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How to get your window sizes right

To determine the finished frame dimensions of your windows, you need to consider the overall size of your structural openings and any tolerances that may be required and deducted for.

The structural opening refers to the opening in the structure which your window will be placed into. The structural opening is typically measured ‘brick to brick’ or ‘block to block’ to serve as a starting point. If you are building a timber frame property, then the structural opening sizes can be taken from your plan as the openings will be the size given. If you are building with internal block work then you will want to take accurate measurements on site rather than relying on architects drawings.

Once the structural opening has been determined, a tolerance needs to be taken to ensure that the window will fit inside the opening and that there is enough room to seal around the outside of the frame. For Idealcombi windows, this is generally 10-15mm of tolerance with 12mm being the recommended tolerance.

You also need to make sure there is enough tolerance for a cill.

If you are going to apply render to wall around the window, we will ask if your render is going go return into your window reveal (the inside face of the opening) and whether the render will be in place before or after the windows are installed.

Who will take responsibility

  1.  You can do the measurements yourself and take all responsibility.
  2.  You can order windows according to drawings and make the builder liable to building precisely to the drawings.
  3.  Get an Idealcombi Approved installer to measure for you.
  4.  Let Idealcombi do a survey and take all responsibility for correct sizes.