The next stage of the project is to build the staircase that will lead up to our new 2nd floor (the loft). The loft was framed out over a two periods:
just before we started the roof and
just before we moved in; it sits over the bedroom, bathroom and kitchen.
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| Cut-away view from digital 3D model (used during design phase) showing how the new staircase leads up-to 2nd floor loft |
Developed during our
design phase back in the summer of 2010 (!), the staircase will consist of 3 parts:
- The first flight of stairs starts at the edge of the bedroom door (where the floor was extended) and runs up to a landing . This will be an "open riser" stair, meaning the vertical elements of the stair (known as risers) are gone. Because the stair sits over the entrance to our terrace (with glass doors), we did not want to block the light, so not having a risers will allow light to pass through the staircase.
- The second part is the landing, which is bolted into the exterior brick wall (just above the door to the terrace).
- The final part is the 2nd flight of stairs, which is turned 90 degrees and starts at the edge of the landing and goes up to the loft. Because everything is so tight, this second flight will pass through the bedroom after passing through the structural wall opening that was framed out yesterday.
While the design intent was established long ago, I only developed the actual detailed design of how it will be built over the last few weeks. These drawings were initially done by hand - once they were finished, I submitted them to Building Control (the London version of NYC's Building Department). After a few minor revisions, Building Control approved the design for structural integrity and deemed it compliance with the
UK Building Regulations (similar to NYC's "Building Code").
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| 3D hand sketch showing the structural elements of the staircase |
This approved design details how the landing becomes a structural element that will be bolted into the brick wall on one side and fastened to the structural stud wall on the other. Because the first flight of the stair has no risers, each tread (the horizontal "step") is notched into a large 2"x8" structural stringer (the diagonal element) on each side. This will make the flight incredibly strong while still allowing light to pass through. This flight is then attached to the landing using heavy screws and steel plates.
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| Section sketch showing the primary stringer and steel plate that assists in the connection to the landing. |
One of the design ideas that made the stair more difficult to build was the idea of keeping the 1st flight a few inches away from the wall. The idea is to allow light to pass through this gap - both from the terrace door, but also from a light cove that will eventually built above (in the ceiling at the edge of the 2nd floor) - allowing the light to pass through should not only provide additional lighting for the stair, but should also create a great looking effect as the light washes down the wall.
From a structural perspective this mean that this 1st flight could only be held at the top and bottom, not also on the sides, as with most stairs. Because the landing is itself partially cantilevered, this meant that only through the combination of both landing and stair would the entire assembly actually be strong enough. This was achieved by allowing the primary stringer to be attached to the side of the landing using an additional piece of 2"x8" wood (creating a heavy angled "L" shape) that's stiffened by a heavy steel plate at the joint. This angled "L" shape will act almost like a column to hold the hanging end of the landing - this can best be seen in the section sketch (above) and plan sketch (below).
While everything looks good on paper, we'll soon see how it well it works in reality...
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| Plan view of landing and how 1st flight of stairs is fastened to it. |
