Design
Design for cladding
Obtaining the best performance from timber cladding depends on good design, proper construction practice and correct installation. Cladding should be considered an integral part of the overall building design as it contributes to aesthetics, comfort and structural performance.
Flashing used with external timber cladding
Flashing is a waterproof layer, used at corners, vertical joints and around openings underneath external cladding
Selection criteria for external cladding
A wide variety of timber external cladding products are available, including solid timber boards in a range of profiles and species, timber shingles or shakes and various types of plywood and exterior grade hardboard in plain or surface textured sheets or planks.
The use of sarking with external timber cladding
Sarking is a liquid proof but vapour permeable flexible sheet material that is fixed directly behind timber cladding or under roofing material. Its primary function in walls is to prevent any water that may have penetrated the cladding from lodging within the framing. It also provides a draught proof barrier to keep wind driven rain or dust out of the wall cavity.
The use of vapour barriers in construction
Whether a separate vapour barrier is required depends on the type of construction, the intended use of the building and the climate of its location.
Wood and its origins
External timber cladding standards
Sawn timber weatherboards are available in a wide range of timber species (imported and local), sizes and profiles. Timber clad walls which will experience moderate to severe weather exposure must use cladding manufactured from the highest available grade of timber.
Moisture content and fixing of external cladding
All timber will take up or lose moisture in response to changes in environmental conditions, and will undergo corresponding dimensional changes.
Sizes and profiles of external timber cladding boards
Timber cladding boards are generally produced in widths between 150 mm and 200 mm. They are available in several different sections.
The storage and handling of external timber cladding.
It is important to keep timber cladding dry and clean from the time it is received on the building site until it is fixed and finished.
Installation
Finishing and Maintenance
Timber cladding can be left in a natural condition, or finished with a preservative, clear, stain or opaque finish.
Recommendations for fastening of external timber cladding
Selection of the correct fixing nails is important to the performance of a finished wall.
Treatment of joints between external cladding boards
Joints between external cladding boards must be carefully designed to avoid ingress of water.
Treatment prior to finishing of external timber cladding.
In general, timber cladding needs treatment prior to finishing.
Rectification
None found
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