--- title: "Requirements of good roof; pitched roof types" subject: "Building Technology" chapter: 4 key: "semester_6/building_technology:roof-requirements-pitch-066j" source: https://www.bctengineer.com/q/semester_6/building_technology/roof-requirements-pitch-066j site: BCT Engineering --- # Requirements of good roof; pitched roof types Building Technology · Chapter 4: Roofs - Asked in: 2066 Jestha (old course), 4+6 marks - Video: [Technical Terms in Pitched Roofs | 1.Pitched Roof | Types of Roofs | Building Construction](https://www.youtube.com/watch?v=SzNYv2IKXBE) — SGK Online Education - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_6/building_technology/roof-requirements-pitch-066j - Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-4 ## Question What is roof? Write down the requirement of good roof. Explain about pitch or slope roof and mention its types with the help of sketches. ## Short answer A roof is the uppermost building part protecting from weather. Good roof requirements: weather protection, structural stability, thermal/sound insulation, durability, fire resistance, drainage, light weight, appearance, lightning/wind safety. Pitched roof has slope >10° for quick drainage; types include lean-to, gable, hip, gambrel, mansard, hip-and-valley, Dutch gable, north-light, butterfly, conical/pyramid. ## Answer #### Roof A **roof** is the uppermost part of a building, supported on walls or columns, which covers the building and protects the occupants and contents from rain, snow, sun, wind and heat. #### Requirements of a good roof 1. **Protection from weather:** must keep out rain, snow and sun and shed water quickly (proper slope, no leakage). 2. **Structural stability:** must safely carry dead load, live load, wind load and snow load (and earthquake forces) and transfer them to the walls or columns. 3. **Thermal insulation:** should keep the interior cool in summer and warm in winter. 4. **Sound insulation:** should reduce rain noise and outside noise. 5. **Durability and low maintenance:** resistant to weathering, decay, termites and corrosion. 6. **Fire resistance:** materials and joints should not help fire to spread. 7. **Drainage:** rainwater must drain freely through gutters and rainwater pipes. 8. **Light weight and economy:** the roof should be light so that the supporting walls and foundation are economical. 9. **Good appearance:** pleasing shape and finish, suited to the building. 10. **Lightning and wind safety:** firmly anchored against uplift; lightning conductor where needed. #### Pitched (slope) roof A pitched roof is a roof with one or more sloping surfaces (slope more than 10 degrees) on timber or steel frames, covered with tiles, slates, sheets or thatch. Rain drains quickly, so it suits rainy and snowy regions. #### Types of pitched roof | Type | Description and example | |---|---| | Lean-to roof | Single slope resting against a taller wall; verandah, shed, outhouse | | Gable (saddle / couple) roof | Two slopes meeting at a ridge, with gable ends; ordinary houses | | Hip roof | All four sides sloping; good wind resistance, no gable wall; bungalows | | Gambrel roof | Two slopes on each side, the lower one steeper; barns | | Mansard roof | Two slopes on each of the four sides, the lower about 60-70 degrees and the upper about 30 degrees; gives usable attic space | | Hip-and-valley roof | Hipped roofs meeting at valleys over L- or T-shaped plans | | Dutch gable roof | Hip roof with a small gable at the top of each end; ventilates the attic | | North-light roof | Series of saw-tooth slopes, with the steep glazed face towards the north for even daylight; factories, workshops | | Butterfly roof | Two slopes falling towards the centre (V shape) with a central gutter | | Conical / pyramid roof | Slopes meeting at a point over circular or square plans; towers | ```text Lean-to Gable (couple) Hip /| /\ /--\ / | / \ / \ /__| /____\ /______\ Mansard North light ____ /| /| /| / \ / | / | / | / \ /__|/__|/__| | | ``` ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What is the primary purpose of a roof? A. Cover and protect from rain, snow, sun, wind and heat B. Carry the floor loads C. Resist only earthquake force D. Provide only privacy Answer: A. A roof is the uppermost covering that protects occupants and contents. (Key point: Roof def) 2. Why should a good roof be light? A. To make it noisy B. So supporting walls and foundation are economical C. So it can float in wind D. To increase fire risk Answer: B. A light roof reduces load on walls and foundations. (Key point: Light weight) 3. What slope defines a pitched roof? A. Up to 10 degrees B. Exactly 45 degrees C. More than 10 degrees D. Only 60-70 degrees Answer: C. Pitched roofs slope more than 10 degrees; flat roofs up to 10 degrees. (Key point: Pitched def) 4. Which pitched roof has all four sides sloping with no gable wall? A. Lean-to roof B. Gable roof C. Butterfly roof D. Hip roof Answer: D. The hip roof slopes on all four sides and resists wind well. 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