Your measurements
Your results
Side view, drawn to your measurements. Orange marks the extension piece. Not to scale for ordering purposes.
These results are estimates calculated from the numbers you entered. Ceiling heights are rarely level, openings are rarely square, and bulkheads and beams change what is possible. Confirm every dimension on site before ordering.
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We do high lift conversions across London and the surrounding area. Send us your numbers and we will come back with a real price on the parts and the labour. No deposit, no pressure.
What high lift actually is
Standard lift, high lift and full vertical lift
A standard lift door runs straight up a vertical track, curves at roughly the top of the door opening, and then travels back along the ceiling on a horizontal track. High lift raises where that curve happens. A straight piece of track, called an extension, gets added between the top of the vertical track and the curve, so the door runs further straight up before it turns and heads back. The torsion shaft, springs and drums move up to match the new curve height, and because the cable now has to wind further to lift the door, you need drums with a bigger cable capacity too.
People convert to high lift so the open door sits higher and further out of the way. That clears space for a car lift, a truck, a storage rack, or a mezzanine, and it lets the door tuck up under a high ceiling instead of hanging low across the middle of the garage. It is a different job from a standard tune-up: a longer shaft, high lift drums, longer cables, extension track, and usually a spring recalculation, since the drum diameter changing affects how the springs need to be wound. It is a parts-and-labour conversion, not an adjustment.
What you gain and what it costs
The gain is headroom in the open position. What it costs is a longer torsion shaft, high lift drums rated to your new lift number, longer cables, one or two extension pieces, and in most cases a spring recalculation to keep the door balanced. None of that is unusual or a sign something has gone wrong; it is simply what a high lift conversion involves.
How this calculator does the math
Track height
Track height off the floor is your ceiling height minus your headroom allowance, or in bulkhead mode, your bulkhead height minus your bulkhead clearance.
High lift
High lift is how much higher your track sits than your door is tall, which is the whole point of the conversion.
Extension piece length
The curve starts at your track height minus the actual height of the curved section, and the extension is the gap between where your vertical track ends and where that curve begins.
Worked example: ceiling 144, door 96, 10 inches of headroom allowance, 15 inch radius. Track height is 144 minus 10, which is 134. High lift is 134 minus 96, which is 38. A 15 inch radius track is actually 17 inches tall, so the curve starts at 134 minus 17, which is 117. With a standard 88 inch vertical track (door height minus 8), the extension is 117 minus 88, which is 29 inches.
There is a shortcut for the common case where the vertical track is exactly door height minus 8, shown on the results whenever that holds:
Drum size
Required drum capacity is your high lift number rounded up to the next standard drum size, which is the minimum a supplier needs to know to sell you the right drum.
Cable length
Estimated cable length is your track height off the floor plus your shaft offset, plus a constant specific to the drum, minus your high lift.
Working around a bulkhead or a beam
Bulkhead mode measures from the underside of the bulkhead instead of the ceiling, using the same 3 inch clearance convention as a starting point. Two things still have to be true on site. The torsion shaft, springs, drums and bearing plates need a full height zone against the door wall, so the bulkhead has to start far enough back from the opening to leave that zone clear. And the radius curve has to finish before the bulkhead begins, otherwise the horizontal track cannot run level underneath it. Confirm both with a tape measure before ordering.