Thursday, 17 January 2013

Shallow brick arch near failure

If you see this cracked and or without any steel lintel in place look out
(2.8m clear span attempted!)
The brick arch arrangement here is close to failure.  The single isolated pier on the LHS of view is rotating outward and cracking 10mm wide or more is well developed near midspan at the centre of the arch soffit.  This now requires propping until its removal and reconstruction is complete.  




Footing suitability to control seasonal movement within a restricted range that a masonry arch could handle would be akin to the volume of an iceberg below the water level (with reactive Brisbane clay soils)  

Monday, 26 November 2012

Bracing wall rod tie-down restraint not at capacity

Insufficient tie rod restraint













Tie down rods typically long M12 bolts (12mm threaded galvanized bar) can develop 27kN of force in pull-out tension during a severe design wind event.  This forces equals 2,752 kg of static load or approx 2.75 tons.  Taking this into consideration it becomes apparent that the top fixing pictured will not allow the tie down rod to reach capacity before its stud connection with a framing anchor (a thin galvanised metal bracket) at each ends will be torn out with only a few nails used for its fixing into the side of the adjacent joists.

The joist blocking correctly shown on the lower photo is the correct code method for the base restraint of a bracing wall tie rod. The rod incorrectly installed above can be extended with a nut extension coupler and a joint blocking piece added.

Monday, 5 November 2012

Roof framing damage from service installations

Installing a ducted air-conditioning system into a congested tight roof space is not a particularly easy task.  Most experienced builders are quite aware that the roof framing including trusses, battens and their connections are not to be damaged or compromised in anyway.

Air-conditioning installing contractors are however not usually licensed builders with a carpentry trade behind them.  This can result in a lack of respect for the integrity of the roof framing and damage if modifications are attempted "on the fly" by the air-con installers.

New Patio Roof added without wind tie-down improved at the house connection

New patio roof additions have become very popular in Australian cities. Stratco Outback, Spanline roofs and Altec Patios have been marketing the benefits of a covered outdoor entertaining space for some time now.

Unfortunately some of these systems and other more conventional patio roof extensions (as pictured) have not been designed/installed well to accommodate the additional roof sail area tie-down restraint forces required to keep the new roof in place during high wind storm events.

Sunday, 4 November 2012

Poor site drainage and foundation movement

Damage to masonry veneer wall
1mm wide wall cracking
Recent detailed structural inspections conducted for a home owner has discovered some adverse outcomes concerning BSA insurance cover for new homes within seven years from construction.

Insurances companies are always looking to provide some exit strategy on their coverage should the worse actually eventuate.  In this regard  the BSA assessors are bound to mirror similar attitudes.

Post corrosion resulting from exterior exposure and non-compliant steel coating protection


This is a significant emerging issue for houses built in the mid 1990's in South East Queensland.

In order to provide a reasonable design life structural elements must be maintained and or protected to achieve the nominal 50 years proscribed for domestic house built in Australia.