Pumped Insulation Method

kev1234

Hi,

I know insulation methods have been covered to death on here but I have not been able to find an answer to my specific query which is: Can pumped cavity insulation be done from the inner leaf?

I'm building a side & rear extension and Architect has recommended 150mm cavity with 110mm K8 Kooltherm insulation and 40mm cavity. However, everything I've read on here and elsewhere would suggest that pumped bead would be better and certainly less expensive. However, one of the external walls will be built as close as possible to the neighbour's wall so there would be no space to get at the external block to pump from this side (Also a reason am not considering EWI). Can the cavity be pumped from the inside block?

Metric Tensor

To answer your question - yes it can be done from inside.

But:
1. Pumped insulation is not always the right solution.
2. How do you plan to plaster/render the outer block if you cannot access it?

kev1234

Metric Tensor wrote: »

To answer your question - yes it can be done from inside.

But:
1. Pumped insulation is not always the right solution.
2. How do you plan to plaster/render the outer block if you cannot access it?

1. In what scenarios would pumped insulation not be right?
2. Very good question! :eek: I hadn't thought of this and the Architect has not mentioned how this will be done. The house is a 3 bed semi-detached. There are loads of similar rear extensions on other semi-detached houses which are up against each other also so it must be possible somehow? I will have to query this.

Metric Tensor

kev1234 wrote: »

1. In what scenarios would pumped insulation not be right?

In many situations where the outer block is not rendered!

See question 2!

kev1234

Metric Tensor wrote: »

kev1234 wrote: »

1. In what scenarios would pumped insulation not be right?

In many situations where the outer block is not rendered!

See question 2!

Ok, will query with the Architect when he returns.
Are these walls that abut against or are very close to a boundary wall always required to be rendered or is it possible they are left not rendered and hence the use of a partial fill cavity as opposed to pumped?

kev1234

Have done a bit of research online but found nothing really in relation to this. However, I was thinking that brick would not need to be rendered so is that a possibility if there is no space to render? Probably a bit ridiculous to spend way more on a brick wall that will never be seen though

Metric Tensor

Not all walls HAVE to be rendered so it's possible to do various things.

Many of the options are significantly helped by the presence of a portion of open cavity (i.e. not fully filled with bead).

But this is exactly the reason why you employed a professional to guide/advise you. Don't stress how you will make it work - that's the job of your professional.

kev1234

Metric Tensor wrote: »

Not all walls HAVE to be rendered so it's possible to do various things.

Many of the options are significantly helped by the presence of a portion of open cavity (i.e. not fully filled with bead).

But this is exactly the reason why you employed a professional to guide/advise you. Don't stress how you will make it work - that's the job of your professional.

Yeah, fair enough. He's on leave this week so this just had me worried given how far on we are with the plans. I'll just wait to discuss with him on return, thanks.