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Getting Weather Tight

Given half a chance, water will find its way into your rental. Vicki Holder explores ways of preventing leaks, rot and damp – and when it’s simply time for a reclad.

By: Vicki Holder

1 March 2016

Keeping your tenants' home weathertight is not only desirable to avoid ongoing health problems but it is also part of your duty as a landlord. Since 2004, the Building Code sets out objectives on how all new buildings or renovations must perform to “Safeguard people from illness or injury, which could result from external moisture entering the building”. That is, dwellings must be weathertight.

Additionally, if a landlord doesn’t meet their responsibilities for providing a safe and healthy weatherproof home, a tenant can obtain a work order from the Tenancy Tribunal to have the issue remedied.

Weathertightness describes the resistance of a building to the weather. It is not necessarily waterproofing, but rather ensuring against undue dampness inside buildings and damage to building elements as a result of moisture.

Reconstruct, Reclad

As Jeff Wicks of NZ House Check says, houses are simply not waterproof. But you can make them weatherproof by ensuring water is deflected. Sometimes landlords can ensure this by remedying small issues without employing a professional. But if it’s a classic leaky house (see below) the only way to repair it is to reconstruct and reclad. This must be done or supervised by a licensed building practitioner.

Buildings affected by the leaky building crisis have the additional issue of a design flaw which means there is no ventilation between cladding and structural elements. Other styles leak, but they are also ventilated. Any moisture entering the cladding system more easily dries out. Landlords with leaks in rental dwellings built outside the leaky homes era are generally looking at simpler, more localised solutions to watertightness.

Common Problems To Look For:

Leaking around flashings: A flashing is a thin piece of metal installed around protrusions on roofs, around windows, doors and chimneys to deflect water from seeping into seams (and into the building) and damaging the cladding. They typically occur at junctions where building materials meet.

It can be quite difficult to detect if flashings are installed incorrectly, says builder Brian Day. If they’re not, water will seep in. “Get them checked by a professional. If the paint is flaky, they may just need a coat of paint."
In older homes, flashings are often missing above window frames or doorways. “There should always be a professionally fitted window flashing up behind the weatherboards and down over the facing of the window. If unsure, get a qualified person – a builder or house inspector – to check all flashings, gutters and ventilation.
“Some basic leaks found on houses with wooden joinery are around windows and doors, primarily caused by paint breaking down over the putty. Water gets into the putty and leaks under the glass and starts rotting under the window pane.” Day advises: “Landlords can fix this themselves. Clean out the old putty. Prime any bare timber in the rebates. Re-putty and repaint after the putty has skinned off."
Wicks says a head flashing above the window should be obvious. “If it doesn’t have one, unless it’s extremely close to the eaves, there’s a high chance the window will leak.
“A lot of weatherboard houses built in the 1980s and 1990s didn’t have scribers – a vertical timber board that runs along the side of the window and fits tightly into the cladding. That caused a problem. A scriber can be easily fitted by someone with basic handyman skills. Check Google or Youtube for instructions
. “Up until 2004, sill flashings weren’t provided. Sometimes this made windows leak. If you have a window with no flashings, it has to come out to install a new flashing. Anyone with basic skills can do this but most landlords will want to pay someone.
“The biggest indicator is dampness on Gib board linings or mildew or dampness on the carpet.

Internal, External Guttering Leak

Forensic engineer Craig Turner, of Forensic Building Consultants, says when you notice a leak from external spouting, guttering or roofing, it normally just needs clearing, fixing and regular maintenance. You might see water stains down the face of the guttering or weeds growing in your gutters.

Day explains gutters collect dirt and grime, leaves and rubbish – particularly if trees overhang, which eventually creates a problem. Water runs back inside the house through the soffit. Tenants notice water running down the wallpaper. “I’m as guilty as any other landlord of this. So I cleared the guttering and it fixed the leak. It was due to a lack of maintenance.”
If gutters have cracked or are rusted through, landlords need to replace them. When replacing, remember guttering needs ‘fall’ for water to drain. Don’t install them level.
“Internal or concealed proprietary fascia gutter systems integral to the soffit can become blocked so water runs back into the building through the eave, Wicks says.
For evidence of internal or concealed guttering, look for mildew on the walls starting just below the ceiling. “That sort of fault will often go unnoticed until it’s quite bad,” he says.
Is there an easy fix? No, Wicks says. “Nine times out of 10, it’s due to corrosion when the guttering is perforated. To fix it properly you have to redo it. It’s only guaranteed for 15 years.” He advises help from a licensed builder.


It’s important to have airflow below a building to reduce cold damp air being uplifted, which ends up in a home’s living space. Houses with masonry perimeter foundations tend to lack ventilation. Or homes where fibrolite or cement fibre have been used as a sub-floor cladding. “You need a good amount of ventilation around the sub-floor so air can flow from all four sides. Sometimes you don’t get that. If it’s vented on one side, it won’t vent well. I often see fungus growth on the ground here. Or particle board flooring becomes damp and fungus grows on the underside,” Turner says.

“If you’re looking at buying a house, it’s got to have cross-ventilation east west or north south. Cut holes in the foundations. Sometimes it’s blocked by a hillside or other structures. Ventilate as best you can. If you have damp ground underneath, it’s a good idea to put a vapour barrier on the ground. Lay a heavy duty plastic sheet under the house weighted with a few bricks and tape up the perforations. If three sides are without ventilation, have the fourth side as open as you can to compensate.”

Plaster Homes

Between the mid-1990s and around 2004, thousands of houses were built in Mediterranean style using cladding systems such as fibre cement sheet and externally insulated plaster system (EIPS), which relies on paint to protect against water ingress. Because there is no drainage and ventilation between the cladding and the framework, water becomes trapped, seeps into the framing, and greatly increases the potential for fungal growth and rot.

In addition, in 1998, the Building Industry Authority (BIA) approved the use of untreated, kiln-dried timber, which compounded the problem. Rot developed even more freely in buildings with inherent design and construction problems.

Many homes of that era still leak and are rotting over time. Eventually they must be rebuilt and reclad.

Builder Craig Shorrock, of Reliant Reclads, says: “It’s only a matter of time before they’ll fail. The longer it’s left, the more deterioration of the framing, which becomes costly.
“If you do a repair job,” Shorrock says, “you need a building consent. It’s very hard to get one for target repairs. And if you do repairs without consent and sell a place, people can sue. Target repairs are like putting band-aids on problems.”

Turner agrees. “The problem doesn’t go away – it’s huge. We have hundreds of thousands of homes that won’t make it past 30 years. The biggest problem is denial. It’s understandable because it involves such huge disruption to people’s lives and creates phenomenal stress.”

But investor Graeme Fowler saw an upside to a dwelling with sub-standard cladding. In November 2014, he bought a house in Flaxmere, Hastings, which had a weatherside exterior. It had deteriorated because the paint had chipped and was causing condensation issues inside. The cladding was fashionable in the 1970s but has been withdrawn from the market and replaced with a superior product. “It turns to Weetbix when it gets wet. So I bought the home to renovate for $88,000 and budgeted $25,000 for the renovation. I spent $12,000 to reclad in a weatherboard type product and painted inside so all up it cost just $18,000 to renovate. The house is now valued at around $175,000 and it’s renting for $310 a week.”

But unfortunately, visual evidence of deterioration in leaky homes may not always be obvious. Some industry professionals use non-invasive moisture metering equipment including infra-red cameras. Forensic Building Consultants look inside cavities with a laparoscope. A spore count can also be done with specialist equipment.

The thing many people lose sight of is that leaky homes are unhealthy. “I haven’t repaired a building where at least one member of the family has not been affected health-wise,” Turner says.

Indications Of Moisture Problems Include:
➜ Cracks to cladding.
➜ Visual signs of sheet joints.
➜ Distortions in sheet joints.
➜ Change in colour of sheets, particularly in the morning.
➜ Swelling of skirting above Gib.
➜ Cracks in the plaster – it may indicate water ingress.
➜ Swelling of fixings.
➜ Smell in the room like a rotting forest.
➜ Problems removing mildew behind curtains and walls, particularly on the northern aspect.
➜ When tenants have trouble heating a house because of moisture in the walls.
➜ Ants, slaters, or borer.
➜ Water dripping from soffits or behind the bottom of wall claddings long after the rain has stopped.
➜ Chronic coughs, colds, sore throats, skin rashes.

The Reclad Process

When a dwelling has been identified as leaky, a reclad is sometimes the only way to remedy the issue.

Dave Hopkinson from Nu-Wall Aluminium Cladding says it's difficult to estimate the cost of a re-clad because once the original cladding has been removed, the extent of the damage to the structural framing can vary greatly.

Typically the tenant must vacate, but Hopkinson says he has seen cases where
the structural damage is minimal and tenants have stayed living under the shrink-wrapped building.

"Conversely, when you see a lot of exterior framing having to be replaced, in these cases it's unlikely that people will stay living there."

Hopkinson says it's difficult to give a standard price for the re-clad of a typical three-bedroom standalone dwelling, because of the variable extent of water ingress.

"The cladding maybe $20,000 for the material and the installation labour might
be 50-70% again of that cost."

Re-clad materials vary greatly and it's important to consider the long term maintenance cost of the replacement cladding. The re-cladding process requires a building consent and reclad products
must have a BRANZ appraisal.

Hopkinson says some landlords who own a dwelling which isn't leaking but has cladding associated with leaky buildings want to over-clad (install new cladding over existing cladding). But he warns this may make it difficult to inspect any potential leaks in the future, as well as unnecessarily raising a red-flag to potential buyers.

As well, over-cladding will not result in a code of compliance being issued, as recladding does.

"A current code of compliance is like gold in terms of its value," says Hopkinson.

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