ESB & phone box on outter wall of build - thermal bridge

fclauson

Barney - as per http://www.boards.ie/vbulletin/showpost.php?p=87248428&postcount=1704

The issue of placing any item into the outer wall that decreases the thickness of insulation will cause a level of reduced thermal performance at that point.

So in the above example you have a ESB box - the cavity I think was 200mm - the ESB box protrudes about 90mm into the cavity - so at this point the insulation will only be 110 thick where as elsewhere it will be 200mm. This will mean that the internal wall will be that much colder than the area with 200mm.

Is this an issues - do the maths - if the temp drops below the FRSI calc numbers as laid out in Part L then yes - you could worse case end up with a rectangle of the wall which is a "magnet" for damp as its colder than the rest of the wall

hope that explanation helps

My advice is YOU MUST keep insulation thickness consistent across all external surfaces otherwise there is an issue.

You could ask the ESB "how does you detail comply with the minimum U-value calcs as laid down in part L"

BarneyMc

fclauson wrote: »

Barney - as per http://www.boards.ie/vbulletin/showpost.php?p=87248428&postcount=1704

The issue of placing any item into the outer wall that decreases the thickness of insulation will cause a level of reduced thermal performance at that point.

So in the above example you have a ESB box - the cavity I think was 200mm - the ESB box protrudes about 90mm into the cavity - so at this point the insulation will only be 110 thick where as elsewhere it will be 200mm. This will mean that the internal wall will be that much colder than the area with 200mm.

Is this an issues - do the maths - if the temp drops below the FRSI calc numbers as laid out in Part L then yes - you could worse case end up with a rectangle of the wall which is a "magnet" for damp as its colder than the rest of the wall

hope that explanation helps

My advice is YOU MUST keep insulation thickness consistent across all external surfaces otherwise there is an issue.

You could ask the ESB "how does you detail comply with the minimum U-value calcs as laid down in part L"

Thanks for this. It's a 250mm cavity but I get what you mean. Will look into this tomorrow and report back. Thanks!

BarneyMc

Contacted the ESB and got the answer I thought I would. They said the meter box had to be within 2 meters of the front line of the house. When I asked if it could be located on the garage they said that this could only be discussed after I had submitted my application to them. Nothing could be guaranteed though. My project manager said that it was too early to submit an application.

The garage walls are now above the level of where the box would be now also. So it looks like the meter box is to stay on the side of the house. I will speak with my project manager about this but I hope to place a PIR board in the cavity against the inner leaf opposite the meter box. We will also make sure to seal around the box, both inside the cavity and from outside.

Is there any foam insulation we could spray on the box from inside the cavity that would not degrade the bonded bead? This might provide an airtight seal and help insulate also.

fclauson

ok

I phoned my local ESB office and spoke to the foreman/supervisor (this was pre-application)

I gave him the brief on what I was trying to achieve and got the verbal "it should be ok - I'll watch for the application - but I cannot guarantee anything." He then dropped by site whilst in the area - and we got further no guaranteed approval it would be ok

I then submitted and was going to argue very hard if they declined my request - fortunately it worked out

The "2 meters from the front line" is really aimed at townies - basically they want to be able to read the meter without you being there.

This is all going away with remote wireless reading of meters

Given what you have I would put board down the back of the meter (its better than bead). Airtightness will happen on the inner leaf.

You will need to make sure where the cables comes through the leaf that its well sealed/taped -