Can I install my own windows and doors?

18th July 2017

Window Window

Can I install my own windows and doors?


As part of Copperfield‘s series debunking some of the myths that surround window and door replacement Craig Smith, Director tells us what you need to know if you’re going to fit your own windows and doors.

This may appear an unusual blog subject for a company that earns its crust supplying and installing windows and doors but the answer is ‘yes’ you can fit your own windows and doors, if you’re fairly handy and most importantly get your measurements right.


So what do you need to know?

  1. Make sure measurements are accurate


Measurement – it’s key.  Our surveyors have years of experience between them but even then, mistakes are always possible.  Not only do our survey teams double and triple check everything they do, but our installers also measure the new window against the old and the aperture, when they get to site.

As a general rule of thumb, you need to measure a frame so that it’s around 10mm smaller than the frame opening. This will give you room to get it level.


  1. Choose your window supplier wisely


If you’re determined to go it alone, your choice of window supplier is going to be key. Good suppliers will help you to dot the ‘i’s and cross the ‘t’s on order forms. They’ll also be able to talk you through the different options for your new energy efficient windows and doors.


PVC-U windows tend to be popular with home improvers. They’re energy efficient, secure and require little through life maintenance. All windows on sale will generally meet building regs. (although double check to make sure that you don’t need special reinforcements) including Part L for energy efficiency.  


Copperfield offers a full range of secure, low maintenance and thermally efficient windows and doors from Profile 22. Designed and manufactured here in the UK, they’re the product of millions of pounds of investment in energy efficiency, security and system development.


Energy efficient and low maintenance PVC-U, they feature a thermally efficient outer frame featuring six ‘honeycomb’ chambers and five chamber sash, plus an energy efficient recycled composite material reinforcement.


With deeper drainage channels carry water away quickly, they also feature 10mm cover on weather seals stopping draughts. Combined with energy efficient double and triple-glazed glazing options featuring warm-edge spacers and low-e coatings they achieve achieve WERs of up to A++ and U-values as low as 0.8W/m2K.


  1. Removing old windows


Let’s keep things positive and assume that you’ve got your measurements right, you’ve found a good supplier and ordered a good window system and its been delivered on time. You now need to remove your old windows.


As we have mentioned, double check sizing of new windows before taking out the old windows. Once you have done so, remove the glass. Taping this so it doesn’t shatter or applying a safety film, makes this process much safer if removing single glazing, while double glazed units should lift out after removing beading.


If they’re timber frames, the easiest way to get the frames out is to cut them in the middle on each side. This sets a limit on the amount of force you apply, which makes damage to brickwork and the window surround less likely. If you’re replacing old PVC-U windows, simply remove the screws and do the same.


Take care, however, to avoid damage to internal plasterwork or tiling. Our fitting teams have fine-tuned the removal of windows to minimise damage. We’d recommend a light touch and pre-cutting plasterwork around the frame. Even then damage can occur so expect remedial work.

  1. Use spacers


Spacers are small plastic inserts used by professional window companies to help to get windows level and sitting within the right place within the window or door aperture. This is key because if the window isn’t level opening sashes won’t work properly, invalidating any guarantees and shortening the life of your new windows.


Packers also have an important role in supporting the window frame within the aperture. It’s is important in making sure that you don’t accidentally pull the window frame out-of-square or damage it by over-tightening screws, as you fix the window to brickwork or timber.


It’s also important to make sure that glazed units sit on packers rather than directly in the channel as this can impact on how effectively your window will drain.

  1. Glaze windows


Windows in the UK are supplied unglazed to make them easier to handle. To glaze them carefully remove glazing beads and ensure that the units sit on packers as highlighted.


It’s also important that the window is properly braced so that the sash doesn’t drop when opening and closing.


Imagine a 5-bar gate - this uses a diagonal timber to give gate structural strength. The only real difference is that in a window, the glass unit as well as being something that you look through, fulfils a structural role.


This is called ‘toe and heeling’. What you’re doing is essentially packing out the window to create (if you could see it) a diagonal loading or ‘brace’ across the glass unit into opposite corners of the frame.  


You should always pack from the top of the lock side first and then the bottom of the hinge side. You may want to use a specialist glass shovel for doing this. It’s made much easier with experience but getting it right is important, otherwise there’s a risk that your sash will drop over time.


Finally knock in your beads with a nylon hammer, fill gaps and seal and you’re done. Well that’s the theory anyway!


(Oh, and make sure that you get your local building control office to sign-off the work, or else it could be a nightmare when you come to sell. As a UKAS accredited installer and member of a Competent Persons Scheme we don’t have to do this as we’re qualified to self-certify our work.)


As with most things, replacing your windows and doors sounds simple enough and on a straight forward installation it can be – but take it from us, window and door installations can be anything but. Our fitters have got masses of experience and are true craftsmen in what they do but we can still run into challenges along the way.


If you get the measurements or order wrong or don’t glaze it properly, let alone re-plastering if things get damaged.

We’d argue that on balance, the peace of mind professional installation offers far outweighs the any additional cost.


For more information, please don’t hesitate to email me on or call a member of our team on 02476 452688





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