About Preserving Period Basement Floors

Only 20% of the houses in England were built before 1919 – most of them in the 1890s. Almost everyone who lives in one enjoys it – they have more character and charm than anything built since. Their owners often want more space or better insulation, but they also want to preserve their character, and that’s not always easy to achieve.

If you love fireplaces, architraves, sash windows and dados, the damage done to our period housing stock over the years probably brings tears to your eyes. Much was destroyed in the sixties to conform to modernist fashions. Then windows were replaced with double glazing in the eighties. Fireplaces are still being torn out by councils and developers. Nevertheless, much to cherish remains – and that often includes the cellars.

Basement construction served two purposes in older houses. It provided a cool storage space (in the days before refrigerators), and put eight inches of air between the timber ground floor and the earth below. To avoid damp rising into the house, they understood that the ground needs to breathe. Tiles and flagstones allow moisture to escape through them – that’s the whole point of using them in cellar and scullery floors.

The wear and irregularity of stone floors can give them oodles of desirable character – but try laying a carpet on top and it won’t be long before you discover the problem. Bare stone has no problem with dampness – everything else does.

Common DIY Mistakes

When someone wants a drier floor the first thing they try is sealing it. They try varnish, paint or lino – which looks awful and makes the problem worse. Then they try vinyl sheeting or bitumen under a layer of concrete. That might even work – in driving the damp into the walls – so they baton vinyl to the walls, and the damp rises into the floor timbers above.

Suddenly you realise why the multi-headed monster battled by Hercules was called “Hydra” – plug it in one place and it springs up in two more.

The Sensible Options

The best solution depends on how you wish to use the space. For wine storage, workshop space and laundry rooms, you may not need to change the floor at all. Mild damp entering the air can be alleviated by better ventilation and heating, and porous floor coverings of certain natural fibres allow moisture to evaporate but are softer on the feet. You can even install underfloor heating beneath flags and quarry tiles without interfering with natural evaporation (in layers of Limecrete or glass-fibre).

The other option is to bite the bullet and call in basement construction specialists to tank the basement properly. This will entail lifting your original flagstones, but they can be carefully re-laid on top. The finished job will have all the charm, and probably fewer imperfections, than the original.