Weathertightness Overview (Durability) (Moisture-Treatment-Invasive-Testing) on BNet

Weathertightness Overview (Durability) (Moisture-Treatment-Invasive-Testing)Moisture

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3 Birkhall Grove Strathmore Folder

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Weathertightness details:

Window sill: The windows are recessed with the window flange set back from the line of the cladding. This means their must be a flashing of some kind to deflect rainwater back over the cladding. The image gives the appearance of Insulclad detailing which have pvc jamb and sill flashing embedded into the plaster. These systems have systemic defects at the corners and separation of plaster which allows water in and wets the framing. Invasive test bottom plates to at least a selection of East and North facing walls. window sill

Kick out flashings: The apron flashings must have kick outs to deflect rainwater out past the cladding and into gutters. These are often missing or poorly constructed. They may have been recently installed. In this wall there is what appears an 'overtexture' above the apron which is one way of upgrading the kick outs. However invasive testing is required below these to ensure the repairs included replacing decayed timber or if not yet upgraded to ensure the wall framing has not been damaged. kick out flashings

Ground clearance of cladding: The cladding must overlap the concrete slab and must be clear of the ground to prevent wicking of water up the cladding and wetting the framing. Conduct invasive tests in selected test locations to ensure the bottom plates are not already damaged.

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Pagoda connection: Pagoda as illustrated show beams penetrating the cladding. These allow rainwater to penetrate and wet framing. In some case sealants have been used to stop water penetrating - this is ineffective or at best have short durability. Invasive tests are required to bottom plates and possibly studs further up.

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Stringer connection: Horizontal joist mounted on the cladding surface normally have screws, bolts or nails to secure it to the house framing. These require full flashings back to the framing and a gap to allow drying behind the stringer. The failure is wetting of the framing which leads to decay. Invasive test at least bottom plates either side of windows and doors. If systemic invasive test further locations. Generally need removal and rebuilding.

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Window sill: Recessed windows rely on sill flashings to prevent water entry. This detail mimics the Insulclad recessed window system. Check what cladding it is. If it is confirmed to be Insulclad it is likely the pvc separates at the jamb/sill connection allowing water in wetting framing and decay. Sometimes attempts have been made to repair small shrinkage cracks but these are always unsuccessful. Invasive test framing bottom plates to East and North walls as a start. See window sill

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Windows with curved heads: These have - or should have - curved window head flashings. The ends must be turned up like kick out flashings to divert rainwater out over the cladding. These were never done correctly which allows rain water in behind the cladding wetting framing and causing decay. Historical attempts using sealants may be found. Always invasive test bottom plates directly below. To define the full extent of decay invasive test studs and sill trimmer.

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Penetration: Beams penetrating the cladding allow rainwater entry. Invasive test bottom plates at key points below - corners, beside doors and under windows.

Saddle: balustrade joints to claddings need saddle flashings to prevent water entry. Often these rely on paints. Invasive test bottom plates below and opposite these connections. NB: also check for top mounted stanchions and sloping plaster tops to allow drainage.

Clearance: Step butting over cladding can cause drying issues. Invasive test bottom plates at step ends.

Weathertightness Overview
Posted 25 July 2023
Prepared from public images for this house. The following images represent visual weathertightness details that require invasive testing. Refer to Residential Property Inspection New Zealand Standard 4306:2005 section 4 Special Purpose reports - Weathertightness. Although the standard is silent on how to conduct weathertightness testing the following information provides guidelines for important inclusions to a formal weathertightness inspection.
Our records show this home has not been invasively tested so the risk to a purchaser is very high. Without invasive testing it’s a guess as to whether the framing is treated, whether it leaks and whether the framing remains in good condition. There is no warranty to pass on. There is no cavity. The cladding manufacturer has distanced themselves from liability. So too has Council. The home was built during the leaky home era. A high level of proof will be required to support a loan and a reasonable sale price.

Framing protection.
The era of construction (1990's) indicates the framing is likely to be treated to H1 which has little protection against decay should it get intermittently wet. IMPORTANT NOTICE AND WARNING. Invasive test below high risk weathertightness details as they could have been leaking for some time which would have wet the framing and caused decay which may need replacing.
Timber condition.
The house is now over 10 years old and was built during an era framing was inadequately treated against decay (and insects). The consequence of this could be framing that is already damaged hidden behind the walls. Invasive testing is required. NB: Gib linings or claddings can be removed but these are more costly to make good.
Cavity system.
The images show and the era of construction normally omitted 'adequate ventilation' within the wall design. The consequence is delayed drying and no immediate drainage should the cladding have faults. This exacerbates framing damage, insulation loss and mould.
Weathertightness testing.
The era of construction allowed cladding systems to be installed without weathertightness verification testing. The cladding systems have been subject to significant rainfall over its life so testing (moisture probes) is a minimum requirement for owners to be confident on the weathertightness performance of the building
Inspection required.
Our weathertightness overview can be verified on site by trained inspectors familiar with weathertightness inspections. For sale images are often directed to the internal features of homes not the weathertightness defences that protect the structure from damage. On site inspections are required to examine not just the framing but other products.
Invasive Testing.
Is conducted by a professional proficient in weathertightness assessment and possess basic building knowledge. See invasive test
A useful tool for owners is to have the invasive testing completed with permanent moisture probes. These can be repeatedly reused to check moisture contents as the building continues to age and to act as an early detection system to find leaks before damage occurs. Keeping a record of moisture contents provides evidence to purchasers when selling see moisture probes
For more information about moisture probes read about moisture probes
The reclad question.
The decision whether this building needs a reclad or any other remediation system depends on the invasive test results. BRANZ/DBH produced a 2010 remediation guide table (unprinted) which provides a useful guide to the level of remediation required depending on the findings from invasive testing of timber framing treatment level, cavities, systemic nature of leakage and damage together with overall weathertightness complexity. To follow this remediation protocol conduct a thorough invasive test of the external walls of the house then apply the findings to the guide table.
What are the 4 D's.
The basic principles behind good weathertightness design are - Durability of the framing and cladding materials, Deflection of rainwater like flashings and depth of eaves, plus Drainage and Drying being the mechanisms to allow water that breaches the cladding systems to escape before damage exists. These have been branded as the 4 D's. They are exact copies of earlier building designs called 'belts and braces' of the earlier era of construction - pre 1980's - well treated framing, adequate ventilation and flashings. It is noted Detection is the way to test the 4 D's see about moisture probes
Future maintenance.
Following the site inspection and results of the invasive test a formal maintenance plan can be prepared. It is noted that repainting and cleaning are part of 'normal maintenance'. To have confidence that these are protecting the walls and keeping them dry requires moisture probes. Regular moisture readings alerts owners to issues as they develop so maintenance can be more responsive to protect the building from damage.
Disclaimer.
This weathertightness overview was conducted by an experienced weathertightness expert based on public available images only. It is essential that a similar professional conduct an onsite review to fully examine the cladding systems, conduct invasive tests collecting adequate samples for treatment testing, decay analysis and moisture contents that fairly represent the condition of the building, or those parts of the building selected to be examined.
Common issues found in this era building include:
Undertreated timber framing susceptible to decay
No cavity for drainage and drying
Defective Insulclad type PVC window sill flashings
Cladding clearance to ground line insufficient to stop wicking
Penetrations that are not flanged
Stringers that are face fixed to the cladding
These require invasive testing.
What’s the big deal with invasive testing: You may be the purchaser looking for a deal or to protect yourself against buying a lemon. You may be the vendor trying to get more than land value but have no proof of your homes condition to dispel the stigma.

As owner you may be of the firm belief your home does not leak and is worth a lot more than nothing. Why should you sell for about land value? That’s like giving it away. You may be right but how do you get that across to the purchaser?
You’ve been convinced by marketing people to put your home up on Google with professionally well-lit gorgeous images. You may have spent a pretty penny upgrading the bathrooms and kitchen, carpets and repainted the whole home inside and out to make it as perfect as can be. This may have worked during FOMO but those days are long gone. Prudent inspectors become very suspicious when things look too perfect.
Whichever side you’re on there is no denying the Bank and the purchasers lawyer want a report. What they have learnt is the house is more than what the eyes can see. The interior and exterior may look like a dream come true but what is it that lurks behind the paint?
An astute purchaser will want to protect themselves by asking for invasive tests. You may think they aren’t needed. You didn’t get them when you purchased so why should the next owner be bothered? Why you didn’t get invasive testing is a question you need to ask your inspector when you purchased. Maybe you should have.
If they purchase, they’ll become the owner, for a while, and then in time one day will become the seller, and just like you will need to convince the next purchaser. How will that go down?
You have probably owned your home for some time. Weathertightness details age which you don’t see and that may not be good for the framing inside the walls. The cladding system on your house is no longer supported by the manufacturer’s for very good reason. Neither is the framing inside the walls. Neither is the fact it has no cavity. There are very good reasons Councils liability ends after 10 years. Even then they’ve had tens of thousands of claims. After that it’s yours warts and all.
Maybe you can afford to let some leads pass you by. Maybe it’s better to be pre-emptive and do the invasive testing first, get the facts so the purchaser can convince the Bank and lawyer and stay engaged.
It’s a free market so it’s your call, be it seller or purchaser.
Without invasive testing how are you going to convince the purchaser it’s a good deal? And how will the purchaser convince the Bank and lawyer?

More about Maintenance
Owners duties are to comply with the purpose of Building Act and to satisfy themselves that their security remains in good condition - to sell, or to use as collateral or income generation. It is useful to adopt a LTMP.

Long Term Management Plan
The Long Term Management Plan is starting well after construction and will require dealing with historical issues identified during the recent probe install about moisture probes. Homes may have had multiple owners and as such the current owners have inherited ‘the effects of previous building policy and owners maintenance actions’. The owners are now taking steps to maintain or repair historical issues and move forward within reasonable capital cost considerations. There is no requirement to bring the home up to new standards, only ensure it remains safe and healthy places to occupy and live in.

It is expected that at some time in the future land values, land utilization, existing building use currently held by owners will be reviewed meaning the site/building will likely be altered or redeveloped to accommodate higher density, or other living to make better utilisation of the asset.

The intent therefore is for the current owner to manage the home as economically as practical within the policies below to meet their needs. Owners remain at liberty to do more if they wish.

The owner(s) are required to ensure standards of building conditions are maintained refer to purposes and principles s3 of the Building Act 2004:purpose of Building Act. If the purposes are to rent the building it may need upgrading to meet Healthy Home Standards.

The policies to enable this are:

Timber framing: Almost all homes constructed between 1992 and 2005 were constructed with external framing that decays if it gets wet. Homes prior to 1992 back to the late 1950's generally have treatment levels to provide reasonable durability against decay and insects - but for limited duration. Homes built more recently (since about 2005) have moderate treatment only which is likely to slow decay for 5-10 years. This means most timber framed homes in New Zealand are at risk from undetected leaks so need a management plan where framing is found to be decayed or susceptible to decay:
The extent of decay will be investigated and

Where the decay has caused loss of strength and structural integrity it will be replaced or redesigned
Where the decay is minor and not caused structural issues RotStop will be injected to kill the decay
Any areas of decay will be identified on the house plans and become part of the discovery process should owners sell or prepare valuations.

Moisture Contents: All homes constructed between 1950's and 2005 had untested weathertightness details including windows, penetrations and flashings. These details have the potential to leak at any time whether from poor installation or design, excessively heavy rainfall or as building details age and wear. To manage moisture and prevent damage to the timber frame and other elements:

The moisture probes about moisture probes will be read periodically normally during winter including visual inspections of the claddings and
Where leaks are causing or likely to cause damage to framing the areas will be injected with RotStop to slow the decay process and the leaks maintained and
Where maintenance cannot prevent leaking the area will be classified as an ‘Area of Concern’ requiring Building Work and a plan for corrective measures be implemented and
If a “safe and Sanitary” notice is received it will be dealt with in an expeditious manner.

Maintenance is defined as any works required to return or recover performance or/and provide similar durability whether on a ‘like for like’ basis or as ‘like as can be like’ provided the intent is to provide similar service.

Building Work is defined as major building work that substantially changes the existing building often outside the exemptions of maintenance work and generally requires a building consent - but not always.

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