Construction Materials: Timber Frames versus Concrete Frame - Assignment Example

Construction Materials Student Name Institution Instructor Course Date of Submission Q1 Timber Frames vs. Concrete Frame Nowadays, most of modern domestic houses are usually framed with either timber or a combination of steel and concrete. Each of these has unique set of disadvantages and advantages, and the selection of material is determined by the nature of the project. The principal difference between building a timber frame house and a concrete house is the selection of material used[Owe13]. The outer walls and cavity in both concrete frame and timber frame are normally similar, and it is usually not easy to differentiate the two by just looking at their external walls, unless the outer cladding is done by timber. Their difference mostly occurs in the construction of the inner wall. In a standard concrete frame, the inner wall is comprised of an aggregate block and an internal coat of plaster. The insulation is generally located directly in the cavity, which is either completely or partially filled. In a standard timber frame, the inner wall is composed of a vapour barrier, structural timber frame, sheathing board, waterproof membrane, and internal coat of plasterboard[Smi081]. The insulation is located between the timber frame uprights. The purpose of this paper is to compare and contrast the use of timber frame with concrete frame in construction. A concrete framed house is built rather differently to a timber framed house. On the construction site, tradesmen work in all weather, building the concrete framed house brick by brick, with several skilled tradesmen being invited to finish tasks before proceeding to another step[Smi081]. For instance, carpenters can be invited when the construction work reaches to first floor level, in order to fit the timber floor joists before the commencement of block work in the next level. Each of the load bearing walls is constructed using concrete blocks, whereas all other partitions and inner walls are built from timber stud frames[Gro13]. Services for electrics and plumbing are buried in the stud frames or chamfered into the block work. On the contrary, a timber framed house gets on the construction site in prefabricated panels that are laid correctly by skilled tradesmen onto a pre-prepared base of concrete floor and foundations. Building the timber frame off site minimizes the vulnerability of work schedules as a result of any exposure to severe weather[Bin07]. When the prefabricated structure arrives on the site, doors and windows are already pre-hung and well placed, reducing errors in work and calculations onsite. A usual timber frame is generally full erected and made waterproof in a period of less than 7 days, therefore permitting every other tradesman to commence his or her work straightaway[Koo06]. The exterior walls are cladded by a watertight envelope of polythene before the block or brick-work facing is built. If the building needs a skim, brick or block finish, this is done on the exterior after fully erecting the house. Concrete framed houses are most preferred globally due to the perceived notion that they can last for many years and therefore provide a legacy to upcoming generations. Although it is hard to precisely quantify durability merits in the varied use conditions of construction materials, concrete provides additional resistance to moisture as well as other environmental elements[Bin07]. Despite the fact that wood is protected within the walls of the building, it is capable of rotting in regions where water enters the external weather-resistant barrier of a house[Mar131]. Reinforced concrete is considered to be one of the most stable construction materials because it has the capability of resisting both compression and shear forces. Properly constructed concrete frame houses may last for so many years. On the other hand, timber frame houses are more resistant to earthquakes and typically more flexible, but decay very fast[Owe13]. Condensation is likely to occur in winter either on the surface of windows, walls or other inner surfaces, or inside the building, which can contribute to a long-term damage[Mar131]. A concrete construction like the cavity wall may be subjected to condensation at the region where the inside warm air has gone through most of the insulation. Little or no harm can be caused here since modern-day insulation cannot rot. However, the occurrence of condensation within a timber frame wall is not easy to treat, and builders and designers have faced a big challenge in trying to prevent it. In terms of fire resistance, concrete walls are considered to be superior in fire resistance than timber frame houses. Solid concrete walls have the capability of sustaining around 4 hours of intense fire exposure, while typical timber frame walls do not go beyond a 1 hour fire rating[Mar131]. In addition, timber is a fuel source that can lead to fire growth and spread in a building, whereas concrete is not. Generally, concrete construction is safer because it has a superior resistance to hazards and natural disasters such as fires, floods, tornadoes, and hurricanes. Cost differences between building either a timber frame house or concrete frame house is actually very minimal. Nevertheless, timber frame houses are comparatively cheap in the long run due to their energy efficiency. In general, timber frame houses are sealed in order to prevent the heat in the houses from escaping out through the gaps. Timber as a construction material is also cheap than concrete, and requires little expertise to work with effectively whereas concrete need proper form-working skills, which necessitate the need to hire skilled workers[Bin07]. Hiring of skilled workers makes concrete frame houses more expensive than timber frame ones. Generally, there is no form of construction that is implicitly better than the other since it depends on the personal preferences of the self-builder and the requirements of a project, as well as several other factors such as constraints and location of the construction site. The principal difference between building a timber frame house and a concrete house is the selection of material used. Their construction process is also different as timber framed house can be built at any time whereas concrete framed house is affected by weather factors. Concrete framed houses are most preferred globally due to the perceived notion that they can last for many years and therefore provide a legacy to upcoming generations. Concrete construction is also safer because it has a superior resistance to hazards and natural disasters such as fires, floods, tornadoes, and hurricanes. Cost differences between building either a timber frame house or concrete frame house is actually very minimal. References List Owe13: , (Owen, 2013), Smi081: , (Smiley Building Services, 2008), Gro13: , (Gromicko & Fowler, 2013), Bin07: , (Bingham & Pfeffer, 2007), Koo06: , (Koones, 2006), Bin07: , (Bingham & Pfeffer, 2007; Owen, 2013), Mar131: , (Marshall, et al., 2013), Pri121: , (Princeton University, 2012), Mit95: , (Mitchell, 1995), Chu12: , (Church Growth Trust, 2012), Q2 a) % of the moisture content of the timber = x 100 = x 100 = 18.35% b) Hygroscopic material refers to a substance that has the capability of taking in or giving off water molecules from the environment surrounding it by either adsorbing or absorbing[Pri121]. This leads to changes in physical characteristics of such substances. Compounds and materials have varying hygroscopic properties, and these differences may contribute to harmful effects including stress concentration in composite materials. c) Timber for internal use requires specific moisture content that is close to the average humidity of the room into which it is to be fixed. This means that timber for internal use is supposed to have lower moisture content than timber which is used externally. This is because higher levels of moisture content in timber for internal use would be reduced by the warmth of the atmosphere leading to excessive shrinking and likely to cause other more harmful defects[Mit95]. d) Signs of dry rot are as follows: Cracking, shrinking, or splitting of wood Wood becomes crumbly, soft and color turns to brown On painted timber surfaces, the painted surfaces may not be destroyed but the surface behind becomes warped, wavy and deformed Floor boards may dip into edges or corners Strands and mycelium may be observed to be spreading behind hidden surfaces Fruiting bodies starts growing on timber surfaces, in corners, through plaster, from behind timber surfaces, or other areas Presence of a mushroom-like odour Presence of terracotta/red colored dust Successful eradication of dry rot may be achieved by first eliminating the cause or source of the moisture which permitted the outbreak to establish, dry out the building, remove infected materials, deal with the fungus, and lastly, repair the damage caused by it[Chu12]. References List Owe13: , (Owen, 2013), Smi081: , (Smiley Building Services, 2008), Gro13: , (Gromicko & Fowler, 2013), Bin07: , (Bingham & Pfeffer, 2007), Koo06: , (Koones, 2006), Bin07: , (Bingham & Pfeffer, 2007; Owen, 2013), Mar131: , (Marshall, et al., 2013), Pri121: , (Princeton University, 2012), Mit95: , (Mitchell, 1995), Chu12: , (Church Growth Trust, 2012), Q3 a) % on sieve = x 100 % passing = 100 – Cumulative % retained Total weight = 1400g Table 1: Particle Size Distribution Sieve Size (mm) Mass (g) % on Sieve Cumulative % Retained % Passing 125 0 0 0 100 75 0 0 0 100 63 88 6.3 6.3 93.7 37.5 55 3.9 10.2 89.8 20 87 6.2 16.4 83.6 10 98 7.0 23.4 76.6 6.3 95 6.8 30.2 69.8 3.35 102 7.3 37.5 62.5 2 129 9.2 46.7 53.3 1.18 89 6.4 53.1 46.9 0.6 85 6.1 59.2 40.8 0.3 90 6.4 65.6 34.4 0.212 92 6.6 72.2 27.8 0.15 84 6.0 78.2 21.8 0.063 90 6.4 84.6 15.4 b) Figure 1: Grading Curves c) Sample 2 has large aggregate particles and it is therefore suitable for direct use as an aggregate Read More