Pumped bead insulation - around chimney

rampantbunny

I'd wall cavities pumped a month or so ago and something has been niggling me.

The chimney is on an external wall and is external i.e. it does not form a chimney breast within the room, but juts out from the side of the house. I'm wondering how pumped bead would fill the cavity around the chimney if holes were not drilled as close to the location where the cavity takes a 90deg turn to start enveloping the chimney stack.
Even if they were drilled at this location, I can't see how the bead would be able to make it's way around to the back of the chimney. Only way I can see this working is to drill from the outside also.

Anyone any ideas? Short of coring a hole or two from the outside to check, is there any way to tell if there is bead there?

Murphy14

I don't think you are meant to pump a chimney with polystyrene beads due to fire rating of bead you could pump around chimney with rock wool or mineral wool ask your installer he will know

hexosan

If the chimney is on the external wall then it shouldnt be built into the cavity. The two side of the chimney should be tied into the external wall behind it.

rampantbunny

Chimney.JPG

The attached shows the construction of the cavity. There's space for bead to encircle the chimney. The bead does not surround the flue itself (red circle).

hexosan wrote: »

If the chimney is on the external wall then it shouldnt be built into the cavity. The two side of the chimney should be tied into the external wall behind it.

Sorry Hex, don't get this. Are you saying no cavity around chimney at all...i.e. one large cod bridge?

hexosan

From your pic there shouldn't be a problem with the bead going around the chimney. Have you the flue lined either side with leca or similar

rampantbunny

hexosan wrote: »

From your pic there shouldn't be a problem with the bead going around the chimney. Have you the flue lined either side with leca or similar

Immediately around the flue is filled.
If the holes bored for pumping bead are lets say 12 inches or more from the chimney (see blue lines in attached), there is a good distance for the bead to travel to encircle the chimney. The pic doesn't do the size of the chimney justice...it's larger in reality to allow for installation of a stove later if necessary. Ideally, wouldn't the holes need to be situated right where the red marks are.

Chimney2.jpg

hexosan

I think they should of went closer on the chimney to be 100% that it wrapped around. But in saying that when I pumped mine I was surprised how far around corners the bead pumped. The benefit of the wider cavity I suppose.

sydthebeat

why would you be pumping the beads from the inside?

Metric Tensor

I've seen it done a few times in new builds where there was decorative stonework externally and also in one place where access was really restricted.

I also suspect it's done on occasion to avoid having to use external scaffolding!

rampantbunny

Metric Tensor wrote: »

I've seen it done a few times in new builds where there was decorative stonework externally and also in one place where access was really restricted.

I also suspect it's done on occasion to avoid having to use external scaffolding!

Stonework in places restricting access from outside...holes could have been drilled but easier from inside. Easier to patch the holes from inside too. If some of the holes are not filled properly it doesn't matter as much as there's no driving rain to worry about.
From chatting lads around here, pumping from the inside seems to be more of the norm than from the outside.

BryanF

Check with Thermal imaging.
Get them back if required

rampantbunny

BryanF wrote: »

Check with Thermal imaging.
Get them back if required

Does thermal imaging work from inside or outside. If inside, will it be able to look 'through' the filled chimney stack?
Drilling some holes would be cheaper I think but granted, not as accurate.

hexosan

All new builds around me are been pumped from the inside. As was mentioned above it removes the need for scaffolding.

sydthebeat

hexosan wrote: »

All new builds around me are been pumped from the inside. As was mentioned above it removes the need for scaffolding.

cant see why theyre not pumped prior to external rendering ????

893bet

sydthebeat wrote: »

cant see why theyre not pumped prior to external rendering ????

Depends on order of works which for self builds as you know can widely vary.

I pumped from inside also.

sydthebeat

893bet wrote: »

Depends on order of works which for self builds as you know can widely vary.

I pumped from inside also.

Yeah understandable.
However it's much easier have quality control when done from outside, you can see exactly the centres of the drills. That's how the certificates work.

rampantbunny

sydthebeat wrote: »

Yeah understandable.
However it's much easier have quality control when done from outside, you can see exactly the centres of the drills. That's how the certificates work.

Sorry Syd, don't get this. The holes internally can be seen and only a little tricky to see continuity when coming to internal walls and ceilings but not difficult. Is that what you mean?

sydthebeat

rampantbunny wrote: »

Sorry Syd, don't get this. The holes internally can be seen and only a little tricky to see continuity when coming to internal walls and ceilings but not difficult. Is that what you mean?

http://www.nsai.ie/Our-Services-(1)/Certification/IAB050226.aspx

have a look at page 9 and ask yourself is it easier to do this from the inside or outside. Did your installers carry the pumping pipes into the attic? to pump at 200mm above ceiling level?

im not questioning the choice to get it done when there stonework to the external or the scaffolding is down... im just making the point that
1. its easier to do, and to check, when done from the outside
2. theres plenty of time between window install and external rendering to organise this. I see no reason whatsoever to leave it until after the external is rendered and the scaffolding is removed.

MicktheMan

rampantbunny wrote: »

Does thermal imaging work from inside or outside. If inside, will it be able to look 'through' the filled chimney stack?
Drilling some holes would be cheaper I think but granted, not as accurate.

Thermal imaging will have no problem picking this up and can be done from both inside and outside (ideally both) assuming proper conditions exist at time of survey.

BarneyMc

Got pumped from the inside myself.

MicktheMan

Interesting.
I wasn't aware that so many newbuilds are being pumped from the inside. At what stage is this being done? I presume before the airtight render is applied to the blockwork.

rampantbunny

sydthebeat wrote: »

http://www.nsai.ie/Our-Services-(1)/Certification/IAB050226.aspx

have a look at page 9 and ask yourself is it easier to do this from the inside or outside. Did your installers carry the pumping pipes into the attic? to pump at 200mm above ceiling level?

im not questioning the choice to get it done when there stonework to the external or the scaffolding is down... im just making the point that
1. its easier to do, and to check, when done from the outside
2. theres plenty of time between window install and external rendering to organise this. I see no reason whatsoever to leave it until after the external is rendered and the scaffolding is removed.

Attic walls also bored and pumped i.e. complete gables were done.
OK, without question it's easier to see the hole pattern better from the outside. But it doesn't overly concern me because on each internal wall more holes were bored than were necessary.
Reason this was done was because I asked specific questions re. hole spacing. The installer said 'we drill more holes than are detailed on the cert because generally customers feel better when this is done'.
My only concern is with the cavity around the chimney...if pumped from outside this wouldn't be a concern at all.

As regards the reason(s) it is done when it is done...there can be many; financial constraints, availability of installer (cost of leaving scaffolding up), lack of time to organise and more. Maybe not good reasons, but reason enough given that the same result should be easily achievable when pumping from inside I would have thought.

MicktheMan wrote: »

Interesting.
I wasn't aware that so many newbuilds are being pumped from the inside. At what stage is this being done? I presume before the airtight render is applied to the blockwork.

Mine was pumped before internal render.

BarneyMc

MicktheMan wrote: »

Interesting.
I presume before the airtight render is applied to the blockwork.

Yip.