My 1950s home is B2 BER rated – why is it so draughty?

We moved in to a 1950s house early last year. Formerly three-bedroomed, it was extended to the side about 10 years ago, creating an additional bedroom en suite upstairs and a further reception room and utility downstairs. The whole house was renovated at that time, new bathrooms, kitchen, flooring, windows etc. The attic was floored, slabbed, and insulated.  With a B2 BER we were optimistic about energy and heat. We redecorated and renewed some of the ground floor flooring.

Our problem? Draughts. Windows, skirtings etc are very draughty. The newer timber-frame extension has a number of vents and we wonder if this is contributing to the draughts? Whom should we consult to assess and advise as clearly some form of remedial work will be required?

It is very difficult to pinpoint a draught entry point, which can be frustrating. There are many opportunities for air to seep into a house. It’s not clear from your question if the draughts are in the extension or in the original dwelling, or both.

With a timber-framed house, the cavity must be vented to avoid condensate build-up. This is achieved by inserting perpend vents in the outer wall at both floor and ceiling level. These are so positioned to dissipate any moisture in the cavity space. So any breach in the inner leaf could lead to air passing through to the house. Let us look at some possible causes.

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Permanent ventilation to a room, as required by the building regulations, is provided by a permanent vent through the external wall. Check that these wall vents are suitably sized; oversized will lead to heat loss, and undersized will lead to condensation. You need to remove the vent covers and check that the cavity within the wall is properly closed around the vent opening. If not, air in the cavity can leak into the room.

Over time, a timber skirting board may shrink or the floor on which it rests may settle. This can lead to a significant gap between the skirting board and the floor. This can be an issue where the floor is a suspended timber floor with a vented void beneath. Suspended timber floors are rarely used today as most floors are of solid concrete construction with a floating timber floor finish if required. In the 1950s, however, they were commonplace.

An existing suspended timber floor can be insulated, usually with rock wool on a wire mesh support between joists. It is important to maintain a through flow of air to the void beneath the suspended floor to avoid timber decay in the future. If the rooms are drylined, this lining may not be brought down fully to floor level leaving the skirting to seal a gap between the wall and floor. This is not what a skirting is designed to do.

Windows

Windows are a constant source of draughts. Doing a basic check of draught seals and handles is a good starting point, but in my experience, it is never the window unit that is the issue but the surrounding opening. How well was it prepared for the window unit installation and how was it sealed and finished once the window frame was installed? This is always down to the builder. Issues arise with the closing of the cavity, position of the damp proof course to the reveal, and proper completion of insulation in the wall to avoid cold bridging around the window. If you see mould in the reveals of windows it suggests poor detailing during construction.

Sometimes the windows are fitted with a trickle vent in lieu of the permanent wall vent. These are an important source of room ventilation and should be kept open. Unfortunately, they are almost always covered by blinds or curtains, rendering them virtually useless. Check yours if you have them.

They say that 40 per cent of heat loss in a poorly insulated house is through the roof. So check the attic. It should be airy as all attic spaces must be ventilated. However, weak points include holes drilled for spotlights in the ceiling or an uninsulated trap door. If there is a room in the attic there are many routes for air circulation as outlined above.

In a house renovated 10 years ago there is likely to be an open fireplace. This can cause a draught as the draw on the flue pulls air through the house. If the fireplace is not in use, consider closing it off with a vent to allow air circulation to the now redundant flue and cap off at chimney pot level with provision there for ventilation also.

The B2 rating is very high for a 1950s property refurbished 10 years ago – I’d have that reassessed. Given the complexity in identifying the source of the draughts, I suggest you get a local building surveyor to carry out an inspection to assess the cause and provide recommendations on solving the problem.

Pat McGovern is a chartered building surveyor and a member of the Society of Chartered Surveyors Ireland, scsi.ie