1960's 1970's & 1980's
1960's, 1970's& 1980's
Extensions to add more bedrooms or living spaces
Remodelling of kitchen / dining / living areas
Converting a garage to an additional bedroom or living space
Replacing windows with double glazing
Retrofitting insulation in the roof space and underfloor
Reroofing and replacing external claddings
WHAT YOU MIGHT FIND IN YOUR BUNGALOW –
AND WHAT CAN BE DONE...
FOUNDATIONS & FLOORS
Timber piles, bearers and joists of treated radiata pine – possible deterioration
Compromised subfloor structures can result in:
· Sagging joists or bouncy, squeaky floors
· Uneven floors
· Sagging decks and porches
Identify areas where foundation structures are causing problems and replace or support with new concrete piles and new bearers and joists
Since 2011 most structural timbers must be treated to protect against insect attack and decay:
GO TO LINK
GO TO LINK
Treated timbers are likely protected with CCA (copper, chromium and arsenic) – banned in most other countries but still used in NZ – or with boron (radiata pine – pink colour)
Handling and cutting treated timber must be done with proper protective equipment – gloves, mask, goggles, long sleeves to cover skin
Any sawdust or offcuts must be carefully disposed of to avoid soil contamination
Depending on your budget you may wish to choose timber treated with more natural products such as MCA (Micronised copper azole)
Continuous foundation wall of concrete or concrete blocks – may have cracking or deterioration
Identify problem areas and the causes – subsidence, earthquake damage, inadequate or compromised foundations
Restore level footings for piles and foundation walls, and repair and replaster as needed
Timber baseboards around the underfloor space
Check for any rot, borer or other damage and replace as needed
This is an opportunity to check ventilation and create new vents or grilles to improve airflow
Deterioration of original damp proof course protecting the subfloor framing from concrete piles and foundation walls
Replace damp proofing membrane layers when renewing piles, joists and bearers and when retrofitting underfloor insulation, to protect the flooring structures and insulation from moisture rising from the ground
This may be done from below but depending on access may be more easily done from above, removing the flooring to make the necessary repairs
Damp proofing sheets are heavy-duty polythene, must cover the entire ground area, and must be well secured to the foundation walls and piles – if your budget allows, get a qualified professional or builder to do this task – proper protective equipment should be worn (mask and gloves) to protect against breathing in dust or mould from rotted timbers
Damp proofing must be compliant with the Building Code E2 External Moisture and E3 Internal Moisture and with NZ Standard NZS 4246.2016::
GO TO LINK
(guidance included)
Lack of ground clearance, poor access and poor subfloor ventilation
If there is inadequate clearance between the joists and bearers and the ground, the best option is to tackle each room from the top – take out the flooring and address the subfloor structures from above before:
· Installing damp-proofing (plastic sealed closely to the subfloor structure to protect against moisture)
· Installing good insulation
Replacing or renewing the flooring
Blocked or deteriorated ventilation grilles
Check ventilation grilles in the foundation walls are clear – if necessary you can create new ventilation grilles to improve airflow
Underfloor insulation
Insulation became a legal requirement in 1977/78 with NZS 4218 establishing basic minimum standards (it has had several updates since):
GO TO LINK
Before that your 1960s or early 70s home may have no insulation – and the insulation in homes built after the late 70s regulations will likely be compromised and probably inadequate in comparison to today’s standards
Underfloor insulation in homes of these decades may be original or retrofitted
Through the 1970s many homes were fitted with sisalation foil, intended as underfloor insulation – this was often installed with a “draped sag” between joists with small holes for drainage of any moisture, compromising any insulation effectiveness
Since 2016 it has been illegal to install or repair sisalation foil in residential buildings because of the risks of electrocution (under the Building Code Clause G9 Electricity) – sisalation foil itself is not illegal, but installation or repair is now banned:
GO TO LINK
Removal should be done by a qualified professional with input from an electrician for basic safety
Retrofit suitable insulation – this may be done from below if there is reasonable access, or if there is inadequate access to the subfloor area, you can go down from the top, removing the flooring to make necessary changes while you install damp proofing and insulation
Sagging or unstable decks and porches
These may have been additions or extensions to the original structure, and may have been DIY projects undertaken by previous owners
Check the deck structures, framing and supports, balustrades and handrails, steps, and drainage – particularly areas where wind driven rain or other moisture may have caused rot or compromised stability, and the cantilever structures, beams and supports joining the deck to the main foundations and cladding
Check deck surfaces – water-resistant membranes may have deteriorated, decking slats may have been improperly installed, or the deck may include asbestos cement decking tiles which will need to be removed and disposed of by qualified professionals (see Asbestos under Cladding below)
Repair and replace as necessary – it may be more efficient and safer to replace the whole deck structure
Concrete slab floors
The 1970s saw concrete slab floors becoming more common, including concrete or concrete block foundation walls and:
· Damp proof membrane – polythene sheet to protect concrete from ground moisture
· Reinforcing steel mesh
· No under-slab or edge insulation – often resulting in significant heat loss around the perimeter of the building, and condensation and mould problems
Add vertical edge insulation (typically extruded polystyrene) around the slab to reduce heat loss – BRANZ advice is that there are very limited benefits of installing edge insulation with a higher R-value than R 1.0:
GO TO LINK
Check drainage around the perimeter and clear vegetation
FRAMING, INTERNAL WALLS & CEILINGS
Radiata pine treated with boron
Commonly used to protect against borer and decay of the timber, this can be identified by the typically pink colour of the wood
Use protective equipment (gloves, mask) and a tarpaulin to avoid sawdust or offcuts from contaminating the soil – dispose of boron treated timber carefully – check with your local council
Exotic timbers – Douglas fir
Increasingly used for house framing in the 1970s instead of native timbers, Douglas fir was often untreated due to its natural durability
Check for any deterioration due to water or insect damage – replace as needed
Particleboard flooring damage
Identify problem areas and the cause of the problem – check for underfloor moisture or leaking pipes causing rot or mould
Repair pipes and address subfloor ventilation and underlay issues – replace flooring panels
Plasterboard or hardboard wall and ceiling linings
Check for deterioration or damage due to internal moisture, leaks or moisture in the roof space or getting through any compromised exterior cladding
Replace with new plasterboard or other linings as needed
Textured ceiling finishes containing asbestos
Textured ceiling finishes popular in the 1970s often contained asbestos
The first check for any renovation is to assess for asbestos in the structure and materials – this must be done by a properly qualified professional
Removal and disposal of asbestos must be undertaken by a properly qualified professional
Exposed rafters in open high ceilings
Popular in living areas and stairwells of 1960s 70s and 80s homes these ceilings may have suffered moisture damage over time around the joints – check for any leaks – repair roofing and replace ceiling panels as needed
The rafters may be constructed from treated timbers – handle with care using protective equipment – see Treated radiata pine in Foundations and Floors above
Insulation in roof space
Insulation became a legal requirement in 1977/78 with NZS 4218 establishing basic minimum standards (this regulation has had several updates since):
GO TO LINK
Before that your 1960s or early 70s home may have no insulation – and the insulation in homes built after the late 70s regulations will likely be compromised and probably inadequate in comparison to today’s standards
Insulation in the roof space is likely to have slumped or drifted over the years
Replace with new properly efficient insulation – make sure that the insulation is far enough away from the roofing structure to avoid condensationInstall effective moisture proofing layers to protect the insulation from damage
No insulation in walls
There are two basic ways to address a lack of wall insulation:
From the inside – strip out the interior wall linings and retrofit:
– Moisture proofing membrane layer / underlay
– Insulation
– Optional service cavity – benefits include minimising thermal bridging
– Install new interior linings with airtightness sealing
From the outside – strip off the exterior cladding and retrofit:
– Insulation
– Moisture proofing membrane layer / underlay
– New exterior claddings
An alternative to avoid disruption or problems with the existing structures and linings is “outsulation” – putting on a thermally-efficient wrap system over the existing weatherboards or cladding – this can include additional framing, water resistant and air control layers, and insulation panels inside a new external cladding
Insulation may include urea-formaldehyde foam or glass wool
Problems include:
· Reduced thermal effectiveness due to shrinkage or gaps
· Moisture retention in the wall cavity
· Health concerns
· Fire hazard
· Environmental impacts
BRANZ study:
GO TO LINK
Remove and replace with new insulation
Removal should be undertaken by qualified professionals using proper protective equipment and disposing of the material safely
Underlay / moisture proofing
Houses in this era may have had building paper or underlay – this may have been bitumen-impregnated paper or felt, or may include asbestos
Wall underlays must now be compliant with the Building Code E2 External Moisture; E3 Internal Moisture; B2 Durability; and C1-C6 Fire Protection:
BRANZ report:
GO TO LINK
A range of modern flexible and rigid underlay options are designed to support the weathertightness of the building, separate external wall elements from internal elements (framing, insulation and linings), protect against water vapour, be fire resistant, restrict airflow and support insulation
BRANZ Guidance:
GO TO LINK
There are two basic ways to retrofit underlay / moisture proofing – from the inside or from the outside – see Insulation below
Walls no longer square or out of plumb
This may be a result of undersized structural timbers – rafters, framing, joists
Check foundations – piles, bearers and joists – and replace or repair any problem areas causing uneven levels
Renew wall linings as needed – rehang doors as needed
Draughts and gaps – no airtightness
1960s 70s and 80s suburban homes will be less draughty than housing from earlier erasHowever, identify problem areas:
· Window and door frames
· Skirtings and floors
· Chimneys
· Vents in ceilings
Seal properly with weather stripping around windows and doors, or sealant (silicon caulking) – if this has been done previously it may need renewing
Check window structures and hinges – retrofit with new double or triple glazed windows (PVC or thermally broken aluminium can be retrofitted into original timber window frames)
Install effective insulationIf replacing wall linings, skirtings or floors, seal the joins properly with tape or sealant
Block off old chimneys no longer in use
Dampness – mould and rot, mustiness and smells
Check the underfloor space for moisture and ventilation
Clear ventilation grilles in the foundation walls or add new grilles to improve air flowInstall effective underfloor damp proof layers and insulation
Replace any rot- damaged timbers
Borer
While borer infestations will likely be long gone the holes remain and create significant risks for moisture getting in to the wall cavity or ceiling space
Replace damaged timbers and linings as needed
Rodent nests
Tackle these with extreme caution using proper protective equipment – mask and gloves – use a tarpaulin or strong bin bag and dispose of the nest and other material safely
CLADDING
Original waterproofing layers or building membrane may be compromised
See Underlay in Framing Internal Walls and Ceilings above
Timber weatherboards – may be cedar, Douglas fir or redwood – possible moisture damage or rot
Assess the extent of damage and replace with new weatherboards or other cladding
Check around:
· Corners and joins
· Windows and door frames
·Bow and bay windows that extend beyond the main exterior walls
·Exposed areas, especially where vulnerable to wind driven rain or extreme sun exposure that would dry and shrink the timber
·Previous renovations that may have compromised the weathertightness of the building
While borer infestations will likely be long gone the holes remain and create significant risks for moisture getting in to the wall cavity or ceiling space
Depending on your budget, you may wish to choose timber and linings treated with more natural products such as CHECK WITH DAN
Brick – likely to have cracking
Identify problem areas and check for subsidence, problems with the foundations, damp, lack of damp proofing, or other problems such as tree roots
Repair and replace as necessary
Remove brick chimneys down to the floor (concrete pad) level
Stucco – likely to be cracked or water damaged
Identify problem areas and issues with subsidence, foundations or wall framing, dampness or rot
Repair and replace as necessary
Concrete blocks or concrete brick “Summerhill stone” – likely to have cracking or mortar deterioration
Identify problem areas and check for subsidence, problems with the foundations, damp, lack of damp proofing, or other problems
Repair and replace as necessary
Asbestos cement sheeting or boards with wood-grain look – likely to have cracking and moisture damage
The first check for any renovation is to assess for asbestos in the structure and materials – this must be done by a properly qualified professional
Removal and disposal of asbestos must be undertaken by a properly qualified professional
Lead paint – banned in 1979
There will very likely be layers of old lead paint – this may be covered over by later layers of other paint
Lead paint must be taken off using proper protective equipment – respirator mask, goggles and gloves – use a tarpaulin so it does not get into the ground and contaminate the soil
Do not dry sand the paint as this will create dangerous dust – use a tarpaulin to ensure the paint scrapings do not get into the soil – lead contamination can be a significant health hazard in the environment, especially for children:
GO TO LINK
Lead paint must be safely disposed of – check with your local council for regulations and collection for hazardous waste
Worksafe Guidelines:
DOWNLOAD PDF
Exterior timber, fences and decks may have been treated with CCA
Since 2011 most structural timbers must be treated to protect against insect attack and decay:
GO TO LINK
GO TO LINK
Treated timbers are likely protected with CCA (copper, chromium and arsenic) – banned in most other countries but still used in NZ – or with boron (radiata pine – pink colour)
Handling and cutting treated timber must be done with proper protective equipment – gloves, mask, goggles, long sleeves to cover skin
Any sawdust or offcuts must be carefully disposed of to avoid soil contamination
Depending on your budget you may wish to choose timber treated with more natural products such as MCA (Micronised copper azole)
Borer
While borer infestations will likely be long gone the holes remain and create significant risks for moisture getting in to the wall cavity or ceiling space
Replace damaged timbers and linings as needed
WINDOWS
Single glazing
Retrofit with new double or triple glazed windows (PVC or thermally broken aluminium can be retrofitted into original timber window frames)
Timber frames give a significant advantage in terms of thermal efficiency – however it does require maintenance and making sure the weatherproofing is in good condition
Timber framing – likely to have rot or other deterioration
Check window structures and surrounds:
· Seal any gaps between the window frame and the walls to avoid draughts and heat loss
· Replace old compromised putty or other window seals
·Repair or replace any joinery that has suffered from dampness, rot, or warping
Aluminium window framing and ranch sliders
The original aluminium framing of this era was not thermally broken (insulated with a thermal barrier between the inside and outside of the frame)
As aluminium is a serious conductor of heat, this results in significant heat loss, and condensation on the inside of the windows leading to interior dampness and mould
Replace with thermally broken aluminium, PVC or timber joinery
Louvre windows in bathrooms and laundries
Many homes in the 1960s 70s and 80s used louvres in bathrooms, kitchens and laundries to provide air flow
Most of these were in flimsy adjustable aluminium frames
Remove and replace with thermally broken aluminium, PVC or timber joinery
Install proper ventilation systems to reduce moisture in the home
Deterioration of rubber or plastic sealing structures and flashings – rubber may degrade releasing harmful VOCs (Volatile Organic Compounds)
Check window sealings and flashings for any corrosion or damage
Replace with thermally broken aluminium, PVC or timber joinery
Jamming or sticking windows
Check window joinery for any moisture damage or corrosion
Check foundations for subsidence and cladding joins for any problem areas
Repair or replace with thermally broken aluminium, PVC or timber joinery
ROOFS AND PARAPET WALLS
Corrugated iron
Long run roofing iron was introduced in the 1960s – reducing the need for multiple overlapping points or joins across the roof and reducing issues with weathertightness and moisture
Most homes of this era will have already had some or all of the roof replaced by now, although this may have deteriorated over time
Check for any problem areas and any resulting damage to the roof structure, ceilings or internal structures below
Replace with new long run steel roofing or other roofing (tiles, shingles)
Tiles
A diverse range of roofing tiles were used in the 1960s 70s and 80s:
· Decramastic tiles, galvanised steel base with a top layer of stone chips embedded in a bitumen coating – may contain asbestos (pre 1980 – likely to have dents and moss, mildew and mould growth
· Clay – likely to have cracking
· Slate – likely to have cracking
· Concrete, sometimes embedded in cement mortar – likely to have cracking
Check for any loose, cracked or broken tiles – replace damaged areas or redo the whole roof
Asbestos-cement panels or shingles – likely to have cracking or moss / lichen growth
The first check for any renovation is to assess for asbestos in the structure and materials – this must be done by a properly qualified professional
Removal and disposal of asbestos must be undertaken by a properly qualified professional
Inadequate or compromised original insulation
See Insulation in roof space in Framing, internal walls and ceilings above
Roofing underlay laid over wire netting over roof purlins
The original underlay is likely to have deteriorated over time
Roofing underlay is now required under the Building Code E2 External moisture (with a few exceptions):
GO TO LINK
When upgrading insulation or undertaking any roof repair or replacement, install effective new underlay over the roof framing for:
· Protection against water getting in to the roof structure
· Absorbing condensation that forms on the underside of the roof
· Reducing air movement in the roof space
· Fire protection
Inadequate moisture control and condensation in ceiling space
The roof spaces in many 1940s and 50s houses had poor or no ventilation (except draughts and gaps, or gable end grilles or louvres)
This commonly results in the air in the roof cavity becoming laden with moisture – from the warmth and activity of people in the house below, or from leaks due to poor weathertightness
When temperatures fall, this moisture condenses on the underside of the roofing material, and can cause mould, rot, or otherwise compromise the timbers and any insulation material:
GO TO LINK
Key factors are:
· Making sure that the insulation is far enough away from the roofing structure to avoid condensation
· Installing effective moisture proofing layers to protect the insulation from damage
· Reducing moisture in the air inside the home – with a proper balanced ventilation system, or other practical steps like ducted extractor fans in kitchens and bathrooms
Lead head nails and lead flashings – pre-1979
Lead-head nails were still used until 1979 – they can result in problems with rust or the nails popping up as the roof framing timbers dry over time
This creates weathertightness issues and water getting in to the roof space – as well as releasing lead into the environment
Check your roofing carefully for missing or compromised nails – replace with galvanised nails or screws
Check for any lead nail remnants in the guttering and dispose of these properly – check with your local council for regulations and collection for hazardous waste
Decks and patios
Decks often featured a roof usually of translucent corrugated polycarbonate or fibreglass sheets – these will likely have deteriorated and become cracked, clouded and unstable over time
Replace with new shelter and shade systems – today’s shading options include retractable and adjustable screens
VENTILATION
No ventilation system
The only ventilation in homes from these decades was from the draughts, from opening windows, and via the open fireplaces
If you are investing in improving the insulation, airtightness and internal moisture control of your 1960s 70s or 80s home, you should consider installing a proper balanced ventilation system with heat recovery – to remove moisture and stale air, and bring in fresh air – heat is transferred from the stale inside air to the incoming air, to help maintain a consistent indoor temperature as well as manage any dampness issues
Stuffy interiors – smells and mould
Some rooms in older houses may have mustiness, mould or mildew, particularly:
· Bathrooms, kitchens or lean-tos at the rear of the villa
· In houses in shady gullies with little natural sunlight
· If leaks or moisture has compromised the cladding, framing or internal linings causing rot
· After flooding
Mould can be a major health hazard and can cause allergic reactions, respiratory problems, asthma, eye irritations, sore throats and skin rashes – some moulds produce toxic compounds, such as Stachybotrys (a greenish black mould that grows on timber, fibreboard, wallpaper and other materials
Mould must be dealt with properly to ensure the safety and wellbeing of people living in the home:
GO TO LINK
If you suspect toxic mould, you should use proper protective equipment (mask or respirator, gloves, protective clothing to cover your skin) to take a sample for testing – if it is contaminated with toxic mould it should be removed by a qualified professional
You may have to remove and replace ceiling panels, wall linings, carpets or other contaminated materials, which should be properly disposed of
For lesser areas of mould, use protective gloves and mask – clean with bleach solution or other mould-removal products, and make sure the area dries completely afterwards – dispose of the cleaning materials carefully
Key factors to prevent mould recurring include:
· Ventilation and good airflow
· Insulation
· Removing and replacing any rotted timbers or linings
· Minimising internal moisture
REFERENCE LINKS
