Stopping heat from building up upstairs

Two phenomena often confused

Warm air rises, that is convection. Heat also crosses the floor by conduction, independently of any air movement. Both happen at once but are not dealt with in the same place, and confusing them means missing half the subject.

The stairwell, a motorway for heat

In a two storey house the staircase links the levels directly. Warm air rises freely and cold air comes back down along the walls. That movement often carries more energy than the floor itself.

What can be done there

Close the opening with a door or a heavy curtain, where the layout allows. It is a simple, reversible operation with no building work, and its effect is measured from the first cold day.

The intermediate floor

That is where conduction acts. A timber floor also lets air through its gaps, which adds a third path. Continuous insulation fitted on the underside deals with conduction and closes the air passages.

The case where nothing should be done

If the upper floor is heated and occupied, the heat that rises is not lost, it is used. Insulating between two heated levels then brings only an acoustic benefit, and it is honest to say so before drawing up a quotation.

The opposite case

An unheated upper floor, a converted loft occupied intermittently or an unused bedroom change the calculation completely. There, every calorie that rises is lost, and the floor becomes a loss surface in its own right.

Airtightness is developed on the dedicated page, and the fitting on the timber floor page.