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Paper presented at ISBP 2015, Porto, Portugal, 24-27 March 2015

Pathology symposium portugal

Finding Faults in Residential Buildings

Buildsure is a private company which has provided house inspection services since 2004. Some 700 inspections have been completed, the majority for a pre-sale house condition assessment. This results in a detailed report and a "House Warrant of Fitness". The inspection takes approximately 4 hours and involves a detailed inspection of the building and site, including assessing the condition of habitable rooms, plumbing services, heating and cooking utilities, electrical, internal stairs and doors, moisture readings at selected openings, roof space, foundations & subfloor, exterior of property including windows, doors and stairs, storm-water and other external services, roofing, decks or balconies, garage and any other external out buildings.

A simple random sample of 70 reports was taken and each abstracted into a spreadsheet for detailed analysis. The large majority of houses had timber framing with different claddings. 46% of the houses had only suspended floors, 30% only slab-on-grade and the rest both floor types. Just one fifth (21%) of the houses could be considered to be in excellent condition. Given that when a house is being sold, the seller wishes to present it in the most positive light, this would suggest there is a very large, currently un-met, need for house maintenance work. Three common issues have been identified: asbestos, moisture levels and sub-floor ventilation 36% of the inspected houses had indications of asbestos cladding. It is most likely that the house occupants had little or no idea of the potentially hazardous cladding, and would be likely if undertaking their own maintenance to expose themselves to an unnecessary hazard.

65% of the inspected houses had mean timber moisture levels of 13% or below. A moisture reading of 14% is considered the point at which "borderline" risk presents itself. The mean disguises a wide spread of moisture levels. In 88% of the houses the level was so high (>13%) in one or more locations as to give concern. 56% of the houses had no locations with a moisture level above 18% but in 3% of the houses there were 7 or more locations with moisture levels above 18%. The majority of these cases are a direct result of poor maintenance by the owner or the owner's agents. There was no obvious relationship between house age and higher levels of moisture - high levels could be found in very new or very old houses.

New Zealand does not have tradition of basements - houses are built over the ground, raised on piles or foundation walls. 53% of the sub-floor pile moisture measurements were in the 16% to over 22% range. Even given that the timber piles are treated with a suitable preservative to withstand long term ground contact, this is a high, and ultimately unacceptable, level of moisture.

The identification of problems is a first step to their resolution. Future analysis of this database, along with other research exploring the condition of New Zealand houses, will help to led not only to improved durability of the houses but also create an improved environment for living.

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