Construction Technology, Services and Materials - Assignment Example

Question a) Types of Foundations A building foundation is necessary to sustain and transmit the loads to the ground. All weight bearing elements; external walls, party walls, chimneybreasts, piers and internal load carrying walls need a proper foundation. In terrains with clay soils affected by seasonal moisture, foundations need to be deeper than 1m. A foundation that is over 2.5m deep is not practical (Ilki & Fardis, 2013). In this case piles, raft or pad and beam foundations are the most appropriate. i) Strip foundations This involves a digger bucket and the foundations are at least 600mm wide but they can extend to 850 mm on sand, silt or soft clay (Taylor, 2013). The picture that follows shows a cross section of s strip foundation. Figure 1: Strip foundation ii) Trench Fill Foundations Trench foundations are deeper than strip foundations. They are practical in areas where soil is loose and unstable especially in places with heavy clay soils (Ilki & Fardis, 2013). In most cases, the trench sides have slip membrane lining. The thickness a trench foundation is usually greater than 500mm and finishes between 50mm to 100mm below ground level. The picture that follows shows a cross section of s trench foundation. Figure 2: trench foundation iii) Raft Foundation A reinforced concrete raft or mat foundations are applicable in terrains with very weak or expansive soils such as clays (Mohd, 2013). Buildings on raft foundations float on the soil. A raft foundation is necessary in places where the soil requires a large bearing area. This becomes more economical to have a large reinforced concrete slab. The picture that follows shows a cross section of raft foundation. Figure 3: Raft foundation iv) Piled Foundation Short bore pile and beam appear where the ground conditions are not able to support strip foundations. When the depth of trench becomes uneconomic, or the soil conditions make them inappropriate, columns (piles) are bored and cast in-situ (Mohd, 2013). Sometimes pre-cast piles are driven into the ground until they reach stronger strata (Ilki & Fardis, 2013). Short bore piles are 2-3m long with steel reinforcement. Each pile connects to the top by a pre-cast horizontal beam of reinforced concrete. In such cases, a suspended reinforced concrete ground floor is built using pre-cast components, or cast in situ (Anumba & Memari, 2013).The picture that follows shows a cross section of pile foundation. Figure 4: Pile foundation b) Factors that influence foundation selection i) Location and type of structure Choices on land and on water are not the same. For moderate loads, the cast-in-place foundations are the cheapest. The structure type also determines the type of foundation. For example, heavy structures with large foundation weight need large-diameter piles. ii) Ground conditions Soil conditions are important in building and construction field. Time is needed to understand the type of soil as it will be supporting the entire building. Sand soil, loam soils and clays all require different types of foundations. iii) Durability Durability is a factor that mostly affects the choice of material for the foundation. The materials determine the type of foundation to be erected (Ilki & Fardis, 2013). For example, concrete piles are usually used in marine conditions since steel piles are susceptible to corrosion in such conditions. c) Drawings of foundations types Figure 5: Hand drawn strip foundation Figure 6: Hand drawn raft foundation Question 3 Alternative type of residential walls Walls come in different forms and using different materials and serving several functions. The design is to make them strong enough to ‘resist the horizontal and vertical forces imposed upon them, as defined by building codes’ (Mohd, 2013). i) Block Masonry This appears residential construction and is still quite popular with most contractors who feel more comfortable with what they have been working with for years (Ilki & Fardis, 2013). ii) Concrete Wall This cast-in-place (poured concrete) construction can be used for the residential wall. It is viable method and popular among contractors who have been working with them for years. iii) Stud Wall Construction It uses wood or metal studs. Studs measuring 2x4 are common in for single family residential and 2x6 studs for multi-family or commercial constructions (Mohd, 2013). Sometimes one uses the metal C-studs instead of wood studs. iv) Structural Insulated Panels (SIP) This are made of two outer skins and an inner insulation core (Taylor, 2013). The structural panels are of either plywood or oriented strand boards (OSB) which are used as skins. Expanded polystyrene (EPS) is used are the insulation core material. v) Pre-cast Concrete Wall Construction High-strength concrete reinforced steel and fibers are used. They have full-length insulation built in to increase energy efficiency (Mohd, 2013). These are the smart walls as they come fitted with convenient features like built-in accesses for wiring and treated wood nailers (Ilki & Fardis, 2013).It takes just hours to install a typical home as the walls have a built in footing. Wall Assembly techniques They are popular alternatives from the concrete type and the wooded type. The two types are applicable in different places. For durability the pre-cast concrete walls are preferred over there wood based structural insulated panels (Anumba & Memari, 2013). However, for any project that needs housing to be erected within the shortest time possible, the wooded or pre-cast walls are the best. Question 4 Difference between Purlin and Trussed roof Rafters are pieces of timber that run from beam to beam or wall to wall (Taylor, 2013). They are either sloped or flat. Roof rafters are constructed measuring 2x8 or 2x10 based on the load they carry. Rafters are the conventional framing. Trusses have the same function as rafters but they consist of top and bottom chords joined by and web members (Mohd, 2013). The top chord and web members are made of 2x4 timbers whereas the bottom chord measures 2x6. The advice for the customer is to use trusses instead of rafters. This is because trusses span much further then rafters and they support heavier weights. Trusses can also build roofs or floors. They involve less labour as they are built in a factory then transported to the construction site. Bibliography ANUMBA, C. J., & MEMARI, A. M. (2013). AEI 2013: building solutions for architectural engineering : proceedings of the 2013 Architectural Engineering National Conference, April 3-5, 2013, State College, Pennsylvania. http://dx.doi.org/10.1061/9780784412909. ILKI, A., & FARDIS, M. N. (2013). Seismic evaluation and rehabilitation of structures. Cham, Springer. http://public.eblib.com/EBLPublic/PublicView.do?ptiID=1398570. MOHD. AHMED; ASSISTANR PROFESSOR, MAHMOUD HUSSAIN, & JAVED MALLICK. (2013). Advances in Piled-Raft Foundation System. Recent Trends in Civil Engineering & Technology. http://www.stmjournals.com/index.php?journal=RTCET&page=article&op=view&path%5B%5D=2916. TAYLOR, G. D. (2013). Materials in Construction An Introduction. Hoboken, Taylor and Francis. http://public.eblib.com/EBLPublic/PublicView.do?ptiID=1501438. Read More