Installing Gas Pipe Through a Brick Clad BISF Wall?

I need to run a larger gas pipe through a BISF home that has had the exterior walls bricked. Are there any special precautions to take, regarding maintaining the integrity of any expected membranes etc.

There is a steel joist at the back of the airing cupboard/wardrobe. Are there any steel joists running parallel to the front aspect, between this joist and the front wall. I need to run the pipe from the front wall to the wardrobe.

Any comments or suggestions will be gratefully received.



  1. Ed, thank you so much for the informative reply. I am sorry I have not replied earlier, but could not recall the password!
    You were absolutely correct, the house in question was not a BISF home. I had worked in the house some time ago, and this new job came via the phone, and for some stupid reason, I thought it was a tin top. There ARE a lot of these around, as well as the concrete panel type home that I was actually working on.

    None the less, your info is interesting and will no doubt be of value in the future.

    Thanks again. TGM

  2. Sorry, I forgot to add that in the external wall the RSJs rest on a large angle steel which would probably get in the way of drilling through the wall there. I’m not sure what sort of vapour control/airtightness membranes might be used in bricking up a BISF house (if any).


  3. Hi gasman and welcome! Are you sure you are dealing with a BISF house? I’m guessing that it is not your own house but someone else’s that you’re working on.

    I only ask because other types of system-built houses are often mistaken for BISF and a few things you’ve said are not typical of a BISF house.

    In a BISF house the gas supply is usually to a meter cupboard under the stairs on the wall backing onto the kitchen so the gas pipe would not run front to back in the house, unless the supply has been moved. Also bricking up a BISF house is fairly uncommon (more typical of precast reinforced concrete homes). Lastly I’m having difficulty identifying the steel joist at the back of the airing cupboard.

    In a BISF house there are no RSJs in the floor parallel to the front of the house. They all run front to back. These rest on a single RSJ that is parallel to the front aspect, but is in the top of the centre wall of the house, below ceiling level downstairs, so would not be in the way of a gas pipe. However the floor boards are supported on a large number of timber noggins that are parallel to the front aspect, so you would either have to lift the floorboards or take down the ceiling to drill them.

    If it was me I think it would be easier to run the pipe through the loft if that is possible.

    Here’s a photo that Grangey posted of floor structure once the living room ceiling is removed:-