How To Measure a Garage Door

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Measuring Garage Doors

How To Measure For a Garage Door

When taking the measurements for any replacement or new garage door it is important not only to remember most garage doors require a fixing sub frame of some description, and that has to be taken in to consideration with the measurements, but also manufacturers ordering size references can vary from one to another.

Different garage door types use very different criteria to specify, order and price the overall door. If you are looking for a new garage door, particularly a roller or sectional door then the most basic measurements to take down to begin discussions are:

  • Width and Height of the existing brickwork opening (without the frame and door)
  • Width and Height of existing sub frame if you are leaving it in place (Timber frames only) for the new door to fix to, providing it is wide enough, always check!
  • Internal Headroom (measuring the clear space from underneath the lintel to the ceiling)
  • Internal Return Widths (the widths of the faces showing either side when you stand in your garage looking out)

Make a note of any obvious obstructions in the garage and you can then begin looking for an appropriate garage door with your measurements at hand - most handy if you are speaking to us rather than the favourite phrase we hear - 'It's a standard size garage door'.

How To Measure for Ordering a Door - Below are some basic tips and facts:

Up and Over Garage Doors

Up and Over Garage Door

Up and over garage doors are always ordered by their internal fixing sub frame dimensions in the U.K. - in other words the internal width and height of the sub frame opening which is usually either timber or steel box section. The exceptions are the purpose made doors where both measurements are best if ordering with a fixing sub frame. Tell us the overall width and height required with the frame and the opening size inside the sub frame, this way we know it has been understood.

Measure your existing up and over garage door inbetween the sub frame (open the garage door) and for example you may get a measurement of 7'0" (2134mm) for the width and then 7'0" (2134mm) from the floor to the underside of the frame head. This is then ordered as a 7' x 7' garage door (7070) and the door panel measurement itself is irrelevant as different manufacturers allow different tolerances in the door panel depending on other factors.

If you do measure the actual panel itself it will always be just under the ordering size width and height - for example 2115mm x 2115mm equates to a 7070 door (2134mm x 2134mm) for ordering, it is smaller to allow for the door panel tolerance inside the sub frame and different makes will be slightly different tolerances. (Up and over garage doors are still ordered in imperial measurements even though the imperial size may not be exactly the same measurements of the internal sub frame)

When a garage door is fitted inbetween a brickwork opening the measurements are much more critical than when fitted behind (inside) the garage opening as operating gear and springs will vary from one manufacturer to another meaning you cannot always just replace an old up and over with a new one with new gear as it may require a wider frame than the old one has - general rule of thumb is you will require timber frame legs of at least 60mm wide and a timber head of at least 60mm in depth to allow for the tracks, springs, etc

Important: ALL up and over garage doors require a fixing sub frame for installation and this must be taken into consideration when measuring, ordering and installing.

General rule of thumb: The ordering size is the fixing sub frame daylight opening size (allow for the sub frame in your calculations!) with some exceptions for purpose made doors on certain manufacturers

Up and Over Survey formFind  out more

Sectional Garage Doors

Sectional Garage Door

Most sectional garage doors are installed behind (inside) the garage opening to maximise drivethrough dimensions and most have quite large space requirements for the frame legs and the height required for the curved part of the track the door panels move in. However because a sectional garage door does not go through the opening it is possible to install sizes larger and smaller than your actual opening on the width and height. Very rarely will a standard size sectional door be the exact size when replacing an old door.

Generally most sectional domestic garage doors require 90mm each side for installation and between 100 and 210mm of headroom above the top panel of the door. (Check each manufacturer carefully before committing)

A sectional door will also come into the garage a lot further on the horizontal rails so it is essential you have clear room at least the height of the door plus 350 - 600mm (on average) into the garage. (Oddly, most sectional garage doors are ordered in either imperial or metric measurements but quite often the imperial measurement is not quite the actual size of the door, but a near order reference size)

Important: ALL sectional garage doors are ordered by the internal dimensions of the steel fixing frame opening and all sectional doors have a steel framework for installation and this must be taken into account. A timber sub frame is often used to create a reveal structure if you do not have piers to install behind.Hormann, Garador, Gliderol and Carteck do offer an inbetween fit kit for this purpose as well but make sure you have the potential colour differences taken care of when doing this.

General rule of thumb: The ordering size for sectional doors is always the inbetween daylight frame opening size (allow for the fixing frame and springs in your calculations)

Sectional Door Survey FormFind Out More

Roller Shutter Garage Doors

Generally for a roller garage door you install the tracks and the support brackets for the curtain roll inside the garage opening for maximum achieved sizes and in many cases because the average curtain roll size for a roller door is between 300 and 450mm it needs to go behind the lintel to maintain the best drive through height. Some smaller 'Compact' roller curtain sizes are available by using smaller slats and this can get the roll size down to as small as 205mm

Modern roller shutters do not require a sub frame as the tracks fit directly to the garage structure. Insulated roller doors can fit inbetween a structural opening where as most non insulated steel roller doors must fit behind a structure as the track guides are very different in construction. (Most roller garage door manufacturers now produce roller doors to exact sizes and you only ever tend to see standard sizes shown in special offers)

For the Gliderol steel single skin roller doors the order width is the curtain width and does not include fixing lugs and support brackets and the height is the top of guide height without the curtain roll

Important: Roller shutter doors are ordered by different dimension references depending on different manufacturers. BEWARE, some use the inbetween guide opening size and others the overall size, some also order the width by the roller curtain width as the reference (Gliderol only).

General rule of thumb: The ordering size for the width includes the side channels but the height does not include the door roll (check carefully with each different manufacturer type) - this is with reference to aluminium roller doors.

Roller Door Survey FormFind Out More

Side Hinged Garage Doors

Measurement for side hinged doors for ordering are similar to up and over doors where the sub frame internal opening size is usually the reference, NOT the actual door leaves which have a tolerance built in depending on panel thickness, etc. In many instances, particularly purpose made doors, the overall width and height including the sub frame is used but it varies from one manufacturer to another.

Various factory fitted sub frame options obviously affect the overall width so always check exactly what you have ordered and ask if you are not sure. Our measuring tabs on individual proucts usually show you the details.

Most side hinged garage doors are installed inbetween the structural opening but can be installed in front (with appropriate weather sealing to frame head) of a garage to maximise length, width and height. (Side hinged garage doors in timber are very versatile in out of square garage openings although timber framework is equally versatile enabling steel, GRP, ABS or timber side hinged doors to be installed)

Important: Side hinged garage doors always need a timber or steel sub frame and with a timber sub frame they need 'hanging' correctly, usually by a skilled carpenter or competent person. Steel framed side hinged doors usually come pre assembled so are far easier to install on site.

General rule of thumb: There is no general rule of thumb for side hinged doors as they vary from one manufacturer to another. Please check individual order confirmation details.

Side Hinged Door Survey FormFind Out More

Always check our auto confirmation emails for any purpose made doors to be sure you understand the references required and make sure you respond to the email and the door will not be ordered until you do.

Please do not hesitate to contact us as obviously the sizing of garage doors of any type is the most important factor to ensure your installation is simple and the garage door can be used for its intended purpose.


Call us on 01926 463888


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