Marianne Suhr on draught-proofing and loft insulation

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I have friends in West Wales who subscribe to the ‘woolly jumper’ school of old house living: if it gets too cold, put another layer on. They have a 1950s stove in their kitchen, which heats all their hot water, a wood burner in the sitting room, and a splendid collection of knitted socks and jumpers. I love to visit them in their beautifully restored farmhouse, but I do admit to tending to steer clear during the winter months.

When it comes to chilly days and frosty nights, I’m not made of quite such hardy stuff. Richard asked me to promise when we bought this house that it would be warm and cosy. I must say this presented a challenge of epic proportions when we first started to look at what was involved, and gradually we have tackled the problem areas. But with the really hard winter weather setting in, I wanted to be sure we’d done absolutely everything possible to keep in the heat.

One of the most important areas to concentrate on is minimising draughts. In fact, up to 75% of heat is lost in this way. Old windows and doors are leaky – there’s no getting around it; it’s just part of their personality. Draughtproofing and secondary glazing can go a long way to alleviate such traits.

Then there’s the wind that whistles down the chimney on a stormy night – the same draughts that are essential to give an open fire a ‘draw’. A canopy over an open fire can be fitted with a butterfly valve to seal off the flue when you’re not using it.

Ironically, it’s the draughts that make old buildings such healthy places to live due to the ventilation they provide. So before you start sealing up every crack and crevice in your home, remember that you actually require at least 0.4 air changes per hour for a healthy living environment; that’s the equivalent of replacing 40% of the air within the room with fresh air, every hour.

So how do you know how draughty your house is? Well I decided to get mine tested by commissioning an ‘Air Tightness Test’. This is now compulsory for all new builds, but it is also useful for owners of old buildings just to establish where the leaks are.

The front door is opened and replaced with a panel containing a giant fan, which blows air out of the building to ‘depressurise’ the internal space. Within minutes, the low internal air pressure causes air to be ‘sucked in’ through every imaginable gap; it is then possible to simply walk around the house and feel with your hand where the air is coming in.

Surprisingly, one of the worst areas for air leakage was through the downlighters, which are set into the ceilings in the kitchen and bathrooms. The sash pulleys, at the side of the sash window frame, were another source of leaks, despite having had the sash windows draughtproofed.

Of course, regardless of how many gaps we filled, we still had to face the reality that the only thing between us and the sub-zero temperatures at night was the four inches of mud and straw that constitute our wattle and daub timber-framed house. The key to successful draughtproofing is to add extra insulation to the areas where it is easy to do so, such as the roof space.

So, with much verve and vigour, I decided to add another 100mm of hemp quilt insulation above the bedroom ceilings. This material is so nice to use, and not at all like the old-fashioned mineral wool that makes you itch and cough. I even thought about rustling up a jumper for Richard with the bit that was left over.

ABOVE (left-right): The fan is connected to a computer to calculate the area of air leakages in the external envelope; A smoke pen picks up any draughts by emitting a puff of smoke; A gust of air leaks through a downlighter in the shower room.
BELOW: The roof gets an extra layer of hemp quilt to insulate the nursery and bedroom ceilings.

Marianne’s draughtproofing plan

• Commission an Air Tightness Test to establish where the problem areas lie. It costs between £250 and £500 and takes about an hour to complete (01621 893226; airtightnesstesting.co.uk).
• Fit draughtproofing or secondary glazing to old windows.
• For a temporary solution to draughty windows, fix a sheet of perspex over the frame.
• Make good any gaps or cracks in the external walls.
• Replace ceiling mounted downlighters with the sealed versions which have been fire checked.
• Where appropriate, install inner doors to sub-divide corridors or create an entrance lobby to minimise heat loss through the front door.
• Add a butterfly valve to any open fires to close off flues when not in use.
• Swap extractor fans with versions that can be closed off when they’re not operating.

WORDS & PHOTOGRAPHS MARIANNE SUHR
Featured in the February 2009 issue of Period Living