This section is about roofs and roofing – the materials and products, methods and certain criteria which are used in the construction of these elements. A more specific purpose is to draw the attention of readers to features and functions of different types of roofs and roofing and the overall cost considerations in choosing different types. Notwithstanding certain roofs suit only certain designs. With an age of diversity in the building Industry and the abundant choice of design and materials, one tendency has become very clear; the increasing complexity of the geometry of buildings, and more especially of roofs. It is therefore simple to deduce that defects increase in direct proportion to this increase in complexity of geometry of the surfaces of buildings; i.e. at the intersections of different planes and materials.
Added to this is the increasing lack of properly skilled artisans in erecting roof structures and the fi tment of the desired roof coverings, associated fittings and accessories; highlighting the need for taking extra care in both design and construction, when it comes to roofing and not only making decisions based on price alone.
One must consider that a roof has numerous functions other than aesthetics that need to be taken into account in the design and costing analysis;
- Protection from sun, wind and rain.
- Strength and stability
- Control of heat loss – insulation
- Prevention of condensation
- Acoustics - exclusion and prevention of noise
- Fire protection and prevention
- Provision of day lighting; where appropriate.
There is an absolute requirement in roofi ng to prevent water reaching the interior of a building, in contrast with some of the other functional requirements where some shortfall may be tolerable. Again; highlighting the need for taking care in design and the construction/ erection of roofs and roofi ng to ensure water penetration into the interior of the building is avoided.
Two kinds of rainfall intensity need to be considered;
- Rain falling vertically
- Rain driven by wind
Both categories contribute to the total quantities of rainwater needing disposal, but the second category particularly affects the weather tightness of lapped roofing, such as tiles and slates, and even the direction and extent of lap of larger sheets; with many manufacturers recommending the use of underlays, fixing of tiles etc. in these applications.
One must remember that rain falling while the wind is blowing affects pitched roofs more than flat (and walls even more so), it is therefore important to consider ones geographical location, associated weather patterns and not only your desired roofing requirements.