The term “sarking” is used in several different ways in construction. In general, it is a panel which is used as an underlayment, and may be used in the construction of walls, or in the construction of a roof. In walls, people may refer to “scrim and sarking” construction, a technique used in many older homes. People doing refurbishment and repair of such homes may opt to reproduce this building technique to preserve the character of the structure.
On a roof, sarking is used as part of the underlayment or roof membrane. It acts as a barrier to prevent moisture from entering the roof and the home, and also helps to reflect heat. The underlayment will help a home stay cool in the summer and will keep warmth inside during the winter, keeping temperatures stable. It can also help make a roof more wind resistant, which can be valuable in some climates.
Several materials can be used for sarking on a roof. Historically, it was done with boards known as sarking boards which were laid under the tiles, shingles, or other roofing materials used. Modern underlayments may be made from felt or other materials, and it is often laid over a secondary barrier material. It is common for roofs to include several layers of underlayment in their construction, and this may in fact be required by building code in some regions of the world.
In walls, sarking is put up in the form of flat panels which historically were covered in a fabric material known as scrim. Wallpaper, plaster, or other finishes could be applied directly to the scrim and sarking. In restoration of older homes, people may notice scrim and sarking construction once they manage to get through the layers of materials added over the years. For those who would like to restore walls which use this technique, the old scrim can be removed and replaced with new material after any damage to the sarking boards has been repaired.
The type of underlayment material under discussion is usually evident from the context. The term “sarking” is used in several nations to refer to various aspects of construction. If one is not sure about what people are talking about, a quick clarifying question should resolve the issue; many people who work in construction are aware that a variety of terms are sometimes used, and they will be happy to explain.