I'm always interested in finding out the history/age/ original details of our house. One quick question that occurs - It's built in sandstone with lime mortar. Internal walls had lime plaster. The exterior is concrete. The concrete is obviously not recent and I assumed was original. The question is how likely is it that a (probably Victorian) house (no dpc of any kind) would be mortared in lime but rendered in concrete?
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Lime mortar and cement render
- Thread starter zunetunes
- Start date
It is possible that it was rendered in cement, or perhaps Rough-Cast.
An extract from an 1890s edition of Longmans' Advanced Building Construction...
But you need to be careful, especially with soft stone and brick. It does raise some questions:
* Were the Victorian builders mistaken in their use of these relatively 'new' materials (by no means new in 1890), which set quickly and were very durable, but perhaps in the long term did more harm than good? Perhaps the old lime based renders shouldn't have been abandoned in favour of cement?
* Would a modern cement render have similar properties to its Victorian ancestor, or are there important differences?
* Is it appropriate to re-apply a cement based render to an old building anyway? It's not in its brand new condition, and has aged and decayed. What was OK for a brand new building is not necessarily right for an old building that's suffered the affects of time.
Personally, based on what I've seen and read (particularly the damage I've actually seen to my own house), I'm very nervous about using modern Portland cements anywhere near soft stone and brick.
I'm using non-hydraulic lime putty instead, and in special circumstances weaker hydraulic limes (chimney stack, ridges etc).
Fortunately I don't have to worry about maintaining or replacing render on my building. But I wonder - what is the best conservation practice for rendering stone - I'd have thought lime render, and no cement at all?
An extract from an 1890s edition of Longmans' Advanced Building Construction...
The material best adapted for rendering the external surfaces of walls is Portland Cement.
...
The objection to Portland cement, from an economical point of view is its first cost,
the greater labour required in using it as compared with that necessary for other cements, and
also the time frequently wasted upon it, for, in consequence of its setting slowly, there is a
tendency for the men to go on working it too long.
But you need to be careful, especially with soft stone and brick. It does raise some questions:
* Were the Victorian builders mistaken in their use of these relatively 'new' materials (by no means new in 1890), which set quickly and were very durable, but perhaps in the long term did more harm than good? Perhaps the old lime based renders shouldn't have been abandoned in favour of cement?
* Would a modern cement render have similar properties to its Victorian ancestor, or are there important differences?
* Is it appropriate to re-apply a cement based render to an old building anyway? It's not in its brand new condition, and has aged and decayed. What was OK for a brand new building is not necessarily right for an old building that's suffered the affects of time.
Personally, based on what I've seen and read (particularly the damage I've actually seen to my own house), I'm very nervous about using modern Portland cements anywhere near soft stone and brick.
I'm using non-hydraulic lime putty instead, and in special circumstances weaker hydraulic limes (chimney stack, ridges etc).
Fortunately I don't have to worry about maintaining or replacing render on my building. But I wonder - what is the best conservation practice for rendering stone - I'd have thought lime render, and no cement at all?
You'd have to get a mortar analysis done on various samples from your house to find out what had been done. It's not impossible that the house was built with lime mortar, and later render over with a cement based rough-cast or similar.
Or perhaps a cement was used in the bedding mortar by the original builders?
Or perhaps a cement was used in the bedding mortar by the original builders?