When installing a stair it is usual to start from the top and work down. There may need to be some preparation of joints and trimming to size of components, where required, before the components are fixed in position and this should be checked prior to starting the installation.
Bespoke Wood Staircase Installation guide
Wall strings, newels and landings will need to be fixed to the supporting structure. Consideration should be given to the type of fixings used to ensure that they provide a suitable level of support and that they are appropriate for the timber, block or other material to which the stair is being fixed.
All fixing points should be prepared with clearance holes (through the piece being secured) and pilot holes (into the structure being secured to). Never force a fixing into any material, unless the fixing is intended for that purpose, as this will cause splitting of timber and will weaken the joint. Care when handling should be taken to protect the delicate birds-mouth joint.
Working at height Care should be taken when installing a stair as the nature of the work will present a risk of falling. Full protection to the outside of any stair will not be afforded until the complete guarding system, balusters or infill panels and handrails have been fixed in place.
As an alternative, a suitably accredited temporary guarding system may be used until the final guarding is in place. (Accredited to EN 13374:2004, Temporary edge protection systems. Product specification.
Temporary fixing of stairs A staircase will not be able to provide its full support until it is installed completely with all fixings in place. Until this is achieved there is a chance that elements of the stair could become dislodged from their positions, for example, a newel could fall from its location over a trimmer, or a missing fixing or anchor, could cause unexpected loading to a part of the stair leading to failure. Bespoke Wood Staircase Installation guide
During the installation process it may be necessary for the installer to use the stair, but this should only be undertaken with caution having ensured that temporary supports, such as a block at the base of the stair to prevent slipping, or temporary propping, is in place before the installer applies any load to the stair.
At this time, no guarding will have been fitted so the installer should also consider any risks associated with falling from the stair. Before a staircase is used for access between storeys the trunk should be fully installed and capable of supporting its intended loads with all fixings, packers and supports in place.
Any edges where there is a risk of falling should be protected by the supplied guarding or balustrade or by adequate temporary guarding. (Temporary guarding should be accredited to EN 13374:2004, Temporary edge protection systems. Product specification. Test Methods)
Clearances The finished size of the stair should not be equal to the sizes measured on site, as this will not afford any flexibility while installing the stair and may not permit parts of the flight to be manoeuvred into position. Consideration should also be given to any finishes that are yet to be applied to the walls of the stair opening, such as, dry lining or plastering. The finished size of a stair can be up to 40 mm less than the “tight” sizes measured on site but any clearances between the stair and any fixing points should be packed out prior to fixing.
Wall string fixings Structural screws, which are CE marked to EN 14592, should be used to fix wall strings to timber stud walls or masonry walls. The screws should have a nominal diameter of 5mm (10 gauge), and should either be of the self-drilling type, or should be installed in predrilled holes. Bespoke Wood Staircase Installation guide
The length of the screw should be chosen to achieve a minimum penetration of 50mm into the timber stud/nogging or into the masonry wall, and 50mm long wall plugs should be used in masonry walls
To facilitate fixing into timber stud walls, timber noggin’s should be provided between the vertical timber studs which follow the intended line of the fixings. These timber noggin’s should be a minimum of 45 mm wide x 72 mm deep, and be fixed to the timber studs at each end using 2No 75 mm long screws inserted perpendicular to the noggin (see Figure 1d). Alternatively, additional studs may be provided at 300 mm c/c to enable direct fixing into studs and avoid the need to insert noggin’s. Bespoke Wood Staircase Installation guide
Straight flight You would usually order your staircase factory assembled, however where access is tight you may require the stairs in kit form. This guide will explain how to assemble your staircase on site.
STEP #1 Start by dry wedging a tread and riser at each end of the stair run, now place the other string on top dry wedging this (look at the plan and ensure the treads are in the correct housings). You can now lay the staircase flat, allowing you to slot all of the other treads and risers into their housings. If your staircase has newel posts be sure to put the notched treads in the correct housings (look at your plan drawing), notched treads should be numbered.
STEP #2 The next step is to board and clamp the staircase before we wedge all of the treads and risers. To do this put some loose timber boards / packers either side of the staircase stringers to prevent marking from clamping, now clamp over the width. Be sure your staircase is square before tightening up all clamps, to do this place one edge of your square against the stringer and let the other run down the riser (you will need to make sure the tread and riser sit fully down in the stringer trenching before checking for square).
Be sure not to over tighten the clamps. STEP #3 Remove your dry wedges, apply a generous amount of glue to the whole set of wedges and slot them in behind the treads. Drive in the wedges making sure all of the treads are completely down in their housings, now do the same with the risers.
STEP #4 This stage is very important, and if done correctly your staircase should be forever squeak free! The first step is to fix the risers to the treads, using a chisel prize open a slight gap between the tread and riser, next run a small bead of glue (we recommend PU woodweld or similar) along the back of the tread where the riser will meet. Beware not to over glue this joint, especially if the flight is not being carpeted as the glue can be difficult to remove from the face of your staircase – its best to run the bead of glue towards the under edge of the stair.
You are now ready to screw the riser to the tread, if your treads and risers are MDF we recommend 40mm screws, on timber 30mm should be ample to fix a 10mm riser.
Use 3-4 screws in the pre-drilled holes, be careful not to over tighten or let the screws spin. If screwing into a hardwood tread you will need to dill a pilot hole approximately 2-3mm in diameter.
The next step is to glue the angle blocks in place with generous amounts of glue, it is very important that these are fixed properly and the glue is allowed to set before use.
Notching top of wall string to fit over trimmer Cut the underside of the string so that the top face of the top nosing piece will sit flush with the surface of the flooring and the back of the top riser sits against the trimmer but a clearance of up to 5 mm can be accepted. Cut the upper side of the string so that it aligns with the skirting. Figure 2—Top of wall string
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