REKAYASA BIAYA KONSTRUKSI

Transkripsi

1 REKAYASA BIAYA KONSTRUKSI Dr. Ir. Budi Susetyo, MT Fakultas TEKNIK Program Studi S2 SIPIL MK 1

2 Bagian Isi 1. Estimasi biaya konstruksi 2. Estimasi biaya tahap konseptual dan detail 3. Biaya dan kontrak konstruksi 4. Ragam kontrak konstruksi 5. Pengendalian biaya 6. Pengendalian biaya konstruksi 7. Review UTS 1. Perhitungan biaya berbasis kegiatan (activity based costing) 2. Contoh perhitungan 3. Komponen biaya konstruksi 4. Contoh perhitungan 5. Pengendalian, monitoring dan akunting biaya 6. Contoh perhitungan 7. Review UAS 2

3 Estimasi Biaya Konstruksi 3

4 Rekayasa Biaya Konstruksi Arti kata rekayasa pada Kamus Besar Bahasa Indonesia (KBBI) adalah penerapan kaidah-kaidah ilmu dalam pelaksanaan (seperti perancangan, pembuatan konstruksi, serta pengoperasian kerangka, peralatan, dan sistem yang ekonomis dan efisien). Rekayasa biaya konstruksi adalah kegiatan penerapan iptek terkait perencanaan, pelaksanaan dan pengendalian biaya pekerjaan pada suatu proyek konstruksi. 4

5 Estimasi Biaya Konstruksi Perhitungan biaya konstruksi dengan suatu pendekatan tertentu untuk suatu tujuan tertentu. 5

6 Pendekatan Estimasi Biaya Konstruksi Fungsi produksi, memperhitungkan rasio antara produk konstruksi dengan inputnya misalnya rasio luas bangunan dengan jumlah tenaga kerja selama konstruksi. Inferensi biaya empirik, menyusun analisis statistik (inferensi) seperti regresi untuk mengetahui hubungan keterkaitan diantara berbaga ikomponen konstruksi. Analisis tersebut digunakan untukmengetahui system atau proses yang efisien. Biaya unit pekerjaan (unit costs for bill of quantities), menyusun biaya berdasarkan komponen pekerjaan berdasarkan satuan tertentu. Seperti biaya pondasi, struktur atas, dst. Total biaya merupakan akumulasi keseluruhan komponen. Alokasi biaya, menyusun biaya berdasarkan alokasi akun tertentu. Pada konstruksi lazimnya dikelompokkan biaya material, alat, tenagakerja, supervise, serta overhead. 6

7 Komponen Biaya Konstruksi Komponen biaya proyek dapat meliputi biaya pengadaaan lahan, perencanaan, pelaksanaan konstruksi, pengadaan barang dan peralatan, pengawasan, inspeksi, pemeriksaan dan pengetesan. 7

8 Unit Cost Method of Estimation If the design technology for a facility has been specified, the project can be decomposed into elements at various levels of detail for the purpose of cost estimation. The unit cost for each element in the bill of quantities must be assessed in order to compute the total construction cost. This concept is applicable to both design estimates and bid estimates, although different elements may be selected in the decomposition. 8

9 Levels of a hierarchy 1. Preliminary Estimates. The project is decomposed into major structural systems or production equipment items, e.g. the entire floor of a building or a cooling system for a processing plant. 2. Detailed Estimates. The project is decomposed into components of various major systems, i.e., a single floor panel for a building or a heat exchanger for a cooling system. 3. Engineer's Estimates. The project is decomposed into detailed items of various components as warranted by the available cost data. Examples of detailed items are slabs and beams in a floor panel, or the piping and connections for a heat exchanger. 9

10 Bid estimates Subcontractor Quotations. The decomposition of a project into subcontractor items for quotation involves a minimum amount of work for the general contractor. However, the accuracy of the resulting estimate depends on the reliability of the subcontractors since the general contractor selects one among several contractor quotations submitted for each item of subcontracted work. Quantity Takeoffs. The decomposition of a project into items of quantities that are measured (or taken off) from the engineer's plan will result in a procedure similar to that adopted for a detailed estimate or an engineer's estimate by the design professional. The levels of detail may vary according to the desire of the general contractor and the availability of cost data. Construction Procedures. If the construction procedure of a proposed project is used as the basis of a cost estimate, the project may be decomposed into items such as labor, material and equipment needed to perform various tasks in the projects. 10

11 Cost Estimates Simple Unit Cost Formula Suppose that a project is decomposed into n elements for cost estimation. Let Q i be the quantity of the i th element and u i be the corresponding unit cost. Then, the total cost of the project is given by: 11

12 Cost Estimates Formula Based on Labor, Material and Equipment Consider the simple case for which costs of labor, material and equipment are assigned to all tasks. Suppose that a project is decomposed into n tasks. Let Q i be the quantity of work for task i, M i be the unit material cost of task i, E i be the unit equipment rate for task i, L i be the units of labor required per unit of Q i, and W i be the wage rate associated with L i. In this case, the total cost y is: 12

13 Pustaka 1. Ritz, G., J. (1994). Total Construction Project Management, McGraw-Hill, Inc 2. Ahuja, H. N. (1980). Successful Construction Cost Control. New York, John Wiley and Sons. 3. Gould, F. E. (1997). Managing the Construction Process (Estimating, Scheduling and Project Control). New Jersey, Prentice Hall. 4. Halpin, D., W. (1998). Construction Management. USA, John Wiley and Sons, Inc.: Hendrickson, C. (1989). Project Management for Construction. Fundamental Concepts for Owners, Engineer, Architects, and Builders. Singapore, Prentice Hall. 6. Humphreys, K. K. (1991). Jelen s Cost and Optimization Engineering. Singapore, McGraw-Hill, Inc. 7. Kerzner, H. (1995). Project Management. A System Approach to Planning, Scheduling and Controlling. New York, Van Nostrand Reinhold. 13