How To Measure a Garage Door

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Measuring Garage Doors

Measuring Garage Doors

When taking the measurements for any garage door, whether it is a replacement or brand new, there are various things to keep in mind. It is important to remember that garage doors require a fixing sub frame of some description, which has to be taken in to consideration with the measurements, as well as the fact that manufacturer's 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 first most basic measurements to note down are:

  • Width and Height of the existing brickwork (structural) opening (excluding the existing 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'.

If you have any questions about how to measure your garage door, give us a call on 01926 463 888.

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How To Measure for Ordering a Garage Door

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 UK - 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 brickwork, opening 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. Therefore, 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 - a 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 sizes are the outer sub frame daylight opening sizes (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 drive-through dimensions and maximise insulation. Sectional doors have quite large space requirements for the frame legs and the height required for the curved part of the track that 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 (Ordering height) (Check each manufacturer carefully before committing).

A sectional door will also come into the garage a lot further on the horizontal tracking rails, so it is essential you have clear room of 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. When millimetres matter please double check on these exact dimensions

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, Seceuroglide and Carteck do offer an inbetween fit kit for this purpose.

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

Sectional Door Survey FormFind Out More

Roller Shutter Garage Doors

Roller shutter garage doorsGenerally for a roller garage door, you will install the guides and the support brackets for the curtain roll inside the garage opening, in order for maximum sizes to be achieved; 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 which can get the roll size down to as small as 205mm.

Roller shutters do not require a sub frame as the tracks (guides) fit directly to the garage structure. Insulated roller doors can fit inbetween a structural opening, whereas 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). Check with the specific brand you intend to purchase and dont assume they are the same as another.

General rule of thumb: The ordering size for the width includes the side channels but the height does not include the curtain roll (check carefully with each different manufacturer type).

Roller Door Survey FormFind Out More

Side Hinged Garage Doors

Side hinged garage doors

When ordering and measuring for side hinged doors, the process can be quite similar to that of up and over doors where the sub frame internal opening size is usually the reference. The actual door leaves are not the reference used; they normally 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 products 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 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. The UK market is fast moving towards the double skinned hinged doors which all come with their own sub frame prefitted.

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 e-mails for any purpose made doors to be sure you understand the references required. Please ensure that you respond to the e-mail; the door will not be ordered until you do.

Please do not hesitate to contact us as 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.


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