Wednesday, September 28, 2011

如何看待针对同一个房产的不同检测报告



我们经常对其他检测公司所出的检测报告提出质疑,也经常有其他检测公司对我们的报告提出质疑,这在房屋检测行业里是稀疏平常的事情。 最典型的例子是在漏水房调节法庭上原告和被告的建筑专家永远都会持不同见解。我们会下意识维护我们的意见,但不排除我们会有错误的见解,就好像任何大夫都有可能误诊。

我们收到一位客人转给我们的一份卖方出具的报告,意图是证明我们所提出的问题不是严重问题。客人当然希望我们对此进行评论。

我们没有做过多的解释,建议客人如果质疑我们的服务,可以找相关机构投诉,但就如下几点提醒了客人:


  1. 卖家的检测报告只对卖家有法律效力,买家可以相信,但如果报告有任何误导,属于自愿;
  2. 每一个检测人员的专业不同,侧重点不同,检测方式,时间,所用工具,天气等不同,所得结论很可能不同;
  3. 检测报告的针对性很强。往往针对买家的关注点不同,报告的侧重点也不同。有些买家只关心房子是否是漏水房,有些买家希望罗列任何细小问题用来作为和卖家进一步谈判的筹码,有些买家不做任何指示,完全由检测人员自己决定,有些买家希望口头描述和书面报告分别针对不同目的,等等;
  4. 在犹豫时,最好咨询自己的律师,看看他认为谁的意见应该采纳;
  5. 再次明确合同方:买家和卖家的检测人员没有任何合同关系。
  6. 我们的忠告:欢迎对我们的意见提出质疑,但请您雇佣您自己的检测专家。

Tuesday, September 27, 2011

Timber treatment testing

Recently a client called for a pre-purchase inspection. His special requirement is to cut a hole through GIB lining and take a timer sample to determine the timber treatment. As he mentioned, he has obtained an approval to do so from the owner.
We tried our best to tell him why this is not appropriate for a pre-purchase inspection and why this does not help him with decision-making.
In another situation, a client has entered into an purchase agreement subject to an innovative condition: timber treatment.
Here is the summary of our opinion regarding timber treatment testing:

Scope of timber treatment
We can not give an Yes or No answer regarding the timber treatment of a regular house. We must define the timber treatment type, retention, distribution and location within a building.


  • Type: Even for framing timber only, there are different types of treatments required for different framing parts. It is common that timber treated to H1.2, H1, H3.1, H3.2 are all found within timber framing of one house. 
  • Retention: One piece of timber may be treated to a certain level, say H1.2. But due to constant exposure to moisture, its preservative is largely diluted and the actual preservative left inside the timber may be far away from H1.2.
  • Distribution: Preservative inside timber frame is never evenly distributed. It is common that a piece of timber specified to a certain level of treatment is found to be under-treated or untreated at all.
  • Location: When legally different treatments required for different areas such as wet area, exterior framing, eave framing, low pitch truss, high pitch truss, high wind zone vs. low wind zone and etc, the on site reality is often different when builders making their own mind.

So, without clarification of the above mentioned scope of timber treatment, we can not answer the question even enough samples are obtained.




How many samples are required and how big samples should be?
If you are lucky, you may get consent from the owner to take a timber sample. But where do you make your cut? bottom plate, top plate, wet area, internal framing? risky area, control point, foundation framing, flat roof framing? What about if a core sample is required to define the treatment in the middle of a piece of timber? How can you take a timber core sample without affect the actual framing integrity?

Who can give you the right answer?
So, if somehow you have got enough timber samples for framing in almost all areas, don't think that a pre-purchase inspector will give you a clear answer straight on site.
So far, base on current technology, the only reliable way to determine timber treatment of timber samples is to through lab testing.
Are you ready to pay for this laboratory test? Are you ready to interpret the complicated test result? Any idea how long you need to wait before the test result can be ready for you?

Why do you need to find out the timber treatment?
Will the result of the timber treatment answer your question: is the house a leaky house? If the timber is treated, will the house be safe? If the timber is treated, will that mean there are no rots? So, if timber treatment is not the answer for the above raised questions, why you are so particular about timber treatment at all?

Within our building industry, sometimes we do need to be precise in terms of timber treatment, for instance, we need detailed timber treatment information for leaky building remediation design work. In that situation, taking samples and making cut-outs through cladding are not a issue. But back to pre-purchase inspections, we can not see any point at all for timber treatment testing.






Monday, September 5, 2011

淋浴房墙面材料

最近有若干咨询淋浴房瓷砖铺设的电话,不妨在此做简单说明,便于大家参考:

如果墙壁是瓷砖,地面是成型塑料(acrylic base),出问题的概率会很高。因为瓷砖墙面并不防水,这也是为什么瓷砖背后要有防水膜(waterproof membrane)的原因。

水一旦在瓷砖背后形成,受重力影响向下流,需要有适合的通路排出。当地面是瓷砖时,墙砖背后的水会流到地砖的下面,然后顺地面斜坡流向地漏。

如果采用成型底托(acrylic base),底托的周边会堵住墙砖的底部,这样一旦墙砖背后进水,不能够顺利排出,堵在背后形成水坝,天长日久导致漏水,对墙体形成损坏。

Sunday, September 4, 2011

有关木结构湿度-regarding timber moisture content

经常看到一种报告叫做湿度报告moisture report,里面罗列了一大堆数字,是所谓检测记录的湿度。最近又有人打电话说签订了购房合同,条件是木结构是否是药物处理的-subject to timber treatment。也经常接到很多电话询问有关湿度问题,是否有“安全湿度”-moisture threshold 这一概念呢?

首先要澄清我们如何获得木结构的湿度-timber moisture content。严格上来讲,除非我们用钻孔的开放式检测,我们无法真正得到木结构的湿度,即使我们用开放式检测,我们也只能得到局部的木结构湿度。更严格讲,只有通过对木头烘干前后的重量对比才能够真正得出木头的湿度,其他的测湿方式都有各自的局限性。
我们当然会用一些非侵犯性的测试仪来检测木结构的湿度,但局限性很多,准确性要结合具体检测人员的实践经验。注意,用红外摄像也不能够得到准确的木结构湿度:红外反映的是物体表面温度,和湿度没有对等关系。

一般的非侵犯性测湿仪的检测深度不超过40mm,如果石膏板加上木墙裙的厚度是20mm,那测湿仪的范围是可以达到木结构的。但测湿仪的范围是在0-40mm之间,所以显示的数字不只代表木结构,如果测湿是在卫生间的瓷砖地面的话,测湿仪显示的是瓷砖,水泥胶,防水膜,木地板等的综合指数。

而且这种湿度指数并不能够转换成为湿度百分比,只能作为参考的根据用于和正常干燥部位的指数进行对比。所以如果你们手里有湿度报告,我首先要怀疑这一报告是如何做出来的。目前世界上还没有任何一种仪器可以通过非侵犯检测方式(non-invasive testing)来得出墙板背后的具体的木结构湿度。

很多检测报告都会说明,如果木结构湿度在18%以上,就有可能腐烂,进而18%被很多人认可为安全湿度。实际上到底湿度是多少才能导致腐烂,目前科学界没有结论。如果我们说得具体一些:

真菌的繁殖爆发湿度(trigger point for fungal decay)大约在30%,意思是,在干燥的环境下,即使湿度达到18%,真菌也不会泛滥。但真菌的存活环境湿度(survival environment for fungal decay)大约是18%-70%左右,意思是如果腐烂已经形成,那即使是湿度降到18%,腐烂也不一定会停止。

那木结构的湿度如果超过18%,是否意味着房子漏水呢?未必。木结构的湿度和周围的空气环境有很大的关系。如果空气的湿度长期保持在100%,那木结构的饱和湿度大约可以达到30%。我们检测过的几个Titirangi 的房子,冬天半地下地基部分的木结构湿度在25%左右,是和Titirangi的森林环境有关系。所以在那里盖房子,政府对房屋设计和木结构药物处理有特殊要求就不足为奇。分析是否漏水,我们不能根据单独的湿度来做结论,要根据怀疑点(subject point)和安全点(reference point)的读数对比来做结论才有可能合理。

总而言之在进行pre-purchase inspection (购房检测)时,由于检测方法的限制(买家不能对要购买的房屋进行侵犯性检测)木结构湿度不能够作为评价房子是否是漏水房的依据,而且事实上也无法真正得到木结构的百分比湿度。

其实房子是不是漏水房,最关键的是要看它的设计和施工工艺,所以检测人员需要懂建筑(construction)和建筑理论(building science)。注意这两个方面是有区别的,前者是知道怎样建房子,后者是懂得材料,建筑方法,工程学等的物理和化学表现。检测仪器只能是辅助工具,不能成为检测的全部。就好比:靠花钱买好设备是不可能成为好医院的,一定要有好大夫才是关键。


Thursday, August 18, 2011

Can we give "Not Leak" guarantee for houses we inspected?

Very Tough question.

To answer that question, I would like to refer to a particular CASE:  TRI-2009-101-000060
In this case a pre-purchase inspector is found to be liable for his report and ordered to pay more than $20000.

So, it has happened. We have to be careful about reports we issued. The key point here is not "guarantee". Focus of judgement here is whether the inspector is negligent.

Our opinions have to be "fair" and "independent" and based on "competency".

In other words, if my opinion is fair and independent, but I'm not competent enough to carry out house inspections, I may be found negligent.

Or, if my opinion is not fair and independent, even if I'm competent enough, I can still be found liable for negligence.

But, if my opinion is fair and independent, and I'm competent enough to carry out house inspections, then I may not be liable even my opinion is proved to be wrong.

So, when I say "Not leak", this is to be regarded as a conditional guarantee. Though I have to say, very hard to find me saying "Not leak".

有关检测资格


根据新西兰相关标准NZS4306规定:
  1. 检测人员需有适合的包括房屋检测在内的建筑行业相关经验
  2. 为相关行业协会会员,或者持有相关学历
  3. 熟练运用房屋检测专用工具
有几点误区需要澄清:
  • 国家没有硬性规定,检测人员必须是:master builder, certified builder, registered builder, qualified builder,但必须有足够相关经验. 
  • 国家没有相关针对房屋检测的行业协会,没有所谓的从业资格认证,没有所谓的资质
有意思的是,Certified Builders Association 以及 Master Builders Association都委婉的表述不希望他们的成员从事购房检测这种高风险行业:请参考NZ Herald的相关新闻

大家不约而同把这一行当拱手让给Institute of Builder Surveyors, 但有兴趣的人可以打电话给所有这个协会网站上所列的building surveyor,看看是否能够找到一个做购房检测的人-prepurchase inspector. 我很想搞清楚,目前是否有哪个行业协会站出来主动承担规范购房检测这一市场。

本人有8年建筑行业经验,2年房屋检测经验
本人持有建筑监理文凭 - National Diploma in Construction Management
本人为房屋署注册二级监理和木匠 - DBH Licensed Building Practitioner Site 2 and Carpentry (LBP)

本人通过如下国家建筑检测师学院(NZIBS) 培训课程:

1. Property of moisture - 水的特性

2. Forensic techniques - 房产诉讼案件调查技巧

3. Identification of risk elements - 鉴别房屋风险点

4. Recording and reporting - 记录和报告

5. Decay, fungi & mould - 腐烂,霉菌和霉斑

6. Repair process based on site investigation - 基于现场调查的修复程序

7. Condition/compliance reporting - 房屋状况及规则符合报告

8. Asset management, maintenance planning - 房产管理及维护计划报告

How long a standard house inspection can take?

First need to understand what is a STANDARD house inspection. Check our website to find out what included in a standard inspection.

Unlike special inspection, such as flooding inspection, some time can only take a few minutes, a standard inspection for a average house (say 3 bedrooms & 2 bathrooms) should in general take 1.5-2 hours or even longer. According to NZS 4306, there are hundreds of items to be inspected to complete a standard inspection. No matter what kind of tools being used to assist with the inspection, we still need to go though the whole process, and we do not see any possibility to shorten the inspection time.

To limit the time spending on site and to be in cooperation with other related parties such as owners and real estate agents, we have two inspectors working at the same time, so that we can significantly shorten the time spent on site without compromise the quality of inspections.

Meanwhile we provide free verbal on site consultation to our clients, specially Chinese and other Asian clients who's building knowledge is very limited. This consultation can sometimes take a hour.

So overall, even we have two inspectors doing one inspection at the same time, it normally take us 1.5-2 hours to complete the site visit. As rule of thumb, see the following table for some ball park figures:

Type of house On site inspection time to be allowedOn site verbal consultation 
Single story brick & tile 3 bedroom house on flat section  30min 30min
Monolithic clad house 1990's 50min 40min
Architecturally designed multi story  60min 30min



Understanding maintenance of monolithic type cladding

Traditionally cladding maintenance was a typical DIY job, consisting surface cleaning, minor repair and recoating, which builders and some traditional families can easily handle.  

Things come to monolithic cladding systems (including EIFS, texture coated fibre cement sheeting, stucco and the like), maintenance of them become very complicated due to the following factors:

  1. Cladding repair of this type of cladding is no longer the Builder’s job. In fact very hard to find out who is the right professional for its maintenance, could be either the carpenter, painter, exterior plasterer, waterproofer or combination of them. Depends on the condition of a particular cladding, it is not easy to work out who is the right person to refer. When you use a wrong person to do this type of cladding maintenance, the job can turn to be a disaster: The photo shows a subcontractor applied interior stopping compound onto the texture coated EIFS surface when trying to do repair for some surface scratches and minor damages.
  2. Once applied, coating and cladding material become one integrated system, therefore common re-coating process such as stripping-off the old paints for timber weatherboard becomes impossible. So the solution could be expensive if the application of the re-coating is wrong. Very common that a new coating system is not compatible with the old coating system, even though the new coating system itself is a very good product. But find out what is the original coating system sometimes can be a mission.
  3. Maintenance can be significant or minor depending on the condition of the cladding system. When the cladding system is systemically defective the maintenance can mean a total re-cladding. In other cases, when not much wrong with a cladding system, maintenance can be a simple washing-off. 
  4. There is no clear line when the re-coating is due. Due to the high possibility of defective recoating job, we do not recommend carry out any total re-coating work to any monolithic cladding without expert’s opinion. We have seen too much recoating disasters. Again who is the recoating expert? 
  5. How can you tell if your cladding is due for maintenance? No clear answer. But very common when somebody has realised that the cladding is due for maintenance, it is too late to realise that. So having your cladding checked every couple of years by an Expert is a wise way rather than decide yourself unless you is the Expert. 
Some clarifications useful when thinking about maintenance of monolithic type cladding:

  • Most of monolithic cladding coating systems are not “paints” normally applied on timber weatherboard, fence palings, garage doors and the like. 
  • Normally carpenters are not specialised on fixing a minor damage on monolithic cladding, nor painters. 
  • Interior plastering and exterior plastering are totally different trades. In fact from March 2012 exterior plasterer will need to be licensed. 
  • Based on the fact that most monolithically clad houses were built 10 years ago, today most of those houses’ wall claddings are due for total maintenance. There are very limited amount of companies are competent in doing that.
  • Significant amount of monolithic houses have wall cladding somehow integrated with roof parapet or even roof cladding and deck balustrade, which make maintenance more challenging. 
  • When there is no clear line between a leaky house and a non-leaker, further more the exterior wall cladding coating is regarded as a part of the whole weathertight system for this type of cladding, it will be hard to find any company specialised in maintenance of plaster system which can issue workmanship warranties.
  • When you see cracks on the monolithic cladding surface, simply squeeze a tube of silicon is not the solution and often can cause disaster. 

The following links may be useful for your further study regarding maintenance to monolithic cladding system. You may find some companies via those links which are experts in this type of cladding maintenance, but currently we do not have any particular name to recommend. We would like to hear from you, if you are competent in doing so and have some references to show.

http://www.duluxacratex.co.nz/assets/pdf/BRANZ/EIFS-BRANZ-approval.pdf

http://www.dryvit.com/fileshare/doc/us/description/ds498.pdf

http://www.resene.co.nz/homeown/h2pyhome/Painting_Concrete_&_Plaster.pdf

http://www.alliedexteriors.co.nz/
--------------specialised in monolithic cladding maintenance. 批灰外墙面维护公司

Thursday, August 11, 2011

Notes regarding Terms & Conditions of a standard inspection report - 3

Estimating the cost of remedying defects is not included in a property report, although it may form part of a special purpose property report.


Notes regarding Terms & Conditions of a standard inspection report - 2

The property report is not a warranty against problems developing with the building after the date of the report.


Notes regarding Terms & Conditions of a standard inspection report - 1

A property report should not be seen as an all-encompassing report dealing with a building from every aspect. 
Our inspection is limited to around 1.5 hour on site and 4 hours of desktop work, so there is no way we can report absolutely every single detail regarding the subject property. Our focus is to report for aspects which regarded as significant.
Yes, often after moving in to the new house, you can always find something which is not reported. Think about that before calling us back: Is it a issue? concern? Is is significant enough to be shown in the report?
我们无法通过短短的1.5小时的现场时间来包含对所有房屋细节的检测,我们只能把有限的时间放在对关键点的检测
很可能入住后,你会发现有某个问题我们没有在报告中描述,这有可能是我们的严重失职,但大部分情况不是这样。
我们有时会接到电话提及“有个地方你们报告上没有写,你们能回来看看吗?”我们正在努力满足这样的要求,但can not promise

Monday, August 8, 2011

检测的目的

根据NZS4306中2.1.2规定:
The purpose of the property inspection is to identify significant defects visible at the time of the inspection
意思是:查出现场可以看得出的重要问题
曾经有一位客人对我们的能力提出严重质疑,因为我们没有看到独立车库的后门难以打开。
当然也有人认为,有一块水泥瓦裂开了,这是一个很重要的问题 - significant defect,而且是现场必须看得出的。

房顶检测高度规定

根据房屋检测国家标准4306的规定,房顶检测部位要不超过3.6m梯子可以够得到的高度。
我们的梯子高度是3.85m,即使这样很多房顶的部位无法看到。
有一位客人,我们检查完所有的项目后,他提出要求,需要看到所有的房顶,我无法满足,但他认为房顶对他最重要,其他位置他自己也可以检查,不需要我们看。
我没有收费,我认为他需要找的不是房屋检测人员,应该是房顶维护公司。
需要提醒的是:对于买房检测,检测人员不允许蹬踏房顶,只能目测。

Should inspector be Registered? Licensed? Qualified? Certified?

According to NZS 4306, an inspector is to:

  1. Have relevant practical experience in NZ building industry including building inspections and
  2. Be a member of a relevant professional or trade organization, or hold relevant technical qualifications and
  3. Be competent to operate any specialized equipment used in the property inspection

Saturday, August 6, 2011

house inspection report: Mould

house inspection report: Mould: "More and more inquiries regarding moulds growing on ceiling linings. Most owners regard moulds on ceiling as signs of roof leaks. In most c..."

Sunday, July 10, 2011

Mould

More and more inquiries regarding moulds growing on ceiling linings. Most owners regard moulds on ceiling as signs of roof leaks.
In most cases moulds growing on ceiling lining has got little if any relationship with roof leaks and often caused by combination of a number of reasons such as:

  1. Lack of or insufficient or unevenly distributed ceiling insulation
  2. Poor home natural or mechanical ventilation
  3. Poor subfloor ventilation
  4. Poor ceiling lining material or coating
  5. Lack of general maintenance
  6. Excessive surrounding vegetation
  7. and other factors 
It normally associated with old houses and not too hard for owners to find out reasons by themselves.
In most cases the solution would be a combination of a total roof service by a roof maintenance professional, retro fit of new ceiling and under floor insulation, installation of heat pump and/or home ventilation system, general cleaning, landscaping maintenance and so on.

Tuesday, June 21, 2011

房顶检测与房顶保修

针对售房检测——pre-purchase inspection,检测人员是不允许登上房顶的,这就意味着很多房顶的部分无法检测或者目测,所以我们会明确强调检测不是保修。
当卖旧房子时,我们会建议入住前找专业的屋顶维护公司做一个全面的维护,他们会在实行维护后给一定期限的保修,但老房顶一般不会超过一年。

Monday, June 20, 2011

房顶维护——镀锌铁皮顶

房顶寿命:镀锌瓦楞铁皮galvanised corrugate iron sheets一般不超过30年,这种瓦顶在1960-1970期间被大量采用,大部分使用至今没有更换。这一部分房顶目前大部分已经使用了50年左右,差不多到了寿命极限,进而频繁出现漏雨的问题。
当远远超过寿命的瓦顶还在使用时,漏雨的可能性很大,而且导致漏雨的原因也很多,特点如下:
1. 经常只有在极端恶劣气候条件下才漏雨;
2. 经常只有小漏,没有大漏
3. 有时几乎无法查出漏雨原因
如果不想花钱更换整个房顶,基本没有办法保证在极端气候下不漏雨,但如下方法可以减少漏雨的可能性:
1. 将所有钉子更换为螺丝
2. 更换老化的挡雨板——roof flashing
3. 加装棚顶保温棉,可以吸纳小量漏雨
4. 每半年检查一次房顶,每一年由专业公司做全面房顶维护
如果一个50年的老房顶在我们检查的时候不漏水,丝毫不意味着当你入住后不漏。我们的房屋检测不是给一个老房顶从新发放保修证。

Thermal Imaging

Due to considerable limitations, we do not regard Infrared Camera as the main inspection tool (specially for leaky building diagnosis):

  1. It is highly weather dependent,
  2. Its accuracy largely affected by mirrors, furniture and reflective items around targets
  3. In many situations, there is little if any relationships between temperature and moisture
Therefore we do not charge for using infrared camera during inspections. It is simply one of varied tools we used to assist our inspection.

It occasionally very useful when we check plumbing leak and flooding issue. Infra-red scanning can quickly locate plumbing leak source, but again not always.

Remember the best tool in house inspection - experience.

Sunday, June 19, 2011

Borer treatment - 蛀虫处理

Pest control
If not borer attack is severe, you can do it yourself by using spray product such as "No Borer" selling in Mitre 10 and many other stores.
But if borer attacks are so severe and access so hard for you to manage yourself, then ask professional to do it, google pest control or borer treatment, you can find heaps of company offering such services.
如果不严重可以买 No borer,
如果很严重,又不方便自己处理,可以找专业的公司,google Borer treatment,或者点击这里的链接
http://www.fraserpestcontrol.co.nz/borer_control_in_your_dwelling.htm

moisture testing vs. timber condition - 1

It to be noted that, numerous destructive investigations have proved that high moisture is not always resulting timber decay, and mostly important timber decay is not always associated with high moisture.
Accordingly we do not provide "moisture report" only as this type of report provides very limited information to support buyer's decision making.