Foundation Stage Inspection

Design of foundations and footings vary according to the dwelling design and the characteristics of the sub-soils.

A slab foundation may typically have a number of features engineered into it to deal with natural movement in the ground – the more reactive the soil (clay for example) the more extensive the engineering required. Various forms of strengthening beams, screw piles, concrete or timber piles and waffle pod designs may be used to provide a stable foundation. In addition to engineering considerations, the slab must also be constructed correctly.

Base or Pre Pour Stage:

BIAS Building Inspection depends on the design of the foundation, but for slab-on-ground constructions, the following are checked:

• That the site is identified is a Builder’s sign and or survey pegs. The site condition including safety, crossover, access, driveway slope, fences retaining walls etc.
• The orientation of the building in relation to the access road. Weather conditions and site gradient.
• The position of the external wall location in relation to the footings and the inclusion of reinforcement starter bars tied to the slab mesh. The steel visually checked for clearance from the base (40mm) and from the slab finish (no less than 20mm).
• Under-slab services including drainage, plumbing, electrical, phone/data checked for defects, and quality of materials used. Installation of the stormwater pipe system.
• Termite control including the type and location of barriers relative to drainage pipes.
• The location of the electrical meter box including the provision of a safety switch.
• The site checked for possible termite nesting sites and other conditions conducive to termites.
• Visually check that the site is clear of building rubbish and materials are stored appropriately.

More Inspection at Base Stage:

Site Conditions:

• Site Gradient
• Cut/Cut & Fill/Fill
• General Soil Type
• Orientation to road
• Weather: Raining/After rain/Dry
• Surface drainage
• Subsidence
• Seepage
• Retaining Walls & location

Site Improvements/Conditions:

• Landscaping
• Driveways/access/slope
• Crossover
• Paving
• Fencing
• Builder’s sign/site identification
• Stormwater pipes

Floor Structure:

• Footings
• Formwork/brick base
• Damp-proofing membrane
• Steel placement and fixing
• Thickening beams/piers
• Sub-base compaction
• Floors below ground level
• Suspended floors

Under Slab Services:

• Sewage pipes
• Plumbing
• Electrical
• Phone/data cable
• Termite control

Building Inspection at Frame Stage:

• Subsidence.
• Visual check that all framing is straight and plumb.
• Wall frame member spacings are adequate with blocking & nogging installed for wall and ceiling linings.
• The connection of frame members.
• Location of under-slab services – visual check that service penetrations through the floor are in appropriate rooms. Building services to wall and ceiling frames installed using new materials, in good condition.
• Roof truss/frame is installed, tied down & braced.
• If installed, the standard of fascia and gutter installation.
• Structural steel members such as columns, beams and lintels checked for support and fixings.
• Window and door openings.
• Visual check for the installation of a perimeter termite barrier.
• Wall frames secured to top/bottom plate.

Information on Standard Framing:

Nominal versus Specific Fixings:

Australian Standard 1684, Residential Timber Framed Construction provides nominal and specific fixing details for various wind classifications. Some confusion has arisen around when specific fixings are required and what nominal fixings are required in addition to specific fixings. The Standard is designed to ensure that even if specific fixings are required to resist uplift forces (tie down connections), that other forces and actions due to gravity, shear, and construction loads are also not overlooked.

For example, a strap over a rafter may be required for a tie-down of roof up-lift forces, but this alone does not provide shear resistance to lateral wind pressure acting on side walls. Nominal nailing requirements (usually 2 skew nails through the rafter into the top plate) can, however, resist this lateral load.

For other situations, the addition of minimum nailing requirements would be redundant because specific tie-down fixings provide a far greater capacity to handle the other forces and actions other than uplift. For example, there are no nominal connections specified for roof battens to rafters/trusses, but specific tie-downs are required. As a minimum, battens are nailed by one nail to rafters/trusses even when a specific fixing is required. For construction purposes, at least one nail should fix the batten to the rafter/truss prior to the fixing of the strap.

In summary, common sense should prevail. If the first fixing used to connect one member to another is a specific fixing, and it also caters for construction and gravity loads, then the additional nominal nailing requirements are not required.

Masonry Anchors for Tie-Down of Bottom Plates to Slabs:

Masonry anchors may be required to resist the uplift forces at the ends of bracing walls and/or the tie-down of walls due to wind uplift. It is important that the designed capacity of masonry anchors be appropriate in terms of minimum edge, and embedded depth, head bearing and pull-through of the fastener on the timber top plate. Rod washers used with tie-down rods must be of the size nominated in the framing manuals or Australian Standard AS 1684. In many cases, it is the washer that determines the allowable uplift force. The minimum allowable washer size for rod connections are as follows:

• 12mm = 50 X 50 X 3mm
• 16mm = 65 X X 65 X 5mm
• 20mm = 75 X 75 X 6mm

Circular washers with an equivalent net bearing area are an acceptable alternative.

Ridge board and Hip Rafter Tie-Downs:

Tie-downs straps or bolts can be vertical or at an angle not exceeding 30 degrees to the vertical. If there are no walls directly under the tie-down point or within the 30-degree angle, then the tie-down can be taken to a strutting or hanging beam and the ends of the beam can, in turn, be tied down to the wall frame or supporting structure using appropriate forms of connection. If the hipboard or hip rafters are tied down to a beam, the uplift forces at the ends of the beam should be determined to ensure that it is proportional to the number and location of the tie-down from ridge/hip.

Roof Truss Tie-Down:

The minimum nominal connection of one framing anchor or a strap plus skew nails are generally in accordance with the minimum connections recommended by the truss plate manufacturers. In most cases, the straps will need to extend not less than 100mm along each end of the stud. This length may need to be increased to prevent splitting of the stud depending on the number of nails required to fix each end of the strap.

Fixing of Top of Bracing Walls:

The floor/ceiling/roof diaphragm is required to be fixed to the tops of the bracing walls to enable lateral loads or racking forces which occur on the external walls and roof to be evenly distributed into all the bracing walls, including the internal bracing walls. Where the bracing wall is not located within an external wall, the bracing wall must be connected to an external wall, ceiling or roof diaphragm. The connection for each bracing wall must be equal to or better than the capacity of the bracing wall.

Internal bracing walls can be connected to the floor/ceiling/roof diaphragm either directly by a connection at the actual position of the bracing wall or at some other position in the same wall within which the bracing wall is located. In the latter case, the top plate in the wall will need to provide a continuous tie from the braced section of the wall to where the top plate is connected such as at an external wall.

“Flat” Ceilings and Ceiling Diaphragms:

One of the common practices now used to achieve a high-quality level of the ceiling is to suspend the ceiling using furring channels “clipped” to the bottom chords of trusses or ceiling joists or to use a full suspended ceiling system. These systems offer the advantages of overcoming differential levels in truss cambers and bottom chord levels, but do present other issues that need to be considered including bottom chord restraint to trusses and adequacy of ceiling diaphragms to transfer racking forces.

The spacing of bottom chord restraints is a key consideration. For direct fixed ceilings or where ceiling battens are directly nailed or screwed to bottom chords, it would be usual to assume bottom chord restraint at 450-600 centres, unless clipped or suspended ceilings are used. In the latter case, bottom chord lateral restraint would be the spacing of the actual bottom chord ties at panel points or at 3 meters maximum centres if required to act as binders as well.

The underlying assumption for bracing wall spacing requirements is that ceiling linings are directly fixed to bottom chords/ceiling joints or fixed to ceiling battens which in turn are directly fixed to bottom chords/ceiling joists with nails or screws. The ability of suspended ceiling systems to act as diaphragms, and to adequately distribute racking forces to bracing walls has been questioned – it is recommended that alternative bracing systems be designed and incorporated to provide the necessary transfer of racking forces from roof structure to the bracing walls. Alternative bracing systems may include:

• Crossed metal strap bracing attached to the upper or lower side of bottom chords.
• Structural sheet bracing fixed to bottom chords.
• Horizontal wind girders (horizontal trusses or beams).

Blocking needs to be provided between floor joists where the joist depth is equal to or exceeds four times the breadth; the joists should be restrained at their supports. This restraint can be provided by fixing a continuous trimming joist to the ends of the joists above bearers or wall plates or by solid blocking or herringbone strutting between end pairs of joists and between intermediate pairs at no more than 1800 centres.

For deep unseasoned joists, where span exceeds 3 meters and there is no ceiling, additional herringbone strutting or blocking shall be provided between all joists, in evenly spaced rows not exceeding 1800 centres measured along the joists. Noggings shall be not less than the stud depth less 25mm by not less than 25mm thick. Nogging does not need to be stress graded.

What BIAS Inspects at Lock-Up/Waterproofing Stage:

• Roofing installed and complete to Standards & manufacturer specifications.
• Roof plumbing.
• Appropriate flashings to openings and penetrations checked for fitting and condition.
• Visually check for the installation of damp proofing.
• Weep holes to perimeter and window openings.
• Brickwork is straight and plumb with sound mortar. Sill bricks secure and brick control joints appropriately sealed to exclude water ingress.
• Windows and doors are fitted using appropriate blocks and fixings to maintain the frame straight and true.
• Ceilings, wall linings and cornice fitted to acceptable standards with comment on the quality of finish and any obvious defects.
• Internal paint finish.
• External paint finish.
• Waterproof membrane to showers & wet areas.
• Fire separation walls where required, checked whether complete to Standards and manufacturer specifications.
• Ventilation including subfloor ventilation.

Information on Waterproofing

The importance of waterproofing is reflected in the consequences of not waterproofing. Water which enters or escapes from buildings can have immediate and long-term undesired consequences including damage to building contents and long-term structural damage if the problem is not successfully dealt with quickly. Building materials have a considerably shorter lifespan when subjected to moisture over a prolonged period of time. Water damage is second only to fire as a cause of building decay and deterioration.

Internal areas that need to be waterproofed include bathrooms, shower recesses, laundries, and toilets. External areas which commonly need to be waterproofed include external roofs, planter boxes, balconies, retaining walls and swimming pools.

The casualties of water damage include:

• Rotting timber structures and finishes
• Corrosion of metals such as steel reinforcement in concrete, steel beams, lintels
• Swelling of plaster boards and subsequent debonding of ceramic tiles
• Electrical hazards causing possible short-circuiting of lighting and power points
• Blistering of paints
• Unsightly deterioration of the building façade
• Health problems due to dampness which may lead to respiratory problems
• Rotting carpet

The importance of waterproofing cannot be overstated. The damage caused to the building coupled with the high cost of rectification warrants the careful design and application of waterproofing. 

To protect a building’s visual and structural integrity, a membrane must:

• Be impermeable to water
• Accommodate any normal movement that may occur in structures
• Be durable, retaining its integrity over time
• Be suitable for its application
• Be able to breathe permitting escape of moisture vapours
• Be compatible with adhesives to ensure long-term adhesion
• Be user-friendly, easy to apply, relatively lightweight, non-hazardous, environmentally safe
• Require little maintenance or be easily repairable
• Provide continuous protection
• Withstand environmental and climatic conditions.

The keys to waterproofing effectiveness are:

• Proper consideration at the design stage
• Choosing the right product for the job
• Adequate preparation
• The correct application

Leaking Showers:

The following is a summary of the most common problems associated with leaking showers.

• Leaks through or around doors or screens
• Water getting behind poorly sealed tap & spout flanges into the wall cavity
• Use of “standard” floor wastes in tiled floors which are difficult to seal and do not provide drainage from the base area
• Use of “smooth” floor wastes to which the membrane does not adhere
• Timber used to form the hub of the shower which swells & disrupts waterproofing
• The surface of the hob sloping “out” rather than “in” so water is directed outside the shower
• Positioning the screens or doors to the outside edge of the hob rather than overhanging the inside edge slightly so that the top of the hob is subjected to continual water testing
• Leaking tap body washers either not tightened at installation or after maintenance
• Nails or screws embedded in the pipework or touching copper pipes causing corrosion
• No flashing in the internal corners behind the wall lining
• No bond breaker at angles/corners
• Wall lining extending too far down into the tray causing “wicking”
• Recessed slab method with no waterproofing
• Nails or screws through the side or bottom of the tray
• Tiling before the membrane is fully cured
• Damage to waterproofing systems by carelessness of following trades
• Use of a non-approved wet area system

Minimum Waterproofing Requirements:

The Building Code of Australia (1996) and the Australian Standard (AS 3740-1994) “Waterproofing of Wet Areas in Residential Buildings” require that the following areas within a bathroom must be waterproofed:

• Full floor within the shower recess including down into the waste or if the shower is not enclosed, within 1.5 meters horizontally from a point vertically below the shower fitting
• If the shower is enclosed, minimum 100mm over the hob or step-down onto the bathroom floor
• If the shower is enclosed and exposed to a shower fitting to a height 1.8 meters above the floor or to a height no less than 150mm above the shower rose if it is within 75mm of the wall
• Immediately behind a bath, trough, sink or similar fixture
• The junction between the floor and wall of the shower; the junction between the wall and the fixture (the flange)
• The full bathroom floor if it is made from timber, plywood or particle board or is above the ground floor
• Tiled finishes over fibre reinforced cement sheeting or moisture resistant plasterboard provide an acceptable wet area lining except at the junction surfaces where additional precautions are necessary.
• A generous bead (10mm wide) of silicone should also be applied to:
• All wall/floor junctions within the shower
• Junctions between 2 wall sheets within the shower recess up to where the tiling finishes
• The perimeter of the waste outlet/floor junction
• The silicone should be smoothed over so that it extends 5mm either side of each junction.

Many councils now require that new waterproofing work to be performed by licensed waterproofing applicators and a certificate be issued once it has been approved by a certifier.

What We Inspect at the Fixing/ Pre-Painting Stage:

• Window openings to shower areas appropriately sealed.
• Doors fitted to acceptable standards and function.
• Windows fitted to acceptable standards and function.
• Skirting fitted to acceptable standards and function.
• Architraves fitted to acceptable standards and function.
• Weatherproofing of single leaf masonry.
• Other Joinery.
• Ceiling/wall linings.
• Garage doors.
• Pergola structural adequacy, materials, workmanship.
• Deck structural adequacy, materials, workmanship.
• Patio structural adequacy, materials, workmanship.
• Verandah structural adequacy, materials, workmanship.
• Carport structural adequacy, materials, workmanship.
• Shed structural adequacy, materials, workmanship.
• Safety glass.
• Smoke alarms.
• Safety switch.
• Vermin proofing.
• Toilet door open out or removable.
• Step heights.
• Balustrading.
• Landings.
• Ceiling heights.
• Termite notices.

BIAS Building Handover Inspection and Stage Inspection Program 

If you are looking for a new building handover inspection and report in Brisbane, BIAS is here to support you!

We will be there throughout your entire house building process, not just to inspect and list off the small decorative defects at the end.  At each step along the way, our qualified building inspector is there to assess the quality of work undertaken.

You can tailor the programme to suit yourself, select all 6 stages of building inspections or simply choose the ones you’re most worried about! If you only need the Building Handover Inspection:

The Programme Consists of 4 Separate Stage Inspections:

• Base Stage – immediately before slab pour.
• Frame Stage – when the frame is complete but before internal wall linings.
• Lock-Up Stage – when external windows and doors are installed and the roof is on.
• Pre-Painting Stage – when construction is complete including cabinetry, but before painting.

Finishing with:

• Building Handover or Practical Completion – a detailed building inspection will be conducted once the builder is satisfied that the construction process is complete and after a final clean has been undertaken.

Followed by:

• Building Warranty Inspection – conducted within 12 months as a follow-up second Building Handover Inspection to detect defects, which your builder is obliged to rectify within QBCC’s 12 month warranty period. Note that the 6 year warranty period applies only to structural defects.

Benefits from our Building Handovers:

You benefit by having an independent assessment of the quality of work so you can make your final payment with confidence.

Your builder benefits from having the opportunity to correct any defects sooner rather than later which can be costly.

Why do you need a structural building inspection?

Builders are increasingly challenged to deliver quality construction with rising building costs in a competitive new home market. Even respected builders can have variations in quality. Most builders are concerned that errors and poor workmanship with the cost of associated re-work may destroy their reputation.

Why do you need a timber and pest inspection?

Even if you have just had new termite barriers installed, you would still need a timber and pest inspection. It is common for the termite barrier, which is installed early in the construction process, to be damaged or compromised during the build.

Typical problems encountered are physical damage to the barrier, relocation of incorrectly positioned slab penetrations such as waste pipes, landscaping and paving built up above the weep holes or rendering over inspection zones. When selecting a builder: 

• Don’t just rely on the display homes, get referrals. Talk to others about their experience with the builder and if possible, visit their home to see examples of the builder’s work firsthand.
• Ensure the builder is fully licensed to build in your state and carries the necessary insurance to protect you.
• Have a solicitor help you negotiate the contract and most importantly, ensure you and the builder clearly agree on what is to be built. Ensure that construction time frames, both best and worst case scenario are acceptable to you.
• If you feel there may be a personality clash between you and your builder, agree to use an impartial third party to act as liaison to handle all negotiations.
• Have BIAS conduct stage inspections, a building handover inspection and a follow-up inspection within 12 months for warranty items and within 6 years for structural problems.

We understand that the thrill of moving into your newly built home can be quickly dashed by finding disconcerting defects later

But you can relax knowing that you continue to be supported by an BIAS Warranty . According to the Rectification of Building Work Policy: