Charred Timber Cladding: Performance Investigation

Abstract

Shou Sugi ban – or burnt timber cladding – is the Japanese method of charring the surface of timber to improve its durability characteristics and aesthetic appeal. In recent years, the popularity of charred timber cladding has grown steadily in both commercial and domestic construction projects. This rise in popularity has led to questions being asked as to the durability the treatment provides and longevity of the surface finish.

One of the advantages of using a charred finish over other types of surface finish is that the process doesn’t involve any man made chemical compounds. Timber is burnt using either gas fired equipment or a tradition wood fuelled fire.

Until now there has been very little experimental research carried out in this, yet manufacturers of charred timber cladding make seemingly unsubstantiated performance claims. To this end, research has been carried out to ascertain the true properties of charred timber and to test manufacturer’s claims against the
tested performance.

This dissertation explores the findings of a 12 month research project. The testing includes accelerated UV weathering, freeze/thaw cycle testing, long term exposure testing and flame spread testing to ascertain the materials performance.

The primary aim of the research is to gather data that will be analysed with a view to test the claims made by users and manufacturers of charred timber cladding. The research will also aim to inform current teaching at Coventry University.

The main conclusions of the project are that the charring process has a beneficial effect on the durability of the surface finish of the timber, with improved performance in most areas of testing. The area that did not align with the current knowledge was the flame test result, where the charred sample performed significantly worse than the uncharred sample. The medium term exposure results show good durability, but long term durability has not been tested as part of this project.

Date of Award	2017
Original language	English
Awarding Institution	Coventry University
Supervisor	Eshmaiel Ganjian (Supervisor) & Carl Mills (Supervisor)