & blowing in new they ought to be able to use same holes for both so all you'll really be paying for is a couple of hours use of a vacuum and possibly a bit of landfill tax (though you could always keep the old PS beads and top up loft insulation with it)

thenudeone

IIRC, polystyrene balls have a higher insulation value than fibre type insulation.

Anyway, even if it's degraded in some places, the extra insulation value you might get from replacing it would be very low compared to the disruption and cost.

If you are genuinely concerned about the best environmental outcome for your money, find a friend with uninsulated cavity walls in their house, and pay for them to be insulated. It will cost a lot less AND give significantly higher greenhouse gas savings than what you are proposing.

EricMears

Whilst I'm sure it would be possible to remove balls & replace with something else, I'd have to agree it's not the best value for money. It's highly likely that the balls have settled over the years and that some may even have fallen out through air-bricks or new holes drilled in wall for other purposes. The quickest, easiest & cheapest 'solution' would be to blow in some more PS balls from new holes at top of wall. If you want even better insulation than that would give, maybe consider external insulation or even a layer of insulation indoors on all external walls.

mickyduck

The insulation is like solid polystyrene foam. I agree sucking the balls out would be reasonably easy sadly as stated that is not what I have.

Dave_Fowler

mickyduck wrote: »

The insulation is like solid polystyrene foam. I agree sucking the balls out would be reasonably easy sadly as stated that is not what I have.

It sounds like the insulation that was put in my first house in the 1970s. It was a chemical which, when mixed with water, expanded into a solid white mass. The installers arrived with a large tank of the chemical and connected a hose to my water supply. They then injected the mixture into the cavity where it set. It spilled out through various holes where the floor joists went into walls and formed lumps of insulation between the upstairs floor and the downstairs ceiling!

I've no idea how effective this form of insulation is compared with the modern blown in fiber. Wouldn't have a clue how to remove it either, as it formed a solid block in the cavity between the walls.

Dave F

Kernel_Sanders

Dave_Fowler wrote: »

I've no idea how effective this form of insulation is compared with the modern blown in fiber.

Much more, I suspect. Remember the insulation jackets that HW cylinders used to wear, made with rock wool? They would lose heat much more quickly than foam ones insulated at the factory, even if the jacket was thicker. OP does it look like this?I think this is spray polyurethane insulation, formed by combining two chemicals (no water involved) at the point of injection. It does look like Gorilla Filler before it turns yellow, though.
According to Wiki, polyurethane typically has an R-value around R-5 to R-6 per inch whilst blown fiberglass typically has an R-Value of only R-2 to R-4 per inch.
This is why my cavities are empty; I want this foam but no organization is prepared to subsidize it.

mickyduck

Foam is not like the above it is a clean white foam... I think from the internet is a urea formaldehyde foam

Dave_Fowler

mickyduck wrote: »

Foam is not like the above it is a clean white foam... I think from the internet is a urea formaldehyde foam

Now you've reminded me, that's what I had for my cavity wall insulation in the old house in the 1980s.

Dave F

Kernel_Sanders

mickyduck wrote: »

urea formaldehyde foam

Isn't that the stuff which was discontinued due to health questions about gases being released into rooms? I thought that polyurethane was the modern replacement.