A/Overview

This document has been written to give clients of Property Protect an understanding of the most mutual types of building defects that may be found in buildings whilst doing an AS 4349.1 inspection. This list gives the reader a basic outline of the more mutual defects and the reader will have to be conscious that there are in a literal sense thousands of forms of building defects. The items which we have listed are the more mutual ones only.

B/Abstract

The report lists a heap of of the more mutual residential building failures including the causes based on the case studies carried out by the writer as a licensed Builder. The writer has likewise included a good deal of of the causes of the failures.

Purpose

The aim of this report is to give the reader a summary of the types of residential building failures and the suggested remedies to these defects.

Method

This report is staged as a case study based on the experience and personal records of the author over the last 15 years as a licensed Builder.

Findings

A huge ratio of structural building failures listed in this report have in my opinion been caused by the mismanagement of stormwater around houses leading to motion in the homes. The remainder of the failures are caused by poor building exercises and or poor maintenance.

C/Introduction

The most mutual forms of Building failure brought up for the duration of AS 4349.1 house inspections by the writer in Adelaide are as follows.

Slab Edge wetting

This is the horizontal ingress of moisture and salts in solution from the soil which enter into footing edges through the capillary action (Suction caused by the concrete) of the concrete. It is caused by a number of components including, Concretors pushing down the Fortecon membrane with edge forms prior to pouring a floor slab, comparatively poor cement concrete in the footing (Many engineers have called for 32 MPA concrete to protest the ingress of salts in lieu of 20 to 25 MPA presently used), Concrete over pours caused when concretors edge forms are not placed low sufficient to stop a horizontal over pour which may lead to water ponding on the top face of the over pour creating a pool of water. The final cause is the lack of a plastic membrane to be placed among the paving and the footing edge.

The harm that may be caused even though this problem includes, mould and rotting to the undersurface of floor coverings internally and the fretting of the concrete through the salt attacking the cement matrix through a hydraulic action both internally and externally. (Salt crystals exaggerate inside the concrete matrix thereby causing it to fret and crack).

Rising Damp in walls

This is a similar problem to Salt damp elaborate below. The main divergence is that Salt damp is in general a 90 to 100% break down of the Damp Course in the wall whilst rising dampness is a partial failure of the Damp Course and the partial failure in general means that the harm to the masonry wall is not as bad as Salt damp. There is a good probability that rising dampness may be found in most pre 1950 homes and the Rising dampness could be fixed to erosion of the mortar joints by as little as 1 to 2 mm from it is firstborn face. The treatment is the same is Salt damp.

The client must be conscious nevertheless that in most cases the rising dampness is not treated as the erosion of the masonry is very slow and it may have taken 50 years for the mortar to erode 4mm deep from the face of the brickwork. I would advise clients to monitor this if the harm is not major.

Salt Damp in Walls

This is caused through the vertical ingress of moisture and salts into a wall which may lead to the wall fretting and not being capable to take structural loads. The harm caused to the masonry is from the salt crystals inside the masonry expanding leading to the bricks and or mortar fretting. In some cases the salt damp may render the masonry unstable.

It is caused by a number of elements including the full breakdown of the damp course (Pre 1910 homes had pitch or bitumen amidst the footing and bricks and this becomes brittle with age), paving and or render bridging the damp course likewise causes this.

Breacher piece failures in showers This is where the breacher piece fails through metal fatigue by way of thousands of heat cycles inside the wall (This is where the hot and cold water meet inside the wall in the shower). Water then flows into the walls. Generally a breacher piece will fail in a shower each 25 to 30 years or so and it is rather common. A tell tale sign of a breacher which has been substituted is two off dissimilar tiles to the walls of the shower.

During inspections carried out by Property Protect the company carries out a survey of the wet area walls in it is premium report using an electronic moisture meter to tell apart this defect. High moisture levels to the walls next to the shower in general indicate that it is leaking.

Brick Growth

Cracks in walls Older homes may have brick growth cracks which ordinarily take place at the end of a wall in a vertical plane. Clay bricks will actually exaggerate as they are porous. If a house does not have control joints in the wall the bricks may exert a compression load on one another leading to cracking.

Terracotta roof tiles

Fired clay roof tiles will fret when exposed to moisture for long periods of time and this in general occurs at the laps of the tiles. The tiles may also fret in seaside environments due to salt attacking the tiles. It is not not common to see these roof tiles fretting to the laps on the undersurface of the roof tiles. As these tiles age they may also become very brittle and are without apparent effort cracked.

In most instances when the tiles are fretting they will need replacing within the short term. Concrete cancer in footings and precast concrete lintels. This occurs when the steel bars inside the concrete rust due to moisture/salt/Carbonation ingress into the concrete. As the bars rust they exaggerate causing the concrete to crack. This may cause cracking in the surrounding concrete elements. The client will have to be conscious that it is very pricey to fix this defect.

Tree harm

Although a great deal of tree roots may cause hydraulic harm from the roots physically moving the building element, most Building failures are caused by the tree withdrawing moisture from the soil. This then leads to the soil contracting which may cause Building parts to drop or move.

In a huge number of inspections over the years the writer has observed walls and footings dropping or moving due to soil contraction when a tree is too close to the base of a wall. In most instances the writer would advise clients to keep huge trees well away from the house. If this is not possible an impermeable root fabric may be applied to stop the tree origins growing under a house.

Stormwater harm and Soil motion

This is caused when gutters, stormwater pipes and downpipes overflow/leak causing the soil around and under the footing to be saturated. Once the soil becomes completely filled it then loses it is capacity to take load and the soil may collapse leading to the Building factor dropping or moving. In a lot of instances reactive soils may exaggerate likewise leading to cracking. This then places uplifting loads on a house which may lead to substantial cracking and motion as well.

In Adelaide reactive (fine soils such as clays) may be found at the base of the foothills where fine silts run off the hills. The fine reactive soils may in general be found in Rostrevor, Athelstone and Campbelltown.

Lack of Paving around the external perimeter. This may cause elaboration and contraction in the soil around the footing leading to motion in the Building. ie Expansion in soil after heavy rains and contraction in the soil in the summer. In a heap of instances the contraction of the soil under the footing (on the external portion) may lead to the footing rotating on the external side as it drops. The author has seen a lot of instances of this occurring and this leads to the whole wall leaning out or in. (Bows out at the base and then leans in at the top). In these instances the wall in general needs to be pulled down and rebuilt.

In some of the Property Protect reports you may see a note detailing seal gaps at the footing paving junction. Many houses inspected by this company have gaps at this junction and this may concede moisture to enter both under the house and likewise underneath the paving. Where the water enters under both elements it may erode the soil away and or cause the soil to either exaggerate or contract. In this instance the gap must be sealed off with a flexible sealant.

Older style wiring.

The author has seen electrical failures from the following for the duration of inspections over the years., -Canvas coated and vulcanised rubber power cables. In the introductory instance the canvas may be eaten by rodents or just physically ages leading to the cables being exposed which may result in fires. The same may take place with older rubber cables which may split.

-Power cables not in conduit in contact with steel frames. I.e. If the cables are damaged the frame becomes live. A number of houses over the years have been inspected by Property Protect and found to have new wiring in all areas of the house but not inside the existent hard plaster. During the premium house inspections this company uses a high powered torch to discern wall patches and chases to the walls. An existent house without wall chases above the light switches and power points would in general indicate that the original wiring has not been removed. In this instance Property Protect would advise the client to engage an electrician to carry out a survey of the house to affirm if the wiring is original to these areas. Hard plaster cannot be got rid of for the duration of a house inspection as the vender would not in general approve this.

Leaking pipes in wet areas This is in general caused through corrosion of lead or galvanised steel waste pipes under or in floor slabs. As the pipes corrode this leads to a leak which may wash away sub fill in a floor leading to the floor and or footing dropping.

This is very pricey to fix as in general the pipes are cast into the floor slabs in the wet areas and they need to be jack hammered up. This is a mutual defect as a big number of houses in pre 1970 properties have galvanised steel pipes cast into the floor slabs. For these steel pipes it is not a matter of if but when the pipes need to be substituted . Having stated this steel pipes altho not draining as well as they will have to do may function for a good deal of years until funds may be found to replace them.

If you have steel waste and or water supply pipes in a pre 1970 house and you are contemplating a wet area renovation with new tiles etc we would strongly advise you to remove the steel pipes prior to the renovation.ie If you renovate the wet areas without removing the steel pipes a failure of the pipes could result in you having to re renovate the wet area at outstanding cost again!

Cracks/Movement in walls

Movement in any home is hard to control. In most instances cracks are caused by changes in soil moisture levels around the footing though trees may likewise cause significant movement. Horizontal cracks may take place in walls if a window lintel sags or if a footing/wall drops.

Diagonal cracks radiating away from window and or door heads are the most mutual form of cracks. Lateral motion cracks may occur with a shear load if a footing rotates (Drops) on one side. Due to Adelaide’s arid climate soil shrinkage affiliated cracking in homes is causing galore problems. This leads to footing settlement (Dropping of the footing) and cracks in all building elements.

Roof frame failures

The original type of failure is for an older style roof which does not have under purlins and or struts. In this instance the failure is in general from the frame not being competent to take the dead loads from the weight of roof tiles. It is mutual to see the frame sag to a great extent and split and this instance repairs may need to be carried out. If a roof frame is sagging from the weight of the roof tiles and the timber frame is not splitting or showing any signs of stress our counsel to you is to closely monitor the roof frame.

In the second instance the writer has seen heavy splitting to timber around faulty gang nail trusses fabricated in the 1970′s. In a good deal of instances the trusses could not take roof loads and sagged.

White ant attack

Property Protect does not carry out a survey for white ants in our inspections and we would advise that you engage a pest controller to do this. White ant attack is a very mutual problem in Buildings with the ants in a literal sense eating any form of timber in a home. As the timber wall frame is load bearing in a brick veneer home this may led to structural failures. The ants will ordinarily enter a home where voids are close to the ground. One example of an entry point is where the paving bridges the Damp Course permitting ants to enter a wall cavity through weep holes (i.e. the paving is poured above the Damp Course in the wall).

A second example is where garden beds are placed up versus walls without any paving and in this instance we would advise on removing the garden bed and then installing paving all around the house.

Poor Workmanship

The following defects are caused by poor workmanship which does not comply with the Building Code. -Render in brick wall weep holes This stops condensation from draining out of a cavity. The writer has seen fretting render caused by blocked weep holes. -Bricks overhanging the footing. BCA allows a tolerance but in a lot of instances concreters’ set out the slab incorrectly. As the wall is not supported the bricks may bow out.

-Render bridging wall Damp Courses In some instances plasterers do not strike a horizontal line through render which may result in ground moisture and salts rising up into the wall by passing the Damp Course. This may cause Salt damp in a wall.

-Concrete slabs poured up versus brickwork. In some instances around porch slabs builders from time to time place the Damp Course one brick course above the footing and pour the porch slab up versus the introductory course of clay bricks. In this circumstance clay bricks are not designed to be exposed to ground moisture and salts for extended periods of time and this leads to fretting of the bricks.

This is at times seen in older houses and it is hard to fix this if the fretting of the walls is heavy. Subject to a internetlocation visit occasionally the best option in this instance is to jackhammer up the floor slab and then repour the concrete underneath the Damp Course. At the end of the day this is an pricey problem to rectify. The writer has seen this in galore garages in pre 1980 houses.

-Puddle flanges to wet areas not installed correctly. Puddle flanges are designed to drain any water caught amongst the waterproof membrane and the floor tiles. In numerous instances the flanges are laid proud of the floor and the trapped water can not drain into the waste pipe. In a second floor building this ponding water may bypass the membrane leading to the timber floor swelling and door, wall and window frames jamming up from compression loads. If this has occurred it is very pricey to repair.

-Waterproof membranes to showers This is in all likelihood the greatest of the observed failures brought up in this article in my opinion. If a shower leaks this may cause heavy harm to the timber wall frame thru wood rot and water damage. In masonry wall long term moisture leaks into the surrounding walls may lead to fretting of the masonry brick walls and render. In a metal wall frame heavy rusting may occur.

In a timber wall frame long term leaks into the shower walls may likewise cause swelling of the wall cladding and wall tiles debonding and cracking. In a masonry wall the high moisture levels may 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 a good deal of tilers still grout these areas which leads to cracking as the grout is rigid. The BCA likewise requires an angle to be installed at the wall floor junction in the shower and in galore instances this is not installed.

Many waterproof membranes are not installed in the right way or the defective 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 a good deal of cement asbestos based cladding in the house. Property Protect may carry out a survey to distinguish this based on our sentiment only in our premium report. This may only be verified by analysing samples beneath a microscope in a laboratory so any survey is based on our sentiment 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 bothered by grinding, drilling or cutting it may be fatal. Areas where it may be found in a house include.

-Backing sheet for the power board -Old floor coverings -Eaves cladding externally. -Wet area cladding Etc.

D/Discussion

In terms of the remedies to the failures identified above these are as follows.

Slab edge wetting

This may rather without apparent effort be solved by stopping the transfer of moisture horizontally into the slab by placing an impervious membrane among 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 may 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 ought to be lowered. If render bridges the Damp Course the render may be removed.

Breacher piece failures

In this instance in general four off wall tiles, the affected render and the primary fitting are removed. The reverse is then carried out with new materials.

Brick Growth cracks

This form of cracking may be stopped by forming control joints in the wall above the windows and doors to grant the bricks to exaggerate from long term moisture absorption.

Terracotta roof tiles

Generally if these tiles are fretting at the laps they must be got rid of and then substituted with new concrete roof tiles or metal roof cladding.

Concrete Cancer

The only way that this may be repaired is by physically removing the affected concrete completely 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 salaried fix mortar. In order to stop contaminants (Chloride ions and carbon dioxide) entering the concrete, a coating (Acrylics) will have to be used to stop water and contaminant ingress. This is employed after the repair is carried out.

Trees

Once minor harm to homes has been caused in general it is not viable from a financial perspective to carry out major repairs. In a good deal of instances this may occur but this is rare. If a wall has dropped from soil shrinkage the most mutual rectification is to under pin the footing. This involves excavating underneath the existent footing, propping, pouring a new footing and then grouting amongst the new and existent footings. Under pinning is very expensive.

If trees can not be got rid of a trench approx 2m deep may be dug amid the house and the tree and then lined with an impermeable root fabric to stop the tree roots growing underneath the house.

Stormwater harm

If the gutters and downpipes are leaking they ought to be repaired and or replaced. In most instances these parts do not drain out to the street. If this is the case the stormwater must be diverted out to the street by way of stormwater pipes.

Lack of Paving.

The necessary parts to control cracking in older homes is to keep the soil around the footing in a stable moisture range. This may be achieved by installing paving .It is primary notwithstanding to water gardens systematically for the duration of 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 probability of an electrical fire, older wiring will have to be got rid of and substituted with new PVC wiring together with the installation of world leakage circuit breakers.

Leaking pipes

In order to check if existent pipes are corroding a plumber may pressure test the pipes or use a CCTV system. Generally any older steel or lead pipes ought to be got rid of and substituted with PVC nonetheless this may be costly as concrete floors need to be jack hammered to access the pipes.

Cracks in walls

Generally the best way to control motion is to articulate a house. This allows it to move by installing wall control joints above windows and doors and slip joints amidst 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 elements 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 by way of 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 fellow member either side with new timber or inserting further and added props (The props in general run from the beneath purlin to the internal wall). In the case of gang nail failures lapped timber bolted either side of the affected timber may likewise solve this defect.

White ant failures.

Ants may be prevented from entering a house thru chemical sprays , Ant caps (Stumped homes) or stainless steel mesh barriers (Termimesh). If existent homes are infested, the homes may be sprayed with chemicals or have bait stations inserted placed around the external perimeter of the home which are in a literal sense baited with poisoned timbers (Sentricon system).

Property Protect does not carry out a survey for white ants in our pre buy inspections and we would advise that you engage a pest controller to do this.

Poor workmanship In each instance the work will have to be carried out as per the requisites 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 versus bricks Ensure that the i.e. porch slab is poured up versus the edge of the main footing.

-Puddle flanges Ensure that the flange is flush with the top of the floor. The timber/concrete needs to be rebated down to grant the flange to sit flush with the floor.

-Membrane to showers Ensure that the membrane is installed in accordance with the BCA.

E/Conclusions

The bulk of the causes of Building failures as elaborate 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 continuous 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 numerous are due to poor maintenance and or construction techniques. Ie Damp Courses bridging paving (Non BCA compliant) may cause white ant infestations and or Salt damp.

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