Why is it so hot in the loft?

If you want to create a comfortable loft room you need to understand why lofts get so hot and how you can keep the temperature down.

Lofts, loft conversions and attic rooms are associated with unbearably high temperatures for a number of reasons:

1. Heat rises so the heat from down stairs has risen, the more storeys in the house the more heat there is to rise.  Computers, electrical appliances and people all generate extra heat within a building.

2. Sunlight beating down on the roof.  The roof warms up and absorbs much of the heat.

3. Lack of ventilation.  In a home the ground floor is the coolest because the hot air rises to higher levels.  When it gets to the loft in a loft conversion it can't get any higher.

So to minimise the temperature in the roof space (excluding the use of air-conditioning) the strategy should include:

• Keeping the temperature down throughout the house.
• Maximising insulation to keep down the effect of the sunlight on the roof.
• Effective ventilation.

All loft conversions or purpose designed and built loft rooms must conform to Building Regulation, which stipulates minimum requirements in relation to ventilation and insulation. Building Regulations are revised frequently and so a modern loft room will be built to much higher standards. Nevertheless, planning to maximise ventilaion to the north of the building and minimise direct solar gain comes down to design.

An introduction to cooling the loft is here.