Black Knight Secondary Glazing
Black Knight Secondary Glazing

Fitting Secondary Windows

Fitting secondary windows is well within the ability of a competent DIY home improver and you will not need any specialist installation tools.


You will need a tape measure, spirit level, power drill, screwdriver, proprietary screws to suit, wall plugs for reveal fix only and either decorators caulk or silicone as necessary. 


When your DIY secondary windows are delivered they will come with a full set of easy-to-understand instructions.


All the windows are fully assembled (very large windows may have the outer frame disassembled for transport & handling) and fully glazed with pre-drilled countersunk holes for fixing.

Fitting secondary windows - Face Fix or Reveal Fix?

Your DIY secondary glazing can be fitted close to the existing window or set back in the window reveal when additional noise reduction is required.


Face Fixing will be through the front of the timber subframe into the primary window



Reveal Fixing will be through the back of the subframe into the window reveal

To make it easy when fitting secondary windows we include a full installation kit with all the parts needed and step-by-step instructions to help you:


  • pack the secondary window so that it is square & level
  • temporarily fix the secondary glazing unit while checking for correct opening, closing, locking & panel removal before final fixing.
  • fix at correct locations to ensure the window is square and level.
  • fit the subframe cover trims.
  • clean before sealing as necessary to give a clean decorating line.


Get a no-obligation quotation



In line with our policy of continuous product development Black Knight Secondary Glazing reserve the right to alter or amend product specification without notice.