Ancillary Structures

Ancillary structures are the minor buildings and structures on a site that are not part of the main building: sheds, garages and carports, bin and bike enclosures, pergolas and gazebos, shade sails and canopies over car parks and play areas, flagpoles, signage structures, monuments and memorials, and decorative water features. Individually small, they are numerous, often built without the scrutiny given to the main building, frequently altered or added informally, and sometimes contain the oldest and most hazardous materials on a site.

Because many of these were added after the main building, they may lack approval, engineering or proper foundations. They are usually exposed to weather on all sides, and their structural margins in wind are often smaller than the main building's.

What shortens life:

• Wind: shade sails, signs and flagpoles carry high wind loads relative to their size, and cyclic loading fatigues them.
• Ground contact: timber posts set in soil or concrete rot at the base.
• Vehicle impact on carport and canopy posts.
• Coastal and industrial exposure.
• Informal alterations: added roofs, enclosures and loads.

Wind failure

Shade sails act like sails: they load masts and fixings heavily in storms, and many are designed to be taken down before severe winds but are left up. Masts bend, footings pull out, and fixings to buildings tear out. Freestanding signs and flagpoles fail by fatigue cracking at welds and base plates after years of wind cycling, often without visible warning.

Post base decay

Timber posts embedded in soil or concrete stay wet at the base and rot from inside; the structure then leans or collapses, sometimes onto people. Steel posts corrode at ground level where water and debris collect.

Vehicle impact

Carport and canopy posts in car parks are struck by vehicles; bent or cracked posts and loosened base plates weaken the whole structure.

Asbestos and hazardous materials

Older sheds, garages and outbuildings are often clad or roofed in asbestos cement sheeting, which weathers, cracks and breaks. Damage and removal must be managed under asbestos rules.

Unapproved or unengineered structures

Structures added informally may lack footings, engineering, fire separation from the main building or boundary setbacks. Their condition is often unknown and their compliance doubtful.

Fire risk

Bin enclosures, storage sheds and combustible structures close to buildings are fire sources; bin fires against walls and under eaves spread into buildings.

Water feature hazards

Fountains and ponds leak, grow algae and Legionella, create slip hazards, and combine water with electrical equipment.

On site

• Leaning structures; posts loose, cracked or rotted at ground level.
• Shade sails sagging, torn or with distorted masts; fixings pulling from walls.
• Rust at flagpole and sign bases; cracking at welds and base plates.
• Impact damage on carport and canopy posts.
• Grey corrugated or flat cement sheeting on sheds and garages of the right era.
• Bin enclosures built against walls and under eaves.
• Water features with green water, slime, leaks or exposed electrics.

In the records

• Approvals and engineering for each structure.
• Shade sail installation certificates and wind instructions.
• Asbestos register entries for outbuildings.
• Inspection records for signs and flagpoles.
• Water feature maintenance records.

Findings are graded by what they demand: safety (can hurt someone now), failure (failed and damaging the building), condition (distress present and progressing), lifecycle (renewal due on age and exposure), deadline (a regulator or ordinance sets the date), check (investigate before sizing works) and nil (cosmetic or stable).

A building surveyor inspects; a structural engineer assesses structures that are leaning, damaged or carry significant wind loads; a licensed asbestos assessor samples suspect materials.

• Inventory of every ancillary structure on the site, with type, age, material, location and use.
• Condition inspection of posts, footings, connections, roofs and cladding, with probing of timber at ground level.
• Wind-loaded structures: shade sails, signs and flagpoles checked for masts, welds, base plates and fixings, with non-destructive testing of welds on tall poles and signs.
• Approvals check against council or authority records.
• Hazardous materials: asbestos sampling of cement sheeting and other suspect materials in older structures.
• Fire separation: distance of bin stores, sheds and combustible structures from the main building.
• Water features: leaks, electrical safety, water treatment and Legionella risk.

The report should list each structure with its condition, safety status, approval status and recommended action, including whether it should be kept, repaired, replaced or removed.

• Post base repairs: replace decayed timber posts with posts on stirrups or galvanised bases above ground, or replace with steel.
• Impact protection: bollards and post guards for carport and canopy posts in car parks.
• Shade sail works: replace fabric on cycle, upgrade masts and footings to engineered designs, and set procedures for taking sails down before severe winds.
• Sign and flagpole works: repair or replace corroded bases, and replace poles with fatigue cracking.
• Asbestos removal of weathered sheds and outbuildings by licensed contractors, or encapsulation where sound and undisturbed.
• Removal of redundant or unsafe structures.
• Approvals: obtain retrospective approval or remove non-compliant structures.
• Bin store relocation or fire-rated enclosures away from the building.
• Water feature treatment or decommissioning.

Inspection and engineering are lump sums. Repairs are itemised per structure or per post. Shade sail fabric is replaced on a cycle and is best carried as a recurring line; masts and footings are lump sums. Sign and flagpole replacement is per item. Asbestos removal is a lump sum per structure including licensed removal and clearance. Demolition of redundant structures is a lump sum.

Safety items are immediate; asbestos and approval issues are code compliance; replacement is lifecycle; maintenance is repairs and maintenance.

• Australia. Minor structures may be exempt development under state planning rules if they meet size and setback limits, otherwise they need approval; AS/NZS 1170.2 sets wind actions and shade structures in cyclonic regions need particular care; asbestos in outbuildings is managed under work health and safety and state asbestos rules.
• United Kingdom. Outbuildings may fall under permitted development or need planning permission and building regulations approval depending on size, use and location; the Control of Asbestos Regulations 2012 govern asbestos in non-domestic premises; signs may need advertisement consent.
• United States. Accessory structures follow local zoning and building codes, with permits above set sizes; ASCE 7 sets wind loads, and signs and flagpoles in high-wind areas need engineered foundations; asbestos is regulated by the EPA and states for renovation and demolition.

• Approvals, permits and engineering for each ancillary structure.
• Shade sail installation certificates, design wind ratings and take-down procedures.
• Asbestos register entries for outbuildings.
• Inspection records for signs, flagpoles and shade structures.
• Water feature maintenance and water treatment records.
• Records of structures added after the main building was completed.
• Incident records involving these structures.