Exposed Lath and Plaster: A Common Find and What to know about it!

Mar 21
3 min read

Whilst working today on an old Victorian Terraced property, we came across something that is there in many peoples homes and without knowing exactly how your ceilings and walls are constructed, an old timber battoned lath and plaster wall. After removing the loose plaster the timber framework was not fastened to wall properly and with the weight of the plaster it had caused it to come away from the wall quite significantly. The build up and how the

Victorians plastered these house is incredible and is a great reminder of the skill and quality of traditional plastering methods but also a good reminder about the hidden risks present in older homes.

What Is Lath and Plaster?

Lath and plaster was one of the most common plastering techniques used in homes before plasterboard became the go to option.

The plaster system is made up of:

Timber laths: Thin horizontal wooden strips fixed across studs or joists
Plaster layers: Lime plaster applied over the laths in multiple coats

Plaster would be applied to the laths and it would be squeezed through the gaps between the laths and once firm would become the substrate on which you would plaster onto which would be anchored into the laths creating a strong flexible substrate which could last for decades and some homes we work on we come across ceilings and walls which have been in place for well over 100 years!

The Hidden Dangers of Lath and Plaster Ceilings

This is in no way to scare people into getting ceilings and walls check but it is good information should you be concerned about any work in your home. Whilst lath and plaster has proved it can stand the test of time it is important to understand that (Like i said above) many of these ceilings and walls have been in place for upto 100 years, A CENTUARY! And over this type issues can develop.

1. Failure of Plaster Keys

The most common problem is the breakdown of the first coat of plaster applied to the wooden laths to create the substrate, over time these can weaken or snap away which causes the plaster to lose its key from the laths.

2. Gravity and Weight

Plaster is heavy. Once the first coat between the laths fails, areas of walls and ceilings can become unsupported — and main concerns are the ceilings!

3. Sudden Collapse Risk

In the past we have been called out to collapsed ceilings, it can vary from small areas to the whole ceiling failing. Its important to remember the weight of the plaster which is up there, it works around 20 kilos per m2 of plaster, so if a ceiling of 10m2 collapses thats 200kg which is dangerous.

4. Vibration and Movement

Modern living introduces more vibration and

thermal expansion which can speed up the failure

process.

Why Homeowners Should Be Aware

If you live in or are renovating an older property, especially one built before the mid-20th century, there’s a good chance lath and plaster is still present.

Signs to watch for include: