Tuesday 24 July 2018

Top 5 Things to Consider When Measuring a Garage Door Opening

Specifying a new garage door isn’t as easy as you might first think, so it’s important to measure up correctly so you can get the right size garage door to fit into your garage door opening. If you’re not sure, have a chat to one of Garador’s installers and arrange for a site survey and quotation, you can find them by visiting the stockist and installer page on Garador’s website.

It might sound pretty obvious but it’s always a good idea to measure the opening and inspect the garage before making a decision on what type of door you are going to fit, as some door types simply might not fit inside the opening or may not be possible due to obstructions inside the garage.

We always recommend having the door specified and fitted by an experienced Garador installer, but if you are a proficient builder and want to measure the opening yourself, then here’s a few pointers to get you started. So what are the top five things to consider when measuring for a new Garador garage door? Let’s dive right in and look at the art of measuring up, we’ll start outside the garage and work our way inwards…

1. Is the garage door opening square?

When measuring your garage door opening it is important to measure the opening three times… not just once for both the width and the height. Why would you want to do this I hear you say? Well it’s pretty simple really… If you are measuring the width of the garage door opening and measure it once at the top of the opening, once in the middle of the opening and once at the bottom of the opening, you can be assured that the width is the same at any point along the vertical axis. It is also worth repeating the process along the horizontal axis, to ensure that the height of the opening is the same on the left-hand side, middle and right-hand side of the garage door opening. By doing a belt and braces job of measuring the garage door opening you can be certain that the opening is square.

Diagrams indicating to measure the garage door opening three times (height and width), to ensure it is square

Failing to measure the opening properly and to ensure it is square could lead to further problems down the line, as the door won’t fit properly. In some cases, you may need to rebuild the garage door opening to make it square before fitting the door.

2. Are the brick reveals square?

When fitting the vast majority of garage doors, they tend to be fitted behind the garage door opening rather than between the opening. But in most cases the wall behind the reveals will not be flat; they will likely be a rough, rugged and uneven surface. This is an important consideration as you will need to ensure that the frame of the door is kept square and true when fitting the garage door behind the opening.


For a retractable up & over door, if the frame is not square when the garage door is fitted, then the frame will try to push the door to one side all the time; resulting in squeaking and scraping sounds, as the door panel passes through the skewed door frame.

So you will need to be sure that the brick reveals are suitably square enough to fit the door behind the opening, and whether any additional building work is required to make them suitable.

3. Is the floor level?

When fitting a garage door on a slope, it is important to look at what whether the floor is level. If you are fitting a roller door, for example, then it is possible to order the door with a bottom chamfer profile. A bottom chamfer profile, can compensate for differences in height across the width of the roller door for up to 300mm in height. For Garador GaraRoll roller doors, the bottom chamfer profile is supplied in Jet Black, but can also be supplied in a colour matching the garage door.

Bottom chamfeur for GaraRoll roller doors installed on uneven surface

For an up & over garage door, if the floor level inside the garage is slightly lower on one side of the opening than the other, then the frame legs will not be fitted to a flat level surface, and that can cause problems (assuming that the frame leg for the garage door is positioned with the bottom of the leg touching the ground). If the garage door is fitted onto an uneven floor surface, then the frame is not level, it is being skewed. This puts a twist motion on the door panel which will result in the door failing to open and close properly.

If the floor isn’t level or if a certain type of door isn’t suitable for their garage, it’s important to make the homeowner aware of the issues they may face, so you can discuss these or look at what steps you might need to take in order to rectify the problem.

4. Are there any obstructions inside the garage?

It is worth bearing in mind that garages can be pretty busy places with all sorts of obstacles that can get in the way of you specifying a particular type of garage door. Gas or electricity meters inside the garage are a common problem, especially when they are positioned too close to the garage door opening, making it difficult in some circumstances to fit a garage door with tracks that go back into the garage. In this instance, a side-hinged garage door that opens outwards or a roller door with externally fitted roller box is preferable. Soil pipes or drain pipes behind the brickwork reveals can also be problematic, as they cause an obstruction when fitting the frame of your door behind the opening.

Electrical box inside garage near GaraRoll roller door

In some properties, the ceiling of the garage may contain a loft hatch, ceiling light or the homeowner may require regular access to the ceiling area and it would therefore not be appropriate to fit a sectional garage door or a retractable up & over garage door where the door panel sits on tracks inside the garage when the door is open. Shelves or shelving on the side walls could also cause an obstruction to tracks going back into the garage, so it’s a good idea to make sure the garage door will fit without having to remove any shelving or storage units.

5. Does the garage have enough headroom for each type of door?

Not all garages were built the same, which is a pretty broad assertion but it is very important when it comes to ensuring your garage has the right amount of headroom for the type of garage door you want to fit. It’s important to factor in how much headroom you have inside the garage, as this could affect the type of garage door you can fit.

Garador sectional garage door inside garage

Here’s a quick list of the minimum headroom requirements for the various types of Garador garage doors on offer. It’s worth noting that this is the absolute minimum headroom (the space between the top of the door opening and the ceiling inside the garage) and ideally you should look to have a bit of breathing room.

Door Type

Minimum Headroom (mm) *

Up & Over Garage Door (Canopy)


Up & Over Garage Door (Retractable)


Side Hinged Garage Door

Overall Frame Size

Sectional Garage Door (Tension)


Sectional Garage Door (Torsion)


Sectional Garage Door (Torsion Low Headroom)


GaraRoll Roller Garage Door (Doors up to 2300mm High)


GaraRoll Roller Garage Door (Doors between 2300mm and 3000mm High)


* Correct as of April 2018. Please refer to Garador price list for current specifications.

Whether it’s a sectional garage door, roller garage door or an up & over garage door, fitting behind the opening can give you a bit more room for error than fitting between the opening.

We also recommend measuring for a garage door in metric, rather than imperial measurements. This will enable you to accurately select and order a garage door from Garador’s price list where all doors are specified in millimetres.

View the full range of Garador garage doors online at www.garador.co.uk