The blog

Roger Hunt is an award winning writer and blogger specialising in sustainability, old houses, housebuilding and traditional and modern building materials. He is the co-author of Old House Handbook and the companion volume Old House Eco Handbook.

Why old buildings need to breathe

Why old buildings need to breathe

Spending three days talking and lecturing at the National Home Improvement Show made me again realise the huge importance of getting across the message that old buildings need to ‘breathe’. Many people simply don’t understand that using the wrong materials can be an expensive mistake which may wreck their home.

The way old buildings work is incredibly simple and, when I say ‘old’, I’m not just talking about ancient structures but virtually all buildings with solid walls – these include Victorian and Edwardian homes.

What has to be understood is that the modern building techniques that we know today began to be introduced in the second half of the nineteenth century and that cement based mortars, renders and plasters only came into general use by the late 1940s. These techniques rely on impervious outer layers, cavity walls and barriers against moisture – such systems are totally incompatible with traditional solid walls which work in a very different way.

In solid walled, old buildings, the bricks and stones were generally bonded with weak and porous mortars made of lime and sand. Where external walls constructed with these materials, and others such as ‘cob’ (earth), were rendered, lime render was used and this was often limewashed so the structure was able to ‘breathe’. When it rained, moisture was absorbed a few millimetres into the external surface but was able to evaporate when the rain stopped, helped by the drying effects of the sun and wind.

Inside, walls were plastered with lime and finished with simple breathable paints. Any excess internal humidity from washing, cooking and human activity, was dispersed via open flues and draughts, or absorbed by the breathable surfaces. In addition, a kitchen range and open fires burnt from autumn until spring, drawing air through the home and keeping internal surfaces at a steady temperature. Provided the building was maintained, the structure remained essentially dry.

In recent times the understanding of how traditional solid walls work has become confused and builders have tried to apply modern techniques to breathing structures. Cement renders, along with ‘plastic’ paints, waterproof sealants, damp proof membranes and even insulation materials can act as a barrier to the building’s natural ability to breathe. This is where the trouble occurs: the mix of technologies traps water within porous materials and exacerbates the very problems that they are trying to resolve.

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Environmental Pocketbook

Environmental Pocketbook

If you’re going to invest in just one book on sustainable, low carbon building I’d strongly suggest that you make it The Environmental Design Pocketbook. Now in its second edition, this useful volume by Sofie Pelsmakers should be essential reading for architects, designers, developers, planners, students, clients and anyone else involved in the construction and operation of buildings….

Fire in old buildings

Fire in old buildings

The devastating fire at the Grade I listed, 18th century National Trust mansion at Clandon Park, Surrey, once again highlights the need to do everything we can to protect old buildings. Whatever the size of the building, there are simple measures that can be taken to reduce the risk of fire, ensure early warning of a…

Adapting old buildings

Adapting old buildings

The need for fresh air and light in buildings is something I’m often talking and writing about because it’s central to creating a good home, but the theme is nothing new. I was reminded of this when I recently visited the King Edward VII Estate, near Midhurst, West Sussex. Here, the former sanatorium is being…

Building lime knowledge

Building lime knowledge

Lime, in the form of mortars, renders, plasters and paints, is a key component of old buildings and essential to their repair – or at least it should be. Today lime-based materials are also emerging into the mainstream and being used within low carbon construction systems, employed in everything from homes to superstores. All this…

Drain problems

Drain problems

A blocked drain is not a pleasant thing to wake up to. What’s worse is the realisation that it’s something that can generally be avoided by doing what I’m always talking about: maintenance. The drainage system is easily forgotten because much of it is hidden away underground but, as with any element of a building, it…

Building remembrance

Building remembrance

Visiting Blood Swept Lands and Seas of Red, the poppy installation at the Tower of London, reminded me that the built environment frequently plays an important part in both remembrance and memory. Each of the 888,246 ceramic poppies that flood the moat of the Tower depicts a death in the British forces in the First…

Materials testing

Materials testing

New techniques and materials aimed at producing low carbon solutions mean this is an exciting time to be involved with new build and retrofit. There are dangers though, in the rush to innovate there may be failures along the way so it’s vital that there’s scrupulously testing and monitoring at all stages. This is why…

Battersea Power Station

Battersea Power Station

This weekend there will be over 800 buildings, neighbourhood walks and architects’ talks to enjoy as Open House London once again reveals great architecture for free. Sadly Battersea Power Station, one of the buildings I visited last year, will not be open as the 42 acre site is undergoing redevelopment. Nonetheless its history and its future can…

Linoleum naturally

Linoleum naturally

Lino is a bit like Marmite, people either seem to love it or hate it. For some it conjures thoughts of cold and institutional floors and it’s often (wrongly) used to describe vinyl. Unlike vinyl, which is petroleum based, linoleum has outstanding eco credentials and antimicrobial and hypo-allergenic properties. A hard-wearing and almost totally natural product, linoleum…

Renovation tale – Part 1

Renovation tale – Part 1

This is the tale of my first major renovation project some years ago… On the table is the surveyor’s report; yellow Post-it notes stick from its pages in such profusion that they no longer have any relevance. Phrases like “needs attention”, “must be thoroughly overhauled” and “a fair amount of dampness” are highlighted by marker…Continue Reading