Access

Tiny Tuesday: Wheel Pad Makes Your House Accessible

/ Scott / Leave a comment

By and large, the world is challenging for wheelchairs. In public settings in the US, new construction and renovations must conform to the Americans with Disabilities Act (ADA), which specifies ramps, elevators, and 5-foot turning diameters to make the buildings accessible to everyone. But private homes aren’t bound by the same standards. That means many people faced with mobility impairments come home to entry stairs, tight bathrooms, and other hazards that may cost a fortune to retrofit.

Enter the Wheel Pad. Designed as a temporary extension of an existing house, the Wheel Pad has a bedroom and bathroom with ADA-standard clearances, a Hoyer lift track built into the ceiling, an entry ramp, and a door to connect the unit to an adjacent house. All this comes in an ultramodern 200-square-foot package on wheels. It’s a novel use of the tiny house concept, and in hindsight a pretty obvious one. Why did it take so long for someone to market this?

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Inside the prototype Wheel Pad. Note the Hoyer lift track built into the ceiling.

That “someone” is a group of architecture students and professors at Norwich University. The prototype Wheel Pad went to a southern Vermont woman who recently became paralyzed from the chest down, and future units will be sold for $60,000 or leased for $3000/month. Since a unit is highway legal, it qualifies as an RV for zoning purposes. A septic tank is built in; water and electrical supply come from the existing house.

Physical access to the existing house is unclear, although the Wheel Pad website says illustrations are available for buyers. Can the entire unit be lifted higher or lower to match an existing door, or must a driveway be built to the correct height? (Settlement could make the latter pretty untenable for long-term accommodation.)

Nothing But the Roof

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A Yestermorrow semester program built an apartment property for Jas. In a win-win arrangement, Yestermorrow students gained real-life skills in design and carpentry, while Jas got free labor. Unfortunately, the class ended this week and the students left the house incomplete. Jas hopes to at least get a cover on the roof before winter sets in.

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The 400-square-foot apartment one week before end of semester.

So I found a free afternoon to get started. As soon as the Yestermorrow class finished installing roof rafters, I joined Allen to begin sheathing the north side. The tasks were familiar: start in a bottom corner, use tongue-and-groove Advantech with the tongue pointed downhill, install sheets so they break in the middle of a rafter. We snapped a chalk line across the rafters to align the top edge of the first 48-inch-wide sheet, wanting a bottom overhang of 1.5 inches. Then we cut the first sheet of Advantech with a circular saw to trim the length for a ¾-inch outside overhang. Once the first one is in place, the rest follow smoothly.

Several characteristics of this project were unique. The rafters are 16 inches on center, which leaves too narrow a space to pass a 96-inch-long sheet out without endangering someone’s safety. Therefore we raised the Advantech from below, with Allen and I sliding each sheet up a pair of ladders before ascending ourselves. The other concern was the location of the rafters in space – alignment is always a concern when you inherit a project from somebody else. The sheathing must stay in one plane so the finished roof doesn’t look wavy, and it should bear on every rafter for structural reasons. I used a long skinny half-inch-thick piece of Advantech to shim out one rafter that sat a half-inch low, sliding and squeezing it between the lumber and the sheathing.

Allen and I lift the sheathing…
…and align it on the rafters.

Jas and Allen soon completed the north side of the roof with Advantech, and then I helped sheath the south side using salvaged T-1-11 siding from the shed removal. It’s a race against the clock to get the sheathing installed and covered with Ice & Water Shield before the weather gets too cold and snowy to work safely. (People do it, but I’m no fan of outdoor construction in the winter.)

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Jas installs a safety harness system to finish the south side with T-1-11 sheathing.

Hoist With His Own Petard

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Chris owns a construction equipment company in Massachusetts. He supplies hoists – temporary elevators – for multistory buildings under construction. If you see a residential or office development going up in Boston, odds are about 1 in 3 that Chris’s company is involved.

Chris needs a structural engineer to design each hoist, and he hired me. All the hoists in his inventory come from the same manufacturer, Alimak-Hek. The mast comes in 5-foot sections and can grow up to 500 feet. (An installation guide gives some ideas for how to build an even taller tower, like connecting three masts together in a triangle shape.) The cab rides along the mast via a rack and pinion system; pulleys and counterweight are built in. The first sections of mast typically get installed when the building is five or six stories tall – that is, tall enough to make stairs and ladders inconvenient. As the building grows, the hoist can grow with it.

When I take on a hoist project, I first consider the weight of the assembly – fixed loads like the mast, base enclosure, and motorpack, and moving loads like the elevator cab and its capacity. I might design a concrete slab for the base to spread and support this vertical load. Next I look at wind, which varies with geographic location, surrounding topography, and height above ground. Wind blows on the elevator cab and the mast itself. Since the operators don’t run the cab above a certain wind speed, I must check two load cases: a “moderate” wind speed in service (mast and cab), and a “high” wind speed out of service (mast only).

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Chris operates a hoist cab.

The wind load dictates how far apart I place tiebacks to the building walls. Attachment points transfer the wind load to the building; typically they’re two or three stories apart. The connection details are largely up to me, and may be quite complex depending on what the building offers for fastening.

A typical tieback.
A more complex attachment.