Flood zones

Using Spantec building products in a flood zone

The Australian Building Codes Board’s Construction Of Buildings In Flood Hazard Areas information handbook defines “flood” as “the temporary condition of partial or complete inundation of normally dry land”, due to the, “overflow of inland or tidal waters or the rapid accumulation of runoff or surface water from any source”.

When your home is impacted by a flood event, it can result in a significant and unplanned for financial burden. Ideally, buildings are strategically located to avoid flood prone land. However, where that isn’t possible it is essential that your home is designed to ensure that it is structurally compatible with flood water during a 100-year Average Recurrent Interval (ARI) flood event.

When designing and building your home in a flood zone, specific building materials and construction methods that are less prone to water damage should be used. All Spantec products are recommended for flood zones

Essential considerations for building in a flood zone

When renovating or designing a building on flood prone land the following factors must be considered:

Wherever possible buildings should be located on the area of the property that is least affected by flooding.
Ensure that long walls are parallel to the direction of water flow and do not block flows.
Remove any obstructions that prevent water draining from under the building.
Design surrounding garden beds so that they do not restrict drainage.
Maximise flow across your property using flood compatible fences.
Do not build on the water course or overland flow path.

Spantec Solutions

Design factors to protect your home in a flood zone
Preferred construction materials for flood zone sites
The Boxspan floor system, Ezipier and Ezibrace

Design factors such as the location of electrical services, sewerage systems and water tanks need to be carefully considered when designing you home on flood prone land. Follow the below guidance to ensure that you minimise the chance of damage to services in a flood event.

Electrical

Mount fixed electrical equipment as high as possible.
Raise power points on the wall above the flood planning level.
Locate house wiring in the roof space and extend down the wall.
Avoid placing house wiring in the slab or under suspended floors.
Ensure that the installation of conduits allows water to drain freely.

Sewerage systems

Install external components that can resist flow and buoyancy forces.
Provide a gully trap outside the building and low to the ground.
Cover exposed pipes and access cover to tanks and pits.
Install a non-return valve in the service connection pipe.
Locate valves in a small pit outside between the house and the mains sewer.
Ensure the gully trap is well elevated.
Place distribution pipes in areas of low flow velocity.
Ensure quick drainage of a trench system during high water levels.
Remove obstructions that may block a valve.

Water tanks

Locate the inlet to the tank as high as possible.
Elevate above ground water tanks and hot water heater and ensure supporting structures are flood resistant.
Use corrosion resistant materials.
Ensure all designs account for a loss of strength under flood conditions.
Secure and fasten exposed components and pipes.
Ensre tanks are securely fastened to prevent flotation.

	Suitable materials & construction methods	Unsuitable materials & construction methods
Foundations	• Reinforced concrete slab. • Galvanised steel ezipiers & columns. • Masonry piers/columns.	· Timber piers.
Roof	• Timber trusses with galvanised connections. • Reinforced concrete. • Galvanised metal construction.	• Traditional timber roof frame construction. • Inaccessible flat roofs. • Non-galvanised structural steelwork or connections.
Windows	• Aluminium frames with stainless steel or brass rollers. • Timber frame, fully epoxy sealed. before assembly with stainless steel or brass fittings.	• Timber with PVA glues. • Mild steel fittings. • Large windows low to the ground.
Walls	• Reinforced or mass concrete walls. • Cavity brick walls. • Fibre cement sheet. • Face brick or block work. • Cement render. • Ceramic wall tiles. • Galvanised steel frames or sheets. • Glass and glass blocks. • Stone, solid or veneer. • Plastic sheeting or tiles with waterproof adhesive. • Common bricks. • Stolid wood, fully sealed. • Stainless steel frames. • Aluminium frames.	• Timber frames in areas that are subject to force from fast flowing water. • Inaccessible openings. • Brick/block veneer with venting (stud frame). • Particle board. • Fibreboard or strawboard. • Wallpaper. • Cloth wall coverings. • Standard plywood. • Gypsum plaster. • Plasterboard. • Exterior grade plywood. • Solid wood with allowance for swelling. • Hardboard. • Exterior grade particleboard.
Floor	• Steel sub floor (Boxspan or equivalent). • Slab on ground or suspended concrete slab. • Suspended timber floor. • Marine grade plywood.	• Timber floor close to the ground and particle board close to the ground. • Standard grade plywood.
Bolts, nails, hinges and fittings	• Brass, nylon/stainless steel, removeable pin hinges. • Galvanised steel, Aluminium.	• Mild steel.
Doors	• Solid panel with waterproof adhesive. • Flush marine ply with closed cell foam. • Aluminium or galvanised steel frame. • Flush or single panel marine ply with waterproof adhesive. • Timber frame, fully epoxy sealed before assembly.	• Standard timber frame. • Standard flush hollow core with PVA adhesive and honeycomb paper core.
Installation	• Clay/concrete tiles. • Epoxy or cementitious floor toppings on concrete. • Rubber sheets (chemically set adhesives). • Vinyl sheet (chemically set adhesive) • Terrazzo. • Rubber tiles (chemically set adhesives). • Vinyl tiles (chemically set adhesives). • Polished floor and loose rugs. • Ceramic tiles.	• Loose fit nylon or acrylic carpet (closed cell rubber underlay). • Wall to wall carpet. • Wall to wall seagrass matting. • Cork. • Linoleum.

Why Spantec

Steel building products from Spantec will help protect your home in a flood event due to being impervious to water, unlike timber building products. Here are three Spantec products we recommend when building in a flood zone.

The Boxspan Floor System: Perfect for ensuring homes in flood affected areas are built to last, the Boxspan Floor System for elevated sub-floors is one of our core products and where we started as a specialist in floor systems. Not only is the flooring system a solid alternative to a slab on ground, it works economically by supporting anything from a lowset granny flat or kit home up to a highset pole house. The three components that make up our floor system (Boxspan beams, EziPiers and EziBrace) have each been designed to make your building process an easy one. The Boxspan floor frame comes pre-cut as a kit.
Ezipier adjustable steel piers: Our highly versatile Ezipier adjustable steel pier components (heads, bases and accessories) work hand in hand with our Boxspan Floor System. The range of pier heads suit specific bearer arrangements and locations in a floor to make installation as seamless as possible. The result is a pier system that is easy for builders and owner builders to assemble and level.
Ezibrace Sub-floor Bracing: The Ezibrace Sub-floor Bracing system is the final essential component of our Boxspan Floor System. Critically, this unique and simple to use component makes the whole Boxspan system incredibly simple and easy to assemble. You’ll be amazed at how quick and easy it is to erect, position and level your new floor system using Ezibrace.

Flood zone buildings have to be raised off the ground, and with the steel Boxspan Floor System, coupled with our Ezipier and Ezibrace solutions, you will be able to build your home to last in a flood zone. We can design and engineer your floor frame, footings and bracing for your project in house. Contact us today for a quote.