The Jobsite Vs The Prefab Process
Building a safe and long lasting staircase requires time and attention to detail. Our approach to notched stringers prevents premature failure by eliminating over-cuts (common when using circular saws). Our shop is equipped with a specifically designed machine that can cut multiple stringers at the same time, allowing precise fit during assembly.
An often overlooked step in stair construction on the jobsite is ripping the treads and risers to the appropriate sizes instead of just using what is provided. Nosing of the tread should also never exceed 1 1/4" to prevent tripping. We intend our risers to help spread the load placed on the treads by attaching them flush to the bottom of the tread. In this way we can apply adhesive on top of the riser (1) and later staple across the top of the tread (2). A bead of adhesive is also applied to the back of the tread where it meets the next riser and here it is also stapled from underneath (3). By using ring-shank nails and 2" staples for fastening the treads, risers and stringers to each other, the staircase acts as a cohesive structure with no structurally compromising gaps (4) or possibility of squeaking.
Here is an example of a poorly constructed staircase with noticeable gap between tread and riser.
Besides not meeting min tread depth (R3184.108.40.206) and max nosing (R3220.127.116.11) requirements specified by the International Residential Code, its pretty apparent the potential problems this home owner will have in the future.