Staircases (Second fix)
Within the scope of a full construction operation, regular staircases are installed as a part of the first fix. At this stage, only the crucial components are installed, typically the flight itself with the treads and risers, the newel posts, and any handrails that are fitted to the newel posts with mortise and tenon joints. These components are subsequently wrapped with protective coverings, to prevent the relatively delicate materials from being damaged during the other first fix operations still to be carried out, as well as the upcoming plastering. The decorative and more delicate components involved in the finished of the staircase are left unfitted until the second fix process begins. The spindles, newel caps, aprons, base rail, and some varieties of handrail are all examples of components that are not crucial to the assembly of the staircase during the first fix stage. Of course, these are common components associated with the installation of closed stringer staircase - with cut stringer staircases often being finished in a slightly more bespoke fashion.
What are the different second fix staircase components?
As discussed during the first fix staircase entry, there are 2 primary construction methods of residential timber staircases in modern western construction. Closed stringer staircases see most of the assembly take place in a workshop, and are constructed from machined materials. This type of staircase is the most common variety installed in residential properties in the UK. Many of the staircase components are integrated into the structural assembly of a closed stringer staircase. The flight of stairs is usually delivered to site partially assembled, with the straight flights arriving as one component. Most of the treads and risers will have been assembled within the 2 machined stringers, eliminating a lot of the assembly work on site. As the staircase is fitted, any newel posts present are likely to be installed at the same time, as the stringer ordinarily receives into them via a mortise and tenon. It’s also possible that the handrail is attached to the newel posts with mortise and tenons, and so all of these components must be installed together. This forms the basis of the staircase structure, with all of the additional components building off of this foundation at a later date. Once this framework has been established, the machined components are covered to protect them from damage, as the stringer, newel posts, and a handful of other components will be on display once the assembly is completed, though they are usually painted. This method of construction allows for the structure of the staircase to be machined and assembled from real premium timber, with staircase companies offering finishes in a range of hardwoods. In these instances, the stringers, treads, risers, newel posts, handrail etc. are all machined from hardwood timber, though there may be elements of timber engineering involved.
This contrasts to the assembly and finishing process of cut stringer staircases, where the structure of the staircase is assembled from framing grade timber. Multiple stringers are cut on site from wide structural timber boards, which are then faced with plywood treads and risers to form the foundation of the staircase. Whilst perfectly functionally, and more accessible to site carpenters, this method of construction requires more work in the second fix stage to achieve the same aesthetic outcome as closed stringer design. When we compare the two styles in their rawest form, we can see that all of the finished elements of the cut stringer are installed during the second fix process, whereas a large portion of a closed stringer staircase installed during the first fix process are finished components. The newel posts, handrails, and stair skirts are second fix components of a cut stringer staircase that would ordinarily be installed during the first fix formation of a closed stringer staircase.
Whilst implemented in slightly different capacities between the two styles, the second fix components themselves remain largely similar. Here we shall look at the different components involved in the finishing of a staircase.
Newel Posts
In closed stringer assemblies, the full newel posts attached to the stringers are generally secured through mortise and tenons. For cut stringers, the newel posts are not typically required to be installed during the installation of the stringers and primary carriage, and can be installed at a later date as a separate component. In either scenario, railings that extend away from the top of the stairs to secure the edge of a landing are considered a part of the staircase, and are ordinarily assembled from matching staircase components. Additional newel posts are installed within the subfloor or housed over the apron of the stairwell to support any handrails that form the landing banister. Where handrails come into a wall, a half newel is often installed to provide a suitable timber fixing and continue the aesthetic of the staircase.
Newel posts that are not directly integrated into the initial assembly of the staircase i.e. a drawbore mortise and tenon secured to the stringer, must be fastened appropriately in relation to the circumstances during the second fix stage and the relevant building code. Where possible, the newel post should extend through the subfloor and be fastened to the joist system below to ensure a suitable fixing. If this is not achievable, specific newel post mounting hardware must be employed to ensure the component is suitably fixed. This is critical, as the newel posts support the handrail, which in turn support people traversing the staircase. Poorly secured newel posts could lead to injury occurring.
Handrails
Handrails provide a critical safety element to staircases, forming a physical barrier along the exposed edges of staircases as well as providing a stable surface to hold onto during travel. The utility of this component is often overlooked by the young and active, but is hugely important to those that are less able and unsteady on their feet. When we consider that people that rely on handrails typically place a lot of weight onto these components, we can see how important it is to ensure that the supporting newel posts are securely fixed. For staircases that run adjacent to a wall and where accessibility is a primary consideration, an additional can be installed up the rake of the stairs, fixed to the wall via brackets. At the top of the stairs, if a landing features an exposed edge, a matching handrail can be installed to secure the landing in an aesthetic that matches the stairs.
In many closed stringer assemblies, the top of the newel posts feature a mortise to receive a tenon cut on each end of the handrail that travels up the rake of the stairs. In these instances, the carriage of the stairs, the newel posts, and the handrails must all be installed at the same times, as the newel posts will not move apart enough for the handrail to be fitted once both of the posts are secured to the stringer. Once all of these components are fitted together, a drawbore pin is installed through the mortise in combination with glue to ensure a stable connection. This being said, there are a range of manufacturers that produce hardware specifically for mounting handrails between two static newel posts. This hardware replaces the traditional mortise and tenon, and allows for the handrail to be installed after the newel posts are fixed in place. This is typically the case with cut stringer staircases, though the hardware can just as easily be implemented into closed stringer designs.
Handrail comes in a variety of different profiles, as well as in many finishes. Its not uncommon to see a hardwood handrail installed between painted softwood newel posts as a design feature. Staircases that feature traditional spindles will be assembled with a handrail that has been routed out on the underside in order to receive the top of the spindles.
Base rails
Base rails are decorative stair components that are installed to house the bottom of a set of spindles. The top of the moulding features a routed groove that matches the groove on the underside of the handrail, and is used to hold the bottom of the spindles captive. The underside of the base rail might also be housed out, or simply planed flat. The housed underside of a base rail is intended to fit over the stair stringer or the outside skirt board in order to facilitate the installation of the spindles up the rake of the stairs. Base rail that features a flat underside is intended to be installed on a flat surface, such as the landing, to house the bottom of the spindles that make up the landing railing. The grooves are available in a range of width to accommodate different thicknesses of spindles, with a matching length of fillet ordinarily being provided to space the spindles appropriately. Base rail can also be purchased without a groove, instead with pre-drilled holes suitable for the implementation of cylindrical spindles. Once again, different diameter holes are available. Base rail without grooves or holes is also available for bespoke applications. matching handrail can be purchased in all of these styles as well.
Spindles
Spindles are a staircase component that play a primary role in the formation of a railing/banister system. Housed within the base rail at the bottom and handrail at the top, the spindles are installed at even intervals up the rake of the stairs/along the landing to block off the exposed edge on the other side of the railing. Whilst there are gaps present between the spindles, they are spaced no further apart than 99mm, and at no point should a 100mm ball be able to pass through the spindles. This ensures a small child or animal will not be able to fall between the spindles. The space between the spindles is maintained with sections of fillet that fill the exposed housing that remains between the spindles. The spindles are installed perfectly plumb, and are spread evenly along the entire run. On staircases where there is no outside closed stringer, or no faux-closed stringer skirt board, the spindles fall directly onto the treads. In these instances, they are space evenly on each tread, whilst still maintaining the maximum spacing of 99mm between them. These spindles might be attached to the treads with special brackets or hardware, or held captive with a shallow mortise cut into the tread. Spindles come in a variety of different thicknesses and profiles, in a wide range of specific aesthetics. They can be purchased in hardwood, as well as primed softwood, and even metal. A general rule for roughly calculating the number of spindles required is to allow 2 spindles per tread of the stairs.
Balustrade panels
Staircase balustrade panels can refer to a few different components, depending on geography as well as the terminology used by merchants. Balustrade panels can refer to pre-assembled level balustrades/railings, that feature a length of handrail and base rail between 2 newel posts, complete with evenly spaced spindles. They are available in a range of lengths, materials, finishes etc. and are intended for the quick installation of balustrades in level areas. An example of this would be installing a short railing at the top of a flight of stairs. These premade panels eliminate a lot of the work involved with the conventional assembly of balustrades.
Balustrade panels can also refer to panels that are installed below the handrail in lieu of traditional spindles. In modern construction, these panels are often made from toughened glass mounted on purpose made hardware, though panels can also be made from timber or metal. These panels are implemented to create an sleek and modern aesthetic, though they are generally on the pricier end of stair installations. The panels must still be installed with no more than a 99mm gap between them.
Newel caps and acorns
Newel caps are decorative components that are installed on top of the newel posts within a staircase. They are typically wider than the newel posts to create an aesthetic design, and will often feature a housing on the underside that slots over the top of the newel post. They can range from relatively simple in their design to featuring a range of mouldings and profiles. Acorns are another type of newel cap that generally slot into a hole drilled in the top of the newel post. Once again, they are a decorative feature.
Nosing
When an open landing is created, a series of beams and trimming timbers are assembled to form the front edge of the stairwell/landing. Depending on the exact layout, the open edge of the landing may also return around a corner - maybe more than 1 in some instances. When the flight of stairs are installed, a part of the framing of the opening is hidden behind. However, the remaining perimeter of the exposed landing is still on display. A series of standard stairway components are installed in this situation, to tidy up the exposed opening with an aesthetic that matches the staircase. The first of these components to be installed is the nosing. This component is sat on the outside trimmer of the opening, overhanging the edge, and providing a point of termination for the subfloor. The nosing is typically the same thickness as the subfloor, and so they sit flush with one another. The nosing features a housing routed along its underside that receives the top edge of the apron that caps front of the trimmer. Sometimes, an additional batten is installed on the face of the trimmer to add a little extra depth, also allowing for the apron to be plumbed up. In either scenario, the back edge of the housing on the underside of the nosing should sit marginally further forward than the front edge of the opening. This will allow the apron to slide neatly up into the housing. The base rail of the balustrade will typically sit on top of the nosing to some degree, though the exact positioning can depend on the width of the nosing and the desired location for the balustrade. The profile on the front edge of the nosing might be round, square, or machined in a manner of other mouldings, depending on the desired outcome.
Aprons
An apron is a finished piece of real or engineered timber that covers the face of the trimmer beam that forms the opening of the stairwell. With the housing on the underside of the nosing aligned correctly with the edge of the opening, the apron can be slid up into the housing and fixed to the face of the opening. Ordinarily, the apron is cut to width so that the bottom edge is flush with the ceiling cover - most commonly the bottom of the skimmed plasterboard. The face of the opening can be packed before the installation of the nosing to overcome any issues with plumb or deviations in the face of the beam, ensuring that the apron sits flat and plumb against the opening.
Cover mouldings
A cover moulding is a piece of trim that covers the transition between two materials/surfaces. In this instance, the a staircase cover moulding is an L shaped moulding that sits over the bottom corner where the plasterboard of the ceiling below meets the back edge of the bottom of the apron. This trim hides the transition between the two materials, and probable cracking that will ultimately appear at this intersection.
Skirtboards
Skirtboards, stair skirt boards, and stair skirts are all names given to a decorative trim that is installed up the rake of a cut stringer staircase to cover the exposed sides of the raw timber stringers. Closed stringer staircases feature a machined, finished stringer on each side of the staircase that projects above and below the treads and risers. Where a closed stringer flight sits against a wall, the stringer touching the wall servers to protect the wall at the level of the treads in the same way that regular skirting boards would. The outside stringer provides a suitable surface to paint or finish however desired. The underside of a closed stringer staircase may be boarded and left open, or framed in with studwork, with the plasterboard come up to meet the underside of the outside stringer.
Cut stringers do not typically benefit from the luxury of a finished outer stringer in their construction. Instead, a common method for boxing in the raw timber of the cut stringers is through the installation of skirtboards. These skirtboards are cut from wide board timber or engineered timber sheets such as MDF in order to emulate the appearance of traditional closed stringers once installed. The common thickness of the skirtboards can range from 15-32mm, with the thicker end of the spectrum being used more often. The inside skirtboard sits above the treads as the inside stringer of a closed stringer flight would, to protect the wall finish at tread height, as well as creating a stop for the skirting boards at the top and bottom of the staircase. When installing a cut stringer staircase, the whole flight can be spaced away from the wall so that the plasterboard and inside skirtboard can be slide down behind the innermost stringer. This prevents having to notch the inside stringer during the second fix stage. If this is not the case, the skirtboard must be neatly notched over each tread and riser so that it follows the rake of the staircase with a consistent upstand from the nosing of each tread. The skirtboard should be installed before the installation of the finished flooring, to allow a larger tolerance to the notches. If the skirtboard must be notched around the finished floor on top of the stairs, great attention to detail must be paid, as the tolerances are extremely small.
The skirtboard installed on the exposed outside stringer of the staircase can be shaped in a number of ways. With little to no notching required, the skirtboard can be installed to project above and below the treads and risers, to take on the appearance of a closed stringer. This provides a positive stop on each side of the staircase for finished floor to come into when installed on top of the treads, as well as allowing for the installation of base rail and spindles up the length of the skirtboard. Alternatively, a set of notches opposite to the inside skirtboard can be cut so that the outside skirtboard follows the profile of the cut stringer, sitting flush with the tops of the treads and the fronts of the risers. This arrangement accommodates the installation of tread and riser capping as the floor finish, tying the aesthetic of the staircase together. Without a point of attachment for the base rail in this scenario, the spindles must come down into the treads. In both of these scenarios, the bottom of the skirtboard hangs low, once again forming a hard edge for a wall finish to come into.
What are the criteria for the installation of these components?
All of these components follow the standard installation criteria or plumb, level, square, true, tight joints etc, with a few component specific criteria. An imaginary line drawn connecting the front nosing of the treads is known as the pitch line. The top of the handrail must fall between 900mm and 1000mm measured vertically from this pitch line. The top of the handrail for a landing balustrade must also fall within this range, measured from the top of the subfloor. Newel posts must be suitably attached to the subfloor or the staircase in compliance with local building regulations. Once again, spindles must be installed with no more than a 99mm gap between them. All components should be secured with suitable adhesives and fasteners.
How are these components installed?
Now that we understand what each of the components involved with finishing a staircase are, we can look at how they are each installed.
Newel Posts
When newel posts are not integrated into the primary assembly of the stairs during installation, they must be installed after the fact in order to carry the handrails. When installed during the first fix stage, integrated newel posts are situated at the top and bottom of staircase, situated centrally about the outside stringer/s. With the centre line of these components falling in the same plane, the following handrail installed between the newel posts and the base rail installed to cap the stringer will also fall in line. This ensures that everything will line up when the spindles are installed, and that everything remains plumb/square/true etc. Seeing as most closed stringer staircase will be supplied with newel posts that are appropriately housed out for integrated installation, the majority of newel posts fitted during the second fix of a staircase will be on cut stringer staircases. In these instances, due to the construction method of this style of staircase, a full depth closed stringer is not present on the outside face of the stairs, hence the installation of the skirtboards to emulate the appearance of a closed stringer. The installation of an outside skirtboard is very common amongst cut stringer staircases that feature a conventional spindle installation. The skirtboard servers as a faux closed stringer, but similarly forms the basis for the installation of the base rail as a capping. As such, the newel posts will typically be positioned so that the centre line of the posts are in line with centre of the skirtboard.
Every scenario is going to be a little different, due to the bespoke nature of staircases, though adjustments can be made a to a standard installation procedure to suit a custom application. Ordinarily, the bottom newel post will sit so that half of the thickness is positioned forwards of the first riser, and centred on the skirtboard. If the skirtboard projects beyond the first riser, it should be cut back so that both components are flush. The remaining half thickness of the newel posts can be measured backwards from the riser along the skirtboard, and plumbed up. This line should be cut down to the top of the tread, and the waste removed. This arrangement will allow for the easiest notch in the newel post to be performed. The half thickness can be marked on the bottom of the newel post for the front to back positioning. The half thickness of the newel, less half the thickness of skirtboard can also be marked in the side to side position. The height for the removal of this waste is measured from the subfloor to the top of the first tread. When removed, this notch will slide tightly over the corner of the first step, centred on the skirtboard and projecting beyond the first riser half the thickness of the newel post. Suitable fixings can be used to secure the bottom of the post into cut stringer behind.
This is the most basic notch achievable, but relies heavily on accuracy for all of the joints to come together tight. There are other criteria that might need to he considered that will add complexity to this notch. Primarily, in terms of a suitable fixing, additional material might need to extend below the subfloor in order for the newel post to be secured to the joists. Once again, every scenario is a little different, and the exact length of the additional material, and the profile of the newel post as it passes through the subfloor will depend on the exact layout of the joists below. It’s possible that a joist or a beam falls directly below the point of installation for the newel post, in which case it cant pass through the subfloor. In these instances, purpose made newel post mounting bolts can be installed into the framing below in order to secure the post, in addition to the fixing installed into the stringer.
Sometimes, the skirtboard above the first tread will remain flush with the front riser, and so the newel post will have to be notched in relation to this angled material. This notch houses the remaining skirtboard, and ensures a tight intersection. Additionally, a notch might be required to house the front of the tread nosing, if an overhang is present at this stage. Where a bullnose step is present as the first step within a staircase, the newel post is typically installed on the next step up. The same positioning criteria apply, sitting centrally on the skirtboard and half the thickness forward of the second riser. However, the notch height will be greater to account for this second step, and additional notches must be made on the lower front of the post to house the tread and riser of the bullnose as it comes into the post. There are no exact measurements for these notches, as every staircase is a little different, but understanding how the components come together can aid in marking out the notches. In all instances, we must ensure that a suitable fixing is used to connect the post to a sturdy structural member.
At the top of the stairs, another newel post is installed to receive the top of the handrail. A level balustrade might also be installed starting from this upper post, if a landing must be enclosed. Similarly to the bottom newel post, the top newel typically projects half of its thickness forward of the top riser. The post is notched around the beam that forms the structural opening of the stairwell, ordinarily projecting a short distance below the surface of the ceiling. This provides an opportunity for a secure fixing into the structural timbers that form the opening. Depending on the space between top riser and the face of the structural opening, the notch around the beam is usually less than half the thickness of the post. The skirtboard is cut back plumb so that it will meet the front of the newel post once installed. A suitable notch for the treads, risers, and possible the whole stringer is made, depending on how far below the ceiling surface the post projects.
The newel posts that form the remainder of a balustrade are installed with the same notch around the beam to ensure the handrail remains true.
The top of the newel posts should be cut to a height of between 50mm to 150mm above the height of the handrail installed between 900mm-1000mm from the pitch line of the stairs/subfloor level.
Further specific explanations will be presented alongside illustrations at a later date.
Along landings, the distance between newel posts should be no more than 6 feet, unless otherwise specified.
Handrails
Handrails that are fitted during the second fix process are ordinarily cut tight between the newel posts, and fixed with specialist hardware, as mortise and tenon joints are impractical once the newel posts have already been installed. The top of the handrail should fall between 900mm and 1000mm from the pitch line of the stairs, or the finished floor height/subfloor level for balustrades. The pitch line is an imaginary line drawn up the rake of the stairs, touching the nosing of each tread. Handrails that are installed level between newel posts are cut exactly to the inside length and installed with suitable hardware, typically handrail connecting bolts. The handrail that runs up the rake of the stairs is also cut tight between the newel posts, but extra care must be taken. Both ends of the handrail are cut to the appropriate angle to fit tightly against the side of the newel posts when installed at the same pitch as the stairs. Care should be taken to ensure that the handrail remains at the same height above the pitch line all the way up the stairs.
Base rails
The base rails is a component installed on both conventional closed stringers as well as the skirtboard of cut stringer staircases in order to facilitate the installation of the spindles. Base rail is also installed between the newel posts of a level balustrade to similarly retain the spindles. Up the rake of the stairs, the base rail is cut to the same length as the handrail, travelling the same distance at the same angle. The same angled cuts are made at each end of the length in order to sit tightly against the faces of the newel posts. A housing on the underside of the rail slides over the stringer/skirtboard and is fixed using suitable nails. When installed as a part of a level balustrade, the base rail is cut square between every set of newel posts. The base rail is situated centrally within the thickness of the newel posts, and will typically sit on a nosing to some degree.
Spindles
Spindles are installed between the base rail and the handrail in order to form a physical barrier, preventing falls from occurring over the exposed edge of the staircase/landing. To achieve this, the spindles must be spaced no more than 99mm apart, to prevent small animals and children from passing through them. When installed up the rake of the stairs, the top and bottom of the spindles will feature and angle cut to receive tightly into the pitched rails. This angle will be the opposite of the pitch of the stairs with a right angled triangle. For a staircase at the maximum pitch of 42 degrees, the angle cut on the spindles would be 48 degrees, a staircase at a comfortable pitch of 37 degrees would feature spindle angles of 53 degrees. These angles are the same for the cut on the handrails and base rails.
To space spindles on a level balustrade, we must calculate the approximate number of spindles that will be used. To do this, take the length of the base rail and divide it by the thickness of a spindle + 99. As an example, a base rail at 1750mm divided by 140mm(99mm gap+41mm spindle thickness) equals 12.5. We obviously can’t have a half of a spindle, and so must we must round the number either or or down to find a whole number of spindles. First we shall try rounding up to 13 whole spindles. Any number of spindles will fit; we are trying to calculate how few spindles we can install without the even spaces between exceeding the maximum 99mm spacing. We multiply the number of spindles by their thickness to determine the total amount of rail that the spindles will occupy. 13 x 41mm equals 533mm. We subtract this number from the total length of the rail to find the total remaining space on the rail. 1750 - 533 equals 1217mm, which can then be divided by a number that is 1 more than the total amount of spindles, to account for the extra gap at the beginning or end of the run, depending on how you count. 1217 / 14 = 86.9, or 87mm. This number will work, but is reasonably shorter than the maximum allowance. We can perform the same calculations again with 1 fewer spindle, to see if the gap is still within tolerance. 12 spindles x 41mm = 492mm. 1750mm - 492mm = 1258mm. 1258mm / 13 = 96.7mm, or 97mm. This new spacing is bordering on the maximum allowance, but is still within tolerance, and so 12 is the number of spindles we will opt for.
To space spindles up the rake of staircase on an angled base rail, the same concept is utilised, though the application varies slightly. The maximum spacing of 99mm is still observed horizontally between the spindles, though in this instance, we are spacing the spindles based on the thickness of their angled cut, as well as the diagonal distance that the 99mm horizontal spacing occupies. In this instance, the base rail up the stairs measures 3460mm at a pitch of 42 degrees. If we make a 48 degree matching cut on the end of a 41mm spindle, we can measure the diagonal thickness, in this case 55mm. If the angle of the stairs and matching spindle cut are correct, this angled cut on the spindle will sit flat along on the base rail along its entire length, occupy a specific distance as a regular square cut spindle would. We must then determine the length of a fillet at the maximum spacing of 99mm, to set a parameter for our calculation. We can achieve this a few different ways, but the easiest is to simply incrementally trim the fillet down until the distance between the first spindle and the newel post is 99mm. We can keep checking the distance and carefully cutting the fillet down until the spacing is 99mm. In this instance, the angled fillet piece for a 99mm spacing are 133mm long, from short to long point. With the diagonal lengths determined, we can perform the same calculation as before to find a suitable spacing. 55mm + 133mm = 188mm. The rail length of 3460mm / 188mm returns a value of 18.4 spindles. Based on the results of before, we’ll round down to 18 spindles and 19 gaps. 55mm x 18 spindles = 990mm. 3460mm - 990mm = 2470mm. 2470 remaining gap divided by 19 equal spaces equals 130mm spaces. This is just under our limit, and so this is a comfortable value to work with.
To install the spindles, either horizontally or angled, the process is more or less the same. Once the spacings have been calculated, the length of fillet supplied with the base rail and hand rail can be cut to the length of the spacings. These cut pieces of fillet will drop into the rails and be nailed in place in order to hold captive the spindles. The level balustrade pieces of fillet can be cut square, whereas the angled fillet will have the appropriate angles cut on them to sit tightly against the inside faces of the spindles. If every piece of fillet is cut to the exact same length at the correct spacing, the newel posts were installed perfectly plumb, the base rail and handrail are exactly the same length, and the spindles are all exactly the same thickness, then all of the spindles will be installed perfectly plumb with a consistent spacing between each. However, allowances must be made for minor inconsistencies. Tis perfect scenario might not exist to begin with, and so we must monitor the state of each spindle during installation to ensure a quality outcome.
A pair of fillet pieces can be cut at the correct spacing and tacked in place at the beginning of the rail. Spindle installation begins from the bottom of an angled rail, though direction doesn’t matter for a straight rail. The first spindle can be butted up to the first fillet pieces and checked for plumb. If the spindle is any more than a few mm out of plumb then the newel post must not be level, and attention must be paid to this component first. The calculations for spindle spacing are made based of off the length of the base rail, and so any adjustments made to the lateral position of the spindle should be achieved by trimming or cutting a longer fillet piece. Once this first spindle is plumb, more spindles and fillets can be installed all at the predetermined spacings, up until the halfway point of the rail. At this point, a recalculation should take place to ensure that the spindles are not creeping off of their true spacings. A 1mm inaccuracy in the length of the fillets amounts to a 11mm total discrepancy over 10 spindles, and so we can see the severity of this compounding effect. We must perform the exact same calculation as before for spindle spacing, but with the total amount of spindles remaining as an input value. If the spacings are minimally different, the fillets can be cut to this new distance to overcome the error. If this new spacing is more than 2-3mm, then something has gone wrong with the initial calculation, and the spindles may have to remove and the fillets re-cut. Once the halfway point is achieved, a handful more spindles can be installed until only a few remain. Once more, a check should take place so that any minor inaccuracy can be feathered out over the last few spindles.
Balustrade panels
Balustrade panels are easy to install in both of their implementations, both the glass panels and the pre-assembled spindle/handrail/base rail varieties. The glass must be purchased in the correct angle and shape to be installed with a custom staircase, or ordered as a part of the staircase kit. Specialist mounting brackets are screwed into the base rail, or sometimes mounted directly on the stringer. The glass receives into the mounting clips and is tightened in place between rubber jaws. These same brackets are used for mounting glass on level balustrades. The pre-built panels arrive as a handrail/base rail with the spindles already installed. The spindles are usually space at the 99mm maximum, or can be ordered to be spaced at a specific distance. The rail can be cut to length to fit between existing newel posts. These are them fixed as usual with specialist mounting hardware.
Newel caps and acorns
Newel caps and acorns are decorative capping’s for the top and bottom of the newel posts. These components simply fit over the newel post in combination with adhesives and mechanical fixings to hold them in place. Half newel caps can be purchased for use with half newels.
Nosing
Nosing is a component that is installed at the top of the stairs and around the edge of a landing area. For traditional closed stringer stairs, each tread overhangs the riser by around 16mm, with each tread being around 22mm thick. This thickness matches the common thickness of modern subfloor sheathing. When installed correctly, the rise from the top tread to the subfloor of the next level should be the same as the rise for the rest of the steps within the staircase. A moulding known as a nosing is installed at the top of the stairs to add the 16mm rounded overhang to the top step, and provide a surface for the subfloor to butt into. This nosing is the same thickness as the subfloor sheathing, and is usually around 3-4 inches wide. A nosing is provided with the staircase to add to the top step, though separate longer lengths can be purchased for use with landings. Once again, the nosing will overhang the hard edge of the opening to provide an aesthetic and practical stop to the subfloor sheathing. This nosing can be purchased with a dado on the underside that will receive the top of the apron. To install the nosing, simply line the back of the housing up a fraction in front of the structural opening timber, and nail the nosing into the beam. Care should be taken to ensure the nosing is straight and installed flat. When the nosing is installed during the second fix, the subfloor sheathing is usually installed. As such, its important to either leave the last board fixed with nails so it can be removed and recut for the nosing, or no adhesive applied to the very end of the board so that it can be cut up and removed suitably.
Aprons
An apron is a cover trim/timber that caps the face of a structural opening. In this instance, it refers to the capping that covers the face of the structural opening beam in an open landing scenario. The apron slots into the housing on the underside of the nosing, and is long enough to meet the ceiling surface. The apron is fixed with mechanical fasteners and adhesives, and is simply cut to length along the face of the opening. If newel posts are lapped over the side of the opening, the apron may have to be notched around these, or cut between, depending on how far the newels protrude downwards.
Cover mouldings
A cover moulding in this context is a length of cover trim that is installed to hide the transition between the ceiling surface and the apron that comes down to meet it. This trim is simply cut to length and nailed in place.
Skirtboards
Skirtboards are lengths of trim that are installed to emulate a closed stringer on a cut stringer staircase. The inner skirtboard protects the wall finish just above the treads, and helps to ease the material transition. This skirtboard must be notched around every single tread if the treads come to meet the wall. If planning allows, the inside stringer can be left away from the wall to allow the skirtboard to slide down behind it without having to notch anything. To notch the skirtboard, lay it up the rake of the stairs and carefully trace every single tread and riser with a compass and straight edge. The skirtboard on the outside of the staircase caps the outside cut stringer, and provides a point of installation for the base rail. This skirtboard can be installed without notching in this instance. Alternatively, if the spindles come down onto the treads, the skirtboard might be notches out to match the profile of the stringers, with the floor finish then coming over it.