Air tighting electrical boxes

jimmy_t

Hi all, we have just had our air test and we have some leakage through the electrical boxes. The chases and boxes were all painted with blower proof paint and we don't have any leaks showing up at the spot lights so we assume the leaks are from when the electrician mounted the boxes and penetrated the air tight layer. What is the best way to rectify this, silicone in the box to create a seal?

mfceiling

jimmy_t wrote: »

Hi all, we have just had our air test and we have some leakage through the electrical boxes. The chases and boxes were all painted with blower proof paint and we don't have any leaks showing up at the spot lights so we assume the leaks are from when the electrician mounted the boxes and penetrated the air tight layer. What is the best way to rectify this, silicone in the box to create a seal?

You could try "putty pads"....These are pads that provide fireproofing to the inside of electrical boxes. They seem to create quite a tight seal inside the box.

Calahonda52

you need to get at the holes, IFF that is where the issue is
perhaps take out the screws and push something like this
https://www.ecologicalbuildingsystems.com/Ireland/Products/Product-Detail/pro-clima-Orcon-F
into the holes and reset the screws
or take out one screw and loosen the other and shove some of it behind the box.
Silicone wont be good enough in my opinion

Wartburg

I´d highly recommend a fire rated sealant for sealing around cables and in socket boxes. As far as I know, none of the air tight sealants has a B1 rating.

Sockets and switches do always cause difficulties for the air tightness. There are 4 reasons for potential leakage:
No. 1 - the conduit itself (which should be sealed in an ideal world)
No. 2 - the chasing (which you have treated with air tight paint)
No. 3 - the junction where the chasing penetrates the air tightness layer
No. 4 - the fixing of the socket box

In an ideal world, you have treated the chasings with air tight paint, closed the conduit at the top with tape or sealant and put the top of the conduit and the socket box into bonding. Unfortunately that all has to be done during the first fix and you still have to pray that your electrician is not damaging one of your air tightness strategies later on.

How bad is your house affected by the air infiltration through the sockets? in other words - what is your current result for air permeability or air changes?

jimmy_t

Wartburg wrote: »

I´d highly recommend a fire rated sealant for sealing around cables and in socket boxes. As far as I know, none of the air tight sealants has a B1 rating.

Sockets and switches do always cause difficulties for the air tightness. There are 4 reasons for potential leakage:
No. 1 - the conduit itself (which should be sealed in an ideal world)
No. 2 - the chasing (which you have treated with air tight paint)
No. 3 - the junction where the chasing penetrates the air tightness layer
No. 4 - the fixing of the socket box

In an ideal world, you have treated the chasings with air tight paint, closed the conduit at the top with tape or sealant and put the top of the conduit and the socket box into bonding. Unfortunately that all has to be done during the first fix and you still have to pray that your electrician is not damaging one of your air tightness strategies later on.

How bad is your house affected by the air infiltration through the sockets? in other words - what is your current result for air permeability or air changes?

1. The intention was for the conduit to be inside the airtight envelope, see image
2. Chases are painted
3. Chasing junctions, also painted
4. Socket box fixings, not addressed, these are the issue hopefully, currently getting up to 0.3m/s through some boxes

The house is achieving 0.8 and we are aiming for 0.6 passivhaus standard. We have a leaking sliding door that we need to address also so hoping to patch up the boxes and tighten the door and see where we are then.

Wartburg

First of all I´d say you will not get down to 0.6 ACH @ 50Pa differential pressure just by having your sockets and switches sealed more air tight. You have definitely more leakage areas as this issue and your sliding door. I´d be interested in your total leakage area, as coming from the test report.

As I always write - the cavity wall is the biggest killer for air tightness. As you can see in your case, you still have air infiltrating above the suspended ceiling, even by having x-amount of air tightness sealing done in that area. You probably wouldn´t have the trouble when you would have the chasings completely filled with mortar or air tight foam above your metal frame for the suspended ceiling. Unfortunately it´s too late now. I guess your house is completely finished, because it´s impossible to achieve 0.8 ACH by having no plaster applied to the envelope walls (except you´re building timber frame).

Have you checked all other potential sources for air infiltration? Floor-to-wall junctions are weak, especially if you have upstanding insulation between your wall and floor and no air tightness strategy applied before.
Another source of air infiltration, that came to my attention during my last testings, is the weakness of the most doors and windows between the glass and the frame. I had plenty of different window manufacturers so far, where air was leaking where the glass strips join in the corners. The smallest gap in between the strips was leading to a noticable air infiltration.
Chimneys are great for unwanted air infiltration too. Please check the junction between your chimney and the floor, even for the case that you have her installed on an internall wall.

Regarding your aimed passive house standard for air tightness: do you want to achieve the 0.6 ACH @50Pa differential pressure with the standard testing method or with the "building in use" method, as required for official passive house certification?