Gareth Ryan (MCIAT) is a Member of the Chartered Institute of Architectural Technologists. Contact him at 023 8821807 or 087 7444568.
The use of insulation in the construction of a house is very important, something which was emphasised to us with the snowy weather conditions we had recently. The architectural principle outlined in this month’s column revolves around the heat loss through the fabric of the building and the use of insulation to prevent this loss. The primary locations for insulation in a house is walls, roofs and floors and there has been many variations and upgrades to the building regulations standards in association with these over the years. Insulation comes mainly in two forms, with rigid board such as polystyrene being one and cushiony such as fibre glass, paper and sheep’s wool being the other, with some having specific locational purpose and more with varied locational use. The use and amount used of insulation is also inter-related with other construction elements in the building such as size and design of timber studs giving one the allowable space to put in the insulation. As one may gather there are a lot of variables associated with installing insulation in a house.
To help narrow down the variables involved, I will assess walls first and give a few comments as to how insulation fits in this element of a building. If one would like their house constructed with concrete blocks with a cavity then there is a number of options available including cavity blown insulation where one drills holes in the wall and blows in insulation. This can also be an option for renovating a house that was built with a cavity but without insulation. Alternatively, one can use a rigid insulation board while one is constructing the wall, which is the more common practice. Additionally, one can use an insulated slab board on the interior of the wall to reduce the amount of heat loss through the wall, which is also an option for retrofitting into a house. There is also the option of insulating with a rigid board on the exterior of a building which is primarily used for renovation work. The amount of insulation will be dependant on the product specified but the energy rating of the wall will have to meet or where possible exceed the building regulation standard. The varying options with block or stone walls all have their merits and uses but the simplest way to manipulate the amount of insulation in a standard block wall is by simply widening the cavity of the wall. In a timber frame wall house there are again a number of options but blown and what is referred to as cushiony above such as fibre glass, paper or sheep’s wool would be the most popular. The location for insulation in a timber frame is in the cavity between the timber studs in the wall. The depth of the stud can here again can be varied to increase the amount of insulation with some innovative companies coming up with double stud wall type construction methods so that more insulation can be installed but which is more associated with Passive House standard construction. What I would advise people who are not familiar with the construction industry is that when they are looking at the plans of their house and the walls look thick and cosy, then they can assume that, if constructed to those drawings, then the house might be similarly cosy, as the walls will be thick for a reason and that is more and likely because of the amount of insulation that is specified for the construction.
Floors and roof are not as complicated in terms of insulation use, as one may gather, as one needs rigid insulation in the floor to hold up the concrete and the roof inversely needs cushiony insulation, as it is lighter with less weight for the structure of the house to hold it up easier. Again, one has to adhere to the building standard requirements which the professional you employ should advise you on but trying to exceed the standard is no bad thing with the Passive House standard being to top mark to try and achieve.
One thing to consider when using insulation in a house and which may not be appreciated much this time of year is that insulation in a house also helps to keep the house cooler in summer, as much as it does to keep the house warmer in the winter which, if one experiences the difference between a non-insulated house and an insulated house during the height of the summer, they will appreciate this fact. Next month’s column will examine heating systems and the trade off between them and the overall design and specification of a new or renovation or extension of a house.