In a timber wall frame long term leaks into the shower walls can also cause swelling of the wall cladding and wall tiles debonding and cracking. In a masonry wall the high moisture levels can lead to the tiles cracking and or debonding off the walls.
The BCA (Building Code) requires silicone to the internal wall corners of a shower and many tilers still grout these areas which leads to cracking as the grout is rigid. The BCA also requires an angle to be installed at the wall floor junction in the shower and in many instances this is not installed.
Many waterproof membranes are not installed correctly or the wrong materials are used.ie Bitumen membranes to showers which leach into the grout, liquid membranes not reinforced with polypropylene gauze fabrics. Etc.
Asbestos
Most homes built before 1988 would have some cement asbestos based cladding in the house. Property Protect can carry out a survey to identify this based on our opinion only in our premium report. This can only be verified by analysing samples under a microscope in a laboratory so any survey is based on our opinion only and would need to be confirmed by the Lab. Our premium report does not analyse the samples in a Laboratory.
If this material is disturbed by grinding, drilling or cutting it can be fatal. Areas where it can be found in a house include.
-Backing sheet for the power board -Old floor coverings -Eaves cladding externally. -Wet area cladding Etc.
Discussion
In terms of the remedies to the failures identified above these are as follows.
Slab edge wetting
This can quite easily be solved by stopping the transfer of moisture horizontally into the slab by placing an impervious membrane between the paving and the footing or directly onto the full depth of the footing. Plastic, waterproof membranes (Liquid or sheet) are the best remedies.
Salt damp
This can be repaired by forming a new Damp Course by undersetting (removing bricks and inserting a new plastic membrane) or chemical injection (Silane siloxane injection) where the Damp Course has failed. Where the paving bridges the damp course the paving should be lowered. If render bridges the Damp Course the render can be removed.
Breacher piece failures
In this instance generally four off wall tiles, the affected render and the original fitting are removed. The reverse is then carried out with new materials.
Brick Growth cracks
This form of cracking can be stopped by forming control joints in the wall above the windows and doors to allow the bricks to expand from long term moisture absorption.
Terracotta roof tiles
Generally if these tiles are fretting at the laps they should be removed and then replaced with new concrete roof tiles or metal roof cladding.
Concrete Cancer
The only way that this can be repaired is by physically removing the affected concrete fully exposing 360 Degrees of the bar, placing saw cuts , grit blasting steel, prime steel with zinc cold galvanising, prime and then replace concrete with a polymer modified shrinkage compensated repair mortar. In order to stop contaminants (Chloride ions and carbon dioxide) entering the concrete, a coating (Acrylics) should be applied to stop water and contaminant ingress. This is applied after the repair is carried out.
Trees
Once minor damage to homes has been caused generally it is not viable from a financial perspective to carry out major repairs. In some instances this may happen but this is rare. If a wall has dropped from soil shrinkage the most common rectification is to under pin the footing. This involves excavating under the existing footing, propping, pouring a new footing and then grouting between the new and existing footings. Under pinning is very expensive.
If trees cannot be removed a trench approx 2m deep can be dug between the house and the tree and then lined with an impermeable root fabric to stop the tree roots growing under the house.
Stormwater damage
If the gutters and downpipes are leaking they should be repaired and or replaced. In most instances these elements do not drain out to the street. If this is the case the stormwater should be diverted out to the street via stormwater pipes.
Lack of Paving.
The essential elements to control cracking in older homes is to keep the soil around the footing in a stable moisture range. This can be achieved by installing paving .It is important however to water gardens consistently during summer for a fixed duration and intervals in areas adjacent to the paving. This keeps the soil moist adjacent to the paving (Best to use an electronic watering system).
Older style wiring In order to stop the chance of an electrical fire, older wiring should be removed and replaced with new PVC wiring together with the installation of earth leakage circuit breakers.
Leaking pipes
In order to check if existing pipes are corroding a plumber can pressure test the pipes or use a CCTV system. Generally any older steel or lead pipes should be removed and replaced with PVC however this can be expensive as concrete floors need to be jack hammered to access the pipes.
Cracks in walls
Generally the best way to control movement is to articulate a house. This allows it to move by installing wall control joints above windows and doors and slip joints between the hard plaster and the brickwork. To form a slip joint remove render, install mesh onto bricks and replaster with a lime rich mortar. A lime rich mortar is used to reduce the cement content and hence the rigidity of the render with a 1 cement, 10 sand and 2 parts lime mortar).
In relation to soil shrinkage cracks a number of soil engineers in Adelaide have instigated the direct injection of water into the soil around the footings to the external perimeter of homes (Mainly to Parkside). This keeps the soil in a stable moisture range via the computer controlled injection of water into the soil.
Roof Frame failures
In most instances roof frame failures are easy to rectify by propping the sagged or damaged area and either lapping the member either side with new timber or inserting additional props (The props generally run from the under purlin to the internal wall). In the case of gang nail failures lapped timber bolted either side of the affected timber can also solve this defect.
White ant failures.
Ants can be prevented from entering a house via chemical sprays , Ant caps (Stumped homes) or stainless steel mesh barriers (Termimesh). If existing homes are infested, the homes can be sprayed with chemicals or have bait stations inserted placed around the external perimeter of the home which are literally baited with poisoned timbers (Sentricon system).
Property Protect does not carry out a survey for white ants in our pre purchase inspections and we would advise that you engage a pest controller to do this.
Poor workmanship In each instance the work should be carried out as per the requirements in the BCA ie.
-Weep holes During rendering cut the render out of the weepholes
-Bricks Overhang footing Set out floor slab correctly.
-Render bridges damp Course Cut a horizontal line in the render over the DPC
-Concrete slab poured up against bricks Ensure that the i.e. porch slab is poured up against the edge of the main footing.
-Membrane to showers Ensure that the membrane is installed in accordance with the BCA.
Conclusions
The bulk of the causes of Building failures as detailed in this cast study are due to changes in the moisture conditions in the soil around the footings due to seasonal change. The remedies discussed revolve around keeping the soil in a constant moisture state. The measures discussed include installing paving and electronic garden watering systems, diverting stormwater away from the house, ensuring plumbing does not leak, Keeping tree roots away from footings and articulating older homes to enable them to move.
Of the remaining failures many are due to poor maintenance and or construction techniques. Ie Damp Courses bridging paving (Non BCA compliant) can cause white ant infestations and or Salt damp.
Puddle flanges Ensure that the flange is flush with the top of the floor. The timber/concrete needs to be rebated down to allow the flange to sit flush with the floor.
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