和這位老兄聊了幾句,他竟遞給我一疊名片,(新移民,剛來兩個月,想要有多一些的活,可理解)BY THE WAY, 需要他的聯系電話的,給我短信了。
在溫哥華這個地區用德國slate不是個好選擇。
Material standards for roofing slate
There are two main standards for roofing slate: The EN DIN 12326 und the ASTM which will be introduced here.
If one compares both it becomes obvious that the EN 12326 comprises considerably more investigations and tests to classify a roofing slate. The investigatons of the petrography, mineralogy and fabric are not included in the ASTM. Furthermore, no test for freeze-thaw resistance has to be carried out in the ASTM.
The assessment of the service life within the ASTM C 406 seems to me a kind of simplifying because processes of weathering and the corresponding behaviour of the rocks - no matter if slate or any other rock - is very complex. Due to this, its hard to make statements about service life only based of tests in the laboratory.
In my opinion the EN 12326 leads to more informationen of the properties of a (roofing-) slate and should be therefore preferred.
ASTM C 406 - Standard Specification for Slate
This specification describes the material properties and physical requirements as well as the ways of sampling and testing. The following terms are defined:
service life: the period of time over which it is expected that no replacement or repair is necessary due to weathering.
ribbons: Narrow bands of carbonaceous material whch are darker in colour than the surrounding slate. Ribbons are supose to be inclusions of the original beds and are expected to be softer and less durable the the surrounding slate.
The classification of the roofing slates is as follows:
classification
min. Breaking Load
[lb oder N]
max. Absorption
[%]
max Depth
of Softening [in o. mm]
Grade S1
575/2558
0.25
0.002/0.05
Grade S2
575/2558
0.36
0.008/0.20
Grade S3
575/2558
0.45
0.014/0.36
The standard states that when comparing slate of same grade and equal thickness but from different sources, slates which meet the required breaking load at the lowest specimen thickness will yield the best performance.
The expected service life of roofing slates of different grades can vary, depending on the location and different environments and is as follows:
classification
Service Life (years)
Grade S1
over 75
Grade S2
40 to 75
Grade S3
20 to 40
Furthermore, statements about the appearance has to given:
The commercial colour should be preceded by the words:
"unfading" = colour doesn't alter
"semi-weathering" = little alteration due to weathering
"weathering" = alteraion due to weathering
Standard Roof: Sloping roofs utilising a nominal thickness of 3/16 to 1/4 in. (4.8 to 6.4 mm). The shingles should be rectangular unless otherwise specified. In addition, the shingles shall be drilled or machine punched for two nail holes which has to be located for proper headlap.
Textural Roof Sloping roofs utilising shingles in various colours, sizes, thicknesses and textures for architectural effects. The shingles shall be drilled or machine punched for two nail holes which has to be located for proper headlap.
Graduaded Roof Sloping roofs utilising shingles with a greater range of sizes, thicknesses and exposed lengths. The slates are arranged on the roof so that the thickest and longest occur at the eaves and gradually diminish in thickness and size towards the ridges. The shingles shall be drilled or machine punched for two nail holes which has to be located for proper headlap.
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