A tired lobby interior in downtown Philadelphia needs an update. L2 Partridge Architects is engaged to provide the new look. Front and center in their scheme: a wood feature wall, stretching from floor to ceiling. This is easy to draw, but presents a number of technical challenges. We were brought in to turn that design vision into reality.
The featured photo at the top is a concept created by L2 Partridge
The client loved it. One problem: the wood shown in this image doesn’t really exist – it’s just a generic wood from the rendering program. So our first task was to find real wood species in a similar color range, and to prepare samples of each for the architect to approve. After some back and forth, we settled on white oak.
The wall is quite large: 22 feet wide, 24 feet tall. The design called for planks running horizontally, of uniform width and random length, and no gaps between the individual pieces. Solid wood is not dimensionally stable: it expands and contracts constantly across its width, but not its length. A wall built like this, using solid wood, would vary in height more than 3” over the course of a year.
Without allowance for that movement, the wall could either buckle in the summer or show gaps between the boards in the heating season.
We recommended using a veneer on MDF substrate, as this would eliminate the problem of seasonal expansion and contraction. It would also allow us to fabricate the wall in larger pieces, which would speed installation. We prepared full-sized mockups and met with the architect and client on site to review them.
Everyone thought they looked great. Are we ready to proceed with fabrication? Not quite. A day later, a previously unheard-from decision maker vetoed the idea of using veneer. It would have to be solid wood.
Now we needed to solve the expansion and contraction problem. Here’s how we did it: Under the visible planks, there would be a 1” construction plywood box, which would be a plumb and square foundation for the solid oak planks. These would be 6” wide, milled with a tongue and groove profile, like flooring. Each plank would placed on the wall with tongue up, and nailed through the tongue into the supporting ply. A 1/16” spacer would be placed on the tongue, and the next board placed on top of that, and nailed through the tongue. Repeat from top to bottom, over 48 courses. Each plank would be secured to the building, so that it wouldn’t be supporting the courses above it. And each plank can expand and contract without affecting its neighbor. Since we were fabricating in the winter, we expect the 1/16” gap to shrink in the summer to less than 1/32”, but to never disappear entirely.
This approach was approved. Now for fabrication. The first challenge was to acquire planks that had a nice variation of color and wood grain. You might think that this would be simple, but it actually required ordering white oak in 4 different grades. Every tree, even of similar species, is different from every other. Color, texture, and figure can be drastically different from “normal” depending on the conditions where the tree was growing. Lumber dealers sort all of their wood by color, figure, and the number of knots and defects. Most of the time this is helpful: each board in a particular grade looks a lot like its peers. But when you want a lot of variation, then it’s important to understand the grading standards. We ended up spreading our order across 4 grades of white oak: Plain sawn, rift sawn, quartered with figure, and #2 common.
The next step was to produce a plan showing the length of every single board in the wall, irrespective of grain. With that in hand, we started sorting through the 4 piles of wood and assigning each board to a location on the wall. Then we cut them to length and laid them out on the floor to take a look. We sent pictures of our first sort to the architect and client (the wood has been swabbed with water to show its finished color, and photoshopped to show the the proper shape of the wall):
Feedback came quickly: not so many knots.
So we took out some boards, added others, and sent these out again:
Success! Next step was to cut all of the boards to final size. Every piece of wood in the wall was sanded to be flush to its neighbors, and numbered so that our approved scheme could be replicated on site. We then fabricated all of the mitered corners, reinforcing them with splines, and slightly rounding the corners so that pedestrians can’t catch their clothes on a sharp edge. Next we applied a catalyzed polyurethane to both sides of each board. Finally, all of the material was sorted into stacks, in order, so that the installers would be able to put it up without rummaging through a huge pile in search of the right board – or, alternatively, installers being what they are, putting them all up in the wrong place. Attention to detail paid off: the wall was installed in 3 working day.
And the results? Magnificent, just like the original design:
Lessons learned? A solid wall is a lot more complex than just putting a floor on a vertical surface. It’s critical to understand wood movement, wood grading, proper fabrication, and how careful packing and labelling makes for easy installation. Are you working on a feature wall? Contact us for help.