The Structural External Wall Insulation System (SEWI) is what sets Structherm apart from the rest. Whilst a standard EWI system can significantly improve the thermal properties and the aesthetics of a building, the unique Structherm Structural EWI system can go one major step further by adding to the structural integrity of a building too. This makes it particularly attractive for the refurbishment of non-traditional property types and is what makes Structherm the UKs number one “go-to” company when it comes to the external refurbishment of such non-trad homes.
Why Structural EWI?
The majority of non-traditionally constructed houses and buildings where built with little regard to thermal performance. With the most significant heat loss being through the walls the need for an external wall insulation system is obvious. The Structrual EWI system provides the solution when the substrate is defective or not in a condition to provide the anchorage for a directly bonded EWI system.
Structherm Structural External Wall Insulation – Our Panel
The SEWI system is based on a unique, lightweight prefabricated panel composed of a rigid insulation core encased in a steel wire cage – the Structural External Wall Insulation panel.
The panels do not attach to the substrate but are instead fixed to the structure of the building itself. This, in effect, forms a new substrate which is structural in a reinforcing capacity – not load baring.
These panels are then joined together with mesh to provide a stable, continuous envelope around the building which adds real structural integrity to the entire property.
The panels are immensely strong and rigid, yet light enough to be carried by one man, and can be installed both vertically or horizontally. The diagram to the right shows a typical build up of the Structural External Wall Insulation system.
A layer of base-coat render is then applied to the system which works with the panels to provide extensive spanning / racking strength.
To complete the system we have a wide choice of final renders, colours and textures along with various brick effect finishes.
Structherm The Non-Traditional Housing Refurbishment Experts…
Following the First and Second World Wars and up until the late 1960s approximately 1.5 million properties were built in the UK using non-traditional methods. With a population boom, these homes needed to be built fast. Skilled labour was not readily available and traditional building materials were in short supply, so new building methods were created.
Most of the properties were only designed to last 20 years! Yet people are still living in these properties today; properties which have very little, if any, insulation. Worse still, many are designated as DEFECTIVE by the Building Research Establishment (BRE).
We’re not just talking about low-rise homes either – many high rise blocks were also built in most major UK cities. Many of these blocks were built from non-traditional materials such as commonly used Wimpey No-fines concrete and again, with poor thermal performance.
The unique Structherm Structural External Wall Insulation (SEWI) system is a cost effective way of extending the life of these non-traditional defective properties, both low rise and high rise. It can work even when a standard EWI system will not.
Low Rise Refurbishment
Structherm’s Unique Structural External Wall Insulation system has been manufactured at our factory in West Yorkshire since 1983, over which time we have built up an impressive portfolio of projects including the refurbishment of many different non-traditional and prefabricated reinforced concrete (PRC) low rise house types such as:
- Swedish Timber
- Wimpey No-fines
- Cruden Rural
- Dorman Long
- Vic Hallam
- Weir Timber
- Lowton Cubitt
- Weir Multicom
- Concrete Block
- Atholl Steel
Whilst there may be literally hundreds of different types of non-traditional house types they will all fall into one of four categories – those built around a metal frame, a timber frame. precast concrete or in situ concrete. The SEWI system differs from a standard EWI system in as far as the metal cased insulation panels are fixed together and back into the frame or load bearing columns of the building as per the sections below:
- Metal Framed Non-Traditional Houses
- Timber Framed Non-Traditional Houses
- In Situ Concrete Non-Traditional Houses
- Precast Concrete Non-Traditional Houses
In this case the structural EWI panels are fixed through to the load bearing columns and joined together with a rigid mesh prior to basecoat render and finish.
The direct platform frame construction method was often used to build timber properties. Construction consists of storey height timber frame panels, sheathed internally and externally clad.
The SEWI solution for these type of properties is for the structural panels to be fixed through the existing cladding panels and into the load-bearing timber frame. The panels are then joined with a rigid mesh, prior to a thickcoat render base and finish.
The construction of in situ concrete properties involves three basic elements; formwork, concrete and reinforcement. Steel reinforcement is added between the formwork after which the liquid concrete material was poured in.
In this case the structural EWI panels are installed by using primary resin anchor fixings which connect both the inner and outer in situ concrete loadbearing panels with restraint ties used to tie the system to the floor joists. The panels are then connected together with a rigid mesh and finished to suit.
Precast concrete (PRC) is produced by casting concrete in a reusable mould or “form” which is then transported to site and lifted into place. Construction therefore consists of load bearing concrete columns with external concrete cladding panels.
As some PRC properties are designated as defective the structural EWI panels are fixed using primary fixings through the the existing cladding panels into the load bearing concrete columns with secondary fixings also used to restrain the cladding panels. The SEWI panels are then joined with a rigid mesh, a basecoat render is then applied and a finish of choice.
Medium & High Rise Refurbishment
The Structural External Wall Insulation system can also extend the life of defective medium and high rise blocks to transform them into modern, thermally efficient and structurally sound buildings.
There are many different types of medium and high rise buildings which were built between the 1950s and the late 1970s, most of which now exhibit one or more significant defect along with poor thermal performance and penetrating damp. The Structherm SEWI provides a unique solution for this scenario.
Refurbishment programmes in this sector can include all of the solutions for low rise properties as well as the following options:
- Enclosing balconies or walkways to increase internal floor area for residents. Particularly useful when balconies are infested with roosting pigeons, and an extremely popular choice among residents.
- Re-modelling of parapet / gables to increase safety and transform the skyline, an important factor for some Local Authorities as these buildings can often be seen for miles around and can improve the image of the whole surrounding area.
The illustration to the right shows the typical fixing method for Structural External Wall Insulation on to a typical high rise building.
Vertical and Horizontal Panel Spanning
Assuming the building has a structurally sound frame the structural external wall insulation system panels can be fixed to span both floor to floor vertically and column to column horizontally.
In both cases a unique fixing bracket is used which allows the transfer of shear forces into the building frame, thus providing the necessary structural support to prevent movement and cracking.
System Built School Solutions
Of course it’s not all about housing – around 46% of the 13,00 schools built in England and Wales between 1945 and 1975 were system or modular built.
Whilst other types of modular / system school buildings exist, construction predominately consisted of a relatively light-weight steel girder framework with panel infill and incorporated little in the way of insulation.
The Structural system can be used to over clad failing infill panels. Alternatively, the panels can be removed and the SEWI system used to infill between the original load bearing steel columns.
As an added benefit the system can be used to reconfigure the facade in order to reduce the amount of glazed areas in order to improve thermal performance and reduce solar glare in the classrooms.In this case the existing panels and windows are removed and a lightweight steel frame constructed to house the required size of window. The SEWI panels then connect the existing frame to these new frames with primary and secondary fixings.
Contact us for further details and to discuss the specifics of your system / modular build schools project.