Buying a BISF house

BISF House buying & selling advice at BISF

Hello, I’m looking at buying a bisf house.
The survey looks great, the roof is not original so has been done.
It’s rendered in pebble dash how do I check what rendering this ie, insulating or just pretty!!!
Survey says all good but what else should I check?



  1. *I am looking to buy in Sheldon B26, Halifax have agreeded a valuation. But I am being urged to have a full survey, by my solicitor. I am getting worried as there seems to be a negative attitude to these houses. Some of the houses in this area have been beautifully improved. Does anyone have any information good or bad about the Sheldon BISF houses. Thanks 


    1. Hello Rupert
      It is not uncommon for any solicitor to suggest a full survey on any property even though the Halifax may well accept a standard homeowners survey.
      In relation to BISF houses though many professionals are not over familiar with the general construction and to cover themselves and you a full survey is suggested.
      The problem with a full survey is that it may be intrusive, ie parts of the buildings inner and outer coverings may have to be removed to reveal the inner steel structure. This may not be allowed by the vendors and many do not like to have the property hacked into. You would need to find out if the full survey would need to be an intrusive one.
      The main reason for a full survey is to check if the steel stanchions and framework of the house has suffered from corrosion. This does happen when the exterior render has been cracked through neglect or weathering allowing water to enter and cause corrosion. It will also look at the ventilation aspect in renovated properties which if not carried out correctly can also contribute to corrosion. Corrosion damage is rare but it does occur when properties have been poorly maintained.
      It really is a matter of choice for yourself but a word of caution, if the surveyor is not familiar with BISF properties and many are not, you could get a very poorly excecuted survey containing all sorts of misleading information which we see all the time.
      If you do choose to go down this route you must check and insist that the surveyor you use is fully aware of BISF house construction otherwise you could well be wasting your hard earned cash.

  2. You can’t inject cavity wall foam for two reasons. First of all the inner, non-structural layer of the walls is made of plasterboard or hardboard which would bulge out if you put foam behind it. More seriously, that cavity needs to be well ventilated to prevent any condensation forming on the steel structure and causing rust. If you filled it with foam condensation would soak the foam and make the steel rust which would eventually cause structural damage.

    You can put solid foam board insulation into the walls as long as you leave a gap between them and the steel for ventilation. That’s what I’ve been doing and it’s a bit fiddly but not too difficult.

  3. Hi cherrypeach, it’s hard to tell from the photo because you can’t see how thick it is. It seems fairly thin so I’d say it’s probably just cosmetic. Usually the insulated render incorporates 80mm thick insulation so it’s noticeably thicker.

    I wouldn’t worry too much about it though as even if it isn’t extra insulation, the original insulation is better than that found in a typical pre-1930s house and no-one seems to worry about those. Just think of all the millions of Victorian terraces that still exist that can’t even be practically wall insulated!

  4. Hello Cherrypeach!
    Glad to hear that you are looking to buy a BISF house.

    If the render is only on the bottom half of the house, then there is a good chance that it is the original non-insulated render with some cavity fill insulation fitted behind the render when the property was built.
    If the render covers the entire house including the first floor exterior walls then you will probably have an insulated render system fitted. These were typically fitted by local councils or housing associations as part of a government funded better homes project.

    Do you have a photograph of the front of the property as this would help to identify the construction of the wall?