It’s Spring! And you know what the means? Summer is just around the corner (even though with the weather lately it seems it’s already here). In this post, we take a closer look at parapets and how, in Brisbane, they are perfect to give modern homes a clean and crisp look (hiding roof planes & gutters from ground level view) whilst protecting them from harsh weather conditions - like summer storms and bushfires.

A structurally sound roof is crucial in storms that gather high winds and hail.

What's a parapet again?

A parapet is an extension of the wall at the edge of a roof, terrace, balcony, walkway or other structure. Parapets were originally used to defend buildings from military attack, but today they are primarily used as guard rails and to prevent the spread of fires (particularly useful for homes near bushfire prone areas).

Fire protection

They are great for fire protection; when the wall is extended above the roof plane, the parapet wall prevents flames coming up the exterior of the building and immediately igniting the roofing membrane.  A parapet can modify the wind flow over the roof so that the pressure on it is more evenly distributed.  This is called wind-uplift resistance.  

Wind-induced roofing failures generally happen when the force of the wind lifts the edge of the roof and then peels back the entire roof system.  The parapet stops the wind from being able to get between the roof and the exterior walls of the home.  Another safety feature of a parapet roof is that it stops objects and debris from being blown onto or falling onto the ground below.

Don’t fly away

What happens when high velocity winds meet low slope roofs? There’s no simple answer and no way to predict exactly which roofs will have the most trouble, however parapets that remain in place in cases of extreme winds were those with conventional built-up or modified bitumen membranes fully adhered to a structural concrete deck. Gravel-surfaced, built-up roofs fare slightly better than those with modified bitumen systems because the gravel that is well embedded in the flood coat can provide protection from flying debris. The weight of the gravel can also help keep the roof down.

Stay dry

Parapets don’t do so well in cold climates because of the risk of  falling ice or snow, but for this very same reason they’re great during storms. With proper reinforcement, waterproof membranes and areas to drain from guttering, water has nowhere to pool. 

In storm season, it’s not only the roof you need to check

The number one item you need to protect a roof against a storm is to be certain that air conditioning unit covers are attached with all the required screws. Most damage to roofs comes from things that are already on the roof. The worst culprits are mechanical units and their screen enclosures. Air conditioning units, ventilator fans, satellite dishes, antennae and the like are all potential debris during a storm.