Clopay and Wayne Dalton installation manuals, compared figure by figure
A garage door's rough opening is simply the door size. What decides whether it fits is the space inside: headroom above the opening, sideroom beside it and backroom behind it. Clopay and Wayne Dalton publish all three and disagree on each, by half an inch of headroom, up to an inch of sideroom and four inches of backroom. Wayne Dalton's current manual also prints one backroom figure whose inches and millimetres do not match.
The space a sectional garage door needs inside the garage
ft
ft
in
no.
Spring type and track radius are on the door's paperwork or can be seen on an existing door: torsion springs run along a bar above the opening, extension springs run alongside the horizontal tracks. Clopay measures radius as the curve of the track between vertical and horizontal.
Specification summary
Generated from on .
Reopen that address to reproduce these figures exactly.
The size table is printed without a sentence saying whether it includes installation. The same guide says most installers include a labour fee of $200 to $500 in the total estimate, and gives an overall replacement range of $754 to $1,707. Its headline still reads 2025 although the page is dated June 2026. Treat the size rows as a wide bracket, not a price.
The opener unit alone reaches $900 in the source, above the $540 top of its own installed range.
Worked example
A 16 by 7 foot two-car door with torsion springs on 12 inch radius track and an automatic opener. Then the same door 7'2" high without an opener.
Rough opening. The same as the door: 16 ft by 7 ft.
Headroom. Clopay 12 in plus about 3 for the opener, 15. Wayne Dalton 12 1/2 plus 2 1/2, also 15 in.
Backroom. Clopay height plus 18, 102 in, and more for the opener. Wayne Dalton's table for a motor operated 7 ft door: 125 in.
Sideroom. Clopay 3 3/4 in, Wayne Dalton 3 1/2: plan for 3 3/4 in each side.
Ceiling. 84 in of door plus 15 in of headroom: 8'3" clear over the door.
The same door at 7'2", no opener. Wayne Dalton's standard lift backroom table has no row for it; Clopay gives 104 in.
The two manuals land on the same headroom with an opener by different routes, a half inch apart on the track and a half inch apart on the opener. Without the opener they are half an inch apart, and on backroom they are not close at all.
The formula
Three spaces, each from the manufacturer, and the ceiling follows from them:
rough opening = door size backroom (Clopay) = door height + 18 in clear ceiling = door height + headroom
headroom
above the top of the opening, for the door, track and springs; more with an opener
sideroom
beside the opening on the inside wall, for the vertical track and spring brackets
backroom
from the door back into the garage, for the door fully open; more with an opener
track radius
the curve joining vertical and horizontal track, 12 or 15 in on most residential doors
low headroom
kits that cut headroom to 4 1/2 to 9 1/2 in on Clopay's table, depending on spring type
The clear ceiling figure is to the lowest thing over the door's path: a beam, a duct, a light or the opener rail, not the ceiling itself.
Why this page reads two manuals
Garage door sizing pages list standard door sizes and stop. The question a garage actually poses is whether there is room inside, and that is set by the door maker, not by the door size.
Clopay and Wayne Dalton both publish headroom, sideroom and backroom. Read side by side they differ on every figure, so the calculator shows both and plans to the larger.
Checking Wayne Dalton's metric column against its inches found one row that does not convert, whose millimetres match a different table, and a gap in its standard lift backroom table. The site publishes no price of its own.
Space inside the garage, Clopay against Wayne Dalton
Requirement
Clopay
Wayne Dalton
Difference
Headroom, torsion, 12 in radius track
12 in
12 1/2 in
1/2 in
Headroom, torsion, 15 in radius track
14 in
14 1/2 in
1/2 in
Extra headroom for an opener
about 3 in
2 1/2 in
1/2 in
Sideroom
3 3/4 in for track, 4 1/2 in above the opening for springs
3 1/2 in
1/4 to 1 in
Backroom, 7'0" door, lifted by hand
102 in (height plus 18)
98 in
4 in
Backroom, 7'0" door, with an opener
more, per the opener's instructions
125 in
not stated by Clopay
Read 2026-09-13. Clopay manual MOD 0137320-R08-1119 and Wayne Dalton REV12_01/12/2024, as printed.
The opening is the door. The room behind it is where makers differ
A garage door has no rough opening allowance. Clopay's instructions put it in one line:
Rough opening (minus stop mold) = same size as door
The door covers the opening from inside and the stop moulding seals the edge. What decides whether a door fits is the space inside the garage: headroom above the opening, sideroom either side of it, and backroom behind it for the door when it is fully open.
Clopay and Wayne Dalton both publish all three, and they disagree on every one.
Space required inside the garage, as printed by each manufacturer. Difference is this page subtracting
Requirement
Clopay
Wayne Dalton
Difference
Headroom, torsion, 12 in radius track
12 in
12 1/2 in
1/2 in
Headroom, torsion, 15 in radius track
14 in
14 1/2 in
1/2 in
Extra headroom for an opener
about 3 in
2 1/2 in
1/2 in
Sideroom
3 3/4 in for track, 4 1/2 in above the opening for springs
3 1/2 in
1/4 to 1 in
Backroom, 7'0" door, lifted by hand
102 in (height plus 18)
98 in
4 in
Backroom, 7'0" door, with an opener
more, per the opener's instructions
125 in
not stated by Clopay
The gaps are small and they are the wrong size to ignore. A garage with a beam, a duct or a light over the door is usually short by inches, not feet, and half an inch of headroom decides between standard track and a low headroom kit. Plan to the larger of the two, and to the manual that ships with your door.
A manual that disagrees with its own metric column
Wayne Dalton's 2024 manual for its 8300 and 8500 doors prints backroom requirements in inches with millimetres alongside. Every figure converts correctly except one.
The low headroom table gives the 7'1" to 8'0" row as 114 in (2794 mm). 114 inches is 2,896 mm. 2794 mm is 110 inches, which is the figure in the standard lift table directly above it. The same row in the 2017 edition of the low headroom manual read 115 1/2 in (2934 mm), and those two agree with each other.
So the current manual gives three candidate answers for one row: 114 in from its inch column, 110 in from its metric column, and 115 1/2 in from its own previous edition. The largest is the safe one to plan for.
The standard lift table has a gap as well. It runs 6'0" to 7'0" and then 7'3" to 8'0", where the low headroom table beside it starts its second row at 7'1". A 7'1" or 7'2" door on standard lift track has no row. The calculator says so rather than guessing.
Standard garage door sizes, and what the size means
Garage doors are sold by the opening they close, width by height. HomeAdvisor's price guide groups them as one-car doors 8 to 10 ft wide, two-car doors 16 to 20 ft wide and three-car doors 24 to 30 ft wide, all 7 to 8 ft high.
Frame the opening to the door size. Clopay's instructions call for the inside of the opening to be framed with 2 by 6 lumber, jambs plumb and header level, with the stop moulding nailed to the edges of the jambs. Wayne Dalton's manual asks for the same 2 by 6 framing and for the jambs to extend at least 12 in above the opening for torsion springs.
Two doors side by side need a post between them. Clopay's framing figure shows an 8 in minimum center post.
When the headroom is not there
Both manufacturers sell low headroom track, and Clopay's table shows how far each option cuts the requirement: to 4 1/2 in for extension springs on low headroom track, to 8 in with its quick turn bracket on 12 in radius track, and to 9 1/2 or 4 1/2 in for torsion springs mounted front or rear. Wayne Dalton's 6 in front mount low headroom track needs 8 1/2 in.
Clopay marks two of those options as professional installation only. Torsion springs store a great deal of energy, and both manuals carry repeated warnings about adjusting them. Measuring for a door is a homeowner's job; winding its springs is not.
The sources
Read 2026-09-13.
Installation Instructions, Residential Sectional Insulated Steel Doors, Clopay Corporation, MOD 0137320-R08-1119, (c) 2020, a copy of the manufacturer's manual hosted by InspectAPedia because Clopay's own document server refuses automated requests. Step 3: rough opening equal to door size, backroom of door height plus 18 in, sideroom of 3 3/4 and 4 1/2 in, Table 3-A standard headroom by spring type and track radius, Table 3-B low headroom options.
Residential Standard Lift and Front Mount Low Headroom Inside Hookup, Models 8300/8500, Wayne Dalton, a division of Overhead Door Corporation, REV12_01/12/2024, part number 350144, hosted on the manufacturer's own document store. Headroom by track radius, 2 1/2 in extra for a motor, 3 1/2 in side clearance, backroom tables for standard lift and low headroom.
No building code sets garage door headroom or backroom. They are installation requirements of a particular door, track and spring system, and the manual that ships with your door governs. Amarr's installation documents were also sought and refused this site's requests.
Frequently asked questions
How much headroom does a garage door need?
It depends on the spring and track. Clopay's table gives 10 in for extension springs on 12 in radius track, 12 in on 15 in track, 12 in for torsion springs on 12 in track and 14 in on 15 in track. Wayne Dalton's torsion door manual gives 12 1/2 and 14 1/2 in. Add about 3 in for an opener on Clopay's figure, 2 1/2 in on Wayne Dalton's.
How much backroom does a garage door need?
Clopay says at least the door height plus 18 in, so 102 in for a 7 ft door, and more with an opener. Wayne Dalton's table gives 98 in for a 7 ft door lifted by hand and 125 in with a motor.
What is the rough opening for a garage door?
The same as the door size. Clopay's instructions state that the rough opening, less the stop moulding, equals the door size, so a 16 by 7 door goes in a 16 by 7 opening.
How much side room does a garage door need?
Clopay asks for 3 3/4 in on each side for the vertical track and 4 1/2 in on each side above the opening for torsion springs. Wayne Dalton's manual gives a minimum side clearance of 3 1/2 in.
What ceiling height do I need for a 7 foot garage door?
The door height plus its headroom, measured to the lowest obstruction over the door. With torsion springs on 12 in track and an opener that is about 99 in, or 8 ft 3 in, on both manufacturers' figures.
Is the Wayne Dalton backroom table wrong?
One row does not convert. The 2024 manual's low headroom table prints the 7'1" to 8'0" row as 114 in and 2794 mm. 2794 mm is 110 in, the standard lift figure above it, and the 2017 edition gave 115 1/2 in for that row. Plan for the largest of the three.
How much does a new garage door cost?
HomeAdvisor's guide, updated June 2026, gives $500 to $3,000 for a one-car door, $800 to $5,000 for two-car and $1,400 to $7,200 for three-car, with an opener adding $200 to $1,300. It does not say whether the size table includes installation.
Can I install a garage door myself?
Both manufacturers publish homeowner installation manuals, and both warn repeatedly about spring tension. Clopay marks some low headroom torsion options as professional installation only.
How every figure here is verified: Sources & Method. Who builds this: About. Found something wrong? Tell us and it gets fixed or removed.
Figures on this page last checked against the source documents on 2026-09-13. Codes are amended locally; confirm against the edition your jurisdiction enforces.
Space requirements are quoted from two manufacturers' installation manuals, read on 13 September 2026. The manual that ships with your door governs, and figures change with model, track, spring and opener. Torsion springs are under high tension; follow the manufacturer's warnings. Prices are HomeAdvisor's, not this site's.