WEATHERTIGHTNESS (INVASIVE MOISTURE TESTING) ASSESSMENT

Transcription

1 WEATHERTIGHTNESS (INVASIVE MOISTURE TESTING) ASSESSMENT 1 INTRODUCTION Inspection Date: 24 TH August 2016 Job No:47126 Property Inspected: 1-51 Watford Street Christchurch Weather Conditions: Fine Prepared For: Prepared By: Peer Reviewed Scope of Report: Thanyaporn Loakhajorn Don Baker MNZIBS (on behalf of Property Check (NZ) Limited) Darin Devanny MNZIBS, Dip in Building Surveying. Carry out an inspection to the external wall cladding of the dwelling and investigate any risk areas to weather tightness issues and carry out invasive testing where necessary to determine the likely extent of leaks. Date of Report: 26 th August 2016 Christchurch Blenheim Property Check (N.Z.) Limited 9 Nosworthy Street, Blenheim Unit 2, 48 Fitzgerald Avenue, Christchurch PO Box 370, Blenheim 7240 PO Box , Phillipstown, Christchurch 8145 Phone (03) Phone (03) Fax (03) marlborough@propertycheck.org christchurch@propertycheck.org Website:

2 TABLE OF CONTENTS 2 EXECUTIVE SUMMARY 3 3 LIMITATIONS 3 4 BACKGROUND INFORMATION Other Information 4 5 METHODOLOGY Site Inspection 4 Invasive Testing 4 Council Files 4 6 DESCRIPTION OF BUILDING Orientation 5 History of Construction 5 Construction Methods and Observations 5 Risk Factors 5 7 INTERNAL OBSERVATIONS 8 8 CLADDING SYSTEM - DIRECT FIXED/CAVITY 9 9 RESULT OF INVESTIGATION Results of invasive moisture testing CONCLUSIONS Leaks identified 13 Repairs required DISCLAIMER: 14 Page 2 of 14

3 2 EXECUTIVE SUMMARY The building has a direct fixed cladding system of solid plaster known as stucco over a soft board substrate with a bitumen coating applied to one face. Such systems by today s standard are no longer able to be used without incorporating a cavity system. Direct fixed cladding systems have known risks and failures relating to weathertightness; constructed details in exposed locations require sound and robust flashing systems to remain weathertight. The survey has identified leaks (section 9 of the report) that will most likely be originating from poor detailing around the perimeter of the balcony floor and timber framed balustrade walls that are without mechanical flashings system. Damage is likely to extend to timber decay and the need for timber replacement. The full extent of the damage has yet to be established and investigated. Leaks were also identified to the window located on the south elevation (photos 5 and 6) where water has the potential to penetrate between the aluminium frame of the window and the cladding that extends over the face of the frame. Further leaks and damage are likely to be found in those areas not yet tested where constructed details are the same or similar to those found to be leaking now. Low moisture readings were recorded at multiple testing sites around risks associated with detailing around window openings. Windows have a reliance on sealants and future failures may occur if not diligently maintained. It s apparent from some of the design and weathertightness risk features remedial works will be required both to stop the leaks and repair the damage. Consideration should also be given to providing lower risk details around windows exposed to the weather and with a reliance on sealant. In referring to the Building Act there are provisions to allow remedial repairs providing remedial works improve compliance with the NZ Building Code. Schedule 1 of the Building Act also allows repairs to be undertaken without a building consent providing the cladding has met its 15 year durability clause and providing that complete or substantial replacement of any component or structural assembly contributing to the building s structural behaviour is not required. 3 LIMITATIONS Invasive moisture reading results is not on its own a reliable method of determining weathertightness failure as wetting and drying cycles often occur in leaky buildings depending on the weather conditions leading up to the time of testing. Additionally, certain areas of a tested individual section of timber may vary from a wet to dry state along the piece of timber. Therefore it is not possible to determine the location of all leaks or the extent of them without removing the cladding entirely. The extent of damage from any weathertightness issues identified in this report is not known. Further investigation is required at the time of repairs to determine the extent of damage and repair required. The report is limited to the exterior wall cladding areas only unless otherwise stated in the report. Page 3 of 14

4 4 BACKGROUND INFORMATION The client requested Property Check to carry out an assessment on the risk locations of the building followed by invasive testing as necessary to establish the likely extent of leaks Other Information The client s Real Estate agent (Foss Shanahan) on behalf of the client provided a copy of the consented plans for the purpose of which is to establish if the cladding system incorporated a cavity system as part of the design for consent. 5 METHODOLOGY Site Inspection A visual inspection was carried out to the entire building to determine the general risk areas. A Protimeter moisture meter was used in scan mode to assist in identifying damp areas within the cladding, skirting and wall linings. There are limitations with moisture scanning. Scan devices are influenced by rubber, metal and other materials and may provide false readings. Additionally, they are not able to pick up moisture presence deep within the components being tested a wall or ceiling for example. In summary the scan devices are sometimes useful but cannot be relied upon and any results returned that suggest the presence of dampness requires further investigation and not to be taken as conclusive. Photos were taken using a 4 megapixel digital camera Invasive Testing Once risk locations were identified, invasive testing was carried out using a Protimeter MMS to obtain moisture content readings of the framing and logged in Table 1 in section 9.1 of this report. Sealant was used to fill the holes to temporarily prevent leaks at the testing sites. The holes will require filling and painting as a more permanent measure. The cause of leaks identified has not been investigated as this is not part of the brief. Not all areas at risk have been investigated. Once a pattern of readings were returned it has been assumed on reasonable grounds that the areas tested provide a representative scenario for other similar areas Council Files The council files were not viewed during the investigation. Page 4 of 14

5 6 DESCRIPTION OF BUILDING Orientation For the purpose of this report the main entrance is on the east elevation History of Construction Age of dwelling: Circa 1995 (noted on the stamped consent plans) Construction Methods and Observations Foundation type: Concrete wall Floor structures: Ground floor - Concrete slab. First floor Suspended timber floor Wall framing and cladding: Timber framing with a direct fixed plaster (stucco) cladding system. Roof cladding: Long run corrugated steel External Joinery: Aluminium large/small units, without head flashings, recessed, double glazed. 6.4 Risk Assessment Risk Factors Photo examples The building is clad with a monolithic cladding system with a soft board substrate known as Triple S that is directly fixed to the timber framing. It is known that this type of cladding system is at risk of leaks when exposed to weather and not constructed over a cavity system. Cavity systems are now compulsory in such designs and construction methods The external walls have high exposure to the weather and any weak and exposed junctions are at risk to allowing moisture ingress. Page 5 of 14

6 6.4.3 The bottom of cladding previously extended below finished ground that appears to have been excavated away from the cladding that now may allow water to pond and seep into the framing There is no horizontal or vertical movement control joints in the external walls that would prevent stress build up that could lead to cracks occurring The plaster claddings are built up over the sides and lower window frames where cracks are appearing and are likely to allow moisture to penetrate into the wall framing Sill flashings have not been incorporated into the window sill and cladding junctions. Water may be penetrating the junction point which is reliant on sealant and cracks may develop Head flashings have not been fitted. Water may be penetrating the junction point which is reliant on sealant and cracks may develop. Page 6 of 14

7 6.4.8 The cladding finished hard down onto tiled surfaces (balcony) and with no provision of a capillary breaks provides significant risks for moisture penetration Fixings located between tiles securing metal balcony balustrade rails penetrate water-proofing membranes and may allow moisture to penetrate There is no provision of drip edges and visually water proofing membranes appear to terminate behind the cladding and may be allowing for moisture to ingress. Page 7 of 14

8 1. 7 INTERNAL OBSERVATIONS Observations Photo 1. Showing evidence of moisture damage, left side of main garage door Obvious signs of water damage affecting timber skirting. Swelling of timber skirting that appears to be confined to the external walls of the lounge, family room and the northwest bedroom located on the first floor. Moisture scanning recorded slightly elevated readings. The use of short pin probes gave no indications of dampness. Photo 2. Showing evidence of moisture damage right side of side garage door Photo 3. Showing swelling to timber shirting fixed to the external walls. Page 8 of 14

9 8 CLADDING SYSTEM - DIRECT FIXED/CAVITY Investigations have identified the cladding system (Stucco) has being applied without a cavity and with a soft board substrate known as Triple S. Photo 4. Showing the cladding substrate as a soft board with a product name of Tripple S Consented plans show: 3 coat plaster finish on mesh on building paper on Hardibacker. Specification show: Plaster will be 3 coat over diamond rib-lath and building paper Page 9 of 14

10 9 RESULT OF INVESTIGATION 9.1 Results of invasive moisture testing Key: - This key measures the risk to moisture leaks and likely decay. The low risk range is uncertain and depends on whether the timber has reached this range as a maximum or weather it has been at a higher range in the past. Less than 16% = Very low risk, 16% 21% = Low risk, 21% 25% = High risk, 25% and above = Very high risk, Decay = Destructive testing location - = Not able to test Table 1. Invasive and destructive testing results Test Locations Description of Risk Photo 2. South and part west elevation. Risk: Plaster cladding built up over sides and lower window frames. Photo 5. Recording high levels of moisture at 25.5% in timber sill Ground excavated away from bottom edges of the cladding. Results: Leaks identified. High levels of moisture recorded in timber framing and timber architectural plant on window sills Photo 6. Recording high levels of moisture in timber framing 21% Observations: Timber appears firm during drilling. No obvious signs of decay on swarf from drillings. Recommendations: Further investigations that will require the removal of cladding that will allow inspection of timber framing to determine the extent of damage to framing if any. The removal of timber samples for analysis may be required. Page 10 of 14

11 3. West elevation Risk: Plaster cladding built up over sides and lower window frames. Ground excavated away from bottom edges of the cladding No provision of drip edges, water proofing membranes appear to terminate behind the plaster cladding Walls have high exposure to the weather and weak and exposed junctions are at risk of allowing moisture ingress. Photo 7. 23% Recording high moisture levels at Results: Leaks identified High levels of moisture recorded in balcony floor framing. Observations: Swarf from drillings suggests timber decay. Recommendations: Further investigations that will require the removal of cladding that will allow inspection of timber framing to determine the extent of damage to framing and extent of timber replacement. The removal of timber samples for analysis may also be required. Page 11 of 14

12 4. North elevation Risk: Plaster cladding built up over sides and lower window frames. No provision of drip edges, water proofing membranes appear to terminate behind the plaster cladding Walls have high exposure to the weather and weak and exposed junctions are at risk of allowing moisture ingress. Photo 8. Recording very high levels of moisture in balcony floor framing 83.2% Photo 9. Recording very high levels of moisture in balcony floor framing 52.4% Results: Leaks identified Very high levels of moisture recorded in balcony framing. Observations: Swarf from drillings indicates timber decay. Recommendations: Photo 10. Recording very high levels of moisture in balcony balustrade wall framing 34.3% Further investigations that will require the removal of cladding that will allow inspection of timber framing to determine the extent of damage to framing and extent of timber replacement. The removal of timber samples for analysis may also be required. Photo 11. Recording high moisture levels in bottom plate framing balcony balustrade wall 24.1% Page 12 of 14

13 10 CONCLUSIONS 10.1 Leaks identified Leaks have been identified in floor framing of both balconies and in the balustrade walls of the northeast balcony. Very high to high readings together with swarf from drillings suggesting timber decay are a strong indicator that timber replacement will be required. Damage is likely due to water discharging from the tiled floor of the balconies and migrating between the cladding and water proof membranes around the perimeter. Leaks have been identified beneath the window on the south elevation (photos 5 and 6). The extent of any damage will be dependent on the duration and frequency of leaks. Evidence of moisture damage (swelling) to skirting identified in the lounge, family room and first floor bedroom are the likely result of the cladding having been located below finished ground and would have provided risks for moisture penetration by means of capillary action where water would readily be drawn up into the claddings substrate of soft board. Moisture testing recorded low to being elevated. Finished ground appears to have subsequently excavated away from the cladding that would result in low moisture readings Repairs required Carry out further invasive and destructive investigations to identify the full extent of leaks and damage and obtain a repair strategy and design for the replacement by a suitably qualified designer. This may include the replacement of cladding due to the high risk details around balcony wall and floor junctions Timber sampling if required should be undertaken by a registered building surveyor at the time of timber framing being exposed. Obtain a building consent if required. Remove any framing affected by fungal growth and or decay. Timber not affected by fungal growth and decay must be dried out to prevent future risk of decay. Treat exposed timber with in-situ timber treatment to improve durability levels. Install new cladding system or repair as required. Page 13 of 14

14 11 DISCLAIMER: Property Check has carried out thorough inspections to many parts of the dwelling to determine the moisture levels in the framing at various locations so they can obtain indicative readings and information about the likely condition of the framing. Not all locations were tested and no guarantee can be given by Property Check that any particular part of the building is free from damp or decay, including the areas tested as well as untested areas. Information relating to repairs should be used as considerations to the overall repair strategy and not construed as directions for repair from Property Check as we hold no liability for design or instructions to remedial work. All significant maintenance should be carried out by appropriately qualified individuals. PROPERTY CHECK (NZ) LIMITED Don Baker MNZIBS Page 14 of 14