Planning your Staircase Installation

Regardless of the chosen method of construction for your property, planning the staircase must be taken into consideration from a very early stage. We recommend that you engage a staircase specialist, such as Zakuna, to consult with, who will provide you with the necessary information for a successful installation.

Opening

For a premium installation, it is important that the opening is square on all sides. If the trimmer that the stair will fix to is not square to the wall, then this will result in either a tapering gap down the wall or a tapered top tread, neither of which are aesthetically pleasing.

If the trimmer is into timber, it must me at least 100mm thickness and multiple pieces must be glued and bolted together.

If the trimmer is a steel 'I' beam, you must fill the web with timber which is through bolted to the steel at regular intervals. In all cases you must ensure that it is plum, and the floor is level.

Wall design

When installing a Zakuna free-standing staircase, it is highly likely that we will need to tie it to a wall to prevent movement. We will produce a fixing point drawing for you, showing where these will be. It is important that we have something solid to fix to.

For a timber partition wall, we request a minimum of a 100mm thickness C24 (or hardwood) Patrice between studs.

If you have a masonry wall, it must be solid and there must also be solid drywall adhesive 300 x 300 around the fixing point to eliminate crushing of the board.

If your project is a SIP's panel design, the manufacturer will want to install the practices in the factory when producing the panels, so this information will be required at an even earlier stage.

When a Cantilever Staircase is being installed into timber frame construction, we recommend that the timber studs are a minimum of 140mm x 48mm C24 softwood and there is a minimum of 200mm x 48mm C24 softwood running at the same angle as the string dovetail screwed. We do not recommend a Cantilever Staircase being installed onto cinder blocks due to the likelihood of the blocks crumbling and the fixings being undermined.

Floor design

The most common floor design that we encounter is a Concrete Slab + Insulation + Screed. In normal circumstances, a thermally efficient ‘PIR’ insulation is specified underneath the screed to avoid cold bridging. Whilst PIR insulation has very good thermal properties, it does not have sufficient compressive strength to accommodate the considerable load bearing weights.

Compressive stress is a material's ability to maintain its structural integrity when compressed. The higher the compressive stress the better the material is at maintaining its structural integrity. Depending on the weight of the staircase and assuming 2 to 3 people when it is in use, there is a risk that the integrity of the screed and insulation may be impaired or even crushed. We therefore recommend using a rigid insulation such as Kingspan GreenGuard GG300.  This is a high performance rigid extruded polystyrene (XPS) insulation which offers thermal conductivities as low as 0.034 W/m·K and has the necessary compressive stress for the requirements.

For a floor design consisting of block and beam + insulation + screed, your block and beam designer will need to know the loads exerted on the floor from the staircase and take this into consideration. They will probably add additional beams within this location, as the blocks themselves are quite brittle. You will also need to substitute the PIR insulation for a rigid insulation, as described above.

For a timber sub-floor, the insulation is less of an issue as this will be fitted between the joists, but it is still important that your structural engineer allows the correct size and quantity of timber joists to take the loading from the staircase. We normally recommend triple joists are installed, which are through bolted together with coach bolts.

PLEASE NOTE: In all cases, it is imperative that if you plan to have underfloor heating, it is omitted from this area to avoid the risk of the pipes collapsing.

If you require any structural advice, or want help to design your feature staircase,  please contact Zakuna technical team to discuss your requirements. info@zakuna.co.uk