The Construction Technology Assignment Construction Essay
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Published: Mon, 5 Dec 2016
This is the report on development of the house which comprise of ground floor and one upper floor. The detailed specification of 32o pitched roof construction will be attached on the drawing. The report will specify type of cavity wall , section of around the head and cill of the timber window and detailed specification of external brick work. Next paragraph describes drainage requirements for a building and finally detailed examination and specification of the ground floor.
Memebers of the roof
Roof structure- Truss Rafters
The roof that going to cover 15.6 long and 10.6 meters wide House is a traditional pitched roof with a pitch of 38o . I was considering two shapes of trussed rafters on this particular project what was Fink and Howe, but finally I decide to go for Howe because of quite wide span which is 10.2 meters. Rafters will be prefabricated by Magtruss Company from Drogheda Co. Louth. Chemically treated timber used for those is 175x50mm wide. Wooden construction going to be connected by Galvanised steel gang-nail connector plates. Trussed Rafters will be placed at every 600 mm on the 75×100 mm wall plates. For best stability of roof construction will be used diagonal bracing. Holding down roof to the walls is not necessarily in this area.
Insulation is a major part of our project. The roof that will cover the house, is a cold type of the roof what means the ceiling has to be properly insulated. The insulation material that will be used is called Owens Corning PINK. It is a 160 mm thick fibre glass insulation which doesn’t absorb moisture. That will prevent cold bridge forming from the cold roof space to the leaving space.
Roof space ventilation
In fact all new property should have a continues form of ventilation installed on both sides of the roof. Cold Roof spaces should be ventilated to outside air to reduce the possibility of condensation. A more rational approach to reducing the possibility of warm , moist air penetrating a cold roof space. To provide roof space ventilation in the house, Eaves ventilators will be laid over insulation in the eave area, to enable air freely penetrate the roof space (drawing). The air from outside will get through the depth soffit ventilators.
To avoid wind blow into the roof space, breathable membrane – Solitex will be laid across roof rafters from the eaves upward up to ridge. Breathable membranes allow unwanted water vapour to escape from the roof space while still excluding wind. Ventilation through the roof and breathable membranes reduce the potential for condensation to form on the cold surfaces within the roof. Timber battens of 50mm x 35 mm wide at every 330 mm will secure Solitex membrane.
Solitex is designed to replace underlay felt in house construction. Solitex acts like a gortex material on the house, allowing the house to breathe whilst at the same time preventing water penetration. It is lightweight and easy to work with. It is extremely strong and does not tear. It does not degenerate under heat and sun and is guaranteed to last a lifetime. Solitex is much more expensive than underlay felt and many other roofing membranes. Much more expensive means that an increase in roofing cost on a large roof will be of about 400 Euro above the cost of underlay felt. This is very little extra to pay when you consider the resultant benefits and should be considered as money well invested and money very well spent. Solitex is a material that is designed for modern living, being environmentally friendly and offering huge benefits.
Covering- Roadstone SL8 slates
Slates is a traditional roof covering material in many countries. It is a splitted and shaped as a slate stone. They are very durable. Slates bring to homeowner many advantages like non-combustible, resists fire, storm and wind . The fact that they are made of natural stone there is wide range of color combination. Slates are waterproof and they resists climatic changes. The cost of maintenance is very little and accidental breakage is easily replaced.
SL8 is a new generation thin leading edge concrete slate. It has a riven texture meaning that it is not a smooth surface but has the appearance of a river bed sand pattern. Roadstone roof tiles are manufactured to exacting standards at Roof Tile plants in Clondalkin, County Dublin and Currabeg, Ovens, County Cork. The size of tile is 420 x 330 mm and minimum pitch in case of nailing is 25° or clipping 22.5°. SL8 are suitable to cover even 90° pitch roof. Thin leading edges and concealed interlocks give an authentic slate appearance to domestic and commercial developments alike.
The minimum headlap that SL8 can be lied in is 85mm and the maximum 110mm. The possible gauge range is from 310 mm up to 335mm. Covering capacity at 320mm gauge is 10.4 slates / m². The linear cover of one slate is 300mm. Minimum batten size for this particular slate is 47mm x 35mm. Weight of SL8 at 320mm gauge is 51kg / m².
SL8 concrete slates is an economical solution for new or re-roofing work to maintain the character of natural slate. The roof covered by SL8 will enhance the traditional design of a building, particularly in rural settings.
Possible Roof covering
The roof on our project will be covered by SL8 Roadstone slate , however I would like to describe three other possible in our case types of roof coverings which is Plain clay Tile, Asphalt Shingles and metal sheets covering.
Plain clay tiles
Clay tile is still among the most popular roofing materials in Europe, where homes and centres of commerce are designed to last for generations. Their simplicity of form and shape make traditional, tapered mission tile ideal for funnelling and shedding water from pitched roofs. Clay roofing tile is a good choice for homes with a southwestern, Italian, or Spanish Mission design, or even for homes with a modern, clean look. This style is more prevalent in California.
Clay tiles offer the homeowner and roofing contractor numerous advantages. The roof covered by clay tiles typically last for 50 years or longer and do not rust or otherwise deteriorate. There is high range of colours available on the market: from ivory and almond to deep reds and browns, apricot to peach and buff tones. The beauty of natural clay colours is unrivalled, clay tiles mellow and improve with age. With the artificial colours that you get with concrete tiles and many types of clay tile, colour is lost with time, you just have to look at the concrete roofs of the past 70 years to observe this fact.
Clay tiles resist the passage of heat gain from summer sun and winter heat loss. They are more insulating than the other roof covering materials. The mass them provides superior insulation from sound. Tile roofs are non-combustible and protect the structure from burning embers without suffering irreparable damage.
However we need to keep in mind that a clay roof is very heavy, and expensive to install. It requires little maintenance but tiles are fragile, so walking on them can break them. That makes it more difficult to accomplish maintenance like painting or cleaning rain gutters or fireplaces.
Plain Clay tiles are a sustainable product, the longevity of clay means that the energy and raw materials used in their production are offset over the whole life of the roof, which in the case of most clay tile roofs, is over 100 years.
Glass fibre Asphalt shingles
Asphalt shingles are the most common roofing material used today. They are relatively inexpensive, starting at around 0.50 euro per square foot installed and go up from there. Things that determine cost are geographical location, slope of the roof, height of the building, ease of access to the premises, complexity of the project, the particular type of shingle and numerous other factors. Asphalt shingles are very simple to install enabling many homeowners to do the work themselves. They come in a variety of colours and styles, are fairly durable and can be easily repaired and maintained.
Asphalt shingles are commonly available with wide section of sizes ,styles and colours, suitable for most residential applications. Experienced Do-It-Yourselfers would be able to apply asphalt shingles successfully. They are low Maintenance and Easy Repairs. Other more expensive roofing products can require more maintenance, specialized tools, can be more difficult to repair and almost always require professional installation.
Glass fiber shingles have a glass fiber reinforcing mat manufactured to the shape of the shingle. This mat is then coated with asphalt which contains mineral fillers. The glass fiber mat is not waterproof by itself. It’s purpose is for reinforcement. What makes the glass fiber shingle waterproof is the asphalt. However, the asphalt itself will not stick to the mat. For this reason, “fillers” are used. The fillers in the asphalt cling to the glass fibers in the mat. The asphalt then encapsulates the glass fibers, fills all of the little holes and voids in the mat rendering it waterproof. After this cools a bit, an adhesive asphalt is used to cover the mat and the ceramic granules are then embedded.
The ceraminc granules are there for two reasons. The primary reason is to protect the shingles from the sun. The sun’s UV rays are very damaging to asphalt and cause it to deteriorate prematurely. This is one of the same reasons that gravel is used on built-up roofs. The second and more obvious reason for the granules is aesthetics. Asphalt shingles are available in a wide variety of colors to match almost any facade or landscape.
The lifespan of asphalt shingles depends highly upon the environment. Shingles in cooler climates seem to last longer than those installed in the warmer climates. The hotter the environment is, the shorter the service life of the shingles. One thing that’s very damaging to shingles is Thermal Shock. Thermal Shock is what roofing materials experience when the ambient temperature changes dramatically within a very short period of time – usually 24 hours. In Ireland temperatures are comparable stable .
Using a Metal sheets as a roof covering material dates back to the twelfth century. Over many years this technology has been improving until these days. There are number of good reasons to use metal on residential building. First , metal is predictable and stable product. Unlike other single-ply technologies like rubber, a metal panel is not affected by ultraviolet rays, which are one of the leading sources of rood degradation. Second, Advantages in metal coating and finishing technologies have significantly improved the life cycle of metal roof, and related cost benefits.
Metal roofing is also extremely puncture-resistant, which is a valuable benefit to today’s building owner who is looking for long-term , low maintenance solutions. Actually, durability is one reason for metals growing popularity.
Metal roofing is extremely versatile. It is compatible with all types of building materials and can be incorporated into all design concept. Metal roofing would be an effective accent for our masonry house. The construction of metal roof is very light and extremely durable by the time.
Colour and finishes are available to suit any application, from earth tones to exotic tropical hues, from bare, unfinished surfaces to special coatings designed to resist corrosive atmospheres such as Irish.
The use of metal roofing panels on a residence offers pride of ownership to the homeowner who wants to have something different for neighbours. Metal panels are made to simulate clay tile, wooden shakes and slate. For addition they install easily and quickly.
Perhaps the most significant benefit of all , given before , is environmental friendliness of metal roofing, form installation through eventual tear-off. To begin with, many metal roofing products use recycled metal in their initial fabrication.
Second , the building owner and contractor does not have to contend with external flames, hot kettles or noxious fumes during installation. Finally , after the roof has served its useful life , most of its metal is 100 percent recyclable , which eliminates concerns about hazardous waste disposal.
Cavity wall- Partial fill
Cavity walls consist of two ‘skins’ separated by a hollow space. The outer leaf and the cavity serve to resist the penetration of rain to the inside face and the inner leaf to support floors, provide solid internal wall surface and, to some extent, act as insulation against transfer of heat.
The Cavity wall in the house is 302,5 mm thick. The outer leaf will be construct of Cheshunt Multi Brick lied in on stretcher bond . The brick of dimensions is 215mm x 102.5mm x 65mm. Inner will be build of Lightweight Blocks the size of 440mm x 225mm x 100mm. The gap between the walls going to be 100 mm wide. To tie the two leaves together will be used mild steel coated with zinc ties spaced at every 900mm horizontally and 440 mm vertically.
The cavity wall in our project is partial fill one. Partial fill construction requires the use of insulating material in the form of boards that are sufficiently rigid to be secured against the inner leaf of the cavity. Thermwall TW 50- Partial Fill insulation of thickness 250mm is a high performance thermal insulating mineral wool which satisfies the Building Regulations with a product that is BBA approved and that has a Euroclass A1 fire rating.
Because mineral wool is high performance acoustic insulator, flanking noise transmission down the wall cavities is also reduced.
Partial fill cavity walling has been regarded as the best-practice form of wall construction in Ireland for at least two decades. It is the most efficient way to savings on energy heat loss. I compared thermal conductivity values of two Kingspan insulations. First one was 250mm partial fill Thermwall TW 50 and the second 750 mm mineral fibre full fill batt. The result was quite surprising. Partial fill with 0.022 W/m.K beat mineral fibre by 0.012 W/m.K!
However we have to remember that partial fill cavity wall require a clear cavity to avoid moisture penetrating into the board joints and through to the inner leaf of the wall by capillary action. Care should be taken to ensure that mortar does not fall on cavity ties. Were mortar falls on the tie it can also create a cold bridge.While a cavity is clear , such a wall application provides the most effective barrier to rain penetration by allowing the traditional wall cavity to be maintained.
External brick work
The face work is done in Pressed Brick. – The exposed surfaces of the building including the chimneys, to be faced with Cheshunt Multi pressed brick .
All face brick to be laid in the most skillful manner in coloured mortar. Each brick to be dipped in water before laying; each edge of the brick and down the middle to be butted, and all vertical joints to be filled solid from front to back. The brick to be laid with plumb bond and bonded to the backing with a diagonal header to every brick in every course. Special care should be taken to ensure that mortar does not fall into cavity space.
All courses of brickwork shall be kept level, and the bonds shall be accurately preserved. When necessary to bring any courses to the required height, clipped courses shall be formed , as in no case shall any mortar joints finish more than 10 mm thick. All brickwork shall be laid to the lines, and all walls and piers must be built plumb, true and square. Walls to be carefully leveled for floor joist.
All window openings are described on the attached drawings .
Mortar – Cement Mortar – All brickwork below the grade line and parapet walls shall be laid in mortar composed of 1 part fresh cement and 2 parts clean, sharp bank sand, properly screened, mixed with sufficient water to render the mixture of proper consistency. Care must be taken to thoroughly mix the sand and cement dry, in the proportions specified, before adding the water. The mortar shall be mixed in small quantities only, and in no case shall mortar that has commenced to set or stood over night be used.
Colored Mortar. – All face brick to be laid in mortar composed of lime putty and finely-sifted sand, coloured with Pecoria mortar stains; colour brown.
Bricks available through Dublin’s premier supplier -Bricks Ireland. The company is located in South Dublin and its open 7 days a week. They supply both to trade and to the retail market for bricks.
When designing a drainage system for a rural setting dwelling we must respect local authority requirements. Firstly, “A building shall be provided with such a drainage system as may be necessary for the hygienic and adequate disposal of foul water from the building.” (Department of the environment heritage & local government, 1997)
A building also shall be provided with a speared, drainage system for disposal of surface water from the building. These can not be connected to a sewer or septic tank reserved for foul water, and no part of a drainage system conveying foul water shall be connected to a
sewer reserved for surface water. Foul water drainage must be save of leakage.
On our site there is no access to foul water outfall , so necessarily is usage of foul water septic tank. A septic tank must be of adequate capacity and so constructed that it is impermeable to liquids. The proper ventilation has to be provided to avoid collecting dangerous gasses. Septic tank must be located in accessible in case of empting place.
High range of Precast Septic tanks are available on the market. The company called Shay Muratagh (http://www.shaymurtagh.ie/Septic-tanks.aspx) supply concrete tanks that are not prejudicial to the health of any person and do not pollute, so as to endanger public health, any water including ground water.
Foul water Drainage
convey the flow of foul water to a foul water outfall while creating foul water drainage few aspects has to be considered. The capacity of it ( depends on the size and gradient of the pipes) should be large enough to carry the expected flow at any point. In our case water flow rate which based on the typical household group of 1 WC , 1 bath, 1 or 2 washbasins and 1 sink is approximately 2,5 litres/second.
So that the building regulations require to use stack of 75 mm diameter , and recommended gradient to lie pipe underground would be from 1:60 to 1:100. To prevent proper water flow in branch pipes, WC demands pipe of 100 mm diameter and gradient of 9 mm , washbasins, the same as sink 50 mm and 18 mm gradient.
Foul water drainage should be save of blockage or leakage. If a trap forms part of an appliance, the appliance should be removable. All other traps should be fitted directly after the appliance and should be removable or be fitted with a cleaning eye.
While constructing drainage system we must remember to prevent foul air from entering the building under working conditions.
These particular drainage system the same as septic tank must be properly ventilated to prevent the build up of flammable gases. Ventilating pipes open to external air should finish at least 900 mm above any opening into the building within 3 m and should be finished with a cage or other perforated cover which does not restrict the flow of air.
The diameter of the part of a discharge stack which serves only for ventilation
In the two storey houses should be at least 75 mm. The local climate is free of low temperatures so PCV pipes can be lied on the external elevation of the house.
Foul water system also has to be accessible for clearing blockages. All of the trap which forms part of an appliance should be removable. The other traps should be fitted directly after the appliance and also should be removable or be fitted with a cleaning eye.
Branch pipes should discharge into another branch pipe, or a discharge stack, unless the appliances are on the ground floor. A branch pipe should not discharge into a stack in a way which could cause cross flow into any other branch pipe. A branch pipe should not discharge into a stack at a point lower than 450 mm above the invert of the tail of the bend at the foot of the stack in single dwellings of up to three storeys.
Rodding points should be provided to give access to any lengths of pipe which cannot be
reached from any other part of the system. All Pipes should be reasonably accessible for repair.
All stacks should discharge to a drain. The bend at the foot of the stack should have as large a radius as possible and should be at least 200 mm at the centre line.
Stacks serving urinals should be not less than 50 mm in diameter and stacks serving water closets should be not less than 100 mm in diameter.
Underground Pipe work – connection to septic tank by PVC-u BS 4514
The layout of the drainage system should be as simple as possible. Changes of direction and gradient should be minimised and as easy as practicable. Pipes should be laid in straight lines where practicable but may be laid to slight curves if these can still be cleared of blockages. Access points should be provided only if blockages could not be cleared without them. Drains should be laid to falls and have enough capacity to carry the flow. Underground drainage should be adequately protected from accidental damage from sources such as traffic, ground settlement and tree roots. The depth of cover will depend on the levels of the connections to the system, the gradients at which the pipes are to be laid and the ground levels. The minimum depth should be 900 mm under any road and 600 mm in fields and gardens. The system should be ventilated by a flow of air.
Surface water drainage
This drainage is to carry only rainfall water and it is not connected to the any server .
There is no requirement in this Document for the provision of rainwater drainage for areas of 6 m2 , However, following calculation of area drained rule indicates that our area is 146 m2. In this case the most effective will be Gutter of 150 mm dimension. Gutters should be laid with any fall towards the nearest outlet. Where there is a fall, or the gutter has a section which gives it larger capacity than a half-round gutter, or the outlet is round edged, it may be possible to reduce the size of the gutter and pipe. The size of a rainwater pipe should be at
least the size of the outlet from the gutter.
The type of ground floor used in our project is solid floor. Solid floor is meant this floor, which consist for the most part of concrete, receiving continuous support from the ground.
To provide a level base on which to cast a ground floor slab , 150 mm layer of hardcore will be laid. Hardcore raise the levels, reduce the capillary rise of ground moisture, and provide a dry firm base on which work can proceed or carry construction traffic. On the top of hardcore comes 20 mm layer of sand blinding.
Before ling the slab, required is to put DPM below it. It is to prevent moisture form the ground reaching the inside of the building. DPM also prevent the interaction of ground contaminates with the concrete , stopping interstitial condensation and retaining constructional water.
On the earlier prepared ground with hardcore , sand and DPM comes 100mm thick 30 N Concrete slab. For good quality base will be used site mixed concrete of proportions 1:2:4 cement: fine aggregate: coarse aggregate: coarse aggregate by volume. Now floor is ready to be insulated by 50 mm QF therm insulation boards on which will be lied 50 mm screed.
Two main factors made me to arrive with decision of using solid concrete ground floor. That was thermal and acoustic insulation, however there is many more benefits for the home owner .
As we know from physics sound is transmit by air vibration. Sources producing sound waves in air , such as from conversation or television , will in turn produce vibration in floors. On the other hand , floors may also be vibrated by direct impacts such as footsteps or objects dropped onto floor surfaces. The best way to avoid vibration of the floor would be constructing solid, vibration resistant concrete floor. The lowest floor of a building, if carried on the ground , normally does not present problems of sound transmission as the concrete acts as a barrier to sound. Additionally, the concrete prevents air leakage and slows down heat from escaping therefore a concrete home stays warmer in the winter and cooler in the summer. This can help keep utility costs low. For addition applying insulation to a groundbearing floor between the slab and the screed minimises thermal bridging and creates a floor with a rapid thermal response, which matches that of the rest of the building.
Concrete floor has a life time durability and great strength as well. Poured concrete forms a barrier to the elements and can be further strengthened by steel reinforcement.
In case of fire solid concrete floor can slow the spread of the flames giving a time to evacuate to safety. Not only could this could mean the difference between life and death, it could mean the difference between having some repairable fire damage versus the loss of your home and its contents.
Concrete floor construction has a greater resistance to water damage or leakage of any sort due to its solidity. Insects are less likely to infest solid concrete houses.
Environmentally friendly. Concrete is environmentally friendly as the ingredients of concrete are plentiful in supply.
Concrete upper floor
While designing first floor few factors has to be consider. Firstly our client wish to have well thermally and soundly insulated house. The other factors are to do with loads that floor will need to manage. High quality with no increase of cost would be recommended. So that I decide to use precast concrete floor, which contains concrete t-beams (170×115 mm) and lied between concrete fill blocks (440x100x215mm). T -beams will be lied at every 380 mm. Between concrete fill blocks and 50mm reinforced screed will be lied aerobeam infill block insulation of 50 mm thickness. It is important to put DPM membrane under screed, and DPC at joice of floor with the wall. Precast concrete floor will deliver to its user a essential comfort. Concrete upper floors provide improved sound Insulation between the floors and rooms. They also act as a thermal store; this can reduce heating costs especially when under-floor-heating systems are used.
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