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Insulation & Render – EWI FAQ Extended

EWI Specifics

How do you insulate your house?
Up to 35% of energy in the home is lost through the walls. This can be reduced by investing in insulation, either internal or external. Installing external wall insulation has a number of benefits over internal insulation, including no loss of floor space, minimal disruption and an aesthetically upgraded exterior.

How does EWI work?
Insulation is applied to the external walls of the house and covered with a selected render. The insulation itself improves thermal efficiency and protects the original exterior, while render allows for both an attractive upgrade and weather protection. Heat loss through the walls is reduced significantly, meaning savings of hundreds of pounds can be made every year. Solid walls are kept warm and free from moisture to prevent any condensation related issues, e.g mould, from arising in the future.

What is EWI made from?
The insulation used in EWI systems is installed using a thermally efficient and attractive cladding procedure, which simply means to apply one material over another. This is done to improve thermal efficiency, appearance and weather resistance. Alumasc offer three main insulation materials for use with its systems: Mineral Wool (Pro), Phenolic (Supa) and Grey EPS (Lite).

How much does it cost for EWI?
Insulating your home externally typically does cost more than internal insulation. Prices range from £8000 to £22,000, though this cost comes with a number of advantages. Residents may remain in their homes during installation, with assurance that disruption is minimal in comparison to internal insulation installation. Furthermore, financial value is added to the house as the external appearance is improved and savings can be made on energy bills.

Render, Cladding & Finishes

What is a rendered wall?
Exterior walls are exposed to potential problems from weathering and erosion. A coating, render, can be applied. This render possesses weather resistant properties that certify protection from the elements, while its colour and texture variations present a robust, durable and visually appealing finish.

What is the difference between plaster and render?
The main difference lies with the combination of materials used and in what quantities. If the render being made is textured, a coarser sand will be used, while a finer sand is used in a smaller quantity for smooth finishes. Since render is applied externally a rougher texture is preferred; one example being pebble-dash, while plaster holds a smoother consistency for internal use.

What is a polymer render?
Renders typically consist of white cement, sand, lime and water. Polymer renders have added polymers or plastics. This additional material makes the render stronger and less prone to cracking, prolonging its lifespan and making it desirable for specific constructions. Like standard renders, the colour variations are diverse, often eliminating the need for painting after construction has finished.

Can you apply insulation to exterior brick walls?
If a smooth or colour rendered finish isn’t the appearance you wish to attain, many EWI systems fit brick slips. Slips can be synthetic, made from acrylic, or clay. Acrylic slips retain the appearance of traditional bricks with the added advantage of overcoming issues usually associated with traditional brickwork. Both synthetic and traditional brick slips are available in a range of UK brick types, allowing you to match the original brickwork on your house or select something new.

Why is cladding used?
The cladding process involves applying one material or substance over another. The material is used to provide a higher thermal efficiency to the building, as well as protect its exterior from the weather and upgrade its appearance. By applying cladding to the external walls at the end of the EWI installation process, the insulation beneath is protected, along with the original structure beneath it.

What is rainscreen cladding?

About Insulation

How does an insulator keep a home warm?
Insulation is used to increase the thermal efficiency of your home. By retaining as much thermal energy as possible, energy consumption can be minimised in terms of how much energy is used and for how long. When dead air spaces or cells are used in an insulating material, the movement of warm air to colder surroundings is slowed. Applying insulation to the exterior of a house ensures as much thermal energy is conserved as possible since the transfer is slowed down.

Why is it important to insulate your house?
Using insulation may seem like somewhat of an investment. However, the long-term benefits and savings made post installation are of an appealing advantage. During the colder months, houses require heating – 35% of which is lost through the walls if they are not insulated effectively. This figure can be drastically reduced with the use of insulation, saving several hundreds of pounds annually on energy bills. Acoustics and appearance both improve, and the value of your home will most likely increase.

What materials are used for insulation in the home?
The most common materials used in insulation are cellulose, fibreglass, mineral wool, polyurethane foam and polystyrene. However, some are more efficient than others. Alumasc supply three main insulation materials for use on any construction project in conjunction with a range of different frame structures. Mineral Wool (Pro), Phenolic (Supa) and Grey EPS (Lite) – compatible with most Alumasc Facades by K Rend render systems.

How can insulation be energy efficient?
Insulation provides increased energy efficiency within homes and public buildings. By slowing down conduction and convection, heat can be kept within the house for longer periods of time. Heating the house will become less frequent, thus making your home more efficient (and cheaper to keep warm). The lower the U-value of your house is, the more efficient it will be – insulation contributes to this.

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