1930s&1940s
1930s&1930s
Resurfacing of low pitched or flat roofs or installation of modern waterproof membranes
Repair of parapet walls due to lack of weathertightness resulting in rot or corrosion of flashings
Minimal / inadequate insulation under low pitched or flat roofs or in narrow underfloor spaces
Replacement of original windows with aluminium framed windows – often with frames that are not consistent with the Art Deco style, or single glazed
Recladding or repair of original external stucco or weatherboards
Replacement of internal wall linings and ceilings
Replacement of original native timber flooring
Extensions to the rear areas of the home that are inconsistent with the style of the front facade
WHAT YOU MIGHT FIND IN YOUR BUNGALOW –
AND WHAT CAN BE DONE...
FOUNDATIONS & FLOORS
Precast concrete piles
Check the piles are on solid footing and the concrete has not become compromised due to moisture or subsidence over the years
Replace and add new piles as needed
Continuous perimeter foundation walls – may have cracked or deteriorated
Check the status of the perimeter foundation walls – it may not be solid concrete but bricks covered with plaster or a thin coating of concrete
Identify problem areas – check for bouncy floors or sticky windows above
Check for subsidence, earthquake damage, inadequate or compromised foundations - restore solid, level footings
Repair or replace the perimeter foundation walls with new reinforced concrete as needed – this may require lifting the structure to access the foundation and re-level the floors – or focusing work on the compromised sections
Missing or undersized piles and joists
Check for bouncy floors, uneven floors or sticky windows and doors to identify weaknesses in the subfloor structures
BRANZ advice:
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Replace and strengthen as needed – depending on underfloor access this may be easier to do from above
Previous renovations to piles, joists or bearers
Since 2011 most structural timbers must be treated to protect against insect attack and decay:
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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)
Joists and bearers may have rot or borer damage
The borer will likely be long gone but the holes remain, creating risk of moisture getting in to the timbers
Identify areas most affected and replace with new joists and bearers
Lack of adequate waterproofing between the foundations and the timber floor structures
Install 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 Moistureand E3 Internal Moisture and with NZ Standard NZS 4246.2016:
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(guidance included)
Rising damp
Install damp-proofing to protect against moisture
Lack of ground clearance, poor or no subfloor access
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
Poor subfloor ventilation
Perimeter foundation walls may have minimal ventilation – wire mesh or concrete grilles may have deteriorated or become blocked
Check ventilation grilles in the foundation walls are clear – if necessary you can create new ventilation grilles to improve airflow
Lack of underfloor insulation
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
Previous retrofitted foil insulation
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:
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Removal should be done by a qualified professional with input from an electrician for basic safety
Replace with new effective insulation panels
FRAMING, INTERNAL WALLS & CEILINGS
Untreated timber framing, boards and tongue-and-groove
Assess the extent of damage and replace with new timber, plasterboard or other linings
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
No waterproofing underlay / moisture proofing membrane
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:
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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
There are two basic ways to retrofit underlay / moisture proofing – from the inside or from the outside – see Insulation below
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
– 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
– 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
Retrofitted 1970s insulation may include urea-formaldehyde foam
Problems include:
· Reduced thermal effectiveness due to shrinkage or gaps
· Moisture retention in the wall cavity
· Health concerns
· Fire hazard
· Environmental impacts
BRANZ study:
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Remove and replace with new insulation
Removal should be undertaken by qualified professionals using proper protective equipment and disposing of the material safely
Original framing timbers may have been treated with creosote (pre 1940s)
Black creosote made from coal tar was often used to treat timber against insects and rot – both for framing timbers and for weatherboards and shingles
When removing creosote-treated timbers or cladding materials, use proper protective equipment (gloves, mask, goggles, long sleeves)
Creosote is a hazardous substance and must be disposed of carefully – check with your local council for regulations and collection for hazardous waste
Internal linings – plasterboard, hardboard or asbestos-cement sheeting for kitchens and bathrooms
Replace with new plasterboard or other linings as needed – dispose of the old material safely as it may include asbestos
Ceilings:
· Plasterboard
· Tongue-and-groove timber in service areas
Replace with new plasterboard or other linings as needed – dispose of the old material safely as it may include asbestos
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
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 insulation
If 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 flow
Install effective underfloor damp proof layers and insulation
Replace any rot- damaged timbers
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
Lead paint
There will very likely be layers of old lead paint especially in kitchens, bathrooms and service areas – 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
Lead paint must be safely disposed of – check with your local council for regulations and collection for hazardous waste
Worksafe Guidelines:
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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
No waterproofing layers, wall underlay or building membrane
See Waterproofing / underlay in FRAMING, INTERNAL WALLS AND CEILINGS above
Cement-based plaster coating – installed over:
· Asbestos-cement sheets
· Wire mesh
· Timber boards or sarking
· Plasterboard or felt coated in bitumen
· Concrete external walls
Art Deco buildings were designed to present a sleek exterior and clean uncluttered lines – with plaster over the external walls full height to the parapet (hiding the roof line) and continuous with the foundations
However this created significant vulnerabilities – which can combine with problems arising from the typical Art Deco low pitched roof structures (see Roofs below)
Over time the external claddings will likely have become compromised due to:
· Lack of weathertightness
· Lack of eaves protection
· Lack of external surrounds to protect windows
· Continuous exterior cladding not allowing for movement
· Compromised seals and flashings
· Subsidence or earthquake damage
Check your exterior plaster claddings carefully for cracking, corrosion or other damage – check around:
· Corners and joins
· Windows – especially curving window structures with multiple casements – and door frames and shallow porches
· Exposed areas, especially where vulnerable to wind driven rain or extreme sun exposure that would dry and shrink the timber framing
· Where the wall framing meets the concrete foundation
· Previous renovations that may have compromised the weathertightness of the building
If water has got in to the structure it may have travelled through to other areas, finding the lowest point and creating problems in different areas from the original point of ingress
Repair or replace the underlying framing and structures as needed, and ensure adequate flashings and seals, before replastering
An alternative to avoid disruption or problems with the existing structures is “outsulation” – putting on a thermally-efficient wrap system over the existing exterior cladding – this can include additional framing, water resistant and air control layers, and insulation panels inside a new external cladding
Retain and highlight, or replace, any Art Deco style features (chevrons, bars, sunburst designs) – but don’t overdo it, keep it simple to align with the original 1930s aesthetic
Chimneys on external walls – concrete or brick with plaster coating
Remove chimneys down to the concrete pad at floor level
No insulation in walls
See above – Insulation in FRAMING, INTERNAL WALLS AND CEILINGS
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
Lead-based paint on external cladding, windows and doors
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
Lead paint must be safely disposed of – check with your local council for regulations and collection for hazardous waste
Worksafe Guidelines: DOWNLOAD PDF
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
Recess the new retrofit windows within the wall to align with the line of the insulation – to avoid heat loss and significantly improve the thermal efficiency of the home
Lack of facing boards or adequate weather protection to window frames
The issue here is to provide proper weather protection while remaining consistent with the sleek smooth exterior lines of the Art Deco style
Recessing the windows to align with the insulation envelope of the building will require appropriate sealing and weatherproofing
Some 1930s homes included a curved or geometric “eyebrow” shelter above the windows – this may be an option to keep the overall look of the era while giving some protection
Lack of eaves or shading from sun
As with typical lack of facing boards, this can be a challenge to retain the original design aesthetic of the period while protecting the home from over-exposure to the sun and overheating
Install external solar screens or shading as necessary
Inadequate sealing and flashings
Check flashings and window seals carefully, especially in curving windows with multiple casements exposed to the weather
Replace as necessary
Check for any damage to internal framing and linings from compromised window seals – water may travel some distance within the structure to find the lowest point where moisture damage may appear
Window or door frames warping, rotting, sticking or out of plumb due to cracking or moisture – windows or doors not opening or closing smoothly
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
Check for any subsidence or other structural damage affecting the window
Lead paint on sashes and frames
There will very likely be layers of old lead paint especially in kitchens, bathrooms and service areas – this may be covered over by later layers of other paint
See Lead Paint in CLADDINGS above
ROOFS AND PARAPET WALLS
Low-pitched roofs with inadequate drainage
A major challenge with Art Deco era homes is the typically low sloping or nearly flat roofs hidden behind the parapet walls around the front and sides of the house
The original roof claddings included:
· Corrugated iron with lead-head nails
· On flat or very low-pitched roofs – waterproof membrane laid over timber boards / sarking
· Flat sheet metal roofing (copper or zinc) with welded joints laid over timber boards
·Bitumen-impregnated roofing felt laid over timber boards
However by now your Art Deco roof will likely have been replaced with new iron or steel, or new waterproof membrane for flat of very low-pitched structures
Check your roof for any issues with water drainage or ponding (historical or more recent) and any signs of water penetration, rot or deterioration of the roof structures and linings – replace timbers and linings as necessary
Replace with new long run roofing or membrane
No roofing underlay
Tiles that are damaged or cracked are a major vulnerability for weathertightness
Check tiles carefully and replace damaged areas or if your budget allows, replace the whole roof
No roofing underlay
Original 1930s homes would likely not have had a roofing underlay, although some which have had previous renovations may have had an earlier form of underlay put in – however this may not still be in good condition
Roofing underlay is now required under the Building Code E2 External moisture (with a few exceptions):
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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
No insulation or inadequate retrofitted insulation
Many Art Deco homes will have had some insulation installed from the 1970s onwards, but by now this will likely be inadequate for today’s energy efficiency standards
Check any previous retrofitted insulation – replace with new properly efficient insulation
Make sure that the insulation is far enough away from the roofing structure to avoid condensation – this may be a challenge with low-pitched or flat roofs and may require lowering the internal ceilings
Install effective moisture proofing layers to protect the insulation from damage
Lack of weathertightness from inadequate or failed flashings around parapet walls or capping flashings over the parapet
The line where the roof meets the parapet walls is a key area of vulnerability in 1930s Art Deco homes
Check the flashings for any corrosion or deterioration and replace
Check the walls and internal structures below any problem areas for rot or water damage – water may have travelled through to other areas, finding the lowest point and creating problems in different areas from the original point of ingress
Flat or skillion roof on side add-on or rear lean-to areas
Some Art Deco homes have small side wings with a lower flat roof, or a lean-to structure at the rear (perhaps a later addition)
As with the join to the parapet wall, these are areas for careful attention – check for any leaks and water damage
Replace flashings and seals
Shallow “butterfly” roof structure with central gutter
These were fairly common to drain water to a central gutter down to the rear of the house – they can be a major point of weakness and water ingress to the roof space with potential rot of timbers and damage to ceilings and internal structures
Often gutters were “hidden” inside the roof structure and may not be immediately obvious until there is a leak
Redesign your new roof to get rid of any hidden gutters
Asbestos – may be present in roof linings
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
Asphalt applied to roof outlets, junctions and penetrations / pipes through the roof
Original 1930s roofs may have been given weather protection with asphaltRemove carefully using proper protective equipment (gloves, mask)
Check with your local council for disposal options – some asphalt can be recycled
Inadequate ventilation or moisture control in ceiling space
Many 1930s roof spaces, being very shallow due to the low pitch, had poor or no ventilation
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:
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This can result in condensation and mould across ceilings and walls inside the homeKey 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, which may be complicated with the typical lack of roof space, or other practical steps like ducted extractor fans in kitchens and bathrooms
VENTILATION
No ventilation system
The only ventilation in the original 1930s Art Deco homes 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 Art Deco 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
There can be challenges because of the typical low-pitched roof systems and lack of roof space to install a ventilation system – options include creating internal service cavities or ducts with panels or boxing, or installing the ventilation system from beneath the floor if there is adequate access
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:
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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
Building Consents
Structural building – additions, alterations, re-piling and foundation work, and some demolitions
Complete or substantial replacement of a specified system
Replacing exterior wall cladding that has failed within 15 years of installation resulting in damage to the wall framing
Demolition of an internal masonry chimney that is load-bearing (supporting roof rafters and ceiling joists)
Plumbing and drainage where an additional sanitary fixture is created
Installing a woodburner or air-conditioning system
Decks more than 1.5 metres above ground level
Consent Exemptions
General repair, maintenance and replacement of a component or assembly of the building using a comparable component or assembly in the same position – UNLESS it has failed to comply with the Building Code requirements for durability such as external moisture problems with wall claddings
Replacing metal roof cladding (IF it has lasted more than 15 years to meet Building Code durability requirements)
Replacing an old clay tile roof with a metal roof in the same position
Replacing old rotten wooden piles with new treated timber piles in the same positions, UNLESS the work is a complete or substantial replacement
Replacing doors and windows with new aluminium doors and windows in the same position
Repair or replacement of damaged masonry veneer wall cladding
Removal of a building element from a building that is not more than 3 storeys, PROVIDED THAT the removal does not affect the primary structure of the building, any specified system, or any fire separation:
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Removing a brick chimney on an external wall
Primary structure: walls, foundations, floors and roofs
Weathertightness
Fire safety systems
Full contact details
Address or location description of the site
Expected start and completion dates, and how possible delays will be dealt with
Contract prices and the payment process
Description of the building work including materials and products to be used (if known)
Which party is responsible for obtaining building consents and other approvals required
Who will be carrying out and/or supervising the workRemoving a brick chimney on an external wall
How defects will be remedied
How variations will be agreed before work continues
Dispute resolution process
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