Sunday, April 8, 2012

Elevator in a Passive House

Here is our main floor layout:
Why would anyone install an elevator shaft in their house?  Can't people just climb the stairs? - its better for them.  We completely agree.  And if you'v ever used a residential elevator, you'll find it much slower than the stair.
However, there are some compelling reasons to consider the elevator shaft - note the key word - shaft.  We are not installing an elevator - but we are installing the shaft, which turns out to be quite cheap, even with us doing it the expensive way (more on that below).  Here is our thinking:
  1. We've seen seniors close to us living with their grown children.  It is really hard for them to go up and down the stairs.  We want a house which is inviting to our parents.  We've placed a bedroom and full bath on the main floor - but there are still stairs to climb to get to the first floor from the outside.  The elevator facilitates at-grade entry into the building.  It also allows the grandparents to easily visit their grandchildren asleep in their beds upstairs, or to join the family in the den for a movie, etc.
  2. Sometimes a family member is in a wheelchair.  The elevator embraces this.  Not to mention, any one of us can become a wheelchair user overnight. A house ready for an elevator is one less problem during a traumatic life-changing event.
  3. The elevator can make moving heavy or large objects much simpler - like pianos.
  4. Space lost to the elevator is not lost unless the elevator is installed.  The empty shaft (with floors installed on each level) can serve as pantry, powder room (with plumbing), closet, rock-climbing wall (no floors), etc.  We plan to use the shaft in these ways, until an elevator is actually installed.
Intended for economical installation, the shafts for residential elevators are intended to be built using regular framing lumber, with studs spaced extra-close and thicker plywood sheathing, or the use of 2x12's on the flat, flanked by studs within the wall framing.  Exact details are per the elevator manufacturer.  What is not explicitly laid out is that these walls are intended to be of standard height, framed between floors.  The idea is to place the elevator shaft in an area where there is a floor all around it, on all levels.  This did not happen in our design.  As our goal was to make the building accessible from the outside, we needed the shaft to be located near an exterior wall, and we ended up placing the shaft inside a wrap-around stair (the stair is placed on the north corner of the building - see plan).  Thus, a person entering the building from the north door arrives on the stair landing, from which he can enter the elevator.

The shaft walls needed to be about 28' tall.  This height is an added expense to frame, and if executed in wood, would take up a lot more space (tall wood walls tend to use deep studs too).  We therefore made a steel frame - cost of the steel - about $6000 incl delivery.  Concrete pad - $1000 labour and materials.  Crane - $600 minimum charge).
In addition the walls around the stair became very tall - from the footings to the ceiling of the 2nd floor.  28' long 1.75" x 9.5" LVL's (engineered lumber) were brought in to handle this, 12" OC, with double king studs.  The LVL's were about $4.90/ft - as costly as steel! 

Here is a video of the shaft going into the building on March 20, 2012.

...and some images;
The steel shaft arrives right on time from Ontario Steel with all the necessary certifications in a folder.  Our guys get on the truck and measure everything before we offload.  We are very pleased with their work.  Straight and square, and with good welds.  The piece is all 3.5"x3.5"x1/4" thick structural steel tube, and the finished weight is only about 2500 lb.

The crane operator removes the shaft from the truck.  We re-rig it on the driveway and then stand it up and into position.
The shaft in its home.

Look closely to see the 1/16" HDPE plastic gasket under the 1/2" steel plate foot.  Holes in the plates are 5/8".  Steel shims prepared ahead are ready for use.  Standard 1/2" x 8" HD galvanised  anchors are holding the frame to the 30MPa concrete pad with 10M reinforcement at 12"OC both directions.  The pad is about 10" thick - over strong, really.  The bottom of the shaft was prepainted with a finish coat of enamel.  The upper parts were only primed as we intend to weld to it.

You can see the 3" thick high-strength (60psi) rigid XPS foam insulation under the pad.  This material was about $70 for a 2'x8' sheet.

The bolt positioning jig is simply 3/4" plywood raised 1.5" from the concrete. You need to work the bolts well so there are no depressions in the finished concrete around the bolts.

Originally designed to be inside the elevator pit, the sump pit was installed to the side due to concerns about a clause in the elevator code requiring the the pit to stay dry.  We have both exterior and interior weeping tiles, and a very deep and large sump pit to accommodate 2 pumps.  

So how does Passive House deal with the elevator shaft? - I've had no official answer on this question, but assume it will be treated the same as a stair case - Total Floor Area of the elevator and shaft is not counted.  However, since we are installing only the shaft, we are expecting to have the area on three levels included in our PHPP.
I've also yet to ascertain the energy requirements of the elevator over the course of a year.  Again, we will be avoiding this issue (w.r.t. to PH certification) by not installing the elevator.


  1. I think that installing the elevator shaft is a smart idea. You touched on the possible problems with mobility that you may have when you get older (my poor father was unable to go into his basement after he fell as senior citizen making it impossible for him to access the family room, fuse box, laundry, and heating/AC systems). Another reason, heaven forbid, is the possibility that someone in your family becomes handicapped. My sister, a woman in her early 40s lost her leg in an accident recently, and had to move from the home she loved. Your idea of the elevator shaft seems to be a SMART bit of insurance that your family can stay in the home you are no matter what.

    What a great, interesting blog. Take care, and the very best of luck to you.

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