How windows are installed, step by step

When you get professionals to install your windows, what can you expect? Find out in our 5-minute guide.



The new window is installed from the outside and adjusted so it's level. It's then secured in place with screws. Insulation is added to the frame and the window is trimmed and sealed.

4. Final checks

Next, the installer checks the window is plumb, level and square, and that it operates properly. Shims can be used to make adjustments where necessary.

5. Tidying up

Now the window has been installed, it's time to put things back in place. It won't be long before your house is a home once again. Phew!

How long will it take?

This is the million-dollar question: how long will the professionals be in your house?

Well, a standard window can be installed in an hour or less. A replacement window could take around an hour.

More complex, customised or non-standardised windows will naturally take longer. A bay window, for instance, could take two or three hours.

Bad weather can prolong the job, especially exterior work. You could also be looking at a longer job if the windows are in a hard-to-reach spot.

You should also take into account whether the installers will add insulation or weatherproofing. This will, of course, add a bit of time to the process.

In short, a window can be installed or replaced in less than a day. If the job involves multiple windows or complex windows (or is interrupted by bad weather), it could take longer.

That's how long the house will be a building site. But you should also take into account delivery times. You may need to wait for the windows to be delivered or even manufactured. Find this out from your installer ahead of time to avoid disappointment or frustration.

Can windows be completely installed from the inside?

Most of the time, windows are installed from the outside for ease of access. This is one way that installers can minimise the mess inside your home.

In some buildings, however, windows are installed entirely from the inside. These include historic properties, blocks of flats, high-rises and buildings where the windows simply can't be reached from the outside.

Can I do it myself?

The answer is, of course, yes. Some jobs should only ever be done by professionals – brain surgery, say. But home improvements can be a rewarding DIY activity. It all depends on your skill level, your willingness to learn, your patience, your resources and your time.

If you've got a gift for DIY, go ahead. The internet is bursting with how-to guides and the world is full of experienced installers who can point you in the right direction.

If, however, it all sounds too much like hard work, get a professional in. They'll apply all their skills, experience and eye for detail to the task, drastically reducing the chances of a botched job. It can be the difference between so-so and yes, yes, yes.

The main causes of regret following DIY installations relate to evenness and caulking. If the window is uneven, it can be difficult to open and close. And if the caulking is done less than perfectly, leaks and drafts become a strong possibility.

These aren't just a nuisance. They're also bad for your energy bills. Don't end up paying more than you need because of a substandard job!

How we can help 

At Calder Windows, we've been installing windows for more than three decades. We know the process like the backs of our hands – and we carry it out with a smile.

From single standard windows to complex jobs, we've got the experience and expertise to enhance your property.

We stock a wide selection of window styles, including bay windows, casement windows and sash windows. All of them are made out of high-quality materials. They're built to last – and built to withstand the Great British Weather.

Our role doesn't end with the installation. We pride ourselves on providing great aftercare and a 10-year warranty.

So, if you're looking for a window installer in West Yorkshire, get in touch today for a quick, competitive quote. We look forward to hearing from you.