Well-Planned Construction of Roof - Case Study Example

May you always have walls for the winds, a roof for the rain, tea beside the fire, laughter to cheer you, those you love near you and all your heart might desire.” Irish Blessings quotes A roof is the topmost part of any built structure. It is provided as a structural cover to protect the building from the natural elements like rain, snow, hail, wind, heat etc. The roof must be able to perform certain basic functions like supporting the upper edifice of a building, controlling and if possible regulating the temperature inside the enclosure, plumbing cum drainage work of the entire structure, natural air conditioning and so on. The roof consists of the structural elements and roof coverings. This structural element which supports roof covering may be trusses, portals, beams, slabs, shells or domes. The roof covering may be metal sheets, wooden shingles, tiles, slates or slab itself. For this case study I suggest we construct a Pitched roof made of timber. Requirements of a roof: A well planned roof must satisfy the following requirements: It should have adequate strength to carry the load It should effectively protect the building from all weathering agencies (i.e. rain, snow, heat, wind etc.) It should be water proof It should have proper drainage arrangements It should be fire resistant It should provide adequate thermal and sound insulation. (http://www.uvi.edu/Physics/SCI3xxWeb/Structure/BasicStructure.html) Roofs can be classified as follows. ROOF Flat roof Pitched roof Curved roof Single Roof 1. Lean to roof 2. Couple roof 3. Couple close roof 4. Collar beam roof 5. Collar and scissors roof Trussed Roof 1. King post truss 2. Queen post truss 3. Combination of King-post and queen post truss 4. Steel trusses 5. Composite trusses FLAT ROOF: For the construction of a building above the roof the preferred type of roof construction is the flat type. In this type of roof, steel bars and concrete are used to form a roof. Before construction, the thickness of slab, beam and reinforcement needs to be determined based on the span and loading conditions. This type of roof best suits the construction of the intermediate floor. The balance and strength needed for the support of an entire floor is made easy with this flat roof. PITCHED ROOF: This type of roof has the upper surface slanted. This roof is most conducive for houses built in geographical areas which lie in the rain-shed places or those experiencing heavy snowfall. Since the roof in question has a wide span it cannot be constructed with rafters alone. The roof has to be constructed with a structure comprising of frames known as trusses. The following illustration shows the general structure of such a roof. (3120 ROOFING TECH, 12pg., 2004, 14/6/04 2:23 pm, Page 12) VENTILLATION ASPECT OF A ROOF: Houses of now are a lot better insulated because they have doors, windows and roofs which fit tightly and keep the temperature controllable. The air inside the house is kept warm by means of various techniques of circulating the air. A distinction is made on the type of roof based on the temperature it can keep. When the air inside the house remains warm it is known as a hot roof and vice versa. A hot roof allows for the air cavities to freeze and refreeze the snow or ice and in the process taking on the heat. (Richard Taylor, AIA, Hot/Cold Roof, 10/27/2006, www.streetsourcemag.com/forum/userposts.aspx?userid=bagged85) The circulation of air into and out of the building must be moderated by an appropriate structural design. To assure this the construction has been fitted with “Quilt roof insulation between the” Joists. (3120 ROOFING TECH, 12pg., 2004, 14/6/04 2:23 pm, Page 12) The above diagram illustrates the rough construction plan for a house with an intermediate floor and a pitched roof with quilt insulation. The housing structure has been systematically divided into 4 sections (A1-A4) starting from top down. A1: This is the roof portion. It contains interlocking slates nailed to 38x25 softwood battens at max 250gauge on roofing felt trussed rafters. Quilt insulated mats are laid down between the joists here. 12.5 mm plasterboard is laid beneath the quilt for insulation and protection. The window below the roof is made of aluminum extruded gutter by specialist supplier 200x150 fixed by aluminum brackets Sprocketed eaves using 50x75x1000 propriety eaves vent with Fascia grill enhance the structure of the roof. Aluminum extruded gutter by specialist supplier 200x150 fixed by aluminum brackets The housing structure is equipped with 75x50 wall plate with 30x2.5x600c/c girth galvanized m/s wall anchors nailed to block walls @1000 c/c (between windows) with 150 deep strip of XPM filled over plate as plaster key. Heavy horizontal beams or steel lintels are pressed 225mm deep to support the structure and roof. To accommodate for adequate insulation 75 thick c/s screed topping is placed on a 12mm polystyrene slab. (http://www.uvi.edu/Physics/SCI3xxWeb/Structure/BlockConstruction.html) The intermediate floor is constructed with 150 Dp reinforced concrete beam & block construction. 75 deep c/s screed/topping on polythene sheet DPM is used on 150 deep R/C beam & block floor. 50x50 s/w batten & counter battens @max 600 c/c nailed to u/s concrete blocks is planned as support for the 9.5 thick plasterboard Here 6mm thick soffit lining will be used. 100 facing brick / 85 cavity 140 concrete block walls ties 50 thick insulation is proposed. 215 socpier course pressed lintel is utilized in this layer. (Simon Šilih, Miroslav Premrov and Stojan Kravanja, Faculty of Civil Engineering, University of Maribor, Smetanova 17, 2000 Maribor, Slovenia, Received 5 May 2004;  revised 20 September 2004;  accepted 6 October 2004) A3: This is the first floor layer. 140 block on edge is made use of to close the cavity between floors. Single cant brick call 150 wide DPC (fixed with adhesive) 215 high solder course 100 wide DPC strip A4: This is the basement or foundation portion. Pre-cast concrete units have been utilized here to provide strength to the entire structure above. Also utilized is a weak mix to fill cavities obtaining. The completed building of the house from outside shall look somewhat like this: The materials required for construction may be sourced from different manufacturers specializing in their field. A few are listed below: Where to Find items of building: Asphalt Roofing Manufacturers Assn. 6000 Executive Blvd., Suite 201 Rockville, MD 20852-3083 301-231-9050 Cedar Shake & Shingle Bureau 515 116th Ave. NE, Suite 275 Bellevue, WA, 98004-5294 206-453-1323 www.cedarbureau.org CertainTeed Corp. 750 Swedesford Rd., Box 860 Valley Forge, PA 19482 215-431-7000 www.certainteed.com GAF Building Materials Corp. 1361 Alps Road Wayne, NJ 07470 201-628-300 www.gaf.com National Roofing Contactors Assn. Box 809261 Chicago, IL 60680 800-USA-ROOF www.roofonline.org National Tile Roofing Manufacturers Assn. Box 40337 Eugene, OR 97404-0049 541-689-0366 Owens Corning 1 Owens Corning Pkwy. Toledo, OH 43659 800-GET-PINK www.owenscorning.com (Katherine Moloney, How to Choose a Pitched Roof, Copyright © 2007 Time Inc. ) References: http://www.uvi.edu/Physics/SCI3xxWeb/Structure/BlockConstruction.html www.cedarbureau.org/installation/roof_manual/pdfs/roof-manual.pdf Richard Taylor, AIA, Hot/Cold Roof, 10/27/2006, www.streetsourcemag.com/forum/userposts.aspx?userid=bagged85 appendix_a_the_cliff_web.pdf www.building science.com John Straube, Building Science Digest 115. Wood Pitched Roof Construction, 2006-10-26 Katherine Moloney, How to Choose a Pitched Roof, Copyright © 2007 Time Inc. http://www.uvi.edu/Physics/SCI3xxWeb/Structure/BasicStructure.html Marshall Brain, How House Construction Works, http://www.howstuffworks.com/house.htm Simon Šilih, Miroslav Premrov and Stojan Kravanja, Faculty of Civil Engineering, University of Maribor, Smetanova 17, 2000 Maribor, Slovenia, Received 5 May 2004;  revised 20 September 2004;  accepted 6 October 2004. . Read More