Correct method for building construction

Introduction to construction of buildings

Construction is the process of creating and building infrastructure or a facility. It differs from manufacturing in that manufacturing typically involves mass production of similar items without a designated purchaser, while construction is typically done on location for a know client. Construction as an industry is six to nine percent of the gross domestic product of developed countries. Construction starts with planing, design, and financing and continues until the project is built and ready for use.

Large scale construction is a feat of human multitasking.A Project manager normally manages the job and a construction manager, design engineer, construction engineer or project architect supervises it.For the successful execution of a project, effective planning essential. Those involved with the design and execution of the infrastructure in question must consider the zoning requirements.the environmental impact of the job, the successful scheduling,budgeting, construction site safety, availability and transportation of building material,logistics,inconvenience to the public caused by construction delays and bidding, etc.  

Design Principles

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1. Foundations
2. The building needs a coherent structure
3. Joining walls to roof structure 
4. Tying walls to building structure
5. Roof truss ties
6. Cross bracing of walls and roof
7. Drainage principles
8. House elevation and location

1.Foundation 

   A safe building must have a strong foundation

• the ground under the building has to bear the weight of a building.if it is a weak soil,the foundations must be made stronger. If the building has more than one floor the foundation must also be made stronger. Foundation are best when continuous under the house.
• Is the building built on sand,rock,clay? Design foundations appropriately.
• Soil for a good foundation that can carry the weight of a building must be well drained so that it is dry and not waterlogged.
• waterlogged soil can become liquefied in an earthquake-turn to a semi-liquid-so that structures sink into the ground.

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Example of bad foundations.This house is being built in a swampy,waterlogged area. As the foundation and the foundation trench was dug,it filled with water so the builders dropped dry sand and cement into it and then the first row of block were located on top of this mixture these foundations in permanently wet soil are inadequate and will also be weak when impacted by any external hazard.

Example of bad location. This house is located on a river bed, close to running water, where it is very vulnerable to flooding.Not only the house,but also its contents are vulnerable to destruction due to heavy rains. Houses should not be built in such obviously vulnerable locations, or if they are, they should be designed to resist the hazard of their location.

Liquefaction. Example of a well built and well structured house that was not quite finished when a major hazard struck.the house was structurally good but the foundations were poor for this location. Due to a major earthquake the foundations suffered from liquefaction of the ground, and due to the weight of the house, it subsided unevenly into the ground.

Design Principles

2.The building needs a coherent structure if the structure is coherent and strong,it protects the whole house.

• A regular structure
• An integrated structural ring beam around tops of doors and windows connected to columns
• An integrated structural ring beam around top of walls connected to columns 
• Triangular gable end wall must be structurally supported

This regularly structured building is able to withstand the impact of hazards. Notice the structure of columns and floors which are all joined to each other in a regular format. Overhanging parts of the building are all well supported columns to the foundations.

this illustrates good structural design principles for a hollow block or brick wall building with a reinforced concrete structure .A complete structural frame around the building is tied in to the foundation, the walls and the roof structure.Doors and windows have a beam over them to carry the weight of the wall above and to strengthen the columns, by a second reinforced concrete ring beam, and end walls are strengthened.

Good Structure. This is a well structured house that follows all the above design principles. Notice the good foundation, the good structure framing the building,and the 2 ring beams connecting all the building elements at the top of doors and windows and at the top of the walls. Gable end walls are also strengthened with reinforced concrete.

This is an example of bad structural practice. This house has no structural columns and no ring beams to hold the structure together. There are no columns at the corners,or within the walls, and there are no ring beams at the top of doors and windows or at the top of the walls. This building will have little resistance to being destroyed by any impact from nature, like an earthquake or a storm.

An example of proof structuring of a house.The columns are very poor, with concrete poured in stages after the walls were built up, and the concrete has not fully covered the steel so that the reinforcing will rust. The columns are too small and the steel is too close together. The concrete was not not tamped to ensure good compaction.Columns should not be made to fit withing the thickness of the wall because there is not enough room to properly cover the column reinforcement with concrete.this kind of column does little to give a house structural strength. It would have been better to have a proper column at the end of the wall on the right.

Not good structure.Another example of a house which has too little structure to brace the wall against lateral forces. This is common construction fault with hollow blocks. Columns are inadequate, too small, and poorly constructed, and there should be a reinforced column between the door and the window.The window and the door have inadequate structural support. When the forces of nature strike this house,it will progressively deteriorate and be hard to repair.

Good structural practice. A good pattern of reinforced concrete columns and beams to strengthen all aspects of the building including support to strengthen the triangular gable end wall so that it will not fall when a lateral force strikes the building, All end walls of this nature need a reinforced column to strengthen them, or they are liable to fall when the building is subjected to a major lateral force. It also has a reinforced concrete beam to top to all walls.

Connection of Wood frame building to concrete frame/brick stub walls.

It is essential that a wood frame structure mounted on a concrete frame/brick stub wall must be fully anchored together. A bracket, as shown above left, made of non-corrodible metal, must be cast into the bearing structure to provide a structural connection for the whole wall through to the foundation. The wood column must be bolted to the foundation.The wood column must be bolted to the bracket as shown, and the bracket must be fully secured into the concrete as shown on the right.

Design Principles 

3.Joining walls to roof structure 

   Join walls and roof to strengthen each other 

• Column reinforcement should protrude from the top of concrete columns and be bent around roof trusses for structural strength, or roof trusses should be strapped with metal ties to the wall structure.
• Exposed metal should be painted with rust proof paint  to prevent corrosion.

An illustration of binding roof trusses to building structure. Roof trusses should be constructed over columns, ans for a concrete column the reinforcement should protrude at the top and be bent over roof trusses to join the roof structure with the wall structure.Metal straps or plates can be used for this role particularly where the building structure is made of wood.

A good roofing example of column steel reinforcement bent over roof truss to tie house structure to the roof structure. This is an essential detail in areas subject to earthquake and to winds, to keep the roof on the house when a natural hazard strikes the structure. Such exposed steel should be painted with rust-proof paint to mi minimize corrosion. 

Example of good roofing practice. steel roof trusses are connected to columns through welding of truss members to column reinforcing steel and purlins are welded with ties to roof trusses. This will hold the roof firmly on the house in storms or other hazard from nature. 

Example of incorrect roofing practice. The roof structure is good, but no connection is made between roof trusses and the building structure. The roof is resting on the top of the house walls and is subject to moving with high wind or other forces of nature.

Design principles

4.Tying walls to building structure walls tied to columns protect them from falling.

• Wall must be tied into the building structure so that they do not move separately when the forces of nature impact them.
• Wall ties should be hooked into the wall structure.
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Good tying practice. An illustration for a wooden frame building, where metal ties are used to tie wall materials to the main structure of the building.Steel wall ties are to be at a maximum of 40cm spacing.

Good tying practice.An illustration for a reinforced concrete frame building,where metal ties are used to tie walls to the main building structure. Steel wall ties are to be at maximum of 40cm spacing and a minimum of 8mm diameter, and bent at the end.They are for for all openings in the walls.

A good example of wall ties cast into columns to connect the walls with the building structure. Ties are to be at maximum 40cm spacing from bottom to top of the wall. However, in this illustration they lack hooks at the ends at this point in construction.

Result of no ties. This is an example of what happens when walls are not tied to columns. The main part of this building (2 floors on the left) withstood the forces of nature striking it,but the one floor extension collapsed. The columns could not help resist the force of nature on the walls of this house extension because of the lack of ties between the walls the walls and the columns. The one floor part also lacked a strong structure.

Result of lack of ties. Another example of what happens when the walls are not tied to the columns. The wall panel on the left is moving away from the column because it has not been tied into the column.

Design principles

5. Roof truss ties 

    Flexible but strong roof trusses enhance safety.

• The joints wooden roof trusses need to be bolted together and tied with metal straps to provide flexibility but not collapse under the forces of nature.
• Metal roof trusses must be welded together, welded to purlins, and welded to wall reinforcement for strength.

This illustration shows the metal straps tying together the different element of the roof structure at this joint in roofing, so that they will be held together when affected by extreme forces of nature. A plate may also be used.

This illustrate shows a strap or plate across the joint at the apex of the roof structure. This is always good jointing practice. Notice also that for a wooden roof structure, wooden block should be used for support of purlins not a single nail through the purlin into the truss.

Good roofing practice with metal roof trusses, where the roof is strongly connected to the reinforcing in the wall columns by welding,and the purlins are welded to the roof trusses with small brackets to make a strong roof structure.

Design principles

6. Cross bracing of walls and roof.

    The walls and roof need bracing against lateral movement

• In order to resist lateral forces, wall and roof structure need cross bracing at all levels, Particularly if it is a wooden structure.
• This is a major principle in the construction of traditional houses.

Example of a cross bracing system for the walls,roof,and also for the columns under the house for a wooden house structure. The cross bracing system provides strength against lateral forces so that the building does not collapse sideways but is held together. This is system used in traditional house and needs to be continued in modern houses.

Good practice. Traditional Batanes house, which have stood through many storms and earthquakes, are well structured and supported, with good corner columns, and have good arches over doors and windows to bear weight down their sides. The solid stone wall on a good foundation provides resistance to lateral movement.

Design Principles

7. Drainage Principles

    Drainage plans are essential to good house design 

• A high rainfall area requires a drainage plan for roof water to a common drain. Levels of the drainage system need to be included on plans so that rain water flows away and does not form puddles that breed insects around house.
• Drains should be covered or bridged where necessary to allow access over them for people and vehicles.
• Drains should have a V form at the bottom to reduce accumulation of water if levels are incorrect.

Design Principles

8. House elevation and location 

    Safeguards house and contents from flooding, landslides, flash floods.

• The house floor should be elevated above the surrounding ground level, and extra height is needed in vulnerable situations such as locations close to a floodable waterway or a swampy area, or in a tsunami or wave prone area near the sea.Extra height is best provided through stilts.
• House must be located away from places subject to landslides where soil may move down a steep slope, debris flows where soil gravel and rock may be washed rapidly down by heavy rainfall,and flash floods.

Good house elevation. This house is being built in a low laying area vulnerable to flooding. Concrete stilts are being cast on pad footing to raise the floor level of the house so that it will not be flooded or subject to dampness.

Use correct method for construction......