The risks of cement: protecting our older heritage buildings

In 1730, they built almshouses for ‘decayed Taylors,’ but today, it’s the preservation of older heritage buildings that is truly at risk of decay.

While visiting the Merchant Taylors’ Hall in York, I spotted something that sent my ‘building nerd’ self into a total meltdown. It’s a mistake I often see with heritage properties.

A few months ago I went to a meal at the Merchant Taylors’ Hall in York. It’s quite an impressive historic Grade 1 listed building; the original parts date back to 1415, the year of the Battle of Agincourt. A mini hospital, or almshouse, was built on the side in 1730 to house four older tailors—the actual words are that the almshouses were to be used for ‘decayed Taylors’. Quite a fascinating building, with some impressively old glazing. If you search online you can find out more about its history.

A building nerd’s meltdown in York

Something that struck me was the end gable on one side. Some original timber framing was visible, hundreds of years old. The panels between the timber framing appeared to have been rendered with cement render!

My heart sank. My building nerd self went into meltdown. Total meltdown.

A cardinal sin appeared to have occurred, by potentially misinformed individuals trying to do the right thing, possibly in the 20th century.

Why cement is a sin for older heritage buildings

In all seriousness, this is actually serious business. Using cement render to older heritage buildings can reduce the breathability [vapour permeability] of the building fabric. This in turn can trap moisture inside the walls, thus leading to rot and decay of the ancient timber framing.

If you have an older building and are thinking of using more modern building materials on it, please don’t—or at least get professional advice before you do. Relatively modern construction materials are often not suitable for older buildings that behave in different ways.

The breathable alternative: lime render

In this scenario, a traditional lime render [no cement] should have been used. Lime render is breathable and also a lot more flexible, so it can take up seasonal movement without cracking.

If you have questions about vapour permeability or using lime vs. cement on your property, feel free to get in touch. Prevention is always cheaper [and easier and less stressful] than a cure when it comes to older heritage buildings.