How To Measure For New Windows
It is important to measure properly for replacement windows to get an accurate price and for ordering the right size windows. If you order them too small, you will have to be creative when fitting and are likely to have problems. If you order them too big, you’re really in trouble.
Measuring correctly may be very daunting, but in reality it’s actually quite simple for most window types. All windows are measured from the outside of the house. When you order your windows, always give the dimensions as width x height. In the double glazing industry it is widely accepted that the width of a frame is always stated before the height, so stick to this convention or you might cause confusion.
If you have old wooden windows you want to replace either with modern ones or uPVC windows, measure the width first and then the height. To establish the width take three measurements. This is very straightforward. First measure from the top right corner to the top left corner, brick to brick. Then measure in the same way from left to right at the midway point right above where the window locks, and finally measure at the bottom.
If your house is rendered or covered in pebble-dash, it is advisable to chip away some of the material to reveal the brick. For houses with cladding ease away the cladding to find the outer edge of the frame to take accurate measurements.
When you measure, you will probably discover that all your measurements are slightly different. This is quite normal as brickwork is often uneven. It is not a reflection of your measuring skills! Deduct 10mm from the smallest measurement to allow for sealing and clearance tolerances. This is your width.
Measuring the height is not quite so easy, and how you go about it will depend on whether your window has a windowsill or not. If it does, measure from the top of your existing window frame or the head drip to the bottom of the sill. The manufacturer will deduct the sill from the overall height.
Again take three measurements, one on the left, one in the middle and one on the right. If your current window does not have a sill but sits on a concrete sill, the replacement window can be made either without a sill or with a sub-sill. As before, take the smallest measurement and deduct 10mm if your window sits on a concrete sill, otherwise just 5 mm. This is your height.
If you have existing uPVC windows that need replacing with new ones, you need to measure the thickness of your existing units in addition to the width and the height. This is because, if the thickness of the new units is greater or smaller than that of the originals, the new units cannot be easily fitted. The height and width can be measured by removing the glazing bars which may be fitted on the outside for externally glazed, or on the inside of the window pane for internally glazed windows.
Whereas everyone can measure easily for flat windows following the steps above, measuring for curved or rectangular bay windows requires more skill and experience. Ideally these should be measured by experienced surveyors before you order. If you want to measure to get a quote, however, follow the steps below which are a simplified way of measuring.
Measuring for bay windows follows the same principles as for flat windows. A bay window is measured as a series of flat windows and you have to measure the width and height of each part of the bay window. The height will be the same on all.
For the installation of a new or replacement of an existing bow window, measure the width and height and specify the number of facets. Only the overall width of the opening is required for a bow window, as the facets will be sized equally.
Measuring for replacement windows is not difficult, and if you follow the steps outlined above, you will always achieve accurate results.