Introduction to Articles
Being a stair installer in the tri-county area of Sonoma, Napa, and Marin has been challenging over the years and after over 25 years in the business, I have built or remodeled thousands of staircases. During my apprenticeship there were many aspects of stair building that were different than any other woodworking that I had done (general carpentry, fabricating and installing cabinets.). I was presented with a totally new set of challenges dealing with angles and radius's, rise, runs, codes, safety issues, etc. As daunting as all the layout and woodwork was, the chance to work on what I consider to be the focal point of a multilevel home, was and still is quite fulfilling. A stair builder needs to make sure that his product has structural integrity; a staircase is foremost a main artery of egress and safety is so much a factor, but also the staircase needs to have aesthetic appeal and it's appearance is a statement of design and architectural theme.
Determining Rise and Run of a Stair
A budding future Santa Rosa, California stair builder ,and maybe a future handrail installer,(a 22 year old framer who needs to build his first set of rough stairs) asked me how to determine the rise and run of a staircase. I wrote him a short explanation that follows.
For both the rise and run of a stair there are a few things to take into account before actual mathematical calculations take place.
Example -rough floor to floor rise = 108.00"
lower floor finish flooring thickness = 3/4"subtract .75"
Run - The first consideration is the actual length of space that the stair can occupy. If there is a door way or walk way around the first riser then this is a restriction that needs to be factored in.
. The average stair tread,considering walking comfort, is around 10 1/2" plus or minus. Since your total number of risers in the example above is 14, that would leave us with 13 walking treads.
Joining Handrail Transitions
This is a wooden stair building technique that a stair installer needs to master. Typically we attach most handrail transitions mechanically with either screws in the case of miters or rail bolts in the case of handrail fittings. We always use wood glue and if done right, the mechanical fastener is just for clamping while the glue dries, although the fasteners are insurance; they make sure that the glue joint is never stressed. A rail bolt is a metal fastener that has one end with a machine thread and the other end has a wood screw thread. They come in several sizes, but we use the 5/16" x 3 1/2" for joining our rails. The rail bolt is screwed into one mating piece of wood while the machine end is slid into a hole in the other mating piece and alignment is checked, glue is applied and nut is fastened and the 1" hole is covered with a matching wood plug. When the joint is complete, the resulting piece is sanded smooth. The trick is to make sure both holes in the mating pieces are lined up with each other. Some stair builders mark the center lines and use a doweling jig, but I have found that if one takes a 1/4" or so section of the railing and drill a hole in the center, it can be used for marking each mating piece of rail to be joined. Once the center is marked, typically a 1/4" hole is drilled for the 5/16" lag end and a 3/8" hole is drilled for the 5/16" machine thread end and a 1" hole is drilled into the bottom of the rail that accepts the machine bolt so a nut with washer can be inserted, threaded on and tightened.
Hardwoods for Stairbuilding
*WORK IN PROGRESS
Stairs and balustrades have been made with just about every hardwood (and softwood) available. The most common hardwoods for stair building are Poplar, Alder, Red Oak, Hard Maple, Beech, and American Cherry. We have made staircases and balustrades out of Walnut, White Oak, various species of Mahogany, Rosewood, Brazilian Cherry (Jatoba), Caribbean Heart Pine, Santos Mahogany, Padauk, Hickory, Beech, Ash, Ironwood (Ipe) and many other species. The hardwood flooring business is now importing an incredible variety of South American hardwoods and many of our clients have wanted to match their staircase and handrails with their flooring choice. Some woods are not very practical since some hardwoods are imported for flooring only and aren't available in long lengths (These woods can be spliced and laminated if necessary). Because Poplar, Alder, Red Oak, Hard Maple and American Cherry are the most popular hardwoods for staircases, they are usually the most economical because the balustrade parts are manufactured in quantities that yield more reasonable prices.
A specific wood will have different grain patterns depending on how its log is cut. Plain sawn, which gives the most lumber yield per log, is basically just cutting a log into planks as it lays. Quarter sawn cut is just as it is labeled. The log is first halved and then 1/4ed like a pie cut and then sliced from outer layer towards the core. Because of the increase in labor and the reduction of lumber yield it is a more expensive cut. It has straight grain and ray flecks (One sees this cut frequently in antiques made of Oak). Rift is a quarter sawn cut that has the straightest grain and no ray flecks. A rotary cut is produced by putting a log on a giant lathe and cutting a thin slice lengthwise as the log turns. This cut is used as veneer for plywood. When you see a production type oak door, the wild grain patterns are veneers that are produced as a rotary cut.
The following hardwood descriptions have been derived from 35 years of my woodworking experience.
Poplar: We use poplar for any part of a staircase that is to be painted. It is relatively hard, machines and sands with ease and because it doesn't have an open grain and is relatively inexpensive, is a great wood for painting.A few of our cost conscious clients have ordered poplar stairs to be stained. They are usually going dark in color and if the hue is dark enough to discount the greens and purples, the results are very nice.
Alder: Alder is a beautiful evenly colored brownish hardwood that is one of the softest hardwoods that we use for stairway and handrail fabrication (apparently Alder is white when first cut but oxygination browns it quickly). Because it costs less and because it stains easily and evenly, it's a relatively good substitute for Cherry. It is browner in color than Cherry but the grain and porosity are similar. Alders most limiting factor is that it only yields short (mostly 8'-10' with occational 12') lengths where a lot of stairs call for 12+' to 16' lengths.
Red Oak: Red Oak is a very hard open grained wood and has very distinctive grain patterns. It is tough enough to withstand the punishment that comes to stair treads (steps). It machines and sands well and takes a stain evenly and easily. It is prone to have internal checking which has to be culled out during the milling process. We have had clients put a Cherry stain on Red Oak which has taken on a definite Cherry patina but it won't fool anyone who knows a bit about woods. Some woods like Poplar, Alder and Maple can be disguised with stain but because of it's tale tell grain, Red Oak will always look like Red Oak.
Maple: Maple is a denser hardwood than Oak and is an excellent choice for stairbuilding. It has a soft grain pattern and although hard, machines and sands well. It has a light patina and when finished correctly can resemble other more expensive woods. It's downfall is in using stain to darken it. Maple will have a very blotchy appearance unless care is taken in the finishing process. A lot of finishers will apply a 'stain controller' before the stain goes on to assure that the finish will go on evenly.
Beech: (American and European) Beech is a very hard and strong close grained hardwood, light brown in color with darker specks (dashes) throughout. It is available in turned stair spindles, posts and handrails but as with Alder long pieces for railing will have to be spliced. I used European Beech on my home staircase. It machines and takes a finish nicely.
American Cherry: Cherry seems just as strong as maple but isn't as hard. It is a beautiful wood and has been one of the top choices of cabinet makers since colonial times. Cherry has a redish brown patina that gets richer and darker with age. Cherry is the most expensive hardwood that is produced on a production scale for balustrade parts and is made even more costly because it's sapwood is very light (white) and if a client wants their cherry to be homogenous without sap, the culling process can easily produce more than a 1/3 waste. Cherry is great to work with. After its initial drying process it is very stable. It planes and sands well and and takes a finish easily and evenly. I've found cherry to be best with a simple clear finish because it darkens gradually and naturally when exposed to sunlight to a wonderful dark cherry patina.
Some of the other most common hardwoods that we use for stairs are White Oak, Mahogany, and some of the nutwoods like Hickory.
White Oak: It is easy to describe White Oak as it contrasts to Red Oak. White Oak is denser than Red Oak and has a much lighter patina. Red and White Oaks grain patterns are similar but because of White Oaks higher density, it looks smoother (less porous) than Red Oak. It is stronger than and is more durable for treads. From a woodworkers standpoint it machines and sands well and it is incredably aromatic when it is machined. I love the smell of our shop when we run a White Oak stair job through. Because of it's water-tightness, it has been used through the ages for boats as well as wine and water barrels (the aromatic properties are given to the wine when stored in White Oak barrels thus those wine tasters get 'oakey' overtones. White Oaks water resistent qualities should never be tested on an interior staircase.
Mahogany: There are 3 authentic commercial species of Mahogany. The most common is African Mahogany and Tropical American Mahogany (Mexico, Central America, Peru, Brazil) with Cuban Mahogany being available before 1946. Philippine Mahogany (Luan) has some resemblance to Mahogany but is not Mahogany and generally much less dense and includes many species used for economical plywoods. Generally Mahogany is light pinkj to reddish brown and tannish brown. It is relatively hard (although one of the lowest density woods that we use for stairs), machines and works well, can be polished to a high luster, and is very durable. Mahogany trees are huge and the lumber can be purchased in great lengths and widths. Some mahogany planks are amazing. When we have a couple of 3" x 16" x 18' pieces here at the shop it really seems like we must have the whole tree.
Jatoba (Brazilian Cherry)
Bending wood by the process of lamination is not an exact science and takes practice. How wood bends is dependent on many variables, such as what species of wood is involved, the moisture content of the wood, the thickness, width and quantity of your laminants, what kind of glue is to be used, and how acute of a radius is to be bent. Unfortunately, these variables do not lend themselves to proven charts or tables that would make the process a bit more predictable. We have found that the bending of wood by laminating is an art that is picked up by experience and usually even when all the factors are taken into consideration, unless the finish product is to be mechanically held in place, the resulting product will more than likely have some spring back (change of radius). We always take some springback into our calculations and make adjustments for it.
Once a radius is determined (and in our case usually we need to layout for a stair pitch or angle as well) we draw the arc on a plywood laminating deck (see our pictures 'Stair and Handrail Fabrication'). We use metal stantions or wooden 2x6's as a laminating frame. If we are bending for a staircase we will build what we call a drum that is basically a curved wall. Once the wood to be used is resawn and sanded to its final dimention, glue is applied, the bundle is wrapped in several places with plastic wrap to keep the laminants in place for easy handling and with clamps spread out ready to work with (make sure to double the amount of clamps that you think that you need), we set the laminants in place, force the wood into position with muscle power (helps to have several extra hands) and start clamping either from one end or from the middle out both directions towards the ends. We will leave our laminant dry for as long as we can afford. The final radius is very dependant on how long the glue has to set up and again, what kind of glue has been used (most glue that we employ will have a extended cure rate where flexibility decreases with time). When the clamps are released and the laminant is taken off of the drum, the top and bottom edges are scraped of excess glue and the are trued and sanded. Simple as that!