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。

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.

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。

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。