How an old house works

By , May 1, 2015 6:11 pm


The way old houses work is very simple. Walls are ‘solid’, without cavities, and built out of brick, stone or earth. The floors would originally have been of earth and later on up-graded to stone flags, brick or handmade tile. The ouside may have been painted with limewash or left bare and the inside walls plastered with lime. When it rained, the moisture would have been absorbed a couple of millimetres into the external surface and evaporated off again when the rain stopped. Damp would have come up through the floor and again evaporated due to the warmer environment within.

Problems with damp often arise in old houses because they are ‘modernised’ without any appreciation of how they work. Modern houses are built on deep concrete foundations incorporating damp proof courses. The walls are made out of impermeable machine-made brick and concrete block and the entire structure is designed to keep moisture out. If you force any of these ‘renovations’onto an old house, not only do you lose those special qualities that attracted you to it in the first place, but you interfere with the way it works and cause long term problems because the house can no longer ‘breathe’.

Nearly all old houses have been altered in this way now and many have damp walls and blistering paint as a result. The solution is to try and reverse as much damage as possible by removing hard cement where lime was used before. This would mean replacing internal modern hard plasters with new lime plaster and then painting the walls and ceilings with limewash, distemper or clay paints (all easily available online in a large range of colours, but not from your local DIY store);removing hard cement pointing and render on the outside of the house and replacing it with lime mortar/render and taking off modern external masonry paints (which are basically liquid plastic) and replacing with limewash or lime paint.

Of course you may still be stuck with the concrete floor unless you live in that rarest of homes with the original flags or bricks still there. You can take the concrete up and lay an insulated limecrete floor instead, but you will need a specialist to do this (and get planning permission first).However, just doing some of the things suggested above, as and when you have the time or can afford them, are worthwhile. After all, your house has probably been around for a few hundred years and if you look after it properly it will be around for a few hundred more.

The Society for the Protection of Ancient Buildings ( has a free telephone advice line (020 7377 1644) and I can recommend the ‘Old House Handbook’ and the Old House Eco Handbook’ both by Roger Hunt and Marianne Suhr for lots of straightforward, practical advice on old houses.

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