Assessment of Boracol 200RH (FrameSaver) as a remedial treatment to control decay in pre-decayed model timber frame units

IRG/WP 10-30529

Mick Hedley, Dave Page, Jackie van der Waals

Model timber frame units constructed from untreated radiata pine were pre-wetted to approximately 40% moisture content and inoculated with Coniophora puteana and Oligoporus placenta. Units were transferred to a controlled environment room maintained at 25°C and 95% RH for 7 and 10 weeks to allow two levels of decay to become established in units. Following pre-decay, units were disassembled, cleaned of adherent mycelium and superficially dried. They then received either one brush coat of Boracol 200RH (7 weeks pre-decay) or 2 brush coats (10 weeks pre-decay) and were re-inoculated with the same decay fungi. Units were periodically assessed for decay and at 239 or 255 weeks exposure, representative units were dissected and assessed for internal decay. Samples were spot tested for the presence of boron and cross-sections and cores analysed for boron. There was very little, if any, progression of internal decay following application of Boracol to frames with either 7 week or 10 week pre-decay periods. Spot tests indicated that boron had diffused through the cross-section of all unit components. This was confirmed by preservative analyses. Residual boron core retention levels in most components exceeded the toxic threshold for boric acid, which presumably accounts for lack of spread of decay following Boracol 200RH application.


Keywords: Radiata pine, framing, decay, remedial treatment, boron

Conference: 10-05-09/13 Biarritz, France


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