In this regular column, Consultant Barry Hunt answers reader enquiries. If you have a question, email it to: nss@qmj.co.uk marked for Barry’s attention.

Q: Architects are always asking me if there is any way of avoiding movement joints. Is there?

Whether you can avoid movement joints or not depends on what it is you are constructing. Factors such as how the substrate is being constructed and how big the structure is are also relevant.

A rainscreen cladding, for example, has open joints with the panels individually fixed back to the supporting structure, so visible movement joints are not necessary.

Unheated floors less than 10m in any dimension can have peripheral joints hidden under the skirtings and door thresholds. Rigidly constructed setts do not need movement joints. Indeed, if they are included they can be potential failure points.

In many instances, however, movement joints are unavoidable, although with careful thought and the use of good quality jointing systems there are ways to minimise their visual impact.

Movement joints can be installed as thin as 3mm to match the typical nominal width of grout lines of internal floor and wall tiling.

You do not want the joints to be any thinner than 3mm as the flexible materials are difficult to install and do not work as well in very thin joints.

One thing to remember with joints in floors is the narrower the better because the edges will be less susceptible to being damaged.

Furthermore, the stone tolerances need to be tight and the setting out to the highest standard to ensure that even joint lines are achieved.

The use of good quality flexible joint fillers is recommended as these tend to be easier to tool to a good quality finish and are less liable to debonding in conjunction with a suitable joint primer. Furthermore, some specialist materials suppliers to the stone industry produce movement joint fillers in a variety of colours that match a range of their own grouting materials.

While it may be argued that eventually flexible joints will wear differently to the grouted joints in the rest of a surface, they can either be cleaned using toluene or completely replaced because cutting them out should be relatively straightforward.

It is understandable that architects do not want expansion joints because there are many examples of the patterns that stone is laid in being interrupted by the presence of straight line movement joints.

However, with careful planning, movement joints can be positioned so that they follow the joints of the stone pattern. When these are the same width and colour as the jointing grout, the finished movement joints can be quite difficult to detect. This is straightforward if you are using a decoupling layer below the stone, but if you are laying the stone on to a screed layer this will need to be cut to induce cracking to relieve stress at movement joint locations.

Movement joints are often most obvious on external façades, where they are typically significantly larger than the joints in the stone. They are also prone to rapid collection of airborne particulates and rapidly darken, further highlighting their presence.

Horizontal movement joints are easier to lose in lines of the building such as string courses but vertical joint lines are difficult to disguise. Pilasters and other protruding vertical features can be quite effective at covering the positions of vertical movement joints, although few think to use such features for this function.

Movement joints start life as necessary lines added to a drawing and it is often only when the construction has been completed that their visual impact is realised. Few ever say they like the result. But with a little forward planning and care and the use of good quality materials, movement joints do not have to be unsightly.