Why Important
What to look for
Walls were plastered in a similar way to ceilings: timber lathing was either nailed to timber strapping fixed to bilgates (built-in battens) or dooks (driven-in plugs) in the stonework, or fixed directly to timber stud partitions. In some cases, for example in stairs and basement rooms, the plaster was applied directly to the brick or stonework, ie. ‘plastered on the hard’.
The scratch and straightening coats would have been composed of two-and-a-half parts of riddled lime (one part calcinated lime to three parts sand) to one part of slaked or putty lime, with hair added in the proportion of 7 lb to every cubic foot of the mixture; cow hair was usually used. The finishing coat usually consisted of one part sharp sand to one-and-a-half parts of putty lime.
===== How to look ===== Walls which have been strapped and plastered can be tested in a similar way. All testing of this nature must be carried out with great care. The image shows lime plaster being applied over strapping laths.
How to fix
Timber in walls can be affected by rot and should preferably be removed during repairs and replaced by non-ferrous fixings.
Where dooks or bilgates are to be retained or replaced in an external wall, they should first be treated with preservative.
Any patching should be flush with the old plaster and not with the wallpaper. A patch can be hidden by applying lining paper to the whole wall or ceiling before decorating.
When re-plastering, three-coat work is recommended in spite of the delays involved in drying each coat.
Avoiding creating problems
Non-caustic paint removers should not be used in conjunction with steam.