Remedial treatment of difficult to access timber in buildings

IRG/WP 15-40691

T Singh, I Simpson, D Page

The quest to understand remedial treatment for timber framing begun following the ‘leaky building crisis’ in New Zealand which came to prominence in 2000. Several in-situ remedial treatment products are used in New Zealand. However, effectiveness of these treatments is still unclear particularly in situations where not all faces of the timber can be assessed. This research was conducted to determine that in comparison to ‘double coat brush-on’ a system using ‘double coat brush-on plus injection treatment between studs’ (vertical members) would give more complete surface coverage and better retentions of a commonly used remedial treatment chemical, boron. This system was also applied on horizontal members using double lintels of various widths and treated with boron glycol by applying ‘double coat on exposed surfaces and injected’ on concealed faces using injection holes in one lintel member. Results showed that in the ‘double coat brush-on’ process, the concealed surfaces were left largely untreated resulting in variable preservative retention between components and relatively low overall preservative retention in the multiple stud units. However, the ‘brush-on plus injection treatment’ application gave much better preservative spread onto concealed surfaces of both vertical and horizontal members. Most samples tested achieved average cross-section boron retention levels of 0.4% BAE m/m (H1.2 treatment specification), although the treatment was concentrated in the outer 30% of the timber, hence not achieving the required full sapwood penetration. Because of the variability associated with the boron injection process, it is recommended that this remediation method should only be used where there is a high degree of confidence that there is no decay present between studs or lintel members. All attempts should be taken to remove any decaying timber while repairing leaky buildings.


Keywords: boron, framing timber, leaky buildings, Radiata pine, wood biodeterioration

Conference: 15-05-10/14 Vina del Mar, Chile


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