Renovating homes built between the 1940s and 1960s

ARTICLE Trevor Pringle

Many houses of this era have retained their appearance and character – strongly influenced by state housing – but modifications are often necessary and can make a real difference to the performance of the home.
A large proportion of the houses built during the 1940s, 50s and 60s will require upgrading to bring them up to current standards of comfort and efficiency. An advantage when renovating houses built during this period is that the original drawings are often available – something that is typically lacking for houses built in earlier periods.

Design and layout

State housing dominated much of New Zealand building between 1940 and 1960, and a wide range of state house plans was available. The idea was that state housing should not all look the same, in order to avoid the appearance of mass-produced government housing. Though layout and form varied, common themes included fairly small size, efficient layout, orientation for sun, small windows and a roof with a 30-degree pitch. Other common features included recessed porches, minimal space devoted to hallways, and service areas grouped together.
Private housing looked much the same as state housing during the 1940s and 1950s, but from the 1960s onwards architect designed homes started to incorporate ideas from overseas while moving towards a modern New Zealand style.

Common problems and remedies

Structural problems in 1940s to 1960s houses may include undersized framing, inadequate bracing and unsafe chimneys. Any renovation work should begin with a detailed survey of the building structure. If there is any evidence of structural defects a structural engineer may need to be engaged.
Typically, houses of this period have a generous roof slope and eaves to shed water and good ground clearance for subfloor ventilation. They were initially built using quality heart timbers. However, the introduction of new materials and methods of construction during the 1960s meant there was experimentation and a lack of durability of some of the materials, which means that some of these houses may not have performed as well as expected.
With renovations, attention will need to be paid to ventilation to ensure that internal moisture does not become a problem. Other issues to consider during a renovation include dealing with minimum roof pitches if they are below the current minimum slope requirements, the lack of a wall and roof underlay, and the need for a cavity when matching existing work. 
Houses built in the 1940s to 1960s were usually not insulated. Any additions built after 1978 should have insulated walls and ceilings and may have roof space and/or underfloor insulation, but the level may fall short of current standards. There is no mandatory requirement to upgrade the insulation of existing parts of a house, but all new work must meet current standards. A wide range of insulation options is available for roof spaces, walls and underfloor areas.
Houses can let in cold outside air and lose heat from the interior by air passing through gaps between weatherboards, tongue and groove board floors, around window sashes and doors, and through chimneys. Heat loss through draughts can be reduced by foam stripping doors and windows, installing carpet over foam underlay and removing or blocking open fireplaces or installing closed firebox inserts.
Original copper pipes will probably not need replacement but plastic pipes installed during renovations in the 1970s or early 1980s may. If renovations are being carried out, the hot water system should be converted to a mains pressure system – there are numerous options available. The pipework and fittings should be checked for their ability to cope with the additional pressure and it may be necessary to replace fittings.
Roofs will need maintenance and may need replacement. Weatherboard cladding is likely to remain in good condition if properly maintained, but brick claddings may be cracked or have corroded ties, and asbestos claddings may need replacement.

Health risks

Asbestos cement was used in the 1940s and 50s for wall and roof claddings and also in 1960s floor coverings and spray textured ceilings. It becomes a health hazard when old materials containing asbestos are being removed or break down, allowing the fine particles to become airborne and breathed in. It’s easy for specialists to remove asbestos.
Lead was used in house construction in the 1940s to 60s in external and internal paintwork, flashings, valley gutters and nail heads. It is not possible to identify lead-based paint from its appearance. If a building is over 25 years old, assume that it has been painted with lead-based paint. Because inhalation of dust and fumes is the principal way lead enters the body, do not let paint debris become airborne during removal. Wear a dust mask at all times, wet sand, use drop sheets, collect any dust and debris in a closed container or strong plastic bag, and dispose in a place approved by the local authority.

You might be interested in reading: Planning a bungalow renovation.

This article by Trevor Pringle featured in Issue 005 of New Zealand Renovate Magazine. New Zealand's first and only magazine solely dedicated to home renovations.

 

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*All information is believed to be true at time of publishing and is subject to change.