How to measure a straight stair lift
To ensure the best results, contact us for a FREE in-home evaluation for local and regional customers where we will come out and measure your stairs, determine access to power outlets to charge the system, discuss if your application suggests and optional folding rail and other important factors such as warranty and service.
Measuring for a straight stairlift is a fairly straight-forward process, no pun intended. Unlike our more sophisticated custom-curved stairlift systems, straight chair lifts are modular, can accommodate different lengths of stairwells beyond the original installation and therefore can be removed and reinstalled on other stairs. We can forego the photo-targeting systems used for curve stairlift evaluations and simply measure using a simple, standard measuring tape (although we recommend using a longer tape over 20’ to allow for longer stairs when applicable.)
Calculating length of Stair lift Rail
The first measurement we take is to calculate length of the rail needed. To do this, we pull a measuring tape from the floor at the bottom landing, diagonally along each riser/tread bullnose until we reach the top step at the top landing, where the ground levels out. This length is noted, and depending on vendor, we add a little length to ensure the lift lands with the footrest level to the top landing for safer, easier entry and exit. For Harmar, we typically add 7” while on Stannah units, we add 12”. This diagonal measurement plus the added length indicates the amount of rail needed, total.
The Harmar units we sell ship with 15’6” of rail, or two 96” rails jointed at the middle and supported on each end of each section by a stanchion foot mounted to the stairs. It’s often presumed stairlifts mount into a wall—rather, the rail is supported by feet, or stanchions, that are fastened to the stairs’ treads at certain points along the run. The Stannah Siena stairlift ships with 4.7M of rail, standard—just slightly less length than the Harmar units.
When the total length of rail exceeds the standard length provided, we’ll opt for either longer individual rail sections, as is the case with the Stannah offerings, or intermediate splice joints that are inserted between the two standard provided sections to lengthen the rail accordingly and give us the amount of rail needed. This is usually the case with homes that have higher ceilings. We then will use our special metal cutting saws and diamond blades to cut down the aluminum stairlift rails for a perfect fit. Our saws are equipped to cut at lower RPMs and with cleaner results than standard compound mitre saws or Sawz-All tools, keeping the metal cool to the touch following cutting. We then clean up and vacuum all metal shavings to leave a clean installation work area.
Width of Stairs for Stair lift
The next thing we check is stairwell width. If a homeowner wants to keep the handrails intact that are often already mounted on the stairs, we’ll pull a tape across the width of the stairs from the furthest obstruction (in this case the handrail) to the opposite wall’s furthest obstruction. If any trim is present, such as window sills, or large artwork, wall sconces, etc. this is noted and subtracted from the width. We find most homes in San Antonio and surrounding areas have 30-36” widths, which is plenty of room to accommodate a straight stair lift.
Angle or Slope of Stairs for a Stair lift
Most rack and pinion or worm gear stairlifts can accommodate a decent variety of slopes/angles for stairs. Outdoor stairlifts and older cable-trolley style systems require steeper angles to allow gravity to sufficiently provide enough tension on the aircraft cable so they don’t skip without weight and trip overspeed brakes that shut the unit down in the event of slack cable tension being sensed by the systems’ mechanisms.
To figure out this angle, we use geometry to calculate average slope by measuring the ‘rise’ of a few risers (measurement from tread surface to the next tread surface) and ‘run’ of a few treads (from back of step to front of step tread, subtracting any bullnose overhang) and average each measurement to come to our sides of a right-triangle. We can then use this information to determine the angle of the slope. Most homes in the San Antonio area we measure for a stair lift have around 10-11” treads, and 7-8” risers. This usually gives us a slope of around 32-35º which is adequate slope for all types of stairlifts: rack-and-pinion, cable-trolley or worm-gear equipped systems we have available.
Often, outdoor decking steps can have longer tread lengths and shallower rise measurements which will put the slope lower than 30º. Slopes lower than 30º often are not suitable for outdoor stairlifts systems designed around cable trolleys, as the lack of slope reduces gravity’s ability to put adequate tension on these types of systems for them to effectively work as they should. We can measure and confirm this with a free evaluation for a stairlift at your home.
Special Considerations
Often, when a customer opts for a folding or hinged rail, such as the Harmar Pinnacle Auto-folding Rail, we consider how this setup is designed to determine possible rail configuration options that can reduce the amount of joints and feet needed, leading to a cleaner looking installation. A folding rail section is shipped as a 60” hinged section w/ the folding part being 2’ of this and the other 3’ being the part fastened to the stairs. Harmar sends us a 33” splice standard, then another 93” section. In homes where we need extra rail length, instead of opting for a cheaper additional 33” section to extend the rail, we’ll recommend an optional 60” splice and forego two 33” sections butted together to eliminate an extra joint and reduce the amount of feet needed, thereby reducing the amount of holes necessary to mount the sections to the stairs.
Also, on shorter runs, it would be easier to install the full bottom rail, then cut down the top and joint on the remaining rail needed. However, this often means the joint section is offset primarily to the top end of the stairs. If the difference is more than a foot or two or rail length, we’ll suggest to customers to remove the bottom rail cap and wiring system, cut down the bottom section of rail to be symmetrical to the top length, then reassemble to provide a more uniform aesthetic and move the joint towards the middle of the run. This step takes a little longer to do, but we feel like the end result looks much better, which we feel our clients can appreciate. However, if clients wish to keep the full bottom rail intact for future modularity, we’re happy to comply just as well.
TL;DR
When coming out to measure for a straight stairlift in your home, we take the diagonal measurement of the stairs, add a small section of length to appropriately set top landing height of the seat which can vary by manufacturer, and determine how much rail we need. Most homes will work with the standard length of rail provided while others may need more rail length for a proper fit. We also measure the rise and run average to ensure the slope isn’t too shallow or too steep for a conventional stairlift system. Then we also measure width of stairs to recommend options if necessary, and we note bottom and top landings to make modifications (folding rail, taller feet to ramp up height at top) when necessary for the least-intrusive system possible for each customer’s unique home.
