Wimpey no-fines houses
Wimpey no-fines houses
“No Fines In-situ Concrete”, usually built by Wimpey Homes and understood to be under their own patent.
The houses were built mainly for Local Authorities, all over the country because of the speed of construction and a shortage of skilled bricklayers after the Second World War,
Most houses were built between 1947 and 1977. This form of construction tended to die out when cheap high insulation blockwork became readily available.
Previous investigation of this type of house revealed that the foundations are conventional,
External walls and central party wall
Formed in in-situ concrete with an overall thickness including plaster and render of around 13". The concrete is called ‘No Fines’. This means that the concrete is formed with cement and aggregate; there is no sand, The mix is with 20mm aggregate.
The purpose of this form of construction was to reduce cost and leave the wall aerated and thus aid insulation. The wails are un-reinforced and rely on their mass for strength.
The concrete was formed in-situ usually from a batching plant on site and the formwork used to frame out the wall removed after the concrete had set. It is normally the case that “No Fines” construction in domestic dwellings does not have a cavity.
In the case of this house there are vents in the walls, but we believe that these will relate to the previous pantry area and boiler location. During the course of our inspection we did not locate any definite evidence which would suggest that if a cavity exists, cavity wall tie failure was occurring.
In this house the external walls, central party walls are in ‘no fines concrete’, with the external face of the walls rendered to increase weather protection.
1) It can be difficult to replace the render. The render achieves an excellent key with the concrete. Because the concrete has no sand one can often break away sections of the same when removing existing render. The same applies to plaste internally (if not dry lined).
2) There is usually no cavity, therefore the walls can be affected by leaking gutters etc., particularly if the render is not weather—proof.
3) Insulation properties of this form of construction did not live up to expectations. Dry lining and extra render tended to solve this to a certain extent.
4) The method of construction was unconventional. Some people can be prejudiced against the same. However this form of construction is not classed as defective under the Housing Defects Act 1984.
5) Alterations and repairs to walls sometimes prove more difficult than conventional brickwork.
Unconventional, but previous contacts with Local Authorities who have “No Fines” houses report no specific problems with the same, save that mentioned above.