Thursday, 23 May 2024

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Construction Specifications in North America
Specifications in North America form part of the contract documents that accompany and govern the construction of building and infrastructure projects. Specifications describe the quality and performance of building materials, using code citations and published standards, whereas the drawings or Building Information Model (BIM) illustrates quantity and location of materials. The guiding master document of names and numbers is the latest edition of MasterFormat. This is a consensus document that is jointly sponsored by two professional organizations: Construction Specifications Canada and Construction Specifications Institute based in the United States and updated every two years.

Construction Specification เป็นส่วนหนึ่งของเอกสารสัญญาก่อสร้างภาครัฐ อธิบายถึงคุณภาพและประสิทธิภาพของวัสดุก่อสร้างโดยใช้การอ้างอิงรหัสและมาตรฐานที่ถูกเผยแพร่ในทางสาธารณะ ผ่านแบบก่อสร้างที่บอกว่าใช้วัสดุอะไร ปริมาณเท่าใด ที่ตำแหน่งไหนบ้าง โดยรหัสและมาตรฐานที่ใช้อ้างอิงนั้นมาจากหน่วยงานที่เชี่ยวชาญด้านนี้โดยตรงของแคนาดา (CSC) และสหรัฐอเมริกา (CSI)

While there is a tendency to believe that “Specifications overrule Drawings” in the event of discrepancies between the text document and the drawings, the actual intent must be made explicit in the contract between the Owner and the Contractor. The standard AIA (American Institute of Architects) and EJCDC (Engineering Joint Contract Documents Committee) states that the drawings and specifications are complementary, together providing the information required for a complete facility. Many public agencies, such as the Naval Facilities Command (NAVFAC) state that the specifications overrule the drawings. This is based on the idea that words are easier for a jury (or mediator) to interpret than drawings in case of a dispute.

ความเชื่อที่ว่า ” Specification มีศักดิ์เหนือกว่า Drawing ” เจตนาที่แท้จริงคือ เพื่อให้เกิดความชัดเจนในสัญญาระหว่างเจ้าของและผู้รับเหมานั่นเอง  แต่ AIA และ EJCDC เห็นว่า Specification และ Drawing เป็นส่วนประกอบที่เสริมเข้าด้วยกัน เพื่อให้เกิดเป็นข้อมูลที่สมบูรณ์

ในขณะที่หน่วยงานสาธารณะหลายแห่งเช่น NAVFAC ระบุว่า ” Specification มีศักดิ์เหนือกว่า Drawing “มาจากพื้นฐานความคิดที่ว่า Specification  ซึ่งเป็นตัวหนังสือ สามารถใช้ตีความได้ง่ายกว่า Drawing ในกรณีที่ต้องโต้แย้งในทางกฏหมาย

The standard listing of construction specifications falls into 50 Divisions, or broad categories of work types and work results involved in construction. The divisions are subdivided into sections, each one addressing a specific material type (concrete) or a work product (steel door) of the construction work. A specific material may be covered in several locations, depending on the work result: stainless steel (for example) can be covered as a sheet material used in Flashing and Sheet Metal in Division 07; it can be part of a finished product, such as a handrail, covered in Division 05; or it can be a component of building hardware, covered in Division 08. The original listing of specification divisions was based on the time sequence of construction, working from exterior to interior, and this logic is still somewhat followed as new materials and systems make their way into the construction process.

Each Section is subdivided into three distinct Parts: “General”, “Products” and “Execution”. The MasterFormat and Section Format [17]system can be successfully applied to residential, commercial, civil, and industrial construction. Although many Architects find the rather voluminous commercial style of specifications too lengthy for most residential projects and therefore either produce more abbreviated specifications of their own or use ArCHspec (which was specifically created for residential projects). Master specification systems are available from multiple vendors such as Arcom, Visispec, BSD, and Spectext. These systems were created to standardize language across the United States and are usually subscription based.

Specifications can be either “performance-based”, whereby the specifier restricts the text to stating the performance that must be achieved by the completed work, “prescriptive” where the specifier states the specific criteria such as fabrication standards applicable to the item, or “proprietary”, whereby the specifier indicates specific products, vendors and even contractors that are acceptable for each workscope. In addition, specifications can be “closed” with a specific list of products, or “open” allowing for substitutions made by the Contractor. Most construction specifications are a combination of performance-based and proprietrary types, naming acceptable manufacturers and products while also specifying certain standards and design criteria that must be met.

While North American specifications are usually restricted to broad descriptions of the work, European ones and Civil work can include actual work quantities, including such things as area of drywall to be built in square meters, like a bill of materials. This type of specification is a collaborative effort between a specwriter and a quantity surveyor. This approach is unusual in North America, where each bidder performs a quantity survey on the basis of both drawings and specifications. In many countries on the European continent, content that might be described as “specifications” in the United States are covered under the building code or municipal code. Civil and infrastructure work in the United States often includes a quantity breakdown of the work to be performed as well.

Although specifications are usually issued by the architect’s office, specification writing itself is undertaken by the architect and the various engineers or by specialist specification writers. Specification writing is often a distinct professional trade, with professional certifications such as “Certified Construction Specifier” (CCS) available through the Construction Specifications Institute and the Registered Specification Writer (RSW)[18] through Construction Specifications Canada. Specification writers are either employees of or sub-contractors to architects, engineers, or construction management companies. Specification writers frequently meet with manufacturers of building materials who seek to have their products specified on upcoming construction projects so that contractors can include their products in the estimates leading to their proposals.

In February 2015, ArCHspec went live, from ArCH (Architects Creating Homes), a nationwide American professional society of Architects whose purpose is to improve residential architecture. ArCHspec was created specifically for use by Licensed Architects while designing SFR (Single Family Residential) architectural projects. Unlike the more commercial CSI (50+ division commercial specifications), ArCHspec utilizes the more recognizable 16 traditional Divisions, plus a Division 0 (Scope & Bid Forms) and Division 17 (low voltage). Many architects, up to this point, did not provide specifications for residential designs, which is one of the reasons ArCHspec was created: to fill a void in the industry with more compact specifications for residential use. Shorter form specifications documents suitable for residential use are also available through Arcom, and follow the 50 division format, which was adopted in both the United States and Canada starting in 2004. The 16 division format is no longer considered standard, and is not supported by either CSI or CSC, or any of the subscription master specification services, data repositories, product lead systems, and the bulk of governmental agencies.

อ้างอิง : https://en.wikipedia.org/wiki/Specification_(technical_standard)