When Is An Opening Ready To Survey?

Surveying for the installation of aluminium doors and windows is an art form in itself. There are many things to consider of which we will cover some of the most important ones in this article.

A Diagram of a Typical Opening

When installing flat aluminium doors and windows it is imperative that the opening is ready before the survey is undertaken. Problems can and usually do arise if the opening is not complete as any slight changes or differences in the finished opening can be costly and a major inconvenience.

Aluminium Door and Window Structural Opening Diagram

The diagram above is a typical diagram of an opening showing the key points with regard to aluminium door and window surveying. The magenta lines that travel vertically, horizontally and diagonally are generally where measurements are taken. The wider or taller the openings the more measuring points need to be used to ensure the manufacturing sizes are correct for the opening.

Head and Base

The head and base need to be level to ensure the aluminium door or window can be installed square into the opening.  Likewise the sides of the opening need to be true and plumb for the same reason.
If the head and base are not level it can be problematic for the operation of the doors and windows. This is especially true for bi-folding and sliding doors as the guides and rollers can become free from their tracks if there is any gap.


It is as important to make sure the sides of the opening are true and plumb as it is for the head and base to be level. If the sides are not plumb it can cause problems when it comes to installation. Not being true relates to the sides being flat and measuring the same distance at each point across the opening.

You can tell if the sides or head and base are not level, plumb or true by taking an angle measurement at the corners of the opening. If they are not 90 degrees then the opening is not a perfect rectangle.

Door Thresholds

In addition to the base additional care has to be taken when surveying for aluminium doors. Bi-folding and sliding doors are less forgiving than windows as the tracks, runners and guides need to be level.

If at any point across the opening there is a difference in height then bi-folding and sliding doors may not operate properly. This is true if the height is either too high or too low. There are other considerations with regard to door thresholds but this is covered in a different article.

Manufacturing Sizes

When the aluminium door and window survey is complete the production team will then determine the manufacturing sizes. To calculate the manufacturing sizes we use the minimum distance of all of the measurement points plus an additional deduction to allow for expansion and contraction.

Using the diagram above as an example we will go from left to right. The vertical dimension for the first measurement may be 1200mm, the second 1195mm, the third 1205mm and the last 1190mm. The same for the horizontal measurements they could be 1800mm for the bottom measurement, 1805mm for the middle and 1790mm for the top.

To calculate the manufacturing size, we would use 1790mm horizontally and 1190mm vertically less 15mm to allow for expansion and contraction. The above would give us a final manufacturing size of 1775mm wide by 1175mm high.

Closing Comments

There are many other things to consider such as drainage, reveal depths and glass specifications but these will be covered in a future article. All of the above and more should be discussed with you when the surveyor has finished.

It is as important to us to be comprehensive in undertaking a survey as it is for you in ensuring the aluminium doors and windows are not only fantastically designed and manufactured but also expertly installed.

Hopefully this guide has been helpful and there is enough information for you to make an informed choice. For additional information please do not hesitate to contact us here at Reveal Doors and Windows. We are always happy to help you and discuss your requirements in further detail.