Roof structure danger from poor construction.
Poorly built roof structure. Identified by Peter Weddell owner/operator of Qld Home Buyers Inspection service and Queensland Building Inspection Service, QBIS.
A tiled roof supported off an undersized ceiling beam (binder) which is also causing sagging of the ceiling joists below.
This is a common fault with roof structures of many homes built in Brisbane around the 1940’s through to the 1980’s.
Insufficient support below under-purlin of a roof structure
This roof is sagging considerably from lack of support between props of an under-purlin. Without restructuring this may cause the roof to collapse.
Method of fitting more support to a roof structure
A potentially dangerous roof structure can easily be rectified by having a Barap Bolt fitted. They were used where roof support could not be achieved off an internal wall.
What is a Barap Bolt ? (in photo above)
- A threaded rod fitted below an under-purlin with props for support between the rod and purlin.
- Brackets are secured to hips, underpurlins or rafters where props are placed below the brackets for support, off the internal walls.
- Support must be fitted below ends of the Barap Bolts brackets where they are secured.
- Occasional retensioning of the rods nuts are required to help alleviate sagging of the roof.
Although no longer manufactured, they can easily be fabricated by an engineering business.
Poorly built roof structure, supported of a ceiling!
They don’t build them like they used to!
A poorly constructed roof structure above a Post War house, in a southern suburb of Brisbane.
- The main beam (binder) supporting this roof is fractured considerably and dangerous!
- Binders are not designed to support any part of a roof structure.
- Roof structures must be supported off the internal walls (where possible) not the ceiling structure.
An extremely dangerous situation that required immediate restructuring of the roof.
Alternative solution to restructuring of a roof.
Rather than restructure the roof, it would be worth considering replacing the concrete roof tiles with metal sheeting. This would reduce the roof weight considerably and may only require more securing of the roof structure (for tying down).
Some related material that may be of use:
Queensland Government Technical notes on roofing
For independent Building Inspections Brisbane in all suburbs, Qld Home Buyers Inspection Service. qbis.com.au