Siding: Steel and Wood

As I stated in an earlier post, maybe the first, one of the drivers for the design is to end up with a house that doesn’t require the standard maintenance of most houses. No painting, no cleaning gutters, I guess we will clean windows from time to time, but since they all open in that ought to be easy.

Obviously the siding plays a key role in achieving zero maintenance. For this to work the exterior cladding has to cover and protect the house and be a material that can stay outside for a long time without deterioration. A long time meaning fifty years or more. That is a lot to ask of a building material. Early on we decided against brick, stone, or concrete, three things that can support and protect buildings for hundreds of years, pretty much leaving us with metal or durable wood for the exterior. We chose both. Sheets of a weathering steel alloy for the bottom 8 feet, and durable wood, in our case white oak, for the rest of the wall surface.

The first steel panel going on the house

Steel

With the windows and doors fully installed and weatherproofed our next step was to fabricate and install metal trim pieces to provide a transition between the flat metal panels and the exterior surface of the window frames. After that we installed a drip flashing at the base of the wall to provide a clean termination at the bottom of the metal panels. The metal panels are screwed directly to the battens with #10 pan head screws. We installed the panels with an 1/8″ gap on all sides and at corners to provide more flexibility and since the steel is pretty thin (22 gauge) we tried to stretch the panels to provide tension in the interest of keeping them flat across the spaces between the battens. This was generally slow and hot work, we started using an abrasive blade on a circular saw to cut the panels, but moved to electric shears by the end. The shears produced a cut nearly as straight without the sparks and noise of the abrasive blade.

the steel trim pieces installed on the bay window

using the abrasive blade to cut the steel siding panels

Everyone who touched one of those panels would have preferred to have been doing it in some other month than July. The material sitting in the sun would heat up to the point you couldn’t handle it without gloves and the sweat marks from forearms pressed against the sheets when they were installed rusted quickly to a deep purple. But as hot as the metal got it wasn’t anything like burning the wood siding in mid-summer under the relentless sun we had this July.

steel panels completed across the rear of the house and working up the bay

And Wood

The treatment of the wood for the siding is something I haven’t ever done and I was still a little unsure of. I am not going to say skeptical because it made sense to me, charcoal is a very durable material, and the wood we planned on charring is a naturally weather and rot resistant wood , white oak. Still the extent of my knowledge of the process was pretty much limited to online video; that should give anyone pause. I bought a weed burning torch, got three 20 lb propane tanks filled and layed some concrete block on a barren patch of dirt and started burning wood. When we started it was hot even for July, highs approaching 100, and the spot available for the burning was on the western side of the house, prompting comments about what the heat would be like using the torch with the afternoon sun overhead. I ended up doing most of the burning and I have learned that the torch is so intensely hot that I honestly forgot about the afternoon sun, so hot that the guys installing the siding 10 feet above me could feel the heat where they were working when the wind took it their way, so hot that when the wind shifted it would singe the hair on my lower legs.

Receiving the wood from Water’s Edge woods in Comer, GA

A little more than half the stack

burning the oak siding

My goal was an even and complete blackness, but without much alligator skin from coals forming on the surface of the wood. This was relatively easy to accomplish; if we had wanted a lesser and consistent amount of charring it would have been hard to get at the rate I was burning the wood. Completely burned is pretty easy with the amount of gas coming out of the torch, half-burned would be hard to control.

To move systematically through our large pile of white oak, I would put three pieces of wood on the concrete blocks about three inches apart. Burning the center piece from directly overhead with an aggressive flame would char the top of the center board and the adjacent edge of the outside boards. A pass down each side board at an angle would char the top and remaining edges; it wasn’t perfect but pretty efficient with a little touch up here and there we got three charred sides on each board. Before starting I figured I could burn 3 boards in 3 minutes, the actual rate was more like three boards in 10 minutes; in the end we used 180 pounds of propane. I have done a careful analysis of the time differential to a more traditional method for weather protection, say stain or paint, but my gut says this wasn’t much different, and if it doesn’t need additional maintenance in the future, the life cycle costs will be much less. You have to like a black house though.

We have been lucky recently here in Athens that a nearby specialty wood supplier has started to buy local logs, saw, dry and mill them and offer hardwood flooring and dimensional hardwood lumber that are locally sourced. Much of this comes from residential trees that tend to be knotty. I have used the white oak flooring in projects for clients in the past and got the same company to provide the oak for our siding. The knots are generally cut out for the flooring and for our siding, since it was all burned, didn’t matter much. An unexpected happiness: the charring of the surface transformed the grain in the wood to a contrasting iridescence in tones of black, the plain sawn boards with the typical wood grain pattern and the quartersawn pieces with the rays still visible wriggling across the surface.

The wood grain still visible on the surface of the charred white oak

To add visual interest and texture I decided to use two different width siding boards, a 1×6 and a 1×3. We installed in a pattern of two 1×3’s topped by one 1×6. All the boards are screwed to the battens with exterior trim screws. Even though we rinsed the boards with a hose after the charring process, the charcoal would readily rub off when touched. At the end of the day the guys installing the siding would look like they had climbed out of a coal mine.

The first wood to go up

The oak run to the top of the bay

working on the north side

A close up of the wood and steel juncture

For most of the house the charred siding is out of reach so there isn’t any danger of smudging against the charcoal, on the front porch, though, the wood is the main wall surface and to avoid rubbing up against charcoal I had planned on staining the porch siding black instead of burning it, but after putting the wood on the wall it seemed too beautiful to cover, so within the screened porch we are now going to give it some minimal finish to provide a little protection from the elements but keep the natural wood.

A view of the uncharred siding on the front porch