Installing and using Arke Karina alternating tread stairs: a review
As a fan of alternating tread stairs, and the owner of a rare city-permitted custom made set of them in the granny cottage I built, I’ve always been curious about one staircase option I did not use: the Arke Karina stair kit.
My own alternating tread device, like most I see around on the internet, was custom made out of wood by a carpenter, and is straight. However the Arke kit uses a modular metal unit as its spine, giving it a lighter appearance, and giving it the ability to curve. The Arke kit isn’t cheap ($1600 minimum, plus >$200 extra if you want a second handrail), though custom carpentry isn’t either. Neither a custom made wood alternating tread stair, nor the Arke kit, meets most residential codes in the US so it’s a wash in that respect. What’s the better choice for someone building or modding a small house?
I finally got a chance to see an Arke Karina kit in action, when I helped a friend of mine install one in a narrow closetlike space in his farmhouse in the country.
Installation was not the short and simple process that Arke’s videos would like you to believe. It took a minimum of 3 days to do a curved setup with two handrails. The difficulties came partly from the poorly translated manual, and partly from the heavy steel components. Once the spine is assembled, you really need two people to guide it into place and bolt it in; the total product weight is listed as 257 pounds, which includes the treads. At that weight, we felt we needed to make sure the upper and lower ends of the spine were solidly connected to structural parts of the farmhouse, which added more labor. Perfecting the curve, rise, and level required some strength, as heavy elements had to be held in position while bolts were turned.
After that, the modular handrail turned out to require literally hundreds of small machine screws, washers, and other parts. Now that the stair is done, my friend is going back and applying (removable) threadlocker to all those connections, as protection against vibration, adding a fourth day of work. Another frustration: the instructions suggested drilling the holes in the treads for the balusters before attaching the treads to the stairs — but that only works if you are using a straight layout. If not, drill the holes later, when you figure out where the balusters really need to go. Otherwise the treads will be swiss cheese.
But, having said all that: the results were worth the trouble. The stair looks sharp and feels sturdy, and the numerous metal parts seem heavy enough to last a long time (with the possible exception of those tiny screws in the handrail, which I would recommend inspecting periodically). The alternating tread action is better than some other custom alternating tread stairs I’ve tried, and with two handrails you can go down facing forward with a definite feeling of security.
The most fantastic feature of the kit, though, is its flexible ability to curve. Arke’s manual gives four suggested layouts, but you are not limited to them. Curved layouts can help direct the eye, and foot traffic, giving the space a better sense of flow. And curves may be the only way to deal with certain problematic spaces.
Despite the difficulties in permitting them, these kits are so useful I expect to see more of them around.