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What type of house construction ?  




I have some questions regarding the attached photo of the property 

  • Can you please tell me the detail of this type of Construction  ? 
  • How easy is it to get mortgage ? If mortgageable, Will bank charge high interest?
  • How easy to sell in near future?

will appreciate your help.


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Hi Jaspinder, could you please supply the postcode of the address please?

If you don't want to post the location on the forum, please send it to and we can take a look for you.



Hi BSIF Admin,

Thanks for the reply. I have emailed to you regarding the postcode .



2 Answers

Hello again Jaspinder, thank you for forwarding the location details.

After much investigation I can confirm that this property is of a construction type known as The Bison Crosswall. The Bison crosswall system was introduced in the late 1960's where it was used for the the erection of low­ and medium-rise constructions, such as houses and low rise blocks of flats.

The system comprises of solid precast reinforced concrete panels which form the loadbearing walls which run from the front to the back of the dwellings. These walls become are called the flank walls and they also form the load bearing party walls that are situated between dwellings.

Wide precast reinforced concrete floor units form the floors between the flank walls. The flank walls are constructed with inbuilt cast wall ties which enables the connection of a brickwork outer leaf which closes the structure.
Party walls are usually fair faced (smooth finished) on both sides. The front and rear facades of the property situated between the load-bearing walls are usually constructed from lightweight timber­ framed panels or constructed from a cavity-wall with a masonry infill.

The way in which the loadbearing panels are erected is similar to that used in a type of construction called the Bison Wall Frame, which was used extensively in high rise blocks.

I've created a few images that show roughly how some of these properties were built.

1 bison crosswall units 1111
2 bison crosswall units aa
3 bison crosswall units e
4 bison crosswall units d

Obtaining a mortgage.

As with all non-traditional properties, mortgages are available but only from certain providers. In the UK we have a variety of providers who are happy to consider all types of non-traditional construction, providing that the property is not listed as defective under the housing act 1984. Where properties have been designated defective, they will only be considered for lending purposes if they have been repaired under an approved repair scheme.

Fortunately, the Bison Crosswall has never been classified as defective.

Each lender will have it's own lending criteria and each will assess the property on it's own merits and in accordance with it's current lending guidelines. A sound and positive survey will also be critical toward loan approval.

There are a number of mortgage providers that you could approach, including BM Solutions, Santander and Halifax to name a few, although I have heard that Halifax can be a little tricky at times with certain properties.

When a precast concrete panel property is surveyed, particular attention will be paid toward steel ties and steel fixings that are embedded in the concrete. This is because in certain situations, the chemicals within the concrete can react with the steel, causing carbonation and corrosion. If this is found and it is judged to be serious, the mortgage would most likely be refused. However, not all properties suffer from this.

As for resale in the future, this will very much depend upon local market forces and the overall performance of these properties in years to come. I see no reason at present not to consider this property. You will likely find that the asking price is set slightly lower than comparable brick properties in the area which tends to be quite normal for many non-trads. Therefore, it is also likely that any future resale will also reflect this reduction in value.

Unfortunately the Building Research Establishment (BRE) has never fully investigated this form of construction, so I am unable to advise you on any specific issues that may be present.

However Bison also produced a very similar structure called the Bison wall frame which did occasionally suffer from the following:
(i) Rain penetration, through roof parapets, through vertical and horizontal panel joints, and around window openings, resulting in accelerated deterioration of the internal finishes, and of the structure itself.

(ii) Differential movement: this may occur between the cladding panels, and between the panels and the window frames. This can result in cracks appearing internally, at vertical junctions between panels, and also between ceiling and floor levels. There may also be leaks around windows, causing the frames to rot.
(iii) Condensation: a very common problem, especially in high rise blocks, due to wind exposure and lower temperatures athigh levels. The system suffers from "cold bridging" at floor and ceiling levels, due to the poor thermal insulation properties of concrete.
(iv) Roof problems: these units were built with flat roofs. Many suffer from leaks and water penetration through the roof.
Due to poor insulation, there may also be dampness due to condensation forming inside the roof. Further problems arise when felt roof-covering fails as a result of stress cracking, due to its inability to cope with differential movement.
(v) Sound insulation poor, due to gaps between panels and poor jointing. As a result, smells and smoke may also be transmitted between units.
(vi) Spalling concrete: causes bits of panels to break off. It may be due to lack of tolerance - that is, fit - between panels. A more common cause is the use of calcium chloride in the concrete mix at the factory. Spalling exposes the steel reinforcement, causing it to rust. This can lead to major structural problems.
(vii) Asbestos: commonly used as a lightweight insulating product, but as it deteriorates and fragments it becomes a major health hazard. It was used for fire-protection, fire stopping between units, and for some cladding panels.

I hope this helps Jaspinder.

Best Regards


Jaspinder, I have moved this thread into the house identification request section.  ? 


Hi Marc,

Thanks for your information. Just like to know if we can change Bison Crosswall  house to Traditional house using Brick and Mortor construction. If we can, how expensive will it be ?

Look forward to hearing from you.





Hi Jaspinder,

Unfortunately it's not quite as simple as just changing your front and rear walls to brick as many lenders may still view the property as non-traditional unless all the attached properties on either side have also been converted also.


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