Education: August 2017

TABLE OF CONTENT

• CHAPTER TITLE PAGE

• ACKNOWLEDGEMENT 1

• ABSTRACT 2

• TABLE OF CONTENT 3

• INTRODUCTION 4

1. GENERAL BACKGROUND ON PREFAB

2. OBJECTIVES

3. RATIONALE OF THE PROJECT

· LITERATURE REVIEW 5

1. INTRODUCTION OF PREFAB

2. ADVANTAGE OF USING PREFB HOUSE

3. FACTOR AFFECTING PREFAB HOUSE

4. COMPARESION BETWEEN PREFAB HOUSES AND RCC BUILDING

· METHODOLOGY 10

1. LITERATURE REVIEW

2. DATA COLLECTION

3. DATA ANALYSIS

· CASE STUDY 11

1. SITE VISITE

2. DATA COLLECTION

3. DATA ANALYSIS

· EXPECTED OUTCOMES 12

· CONCLUSION 12

• RECOMENDATION 12

• REFERENCE 13

INTRODUCTION

1. GNERAL BACKGROUND ON PREFAB

Prefabrication is the practice of assembling components of a structure in a factory or other manufacturing site, and transporting complete assemblies or sub-assemblies to the construction site where the structure is to be located. The term is used to distinguish this process from the more conventional construction practice of transporting the basic materials to the construction site where all assembly is carried out.

2. OBJECTIVES

v MAIN OBJECTIVES
The main objective of the proposal is to study the feasibility on prefab housing in Nepal with high strength and low costing then exiting technology.

v GENERAL OBJECTIVES

-To fulfill the course objective of civil and rural engineering project II

-To make earthquake proof housing

-To make environment friendly housing

-To secure people life from natural disasters

3. RATIONALE OF THE PROJECT

-It is a new technology for people and for developing countries

-Its can be constructed within certain period of time

-It is very much effectively used in different part of the world

-It is affordable because of its low cost compare to Rcc building

LITERATURE REVIEW

INTRODUCTION OF PREFAB HOUSE

The term prefab can apply to any construction method where a significant part of the construction takes place off-site in a factory that produces relatively large, complex pieces that are then assembled at the site into the finished building .Since prefab is such a loosely defined term, it helps to show where prefab as we define it fits into the spectrum of construction methods ranging from completely off-site to completely on-site. At the extremes, recreational vehicles are an example of completely off-site construction, while igloos and straw huts show completely on-site construction. As more realistic examples, HUD-compliant manufactured homes (commonly called trailer homes) are brought to the site almost completely finished, while in traditional wood, steel or concrete construction, homes are

built almost completely on-site from thousands of basic materials. Prefab fits in the middle of this continuum: it bridges the gap between manufactured housing and traditionally built homes, offering many of the advantages and opportunities of each.

Prefab materials

A number of new construction materials are starting to be used as components in prefab housing. Here we examine two of them: structural insulated panels (SIPs) and insulating concrete forms (ICFs). Other prefab materials include prefab foundation systems, steel framing, concrete framing, large-modular systems, and many others.

Structural insulated panels (SIPs)

A structural insulated panel (SIP, often called a sandwich panel) consists of a pair of oriented strand board (OSB) or plywood panels with a core of extruded polystyrene (EPS) foam in between, attached with an adhesive. Panels are available in a variety of thicknesses. They are usually produced in 8-ft-tall panels, but they can be cut to custom shapes at the factory, even with cutouts for windows and doors. As the name implies, SIPs can be used structurally, with the OSB panels playing a similar role to the flanges of an I-beam, and the foam core acting as the web. Structural use of SIPs reduces the number of studs needed in a conventionally framed house. SIPs can also be used as nonstructural walls in timber-frame and post-and-beam construction. One of the main advantages of SIPs is their insulating value, which depends on the thickness of the foam core. The foam core forms a continuous energy barrier, and the smaller number of studs leaves less opportunity for heat conduction. SIPs are fabricated to very close (1/8 inch) tolerances, and the edge connections, which vary by manufacturer, are designed to fit snugly together. This property, combined with OSB’s resistance to warping, results in a very tight structure whose walls are unlikely to shift and crack after construction. On-site labor can be further reduced by using SIPs with drywall preinstalled on one side. Every material has disadvantages, and SIPs are no different. One of the biggest concerns about SIPs is their resistance to insects. While the EPS foam core provides no nutrition to insects, it offers an easy way for them to tunnel into the structure. Borate additives can be mixed into the foam during manufacture, providing some amount of insect resistance. Some manufacturers offer a 25-year warranty on their SIP products. Although SIPs have been around for several decades, they have come into widespread use relatively recently, and questions remain about their performance in the long term. Delamination caused by failure of the adhesive is a major concern because it would affect the ability of structural SIPs to carry load. Fire resistance is also a concern, though manufacturers claim that as long as fire does not breach the OSB panel, SIPs perform just as well as traditional wood frames. There are also questions about the difficulty of remodeling buildings constructed with SIP walls. SIPs are manufactured by dozens of companies; Premier Building Systems is one of the largest. They are growing in popularity for prefab construction, used by companies like Timbercraft Manufacturing of Washington for timber-frame construction and by architects such as Anderson for modernist prefab projects. The Structural Insulated Panel Association is an industry group that promotes the use of SIPs.

Insulating concrete forms (ICFs).

Insulating concrete forms (ICFs) are a prefab construction material consisting of hollow EPS foam blocks that are stacked and glued together on-site, creating a form that is filled with reinforcing bars and concrete. The unique property of ICFs is that the foam blocks are not removed after the concrete hardens; instead, they help insulate the building, while the concrete provides structural integrity. Although ICFs are really a hybrid prefab material, since installing rebar and pouring concrete is done on-site, they offer many of the cost and environmental benefits of pure prefab. Compared with traditional concrete construction, it is faster to stack ICF foam blocks than to build a wood form, and since the foam blocks are not removed, there is much less waste. Some manufacturers offer large prefab foam panels rather than blocks, which further reduces the amount of onsite labor. Manufacturers claim that ICFs provide much better thermal insulation than conventional framed construction. Four inches of polystyrene foam plus a typical five-inch-thick concrete wall is rated at R-17, and since the wall is solid, there is no possibility of convection within the wall. Sound transmission is also much

lower than conventional frame walls with fiberglass insulation. One of the disadvantages of ICFs is the potential for improper installation due to problems with the concrete. The concrete must be fluid enough to fill the foam blocks without leaving air pockets, which would severely detract from the structural integrity of the finished wall, yet must be solid enough not to exert too much horizontal pressure on the foam, which can cause the forms to fail. Manufacturers seem to gloss over these problems when they claim that almost anyone can install ICFs easily. As with SIPs, questions have been raised about the fire and insect resistance of ICFs. Since ICFs are often used both for the foundation and as walls, foam comes in direct contact with the soil, providing an easy vector for insects to invade the structure. However, insect-resistant additives can be mixed into the polystyrene

foam, and manufacturers claim that fire-retardant additives make ICFs perform much better than traditional wood-frame walls in fires. ICFs have been used for three decades, and originated in Europe where concrete and masonry are the most common forms of residential construction. Many manufactures provide ICF products. American Polysteel of New Mexico is one of the largest. The Insulating Concrete Form Association is a good resource for information about products and manufacturers.

ADVANTAGE OF USING PREFAB HOUSE

The goal of prefab is to offer a third way—a way for an average person to get a well-designed house that is at least roughly design to his needs. Compared with traditional methods of home construction, prefab offers a number of advantages:

1. Reduces The labor Costs: Fabricating most of a home’s components at a central location can take advantage of economies of scale and specialization. For example, rather than paying a team of framers to travel to a job site, cut lumber, nail it into place and clean up, framing panels can be produced at a factory by people who do one job and do it well, in a facility that lets them work at maximum efficiency. Depending on the type of construction, a job that normally takes months to complete on-site can be finished in days or even hours of on-site work.

2. Reduces The Material Costs: Again, off-site fabrication benefits from specialization and economies of scale. A company that manufactures certain products in large quantities can negotiate better prices from its own suppliers, and competition forces companies making similar components to pass these savings along to the customer.

3. Higher quality materials: Components produced off-site can often be manufactured to tighter specifications and using better raw materials than the same components built on-site. For example, as the overall quality of dimensional lumber declines, local builders are now stuck using lumber that they would once have tossed into the scrap heap, while off-site manufacturer located near sources of better wood can fabricate higher-quality components efficiently. And since manufacturers can use specialized tools and control the conditions under which the components are made, the resulting components can exceed the quality of anything built on-site.

4. Environmental Friendly: Off-site manufacturing processes can be optimized to reduce the amount of waste generated during fabrication. Since on-site work is reduced to assembling prefab components, much less waste is generated at the job site than is typical of traditional construction methods. Some prefab components are also designed with energy efficiency in mind.

5. Earthquake proof : Its structural is made in such a way that it can resist general earthquake which Rcc building cannot ,because of this prefab house we can ensure the safty of lifes which are being killed or collapse due to earthquake.

FACTORS AFFECTING PREFAB HOUSE

Since each of these prefab ventures has at best achieved only moderate success, it is worth examining the difficulties faced by prefab:

1. Design limitations: Although every type of construction has limits on what designs are feasible to construct, certain designs may stretch the limits of the prefab components chosen for a project. For example, while a prefab system intended for construction on a flat slab could be adapted for a steep slope, the amount of foundation work required may outweigh the advantages that are offered by that prefab system.

2. Smaller pool of local builders and laborers: Builders unfamiliar with a certain method of prefab construction may be unwilling to devote extra effort to learning it, especially if there is money to be made by building using traditional methods. Another difficulty is the lack of laborers skilled in the construction method. With less competition among builders bidding on a project, the overall cost may be higher or quality may suffer.

3. Little or no cost advantage: The labor and material cost advantages of prefab over traditional construction mentioned above depend on economies of scale, which will not exist for a new prefab product. This presents a barrier of entry for bringing a new product to market, because the market will initially be limited to consumers willing to accept higher costs in exchange for other advantages of the product. Furthermore, traditional dimensional lumber construction can itself be done in a highly efficient manner, especially in large developments of thousands of new homes where a veritable mini-factory is established on the site.

COMPARESION BETWEEN PREFAB HOUSES AND RCC BUILDING

In classical construction process, suppliers ship the raw materials (including cement, bricks, reinforcing steel bar, sand, and woods) to construction sites. Using these materials, workers make customized housing components on-site and assemble them to build the house. In classical construction, most of the cost (e.g., 90%, Shang 2006) occurs on site. In contrast, “Prefabricated housing” refers to a construction process where the housing components (e.g., walls, floors, balcony, stairs, etc.) are prefabricated in batches in factories, and then shipped to sites for assembly (see Figure 1.2 for a comparison). Although the complexity of the pre-fabricated housing components and off-site procurement cost vary from project to project, from one country to the other, one common feature of prefabricated housing is off-site production plus on-site installation/assembly.

Fig. 1.2 Prefabricate Housing Construction vs. Rcc building

METHODOLOGY

LITERATURE REVIEW

DATA COLLECTION

DATA ANALYSIS

TESTING

LITERATURE REVIEW

The detail study of prefab housing and construction study will be done so, to overcome from factor affecting as well the constructed houses will be eco-friendly and earthquake proof.

DATA COLLECTION

Required data will be collected by the oral questions asked from the engineer working in this feild and some of the calculations will be done by the help of our project supervisor.

DATA ANALYSIS

After the collection of data it will be analysis and net calculation can be done, which is important part for construction of project.

TESTING

After data collecting and data analysis the testing is done in the lab to ensure the safety of life.

CASE STUDY

1. SITE SURVEY

During our different site visit we collected many of information about prefab house. Which where being used by the people of outside the valley. Discussion with stakeholder We found that they where very much happy and comfortable with this new type of technology ,because it cost less than Rcc building and also it is lighter than Rcc building.

Source: Sindhupalchowk, Chautara

Size: 600 Sq.ft

Costing: 10-12 lakh

2. DATA COLLECTION

Prefab House Cost Estimation

Size(Sq.ft)	Type of House	Cost
32 m²	Type ‘A’	3,35,000/-
42 m²	Type ‘B’	4,25,000/-
58 m²	Type ‘C’	5,75,000/-
63 m²	Type ‘D’	6,25,000/-
66 m²	Type ‘E’	6,50,000/-

Source : Microtech m & e Pvt.ltd

3. DATA ANALYSIS

During our site visit we found the newly built prefab house which was located at sindhupalchock,Chautara of size 600 sq.ft. with our direct conversation with site engineer (Er shiva ram Dhakal) .He provided much more information about prefab house which was required for us.when we asked about total costing then it was nealy 10-12 lakh NRS. The house was build by USAID international organization.

EXPECTED OUTCOMES

• Detail study of prefab house is achieved.

• Alternating source will be utilized instead of Rcc building.

• Replacement of heavy construction and saving of time during construction.

• Course objective will be fulfilled.

CONCLUSION

Prefab offers one way to satisfy the demands of the peoples, through the use of new materials and through the design and construction of homes as by demands. The good news for architects is that this market gives them an opportunity to expand their skills and play some role in revolutionizing an industry. It also empowers the new technology which makes human life simple and easy. It cost less than Rcc building and also lighter than Rcc building.

RECOMMENDATION

Ø Importance of prefab house should be broadly known to everyone.

Ø It should be made tax free by government so that it cost will be affordable.

Ø Finance facility should be provided.

Ø It is best project for developing countries because of costing and earthquake proof.

Ø NGOS and INGOS should encourage to build in all area where earthquake affected.

REFERENCE

Peter Anderson, Site-specific design for offsite construction, lecture, AIASF,

April 6, 2005.

– Beyond the trailer park: designer prefab (web site),

http://www.lynnbecker.com/repeat/beyondtrailer/introduction.html.

– fab prefab – modernist prefab dwellings (web site),

http://www.fabprefab.com/.

– Prefab reflects well on tasteful owners, Los Angeles Times, September 25,

2004.

Structural insulated panels

– Structural Insulated Panel Association (web site), http://www.sips.org/.

– Michael Morley, Building with Structural Insulated Panels (SIPs), Taunton

Press, 2000.

Insulating concrete forms

– Insulating Concrete Form Association (web site), http://www.forms.org/.

– Concrete Homes (web site), http://www.concrete-home.com/.

Productizing architecture

– Michael Sylvester (editor, fabprefab.com), Prefab as productized architecture,

lecture, AIASF, April 21, 2005.

Sunday, August 6, 2017

prefab