ERAS

1940s and 50s Houses

POST-WAR PRACTICAL
Through the later 1930s Depression years and after the Second World War, NZ Government programmes to fix a widespread housing shortage resulted in the construction of thousands of State Houses – still common and very popular today. Designs and external features were varied to avoid uniformity, although internal structures and materials were standardised for economy of scale. Originally there was minimal decoration to these sturdy little homes, although many have since been creatively transformed.

1940s homes were commonly rectangular, or T or L shaped in plan, with three bedrooms and separate living and dining rooms and kitchens. Ceilings were lower and rooms smaller than the generous spaces of earlier villas. State Houses usually had higher-pitched roof structures, either a central hip or gable ends, narrow eaves, and relatively small banks of narrow timber-framed multi-paned windows. A range of claddings were used including timber weatherboards, asbestos-cement sheets or shingles, brick veneer or stucco. Foundations were usually concrete piles, with continuous concrete foundation walls supporting brick veneer. Flooring and framing were timber, and internal linings were plasterboard and hardboard, with softboard ceilings.Roofing was tile, corrugated iron or asbestos-cement. Heating was an open fireplace in the living room with a chimney of concrete or brick.

In the late 1940s a change of Government led to an increase in private construction, although the designs and methods remained very similar to the State House model for a basic family home through into the 1950s..

DEALING WITH PREVIOUS RENOVATIONS & CHANGES

‍Very few 1940s and 50s houses still remain in their original state today, and most renovation projects will have to deal with modifications that have already been made over the years. In many cases these changes – reflecting the techniques, materials and fashions of the 1960s, 70s or 80s – will not be adding value to the performance, the charm or the liveability of the home. Some may be the result of dodgy if well-intentioned DIY projects and not up to basic standards.

Today’s methods and technologies can solve such messy problems – but the renovation process will need a careful review of any earlier changes and conversion work:
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Extensions to provide additional living spaces or bedrooms
Removal of internal walls to create open-plan living / dining / kitchen areas
Replacement or repair of original roofing or external cladding
Insulation in the roof space or under the floor
Replacement of original windows with aluminium frames – may be single glazed
Replacement of original kitchen and bathroom fittings

WHAT YOU MIGHT FIND IN YOUR 1940s / 50s HOME – & RECOMMENDATIONS...

FOUNDATIONS & FLOORS

Missing or inadequate piles and joists

FIX – ????????

Sagging joists or bouncy floors

FIX – ????????????????

Uneven floors

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Rising damp

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Cracking or deterioration of concrete foundation walls

FIX – ????????????????

Blocked or damaged ventilation grilles in foundation walls

FIX – ????????????????

Lack of ground clearance and poor subfloor ventilation

FIX – ????????????????

Lack of underfloor insulation

FIX – ????????????????

Retrofitted insulation that is inadequate or deteriorated

FIX – ????????????????

FIX – ????????????????

FRAMING, INTERNAL WALLS & CEILINGS

Untreated native timber framing and boards

FIX – Retain if sound; treat for borer if needed

Plasterboard or hardboard – may have deteriorated

FIX – ????????

No insulation in walls

FIX – ????????

Retrofitted insulation may include urea-formaldehyde foam

FIX – ????????

Walls no longer square or out of plumb

FIX – ????????

Draughts and gaps – no airtightness

FIX – ????????

Dampness – mould on walls and ceilings in rooms with inadequate ventilation, rot, mustiness and smells

FIX – ????????

Asbestos

FIX – ????????

Borer

FIX – ????????

Rodent nests

FIX – ????????

CLADDING

Timber weatherboards with lead-based paint or creosote weatherproofing

FIX – ????????

Rot in external timber cladding

FIX – ????????

Asbestos-cement sheets or shingles – likely to be cracked or water damaged due to poor drainage or ventilation

FIX – ????????

Brick veneer – likely to be cracked or water damaged due to poor drainage or ventilation

FIX – ????????

Stucco – likely to be cracked or water damaged due to poor drainage or ventilation

FIX – ????????

No waterproofing layers or building membrane

FIX – ????????

No insulation in walls

FIX – ????????

Retrofitted insulation may include urea-formaldehyde foam

FIX – ????????

Lead paint

FIX – ????????

Borer

FIX – ????????

WINDOWS

Original timber framed windows – single glazed

FIX – ????????

Lead paint on sashes and frames

FIX – ????????

Inadequate sealing and flashings

FIX – ????????

Windows warping and sticking

FIX – ????????

Rot in sashes and frames

FIX – ????????

Corrosion of metal flashings and hinges

FIX – ????????

ROOFS

Corrugated iron with lead nails / coatings

FIX – ????????

Asbestos cement sheeting or shingles – may be cracked or corroded, or have moss or lichen spreading across

FIX – ????????

Tiles – may be cracked or corroded

FIX – ????????

Inadequate insulation or retrofitted insulation that has deteriorated

FIX – ????????

Leaks and historical roofing repairs

FIX – ????????

Moisture damage or cracking to cladding under eaves

FIX – ????????

Lead paint and lead flashings

FIX – ????????

VENTILATION

No ventilation system except draughts and opening windows

FIX – Add balanced MVHR system with low-VOC ducting

Stuffy interiors – smells and mould

FIX – ????????

STATE HOUSES
(1930s – 1960s)

INTRO NEEDED FOR STATE HOUSES...
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ISSUES / RECOMMENDATIONS:

FOUNDATIONS

Asbestos DPCs (Damp Proof Courses) occasionally used; concrete with poor drainage

SUPERHOME FIX / UPGRADE – Replace with PE (Polyethylene) vapour barriers

FRAMING

Untreated timber; often still solid

SUPERHOME FIX / UPGRADE – Seal gaps; install membranes internally

BUILDING MEMBRANES

None or black bituminous paper (off-gasses)

SUPERHOME FIX / UPGRADE – Remove and replace with modern WRB (Weather-Resistive Barrier)

INSULATION

Often loose-fill mineral wool or glass fibre

SUPERHOME FIX / UPGRADE – Remove & replace with safe batts or blown-in cellulose

CLADDING

Asbestos cement sheets (e.g. SuperSix)

SUPERHOME FIX / UPGRADE – Licensed removal; reclad with breathable timber or fibre-cement systems

WINDOWS

Aluminium + bituminous sealants

SUPERHOME FIX / UPGRADE – Replace with low-VOC joinery systems

ROOF

Iron or asbestos-containing concrete tiles

SUPERHOME FIX / UPGRADE – Replace with modern roofing. Use breathable underlay.

VENTILATION

Passive vents only

SUPERHOME FIX / UPGRADE – MVHR upgrade with air quality monitoring

MOULD

Hidden in ceiling cavities

SUPERHOME FIX / UPGRADE – Fix thermal envelope; use mould-resistant linings

1970's – 1980's Suburban Homes

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ISSUES / RECOMMENDATIONS:

FOUNDATIONS

Bitumen DPMs (Damp-Proof Membranes); potential off-gassing

SUPERHOME FIX / UPGRADE – Retrofit with new poly barriers and insulation

FRAMING

Untreated framing timber

SUPERHOME FIX / UPGRADE – Add service cavity, membrane, and insulation

BUILDING MEMBRANES

Early building wraps degraded or tar-based

SUPERHOME FIX / UPGRADE – Replace with airtight but vapour-open membranes

INSULATION

Glass wool and foil insulation (now banned)

SUPERHOME FIX / UPGRADE – Remove foil; replace with safe, fire-retardant insulation

CLADDING

Hardboard, asbestos cement, or early fibre cement

SUPERHOME FIX / UPGRADE – Test and remove; reclad with safe cavity systems

WINDOWS

Aluminium single-glazed; rubber seals may degrade into VOCs

SUPERHOME FIX / UPGRADE – Replace with non-toxic thermally broken units

ROOF

Decramastic tiles (lead bitumen); asbestos flashings

SUPERHOME FIX / UPGRADE – Replace with modern steel or tile roof; ventilate roof space

VENTILATION

Internal moisture issues

SUPERHOME FIX / UPGRADE – MVHR system with washable filters

MOULD

Grows behind foil insulation and in ceiling corners

SUPERHOME FIX / UPGRADE – Upgrade thermal envelope and ventilation

Leaky Buildings
(1990s – 2004)

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ISSUES / RECOMMENDATIONS:

FOUNDATIONS

Slab-on-grade with no insulation; some chemical damp-proofing

SUPERHOME FIX / UPGRADE – Add external insulation and control layers

FRAMING

Untreated pine – often decayed, not toxic but dangerous

SUPERHOME FIX / UPGRADE – Remove and replace with H1.2+ treated or engineered wood

BUILDING MEMBRANES

Monolithic EIFS (Exterior Insulation and Finish Systems) with polystyrene; non-breathable

SUPERHOME FIX / UPGRADE – Remove and reclad with breathable, drained WRB (Weather-Resistive Barrier) system

INSULATION

Polystyrene or glass wool; often poorly installed

SUPERHOME FIX / UPGRADE – Remove EPS (expanded polystyrene); upgrade with non-toxic batts + rigid board externally

CLADDING

Polystyrene systems (toxic in fire); fibre cement may contain silica

SUPERHOME FIX / UPGRADE – Replace with low-toxicity ventilated cladding (timber, metal, etc)

WINDOWS

Sealants off-gassing; poor flashings

SUPERHOME FIX / UPGRADE – Replace with uPVC or thermally broken aluminium; safe low-VOC sealants

ROOF

Membrane roofs may use PVC or VOC-heavy glues

SUPERHOME FIX / UPGRADE – Re-roof using TPO* membranes or steel with natural underlays.
*(TPO (thermoplastic polyolefin) waterproofing membrane).

VENTILATION

Poor air quality

SUPERHOME FIX / UPGRADE – Full MVHR with VOC & CO₂ sensors

MOULD

Hidden in cavities; triggered by trapped moisture

SUPERHOME FIX / UPGRADE – Strip walls, re-insulate, and rebuild envelope to breathe

Modern Homes
(2004 – Present)

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ISSUES / RECOMMENDATIONS:

FOUNDATIONS

Slab insulation often missing; minor emissions from treated timber or adhesives

SUPERHOME FIX / UPGRADE – Design warm slab or retrofit slab edge insulation

FRAMING

H1.2 treated pine (boron – safe); some LVL glues contain formaldehyde

SUPERHOME FIX / UPGRADE – Specify FSC-certified, low-emission engineered wood

BUILDING MEMBRANES

Modern wraps sometimes non-breathable

SUPERHOME FIX / UPGRADE – Choose vapour-open, airtight WRBs (Weather-Resistive Barriers) with ecolabels

INSULATION

Glass wool; some foams still high in embodied carbon/toxicity

SUPERHOME FIX / UPGRADE – Upgrade to wool, recycled PET, or hemp; avoid PIR/PUR

CLADDING

Composites or fibre cement with crystalline silica

SUPERHOME FIX / UPGRADE – Prefer timber or low-tox fibre cement with safety cutting tools

WINDOWS

Aluminium; off-gassing in some composite seal

SUPERHOME FIX / UPGRADE – Use low-tox, thermally broken frames and non-toxic sealants

ROOF

Generally sound; some asphalt-based products still used

SUPERHOME FIX / UPGRADE – Warm roof design with low-tox insulation and breathable membranes

VENTILATION

HRV = air recycling; still VOC build-up

SUPERHOME FIX / UPGRADE – Specify MVHR with HEPA and carbon filters; ensure full duct cleaning

MOULD

Appears from thermal bridging

SUPERHOME FIX / UPGRADE – Use thermal breaks, warm junction detailing, and airtight layers

Common NZ House Styles

1940s and 50s Houses

STATE HOUSES(1930s – 1960s)

1970's – 1980's Suburban Homes

Leaky Buildings(1990s – 2004)

Modern Homes(2004 – Present)

STATE HOUSES
(1930s – 1960s)

Leaky Buildings
(1990s – 2004)

Modern Homes
(2004 – Present)