How To Choose Wall Insulation

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Wall insulation is one of the most effective ways to reduce heating bills in the winter, lower air conditioning bills in the summer, increase the value of a property, reduce carbon emissions and overall improve the comfort level of a home.

There are three different types of wall insulation: internal, external and cavity - each with its own pros, cons and price tag. If you are thinking about insulating your walls, check out the following tips before making your decision.


External Wall Insulation
External wall insulation involves fixing an insulative layer to the exterior walls of the building. The insulation layer comes in the form of fixed slabs that can be fitted to the exterior wall using adhesive and fittings. The slabs, which are usually around 110mm thick, can be made from a variety of materials e.g. expanded polystyrene or mineral wood. After the slabs are fitted to the wall they are covered with a weather-resistant material, e.g. cement-based render, cladding or brick.

Important: You must also apply a layer of insulation to the edges of windows and door openings to combat thermal bridging (gaps where heat loss occurs).

Pros:

• Minimal disruption to interior space and no redecorating required
• Doesn’t reduce internal living space
• No need to remove radiators, sockets and other interior fittings
• It’s an excuse to rejuvenate your home’s facade
• Maintenance-free and lasts a lifetime

Cons:

• Most expensive option
• All pipes, gutters etc. will have to be removed to get the job done
• Window sills and roof overhang may need to be extended
• Not always effective because air can still leak from inside into wall cavity
• May require planning permission
• Not always suitable for terraced or semi-detached houses

Internal Wall Insulation
Internal wall insulation, also known as dry-lining, is when a fixed slab of insulative material is fitted to the interior wall. The slab is usually made from expanded polystyrene, polyurethane or fibreglass.

Polyurethane is generally considered to be the most effective option because a thin slab of polyurethane will do the same job as a thick slab of polystyrene. When the insulation is fitted it is covered with a vapour barrier (e.g. polythene sheet) and plasterboard.

Important: The barrier vapour barrier must be sealed at all gaps, e.g. light fittings, doors, floor etc.

Pros:

• Less expensive than external insulation
• Eliminates condensation
• It’s an excuse to redecorate your interior
• Maintenance-free and lasts a lifetime

Cons:

• Decreases the room space
• Disrupts your living space
• Radiators, sockets, skirting boards and light fittings need to be removed

Cavity Wall Insulation
Cavity walls are when two walls are built side by side with a small hollow space (usually 60mm) between them.  They were popular in the 80s because they were an innovative way to prevent moisture from seeping in from the outside. Cavity walls can be insulated by pumping insulative materials (e.g. cellulose, fibreglass, rock wool, expanding foam) in to the cavities. Holes are drilled into the cavities from the outside and the insulation is sprayed in.

Pros:

• It is the least expensive option
• It is possible to get cavity wall insulation that is made with recycled materials

Cons:

• Some materials used for cavity insulation (e.g. fibreglass) can irritate skin and lungs during installation if protective clothes are not worn
• May need to be replaced eventually: some cavity insulation materials (e.g. rock wool and cellulose) will naturally settle or compact over time. This will reduce its insulating ability.
• Spray foam is flammable

Featured images:

•  License: Royalty Free or iStock source: http://commons.wikimedia.org/wiki/File:Cavity_wall.JPG

This article was written by Jenna Crotty who recommends Warm House Insulation Systems for wall insulation.