A house roof is a fairly complicated structure made up of joist, battens, trusses and the roof cover such as corrugated sheet metal. Aside from the structural components, it is fitted with insulation and roof sarking.
What is Roof Sarking?
Roof sarking is an thin insulating membrane that helps protect the roof space from water and dust. It is fitted under the battens and made from a variety of materials such as felt, foil, or polystyrene. In Australia, foil is the most common product used for sarking.
Aside from providing insulation and leakage protection, sarking also serves a number of practical purposes:
During heavy rains, sarking can act as a means to channel moisture into the gutters, therefore protecting the home from water damage.
- In places prone to bushfire, the sarking also helps protect the roof space from embers.
- It can help make the home more energy efficient. Because it can trap heat during winter and keep it at bay during summer, sarking can reduce the energy needed to keep the home at desirable temperatures.
Is Roof Sarking Mandatory?
Because of its benefits, roof sarking is definitely recommended. However, it only becomes mandatory in certain circumstances. Such situations are defined in the Building Code of Australia (BCA).
- Tiled residential roofs, regardless of pitch with rafters longer than 6 meter.
- Tiled roofs with a pitch of less than 20 degrees and rafters longer than 4.5 meters.
- Those homes that, under the Bushfire attack Level assessment, need to comply with a BAL-12.5 to BAL-40 classification (the sarking needs to have a flammability rating of not more than 5).
- Those in the Flame Zone areas.
Since sarking acts as a general defense against the elements, various other factors such as the terrain, climate, wind speed, and proximity to bodies of water or other places that tend to use sprinklers (farm lands, parklands, golf courses). Those closer to airports or major highways are also advised to have sarking installed to prevent dust from entering the residence.
How to Install roof Sarking in Existing Roof
Sarking should be installed by a professional tradesperson. Sarking is almost always installed when a new roof is being put on a new house. It is not very common to retrofit. it is placed underneath the roof battens.
However, you can always retrofit your roof in order to install sarking. You can also replace old ones that have been worn out. And if you’d like to do it DIY-style, here are the steps.
The first would be to identify the area you want the sarking in, and how big a surface you need to cover. Know the dimension of your roof, and contact a sarking supplier who will tell you how many sarking sheets you need to buy. Then, proceed with the following:
- Unfasten all the roof clips that hold the roof tiles down. To do this, you will have to remove the capping on the ridges first. Note if any of the clips are damaged, so you can replace them later.
- Dismantle the battens. This will give you space to lay the sarking on.
- Now you can lay the sarking sheets. If you’re just changing them, remove the old ones first. Be careful and make sure you don’t leave any gaps when laying the sarking down. You can fix them in place using a nail gun or a staple.
- Put the battens and the roof tiles back on. Place the ridge cappings back in place, and make sure they are properly aligned.
If you have a metal roof, you can also do these steps by removing the metal sheets instead of roof tiles. And make sure to wear safety equipment such as a hard hat, goggles, a harness, and non-slip footwear! It is also best to have someone assist you if you’re working on retrofitting.