SIP CONSTRUCTION WITH EPS AND GALVANISED ELECTRO-WELDED MESH

: SIP stands for structure insulated panels which is usually constructed of oriented strand boards (OSB) on the interior and exterior sides with foam like Expanded polystyrene (EPS), extruded polystyrene (XPS) or rigid poly-urethane foam, sandwiched in between the OSB sheets. Around the polystyrene; plywood, pressure treated plywood, aluminium, thin mesh of steel, stainless steel etc can also be used in replacement to OSB panels. This article focus on a new idea which is using polystyrene sheets 170mm thick, 2.4m long and 1.2m wide with 3mm electro-welded mesh on both faces with both main and distribution bars. Depending on the loading the spacing can be reduced and some extra bars at length L/3 can be welded to the mesh. The SIP with galvanized electro-welded mesh acts like RC structure and if installed by trained persons it is suitable for all design loads as all the factory tests have been conducted on them. The advantages of using SIP panels with electro-welded mesh are easy to install, economical (at least half a price of traditional build), speedy construction (takes about half of the time as compared to traditional build), light weight, fire resistant, flexibility, thermal properties, easy transportation etc.


1-Introduction:
SIP stands for structure insulated panels which is usually constructed of oriented strand boards (OSB) on the interior and exterior sides with foam like Expanded polystyrene (EPS), extruded polystyrene (XPS) or rigid poly-urethane foam, sandwiched in between the OSB sheets.Around the polystyrene; plywood, pressure treated plywood, aluminium, thin mesh of steel, stainless steel etc can also be used in replacement to OSB panels.Alden B.dow, an American architect, in 1952, invented a new type of building structure system which is called structure insulated panel.In SIP construction, Dow used polystyrene which was manufactured in his own chemical's company i.e.Dow Chemicals.The houses constructed with SIP are cool in summer and hot in winter (Alden B. Dow, 1952).This idea of building was developing and progressing with the period of time.Nowadays people across Europe and UK are using this idea of construction with some modifications.As the SIP with OSB was considered to be costly that's why some companies across UK and Europe started to modify trying some more materials.One of the modification, which nowadays manufacturing company account for is, use of sheets of Expanded polystyrene with electro-welded mesh on both faces of polystyrene.And this is the topic, which this article will cover.
2-Literature Review: SIP was introduced in 1935 at Forest Product Laboratory.The famous architect Frank Liyod Wright used structure insulated panel in construction of some of the houses built in between 1930's to 1940's.Alden B. Dow, who did apprenticeship with Frank Liyod Wright, followed the work of Frank and used his own company's manufactured polystyrene in construction of houses in 1952 and observed a very good thermal performance of SIP.Literally, Dow was the first one who used the first true SIP as construction material.The energy prices across the world went high in 1973, so this idea of building gained attention and people started building with SIP in US, Canada and later on throughout the Europe.In 1980, Oriented Strand Boards (OSB) were developed, in which polystyrene was sandwiched between OSB.So in this way, this economical material progressed and nowadays, it's widely been used in UK and Europe as construction member with some modifications.As it progresses more and more, so nowadays even no OSB's are used, instead galvanized electro-welded mesh are used on both sides and then shotcrete is applied on both sides.
In 1990, SIPA (Structural Insulation Panel Association) was established which was working as trade organization (Akay and Hanna, 1990;Basunbul et al., 1991;Johnson and Sims, 1986;Smith, 2011).Nowadays in UK and Europe, SIP construction is gaining interest of researchers and builders as its features of being cost effective, environment friendliness, easy handling, easy transportation, light weight, thermal insulation.Also builders and researchers are trying to modify it with new ideas.SIP is panel in which polystyrene is sandwiched and used as structural members like as roof, wall, floor for houses or low storey structures (Smith, 2011).In the last decade, numerous studies have attempted to investigate the behaviour of sandwich panels from different perspectives.From the last couple of years, researchers have investigated about the SIP's behaviour as building structural members (

MODIFICATION IN SIP:
As SIP was considered as high costly as compared to traditional build, but nowadays a lot of modification has been done in SIP's.One of the most followed modification which is widely used in most parts of UK is use of sheets of polystyrene with galvanized electro welded steel mesh on both faces.And this is what this research paper is focusing on.

SIP with EPS and Electro-welded mesh:
The components of SIP with EPS is 170mm polystyrene with 3mm electro-welded mesh on both faces of polystyrene.The mesh is single with both main and distribution bars and can be doubled up depending on loadings.The spacing of the mesh depends on loading but commonly it is 10mm.The SIP's are 2400mm long and 1200mm wide, so in case of a long and wide structure we combine the sheets together and bind it with an extra electro-welded mesh extending them by L/3 on both sides to avoid negative moment.

Methodology:
The process for SIP construction is simple and easy.It just need a trained person who can align the SIP sheets accurately with different tools and then at the timing of finishing, apply proper finishing thickness.

1-How SIP works:
The SIP works like RC structure on low storey buildings like one or two storeys buildings, extension projects.This reduces the cost by about half of the cost that will be incurred by traditional build.Also this method of construction gives you a speedy structure about half less time consuming as of the traditional build.

2-Structural loads
SIP holds all the structural loads of the structure as per design, either the structure needs single layer of SIP sheet or multiple layers of sheets.Usually for two storey house or structures it needs a single layer of SIP.The loading calculations of SIP sheets on different projects have proved that it holds all the structural loads and the structure is sound.
Starting with the foundation, trench is excavated for the perimeter of building and inside the plan where it shows internal SIP partitions.RC is laid in the trench and the mild steel length of L/4 of clear height is erected at distance not less than 0.5meter centre to centre.The next step is to compact the internal ground by compacting machines and laying DPM sheet to stop moisture coming to structures and then SIP sheets as per designs are laid and the concrete is poured as per design and thickness.Picture A and B elaborate the process and use of SIP sheets in foundation more vividly.