~~ CONSULT AUSTRALIA

~I

lhc lna1Uut10n

of Englnee-rs, Auetrell•

21•t June 2016

AAI Limited TIA Suncorp Insurance GPO Box 1453 BRISBANE QLD 4001

Attention: Repair Co-ordination Team

Dear Sir I Madam,

Eil- umnttmn11m LOCHINVAR. NSW. 2321 BUILDING MOVMENT CLAIM

CLAIM No.:'@f" INSURED: BRUCE HEALD

REVIEW OF THIRD PARTY REPORT

SUN.0702.0004.1788

This letter report follows receipt, on 9th June 2016, of the third party report by Burke Engineering Services Pty Ltd commissioned by the Insured. We confirm that we have reviewed the report in relation to the claim as requested.

The Burke Engineering Services Ply Ltd (BES) report is dated 31 81 March 2016, and includes a geotechnical investigation undertaken by Valley Civilab and a survey undertaken by Scott Crisp Dilley and Wills. The report is not reproduced.

The original dwelling was constructed in 1984 I 1985. The dwelling structure was designed by HP Planning Service Pty Ltd (HPPS), of Cardiff, in 1984, with a letter dated 21/9/84 and associated sketch outlining the structural details, issued to Council.

At the time of original design and construction of the dwelling the building regulation was Ordinance No. 70 under the Local Government Act, 1919, and the last reprint was dated p t June 1983.

Australian Standard AS2870 Residential Slabs and Footings was first published in 1986, after the dwelling was constructed, whilst the current issue was published in 2011.

We provide the following comments in relation to the BES report and relevant current and historical (where readily available) Australian Standards and building regulations.

1. SITE FOUNDATIONS

i. HPPS Specifications

a) The foundation soil was noted in the HP Planning Service specifications as being "alluvial soils".

Alluvial soils are commonly described as a sediment (such as sand, silt clay or gravel) deposited in riverine landscapes.

ii. Ordinance No.70

a) Group VI. Structural Provisions, Part 32 - Foundations:

•

2lS357iun1e tet Confidential

sub-part 32.1 states: "The adequacy of foundation shall be assessed on the basis of - (a) well established and relevant local knowledge and experience of

Page 1o! 12

SUN.0702.0004.1 789

f oundations conditions in the vicinity of the proposed building; or (b) tests on the foundation or the materials comprising the foundation".

• sub-part 32.3 (1 ) states: "The bearing pressures on the foundation of a building shall 1101 exceed the values in Table 32.3 unless a foundation investigation has been carried out ... that higher bearing pressures are justified'.

• Table 32.3 states: for "Soft clay or loam" the allowable bearing pressure in kilopascals is "/ 00". An extract of the table is reproduced below.

0 1di11ance No. ?(}--£.uc41/ G uve1nm e1"j Act, ,9J9.

1'1\81...B J?). I

' Allo_.lt~

Po"""<l•lion btlllllJt ......... in kilopa.scak

Madt- 11ound .. . ~,..

ion day ur ioam . . ... ~,:;tsarui llt

Mcdiul!'I cl~_y oc- J.tndy clly :WO

iii. AS2870.1-1988 (second edition)

a) Section 2 Site Classification, clause 2 .4 Class P Sites

• Sub-clause 2.4.2 Soft Soils states: "Soj/ foundations are classified as Class P where - (a) the allowable bearing pressure at foundation level is less than 100 kPa under strip or pad footings".

b) Section 6 Construction Requirements. clause 6.2 Strip and Pad Footings

• Sub-clause 6.2.2 Foundation states: "the foundation shall satisfy the following: (a) The foundation shall provide an allowable bearing pressure of JOO kPa".

• Sub-clause 6.3 Building Practices for Class M, Class H or Class E Sites states: "{a) For Class Hand Class E sites, the masonry construction shall be detailed in d1·awings to show method(s) used to minimize the damage due to foundation movement", and "(c) Water run-off shall be collected and channelled away from tJ12 house'.

iv. AS2870-2011

215357~n16 ler

a) Section 2 Site Classification

Sub-clause 2.1.3 Classification of Other Sites states: "A site shall be classified as Class P if - (a) the bearing strength is less than that specified in Clause 2.4.5: (b) excessive foundation settlement may occur due to loading on the foundation; (c) the site contains uncontrolled or controlled fill as idemified In Clause 2.5.3; (e) the site may be subject to moisture changes due to site conditions more severe than the normal site conditions: (/) the site may be subject to other factors resulting in foundation movement beyond the reactive soil movements resultingfrom moisture changes due to the normal site conditions".

Sub-clause 2.4.5 Bearing Capacity states: 'Detem1inatio11 of adequate bearing strength shall be considered as fallows: (a} The design hearing capacity at foundation level shall be not less than 100 kPafor strip at1d pad footings".

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SUN.0702.0004.1790

v. BES report (based on the Valley Civilab report)

a) Page 9, bullet point 1 states: "The site consists of between I 50mm & 350mm of si/ry sand, sandy clay, and crusher dust fill materials, overlying natural silty sandy clays and medium 10 high plasticity clays to a depth of approx. 2m. Weathered rock was encountered below this levef'.

b) Page 9, bullet point 2 states: "n1e site has been classified as class P (Problem) due to the presence of fill material, with a reactivity of class HI (Highly Reactive)".

c) Page 9, bullet point 4 states: "It is noted that very weak material was encountered in Borehole I (BHI < 25kPa), and borehole 2 (BH < 25 kPa) at depths of500mm where the footings would likely be founded. 100 kPa bearing is considered minimum adequa1e bearing capacity for this type of residential structure'.

vi. Valley Civilab (report reference P812, dated 161h March 2016)

21S357j.Jn1 6 lat

a) Photo 1 (page 55 of BES report) shows that Bore hole 1 was taken in the rear northern external loose laid masonry paved area (with covered metal awning).

b) From Table 4 (page 51 of BES report), at Bore hole 1, shows:

At 0-0.1 Sm depth there is filling.

• At 0.15m-0.3m depth, firm clay with an Allowable End Bearing Pressure of 75kPa.

At 0.3m-0.5m depth, very soft to soft clay with an Allowable End Bearing Pressure of <25kPa.

• At 0.5m-1.2m depth, stiff clay with an Allowable End Bearing Pressure of 150kPa.

c) Photo 2 (page 56 of BES report) shows Bore hole 2 was taken inside the rear (northern) laundry area.

d) From Table 4 (page 51 of BES repor1). at Bore hole 2, shows:

• At 0-0.35m depth there is filling.

• At 0.35m-0.5m depth, very soft clay with an Allowable End Bearing Pressure of <25kPa.

• At 0.5m-1.4m depth, stiff clay with an Allowable End Bearing Pressure of 150kPa.

e) From Table 4 (page 51 of BES repor1), at other borehole locations in lawn areas around the dwelling the bearing capacity of the stiff clay soils at 0.3m to 0.5m depth was noted as 150 kPa .

./) Point 8. Recommendations on Possible Cause of Cracking (page 52 of BES report), states, "Based on investigation results possible causes of cracking may be as follows:

The presence of very soft to soft natural clays up to 0.5m depth (BHf and BH2) which have low Allowable End Bearing Pressures:

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SUN.0702 0004.1791

• The presence of high moisture effected clays up to I.Im depth (BHI and Bf/4) possibly causing abnormal reactivity within the foundation soils;

The possibility of poor site drainage causing the above;

• The presence of roots possibly causing root j ackin){;

• Tire possibility of a slab and/or structural brickwork that does not accommodate for a Reactivity of Class fil having an expected free surface movement (ys) o/20 to40mm.".

vii. Comment

a) It is presumed the likely foundation bearing capacity at the time of the HPPS design would have been 100 kPa in line with Ordinance 70.

b) The minimum allowable bearing pressure for strip footings under current Australian Standard AS2870-2011 is 100 kPa.

c) At 100 kPa bearing capacity and the HPPS specified strip footing width of 650mm, this equates to a line load of 65 kN/m.

d) The unfactored total imposed (dead and live) load along the perimeter footings to the 2 storey dwelling are likely to be of the order of 30 to 35 kN/m which is significantly less than the 65 kN/m at 100 kPa. Based on the 650mm width of the HPPS specified strip footings this equates to a bearing pressure of approximately 45to 55 kPa.

e) The BES I Valley Civilab reports indicates the general bearing capacity of the foundation soils to the property at high level (300mm to 500mm below ground level) are typically 150 kPa, whilst there appears to be a 200mm depth band of less than 25 kPa soil through the central north-south area.

f) The actual depth of the dwelling footings has not been determined, as such it is not known if the footings are founded within the extremely low strength (less than 25 kPa) soil band or within the typical 150 kPa soil.

2. DWELLING FOOTINGS

i. HPPS structural details

a) The perimeter strip footings are indicated as 300mm deep x 650mm wide, reinforced with 6-FSTM top and bottom separated by R6 ties at 600mm centres.

b) The internal footings are indicated as 300mm deep x 400mm wide, reinforced with 3-F8TM top and bottom separated by R6 ties at 600mm centres.

c) The strip footings were to be locally widened at brick piers supporting steel bearers.

d) The ground floor slabs are indicated as 100mm thick infill slabs on ground reinforced with F62 fabric and constructed between the ground floor walls.

ii. Ordinance No. 70

a) Group VI. Structural Provisions, Part 33 - Footings Not on Piling or Caissons

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SUN.0702 0004.1792

Confidential

• sub-part 33.2 states: "Footings. including slab-on-ground footings, shall be designed and constructed so that any relative movement or separate footings and of different parts of any one footing under loading, or of a fooling and any other element of the substrucltlre will not impair the stability of or cause significant structural damage to the superstructure" .

• Sub-part 33.3 (5) states: "Strip footings constructed of reinforced concrete shall - (a} have a width and depth according to Part I of Table 33.3(5)".

• Part I of Table 33.3(5) states: 300mm deep x 450mm wide concrete footings for full masonry single storey building, and 300mm deep x 380mm wide concrete footings for masonry veneer double storey building -founded in soil "not subject to significant movement or loss of stability with climatic changes" (and not founded within sand or gravel).

• Part II of Table 33.3(5) states: for a 380mm wide footing reinforcement shall be 3-F8TM; whilst for a 450mm wide footing reinforcement shall be 4-F8TM.

b} An extract of the Table 33.3(5) is reproduced below.

IAtlLI) t J l f'>

..... . · - -:. ............ o.c-.. - · uo----- <)oo• " ..... _ __ c-... ....... .. F--

;?'.~=..--:=~ ..... ,.... .. ,. ..

iii. AS2870-1986

215357iun16 lel

a} Section 1 Scope and General

•

•

Clause 1.3 Design Requirements states: "The footing systems specified in this Standard are designed to ensure that acceptable probabilities of serviceability and safety are achiel'ed during the design life of the building".

Clause 1.3 Design Requirements states: "For the purpose of this clause - (a) the acceptable probability of failure is tire traditionally low rate for reasonable site conditions which include foundation moisture variations caused by seasonal and climatic changes, the effect of the building and subdivision, normal garden conditions and site conditions. A higher probability of significant damage is accepted in this Standard/or extreme site conditions such as (i) planting of trees too close to a footings: (ii) excessive watering to gardens adjacent to the house: (iii) lack of maintenance of site drainage; (iv) failure to repair plumbing leaks.".

Paga 5of 12

SUN.0702.0004.1793

Confidential

b) Section 4 Design of Footing Systems - Class M and Class H Sites

• Figure 4.7 Strip Footing For Articulated Masonry Veneer, Class H Site shows: 600mm deep x 300mm wide concrete strip footing with 3-12TM reinforcement top and bottom.

iv. AS2870-2011

a) Section 1 Scope and General

• Clause 1.3 Performance Of Footing Systems, sub-clause 1.3.1 General states: "Buildings supported by footing systems designed and constructed in accordance with this Standard on a normal site (see Clause 1.3.2) that is - {a) not subject lo abnormal moisture conditions; and (b) maintained such that the original site classification remains valid and abnormal moisture conditions do not develop (see Note l); are expected to experience usually no damage. a low incidence of damage category l and an occasional incidence of damage category 2 (see Note 2). NOTES: I Appendix 8 provides information and guidance on the maintenance of site foundation conditions. 2 Class A sites (as defined in Section 2) are not reactive to moisture and may have a lesser risk of damage to buildings constructed thereon.".

• Clause 1.3 Performance Of Footing Systems, sub-clause 1.3.3 Abnormal Moisture Conditions states: "Abnormal moisture conditions are those that result in foundation moisture variations beyond those for normal sites (see Clause 1.3.2). Buildings constructed on sites subject to abnormal moisture conditions have a higher probability of damage than those described in Clause 1.3. I.".

b) Section 3 Standard Designs

• Figure 3.6 (in part) Strip Footing Systems, Class H1 Site, Masonry Veneer shows: 850mm deep x 300mm wide concrete strip footing with 3-N16 reinforcement bars top and bottom.

c) Appendix B Foundation Performance and Maintenance

• Clause B3 Performance of Walls states: "It is acknowledged that minor foundation movements occur on nearly all sites and that it is impracticable to design a footing system that will protect the building from movement under all circumstances.".

v. BES Report

a)

2t5357jun16 lel

A comparison of the original HPPS footing specifications and AS2870-2011 requirements has been undertaken. The tabulated results (page 12 of BES report), see the extract table below, show the significant difference in the bending capacity of the strip footings of the original design and strip footings to AS2870-2011 . h h' h . I , Wit w IC we are m aenera aareeance.

I I Auumtd ,,.builr · Equiv1lrn£ roodai co "-ifl<dl"ooti .. ASWD lOll

l.ottdo. External lnttm1l EA1cmal ln1cn,l\f footing Foot in it Footiow FOOlinu

I Foodni Sia 650\V' JOO 0 -IOOW • lOOD R500 .d001V 850Dx JOOW

I Main 6 ;\ "'"'" bar Jx Kntm bar ) ·"- Nl6 bou l:tNl 11Nu Rt '•rorttSDHI 1nn & h11n 100Abll'U .... .tbun l('lf]t\ hlm I C1k ul1ud Momtul

Can•ril tKN.m\ l6 I 20 IH6 I Xb

Page 6of12

SUN.0702.0004.1794

b) The report (page 13 of BES report) states: "It is considered thaJ a loss of bearing capacity in the foundation material. and foundation settlement resulting from water inundation have induced excessive movement in the fooling system".

c) The report (page 13 of BES report) states: "The footing system's lack of capacity lo resist this movement combined with the lack of artic11/ation joints in the external masonry walls are considered to be the major contributing factors in the walls inability to <kjlect wilhoul suffering damage wider applied loads'.

vi. Comment

a) The HPPS specified strip footings, in particular the perimeter footings, are considered to be in accordance with the requirements of Ordinance No. 70, the building regulation at the time of design and construction.

b) The unfactored total (dead and live) load along the perimeter footings to the 2 storey dwelling are likely to be of the order of 30 to 35 kN/m. Based on the 650mm width of the HPPS specified strip footings this equates to a bearing pressure of approximately 45 to 55 kPa.

c) There is a significant difference in footing design from Ordinance No. 70 to ASZBTO, whereby strip footing proportions changed from 'wide & shallow (depth)' to 'deep and narrow (width)' along with heavier steel reinforcement with an overall significant increase in the bending capacity of the strip footings to AS2870 compared with those of Ordinance No. 70.

d) This change from Ordinance No. 70 to AS28TO represented a uniform national approach to footing design.

e) Strip footing sizes within AS2870 have changed only slightly since its inception.

3. MOVEMENT OF PERIMETER WALLS

i. AS2870-2011

a) Appendix B Foundation Performance and Maintenance

• Clause 83 Performance of Walls states: "Crack width is used as the major criterion/or damage assessment. although tilling and twisting distortions can also influence the assessment. l,ocal deviations of slope of walls exceeding I: I 50 are undesirable".

ii. AS3700-2011 Masonrv Structures

a) Section 12 Construction

• Clause 12.5 Tolerances In Masonry, Table 12.1 Tolerances In Masonry Construction, item (d) states: "Maximum deviation from plumb in the total height of /he building (from the base)" is"+/- 25mm".

iii. BES report

a)

b)

215357iJn16 let

A relative survey was undertaken to the external perimeter walls.

Relative wall displacements to each wall elevation varied from mostly 10-19mm, with a maximum of 26mm to the centre area of the northern wall ;

Page 7 of12

SUN.0702 0004.1795

Confidential

c) BES report (page 9) states:

"It is noted that lateral deviations in the order of 25mm over the height of the wall are considered to be within acceptable constmction tolerances under AS4100 (sic) Table I I (sic) - Masonry Structures".

• "The measured deviations are likely a combination of misalignment resulting from construction and subsequent displacements resulringfrom footing movement".

d) The report (page 13) states: ' The footing system's lack of capacity to resist this movement combined with the lack of articulation joints in the external masonry walls are considered to be the major contributing factors in the walls inability to deflect without suffering damage under applied loads".

iv. Comment

a) For an overall external wall height of approximately 5.1 m, the 1: 150 limit of AS2870-2011 equates to 34mm.

b) It would appear that the movement of the external walls some 32 years after original construction is generally less than the construction tolerance of +/- 25mm of AS3700·2011 and less than the 1 :150 limit (34mm) of AS2870-2011.

4 . CRACKING DAMAGE TO WALLS

i. AS2870.1-1988

a) Appendix A Classification of Damage, Table A1 categorises damage to walls. Table A 1 is reproduced below.

/\PPEN OlX A

C L ASSIFICATION OF DAMA08 (This Appendix forms an intc&al P3rt of lhi~ S1 ondr.1d. )

'fAHLE Al Cl .ASSl .. ICATION 01' OAMA<;E WITH REFF.R&NO: "10 WALu;

<;1M:'k1 "'"" I-.! lt'jlQ••,."11 •11.t fMtt\ll~f • .. •nllA 6lllOIW\t • I wwlf -.11 •w.tJ 10 ""' t cpl""..:J . o.,,_... "'"' ... wfO'I~ d d ~ll.'C" t it- , . .. frM'HIJC. WC';ltl.,t . 11 1tlt~\ VIII'• "'"NluN .

< s ...... )ftmto Ufl'laJ (ot oi n .. 11tb<r1 o f ,.,11.:ks >mm 10

S •1'fll ll'I Ol'W:"llf"WP)

• ~ "'"' 1 0 U 1nrn tM.11 uho dcpcnib

on n~iuher or ~-n<ks

ii. AS2870-2011

21S357iun16 lel

a) Appendix B Foundation Performance and Maintenance provides comment on damage to walls. Clause 83 Performance of Walls states:

• "ft is acknowledged that minor foundation movements occur on nearly all sites and that it is impracticable 10 design a fooling system Iha/ will protect the building from movement 111tder all circumstances. The expected performane£ of footing systems designed in accordance with the Standard is defined in Jerms of the damage classifications in Table CI. Appendix C'.

Page So! 12

SUN.0702.0004.1796

• ·For most situations Category 0 or I should be the limit; however, under advene conditions, Category 2 should be expected although such damage should be rare. Significant damage is defined as Category 3 or worse".

• "For Category I or 2 damage, remedial action should consist of stabilizing the moisture conditions of the clay and paying altention to repairing or disguising the visual damage. This should be regarded as part of the normal maintenance of buildings on reactive clays'.

"Even significant masonry cracking with crack widths over S mm often has 110

influence on the function of the woll and only presents an aesthetic problem".

b) Table C1 Classification of Damage with Reference to Walls, is similar to Table A1 from AS2870-1988.

iii. BES report

a) The report outlines cracking damage to various areas of the dwelling with the majority of cracking 1-2mm wide and 2-3mm wide and generally noted as Damage Category 1 to 2, with respect to AS2870. There are some isolated areas with wider cracks widths or a group of fine cracks and local splitting or bricks or loss of window sill bricks which have been noted as Damage Category 3. There Is one instance where there is local splitting of lower courses of bricks along the western wall of the garage and this has been noted as Damage Category 4.

b) The report (page 7) states: 'Most of the cracking to the external walls was limited 10

crack widths between Imm and 2mm, however because of the number and/or close spacing of the cracl<.s or associated damage to masonry units, many of the cracks have been classified as damage category 2 or higher".

c) The report (page 13) states: "The observed cracking to the walls has been caused by induced stresses in the walls as a result of foundation movement.

iv. Comment

a) The extent and size of cracking damage to the walls of the dwelling noted in the BES report is similar to that which we have inspected I observed and reported on.

b) With respect to AS2870-2011 Table C 1, the majority of cracking damage to the dwelling is Damage Category 1 "Fine cracks that do not need repair" to Damage Category 2 "Cracks noticeable but easily filled', and •Even significant masonry cracking with crack widths over 5 mm often has no influence on the function of the wall and only presents an aesthetic problem".

5. BES REPORT RECOMMENDATIONS

i. The report (page 13) outlines issues that need to be addressed that are "underlying cause(s) of the damage" to the dwelling, namely:

"i. The failure of the foundation material to provide adequate support to the footings. ii. The ability of the footing system to provide adequate resistance to imposed loading. iii. The ability of !he ground floor slab lo prevent the ingress of subterranean water flows into the building".

ii. The report recommends (page 14) "the best option for remediation of tire residence is the replacement of the existing footing and ground floor slab with a suitable ground slab complying with the requirements of AS2870 designed for the specific ground conditions known to exist" .

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SUN .0702 0004.1797

iii. The report (page 14 & 15) presents 2 options:

a) "Option 1. Temporary support a11d retention of part of the first floor structure and replacement of the ground floor slab".

b) "Option 2. Complete demolition and reconstruction of the entire structure in accordance with current Australian standards".

6. BUREAU OF METEOROLOGY

We have reviewed readily available data from the Australian Government Bureau of Meteorology records for Branxton, which is approximately 7.0 km from Lochinvar.

ii. The BOM criterion for classifying daily rainfall is:

1 O - 20mm is considered moderate. > 20 - 50mm is heavy. > 50mm is violent.

iii. In the month of April 2015 there was a total recorded rainfall of 359.4mm from the 21st to 22nd April, with recorded daily rainfall of 160mm on the 21st and 199.4mm on the 22nd_

iv. Recent historical records (from 1990 onwards) show recorded violent daily rainfall:

•

•

•

215357).Jn16 let

2014, April 26th, 79.2mm. 2013, November 18th, 98mm. 2013, March P', 53mm . 2013, February 24"'. 88.8mm. 2013, January 291h, 62.4mm. 201 2, March 3rd, 54mm. 2011 . April 17th, 55mm. 2009, April 1111

, 85.4mm. 2009, February 2nd, 182mm, with 260.8mm over 6 days. 2008, September 91h, 52mm. 2008, April 251h, 65.6mm. 2008, January 18th, 57mm. 2007, June 81h, 115mm, and June 9th, 193.4mm, w ith 308.4mm over 2 days (and 327.6mm extended over 4 days). 2006, September 10th, 82.Smm. 2005, March 181h, 72.6mm. 2004, October 21•1, 59mm. 2004, February 25th, 80.Smm. 2002, December 111h, 98mm . 2002, March 3Qth, 59.2mm. 2002, February Sth, 106.Smm. 2001 , March gtn, 75mm. 2001 , February 11 th, 59.2mm. 2000, March 2111, 68.6mm and March 22"d, 75.Smm, w i th 253.4mm over 3 days. 2000, March 9th, 55mm. 1998, August 8th, 62.Smm. 1997, February 12th, 56mm . 1996, December 121t1, 67.2mm. 1990, February 3'd, 145.4mm.

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SUN.0702 0004.1798

• 1990 February 41h, 93.8mm.

v. Over the past 25 years, the locality has had 3 severe storm events, namely in 2000, 2007 and 2009 prior to the April 2015 event; along with regular violent storm events (daily rainfall greater than 50mm).

vi. The recorded rainfall of the April 2015 storm event was approximately 17% greater than the previous highest event of 2007.

7. DISCUSSION. OPINIONS & SUMMARY COMMENTS

Based on the information provided, and review of relevant Australian Standards and building regulations we provide the following comments:

The construction of the dwelling is considered to be typical of its era of construction with shallow strip footings, infill concrete floor slabs on ground and non-articulated external brickwork walls.

ii. The original HPPS (1984) specified typical (perimeter) reinforced concrete strip footings, 300mm deep x 650mm wide. to the dwelling are considered to be consistent with Ordinance No. 70 the governing building regulation at the time of design and construction (1984 I 1985), which required 300mm deep x 380mm wide reinforced concrete strip footings.

iii. The likely adopted foundation soil bearing capacity at the time of the design and construction (1984 I 1985) would be expected to have been 100 kPa in line with Ordinance No. 70.

iv. The unfactored total imposed (dead and live) load along the perimeter footings to the 2 storey dwelling are likely to be of the order of 30 to 35 kN/m (or 45 to 55 kPa) which is significantly less than the capacity of 65 kN/m (at 100 kPa soil bearing capacity) for a 650mm wide footing of the HPPS design.

v. The actual depth of the dwelling footings has not been determined. as such it is not known if the footings are founded within the extremely low strength (less than 25 kPa) soil band or within the typical 150 kPa soil. Local excavations alongside some of the footings would need to be undertaken and the founding soil verified by a geotechnical consultant.

vi. The change from Ordinance No. 70 to AS2870 (nominally 850mm deep x 300mm wide) included significant changes in the design of footings from 'wide & shallow (depth)' to 'deep and narrow (width)' along with heavier steel reinforcement with an overall significant increase in the bending capacity.

vii. The footing system of the dwelling designed and constructed in 1984 / 1985 does not comply with current Australian Standards nor should it be required to do so. The dwelling appears to have been designed in accordance with building regulations and knowledge (of footing systems and foundation conditions) at that time.

viii. Movement of the perimeter masonry walls of the dwelling are considered to be within construction tolerances (i.e. tolerances that would apply at the time of construction of a bui lding) of Australian Standards AS2870-2011 and AS3700-2011; and the SES report also states "The measured deviations are likely a combination of misalignment resulting from construction and subsequent displacements resulting from footing movement', i.e. the movement is not the result of a single event.

215357jun16 let Paoe 11ol12

SUN.0702.0004.1799

ix. The majority of the crack widths to the walls of the dwelling are considered to be within the range of Damage Category 1 (<1mm) and 2 (<5mm) to AS2870-2011, and may be repaired in-situ. AS2870-2011 Appendix B Foundation Performance and Maintenance, Clause 83 Performance of Walls states "Even significant masonry cracking with crack widths over 5 mm ojien has no influence on the f unction of the wall and only presents an aesthetic problem".

x. Over the past 25 years, the locality has had 3 severe storm events, namely in 2000, 2007 and 2009 prior to the April 2015 event, with the recorded rainfall of the April 2015 storm event approximately 17% greater than the previous highest event of 2007. Storm events of similar severity will occur over time.

xi. Based on the majority of the crack widths being less than 5mm, the original HPPS specified shallow wide footings (300mm deep x 650mm wide) of the dwelling appear to have performed very well over its approximate 32 year life, when compared to the current deep footing design requirements of AS2870-2011 (850mm deep x 300mm wide for a masonry veneer dwelling on a Class H1 site), including its performance following the severe storm event of April 2015.

xi i. In conclusion, the observed cracking I movement distress to various areas of the dwelling designed and constructed in 1984I1985 in our opinion does not warrant the extent of works (replacement of footing system or complete demolition of the dwelling) nominated in the Burke Engineering Services Pty Ltd report that indicate its footing system should be upgraded to comply with current Australian Standards.

This letter report shall not be construed as relieving any other party of their liabilities, responsibilities or contractual obligations.

We trust this meets your requirements and please contact the writer should you wish to discuss any aspect of this letter report.

Yours faithfully,

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