There are three main causes of cracking plaster.
1.The first, is the environment in which the plaster dried:
For example, if the heating is whacked on in order to speed up the drying process, this has the effect of sucking the moisture out of the plaster too quickly and this causes uneven drying and shrinkage resulting in cracks.
A similar effect can occur at the top of unventilated stairwells because the heat in the upper section will be considerably higher than that of the lower section.
Ventilation throughout the drying process resolves this issue but is not always possible – perhaps a window or skylight does not open or can’t be left open for security reasons.
If this was the reason for your cracks, then your attempts to fix the cracks – such as filling and sanding – should work if the environmental conditions were different when the remedies were applied.
If the cracks return…
2.The second reason for cracking – wall movement:
Stable, plastered walls do not repeatedly crack dependent on the weather.
If you have walls with recurring cracks, that none of the usual remedies have fixed – this points to there being movement in the walls.
A typical cause of this can be inadequately secured door frames and windows. So, every time a culprit door is closed it moves the wall slightly causing cracks in the surrounding plaster. Poorly installed replacement UPVC windows and doors are known for causing cracks to the surrounding plaster.
If this is the cause of your movement, the cracks will keep coming back while it exists.
You have two solution options: Either, persist with bare plaster and locate the cause of any wall movement, have the wall re-skimmed and control the environment while it dries. With this solution there is always a risk that the problem will return because you may not have found the exact cause of the wall movement.
Second option – have the walls lining papered. Yes, this is covering up the issue but if there is no evidence of an underlying damp problem and if the root cause of the wall movement can’t be located, this is often the most cost effective solution that brings the problem to an end.
3.The third cause of cracking plaster that repeatedly cracks after repair is:
a.Poorly mixed plaster – in other words, the plaster mix was too thin and poorly applied to the wall surface.
b.Structural issues with the property – if you have ruled out all other causes of the cracking and yet the cracks return and grow, then you may have a structural defect that requires attention.
Before you panic and think foundation problems and £££, please double check that you do not have any plumbing work that is leaking unseen, within walls.
If you have any queries about your particular plaster issues, please be in touch.