Exterior Wood-Frame Walls—Wind–Vapour Barrier Ratio in Denmark

Wood-frame walls in cold climates are traditional constructed with a vapour barrier that also constitutes the air-tightness layer. Polyethylene foil as a vapour barrier is likely used; however, other building materials can be used to obtain correspondingly sufficient properties. 1D hygrothermal simulations were conducted for a wood-frame structure to investigate the wind–vapour barrier ratio, and if the vapour barrier of polyethylene foil could be omitted and replaced by other materials. The results were postprocessed using the VTT mould model. The results showed how wood-frame walls can be designed with respect to internal humidity class and diffusion resistance divided into three categories: no risk for mould growth, needs further investigation, and is not performing well as the risk for mould growth is present. For internal humidity classes 1–3, the ratio between wind and vapour barrier must be about 1:5, and 1:10 for classes 4 and 5 to be on the safe side. Simulations were performed for the climate of Lund, Sweden, which were used to simulate climate in Denmark too. Nevertheless, the results are related to climate data and, thus, the location.

Performance of Exterior Wood Coatings in Temperate Climates

Wood used in exposed exterior applications degrades and changes color due to weathering. Expanded use of mass timber is resulting in architects increasingly designing structures with wood in exterior exposure. Coatings can reduce the effects of weathering and prolong the visual characteristics of wood. However, coating performance depends on a variety of factors including the blend of resins, oils, pigments, and binders. Coating manufacturers often claim superior performance for products, but data directly comparing different coatings on different species is rarely publicly available. Premature coating failure increases long-term building maintenance expense while potentially enhancing biological degradation and reducing service life. This study compares the performance of 12 exterior wood coatings on 5 wood species. Performance was evaluated according to changes in the components in the International Commission on Illumination (CIE) L*a*b* color space of images taken at 6-month intervals over 18 months of the wood samples. The analysis was performed using Welch’s ANOVA, Games–Howell pairwise comparisons tests, and a clustering procedure using distances between each pair of groups means for the 18 months ΔL*, Δa*, Δb* values. Most of the coatings lost their protective effects within 1 year of exposure due to combinations of biological and ultraviolet radiation (UV) degradation illustrating the difficulty of protecting timber in exterior exposures. This study provides a guide for users wishing to specify coatings for exposed wood in mass timber structures.

Physical, Optical, and Visual Performance of Coated Cross-Laminated Timber during Natural and Artificial Weathering

Cross-laminated timber (CLT) market demand is on the rise in the United States. Adequate protective measures have not been extensively studied. The objective of this study was to investigate the weathering performance of exterior wood coatings. We evaluated coated CLT sample surfaces based on visual appearance, color change (CIE*L*a*b), gloss changes, and water intrusion. From the five exterior wood coatings evaluated, only two showed adequate performance after twelve months field exposure. Based on visual ratings following the ASTM procedures, coating failure occurs more quickly in Mississippi than in Wisconsin, due to its greater decay zone. Both location and coating type impacted the aging of the samples. Artificial weathering results were consistent with natural weathering indicating the two adequate coatings were the most resistant to failure, color, and gloss change. For future studies, new coatings designed for the protection of end-grain in CLT panels should be a target of research and development.

Analysis of a Wide Range of Commercial Exterior Wood Coatings

This study was focused on measuring the properties of twenty-three commercially available coatings formulated for exterior wood applications. The coatings were characterized by measuring their surface tension, solid content, viscosity, pH, and glass transition temperatures (Tg). Additionally, the wetting properties of coating droplets on wood substrates were measured. The contact angle of solvent-based and water-based coatings were characterized on untreated southern yellow pine wood samples using high-resolution image analysis and the Young–Laplace solution. An innovative image processing technique for determining the average diameter of coating droplets on wood was developed, and an iterative method to calculate the average contact angle using the Young–Laplace solution was applied. The water-resistance of the coated wood samples was evaluated during one week of water immersion tests. In general, solvent-based coatings had significantly lower contact angles and water uptake than water-based coatings. Water-based paint samples had the largest average contact angle (81°), and solvent-based transparent penetrating stains had the smallest contact angle (13.9°). A strong correlation was observed between the coating water uptake and their surface tension and solid content.

EFEKTIVITAS KONSENTRASI EKSTRAK BIJI SIRSAK GUNUNG (Annona montana Macf.) TERHADAP MORTALITAS RAYAP TANAH (Coptotermes curvignathus Holmgren., Rhinotermitidae

One of the insects that cause a lot of damage are termites. Forms of damage that can be caused by termites include damage to building components that made of wood and the contents of the building in the form of furniture, books, cloth, and even securities. One example of a termite species that is dangerous as a pest is Coptotermes curvignathus. Mountain soursop seeds have bioactive compounds that are very cytotoxic, so they have potential as insecticides. This research Used a Completely Randomized Design (CRD) consisting of controls and 5 treatments (P1) 20%, (P2) 40%, (P3) 60%, (P4) 80% (P5) 100% mountain soursop seed extract. The parameters observed were retention, termite mortality, and weight reduction in the test sample. Mountain soursop seed extract is effective as an insecticide against subterranean termites. The concentration of mountain soursop seed extract 40% (P2) causes termite mortality of 100% and a decrease in sample weight by 0.43%. Mountain soursop seed extract has the potential to be developed as an anti-termite species Coptotermes curvignathus Holmgren. The retention value produced in the test sample based on SNI 03-5010.1-1999 shows that the mountain soursop seed extract with a concentration of 20% (P1) meets the standard retention of interior wood use, while extracts with a concentration of 40% (P2) meet the standard of retention of exterior wood use.Keywords: Mountain soursop seeds, Retention, mortality, weight decrease, Subterranean TermiteABSTRAKRayap banyak menimbulkan kerugian seperti rusaknya komponen bangunan yang terbuat dari kayu, beserta isi bangunannya seperti furnitur, kertas, bahan kain dan lain-lain. Salah satu contoh spesies rayap yang berbahaya sebagai hama adalah Coptotermes curvignathus. Biji sirsak gunung memiliki senyawa bioaktif bersifat sitotoksik yang sangat kuat, sehingga memiliki potensi sebagai insektisida. Rancangan penelitian menggunakan Rancangan Acak Lengkap (RAL), terdiri dari 6 perlakuan yaitu (P1) 20%, (P2) 40%, (P3) 60%, (P4) 80% (P5) 100% dan kontrol. Parameter yang diamati meliputi retensi, mortalitas rayap, dan penurunan berat sampel. Ekstrak biji sirsak gunung efektif sebagai insektisida terhadap rayap tanah. Konsentrasi ekstrak biji sirsak gunung 40% (P2) menyebabkan mortalitas rayap sebesar 100% dan penurunan berat contoh uji sebesar 0,43%. Ekstrak biji sirsak gunung berpotensi dikembangkan sebagai anti rayap tanah jenis Coptotermes curvignathus Holmgren. Hasil penelitian menunjukkan bahwa ekstrak biji sirsak gunung dengan konsentrasi 20% (P1) memenuhi standar retensi penggunaan kayu interior, sementara ekstrak dengan konsentrasi 40% (P2) memenuhi standar retensi penggunaan kayu eksterior.