Perth doesn’t often face destructive weather but in recent years when wind and rain has been severe the shortcomings have been extremely apparent. The big storm of March 2010 caused widespread flooding. Many homes were damaged not only by the impact of hail but because gutters in homes could not cope with the volume of water. The vulnerability of many roof structures have also been exposed in recent storms. The image below is from a group of apartments in Scarborough where the roof was peeled off due to insufficient tie down.
On all roofs that Homes by Dalessio constructs we exceed minimum tie down specifications. These specifications include the following:
- Roof batten fixings – these battens are fixed to rafters when the roof has been specified as tin. The metal roof contractors fix the sheets to these battens. In high winds there can be uplift forces that will try and ‘peel’ the sheets off and I have personally seen roofs that have come off and they are still fixed to the battens but these battens have been pulled off the rafters they are fixed to. It is for this reason that fixing these battens to the rafters using 100mm long screws at every batten and rafter junction is extremely important. Some builders will only fix the first and last rows of battens with all other battens only being nailed on using a nail gun.
- Ridge tie down – metal straps are used over all common rafter locations to hold the ridge beam down
- Underpurlin to rafter connection – cyclone ties are used where these two timber members meet
- Triplegrips – these fixings are used to connect the rafters to the wall plate. Like all the other tie down examples these give additional strength to the roof structure to minimise the chance of a roof ever being damaged due to severe winds.
- Roof batten location – my carpenters will always locate a roof batten directly over the cavity where the tie down strap is located. This allows for a stronger connection than if the batten was located further up or down the roof.
Homes by Dalessio want you to be able to live in your home with the reassurance that these additional construction methods have been employed to minimise the chance of damage due to high winds. These items do add to the cost of a home and it is important if you are comparing quotes from builders to check whether these same methods are being used.