Measuring things does not always come naturally to everyone and when the 'metric system' was introduced this compounded the problem for many. Doorsan Ltd have always had a conversion table on our site to assist customers with this aspect of buying a timber door. We can tell by our web statistics that hundreds of people use this facility.
Standard Imperial Internal timber doors are still the most commonly supplied doors in the UK. Internal doors are generally 78 inches in height and 1" 3/8" (or 35mm) thickness, available in widths of 24", 27", 28", 30", 33" and some are 33" x 80"
Standard Imperial External doors 30x78, 32x80, 33x78, 33x81, 34x82, 36x84 and may be 40mm or 44mm thick.
Standard Metric Internal timber doors are usually 626mm x 2040mm, 762mm x 2040mm, 826mm x 2040mm thickness is 40mm but sometimes 35mm
Standard Metric External door sizes are generally a conversion of the Imperial measurement, use the converter on our website to clarify these sizes or the drop down on each door style should help. They are usually 44mm in thickness, some are 54mm.
The conversion is only part of the measuring procedure, most important is choosing the nearest size of door to your requirements. When replacing a door consider that it may have been trimmed to fit, especially in an old traditional property, accurate measuring of all parts of the door is essential before purchasing a new door. Measure the existing door in all directions and choose a door size larger than your measurements but check with Doorsan about trimming tolerances. If the door has been removed then the opening within the frame should be used to take measurements, at the position where the doors sits when closed.
Example Tip: When measuring the height of your existing door it may be, 76" this indicates that it has been trimmed to fit the frame. If you are replacing the frames you may be able to go back to the original standard height of 78" with some work to the door opening, discuss this with your fitter or a professional before any structural work is undertaken.It will be possible to trim top and bottom of the door within the tolerances recommended by the manufacturer/supplier, but not a significantly large amount. This also applies to the width of a door, here the amount allowed to trim is much less, it is important that the structure of the door is not compromised. Some doors such as our Internal Premium Mega, Countryman, Tokyo and St Louis have an 18mm lipped edge yet others are much less, it is important that you check this.
Also measure the thickness of the door Note; fire doors are thicker than standard internal doors and usually 44mm if an FD30 or 54mm if FD60.
Please Note: This is information is a guide, please remember if you are not a DIY expert to contact a joiner or builder to assist you with this process.