Frequently Asked Questions BISF Houses.

Frequently Asked Questions BISF Houses.

We frequently see BISF related questions being asked on various forums and websites across the internet.

Many of the answers provided albeit with good intent, are  often completely wrong and misleading even to the point of being dangerous. Many answers are posted by people with  absolutely no experience or understanding in this type of property.

What is worse is that new or prospective buyers can often be put off from buying a BISF house, which do in fact represent a sound and excellent investments providing you know what to look for.

All too often, common cliches are adopted as soon as the word prefab is raised, leading many readers to wrongly assume that BISF houses  are no different to the temporary prefabricated bungalows built shortly after the war.

Below we shall list some of the more frequently asked questions raised regarding BISF houses and reply with the correct information.

Please feel free to add your own questions below in the comments for inclusion onto the main page.

Q: Why are so many BISF Houses still standing if they were only meant as temporary housing?

A: BISF houses were built as permanent housing.

Unlike many other prefabricated properties which were indeed built as temporary accommodation under the Temporary Housing act. A Tarran Bungalow is an example of a temporary prefab.

Q: I hear that it is difficult to get a Mortgage for BISF house?

A: There are many companies that offer Mortgages for BISF properties.

The process is no more difficult than applying for any other mortgage. As always a structural survey is always advised. Ensure that you do not obtain your mortgage from some of the more unscrupulous providers who charge a higher interest rate for Non Traditional construction homes.

Q: Are BISF Houses classed as defective under the housing act?

A: No.

The defective housing act does applies to many prc properties, however it does not appky BISF houses.

Q: I have read on the internet that the steel frames of BISF houses rot with rust, sometimes causing the building to collapse. Is this true?

A: No this is False.

Providing that a BISF property has been well maintained, just as any property should be, the risk of severe corrosion to the steel frame is very low. Extensive corrosion has occassionaly been found at the foot of steel support stanchions due to water ingress, however, unlike other properties, these stanchion bases can be easily repaired at relatively low cost compared to other steel framed properties.

It should be noted that there are no currently known cases of a BISF propety collapsing, due to corrosion or fatigue.

This rumour was established due to the discovery of severe corrosion that was found in the steel frame of an altogether different Precast concrete built property known as a Airey House.

The Airey house was built using a completely diffent method of construction. Airey Houses incorporated a form of construction that using steel rods embedded inside a concrete frame work. Over time, the chemical composition of the concrete changed causing it to weaken and corrode the inner steel. The decomostion of the concrete was termed, ‘Concrete Cancer’.

Concrete cancer is caused when the steel reinforcing within a concrete slab begins to rust. As the steel rusts it expands, displacing the concrete around it, causing it to become brittle and crack thus accelerating the process. Signs of concrete cancer include: Crazing and cracking concrete (concrete spalling)

Moisture absorbtion was found to accelerate the process of steel corriosion inside the concrete.


An unrepaired PRC home is unlikely to be mortgeable through normal lending sources.

BISF houses do not suffer from any form of ‘Concrete Cancer’.

A 1986 BRE report states that, “The majority of BISF houses are structurally sound”. It went to point out that if indeed any substantial corrosion was found, it could easily be removed and replaced with a new steel section. The report found no significant steel frame problems in the properties that it surveyed.

Q: I heard that BISF houses suffer from lots of problems, is this right?

A: BISF houses do have certain inherant issues, as do traditional brick properties.

The BRE identified a number of issues with certain BISF houses. The main problems reported are listed below.

  • Cracking of the render, which can be caused by EXTERIOR impact damage, and minor structural movement has occurred in some properties. This can result in rusting of the metal RENDER lath LEADING TO FAILURE OF THE RENDER SURFACE. (FAILED RENDER CAN BE EASILY REINSTATED and replaced with a suitable polymer render.
  • Damaed render has no effect upon the structural integrity of the property, as the render and supporting steel lath is not load bearing.
  • Rusting of the steel profile cladding to the upper storey has occurred on a number of properties. It is caused by failure of the water stripping on the gable ends. In rare but severe cases, this has led to rusting of the sheeting rail which supportS the cladding panels.
  • Over the years, the asbestos cement roof sheeting can deteriorate and the material can becomes brittle and cracked. This type of roofing profile is no longer manufactured and the only option is to re-cover the roof with a modern alternative such as aluminium or lightweight steel. (many properties now have replacement lightweight tile roofing systems fitted).
  • Some mild corrosion was found on some of the stanchions surveyed, particularly those at the corners of the building. However during the study no significant corrosion was found that required immediate remedial work.

Other minor considerations include poor thermal insulation material, discoloration of the steel sheeting when not been maintained and rusting to some chimney cowls.


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