Electrical installation How to batten / paster

[SIPselfbuilder]

Hi, 

I need to batten and plaster a new build SIP house.

I want to have these installed :

https://www.screwfix.com/p/lap-2-gang-13a-dp-switched-plug-socket-brushed-stainless-steel-5-pack/68831

https://www.screwfix.com/p/appleby-galvanised-steel-knockout-box-2g-35mm/42695

My plan is to use for :

• internal walls : no battens (electrics an plumbing in the stud wall 100mm with insulation) + 12.5 mm fire resistant plaster + 12.5 mm soundproofing plaster
  
• external SIP with electrics only : 25mm battens + 12.5mm fire resistant plaster 
  
• external SIP with electrics and plumbing : 35mm battens + 12.5mm fire resistant plaster
  

In these 3 cases will this be able to accommodate a 35mm box and the cables needed even for kitchen (oven, fridge, washing machine ) ?

Thanks

 

[Evans Electric]

Whats a SIP house ?   

35mm boxes , if they fit will be good  ,  I'm sure your walls are more than 35mm  deep.      If you are fitting what we call "Flat Plate Accessories "  35mm boxes are a must . 

Battens & types of plaster  are beyond our remit TBH  , it all sounds fine . 

 

[Sharpend]

A sip is a structural insulated panel effectively a timber frame house. 
 

there are different types of sip panel design. 
is the insulation on the internal face or the external face ? If internal face then you will require additional battening/bracings as you are not permitted to interfere with the insulation.  

 

[Murdoch]

What does your spark say/advise?

 

[ProDave]

This is standard practice here.  A 25mm batten and 12.5mm plasterboard comfortably fits a standard 35mm back box.  It is known as a "service void" and allows you to install all cables etc without puncturing or otherwise messing with the building structure.

 

[SIPselfbuilder]

Thanks a lot for these answers.

SIP house is indeed a SIP (structural insulated panel) frame house.

In my case it is 142mm SIP wall that is a rigid insulation core in sandwitch between 2 osb panels.

I do not have extra insulation, on the outside of the SIP, simply a void and wooden cladding.

Inside I hesitate between 25mm and 35mm battens for electrics.

Thanks to ProDave I understand that 25mm is fine.

What about plumbing are 35mm battens fine for wash bassin, waste pipes are usually 32mm ?

Thanks

 

[Evans Electric]

Sounds like you need to go with 35mm battens  then to accommodate the plumbing . 

As mentioned above , I understand you cannot penetrate the basic  thermal wall.

 

[Sharpend]

Hand basin is 32mm pipe but kitchen is 40mm as is bath. You usually find that the waste pipe work is external to finished wall face then boxed in where necessary. The smaller 15mm water pipes would be in the void. 

 

[ProDave]

If done properly the kitchen waste will enter the building, either through the floor or the wall, and be routed in the gap behind the kitchen units.  But t does need planning properly.

15mm copperr with soldered joints will fit in a 25mm cavity, but 22mm copper will require a 45mm cavity.