Replacement Windows vs. New-Construction Windows

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If you’re looking into new windows for your home, you’re likely weighing up the difference between purchasing either new construction or replacement windows. Put simply, new windows are ideal for new homes that also require a new frame. Replacements work well in existing structures because they are designed to fit into an existing frame. To help you make the best decision and outline the differences, we look at when you should use each.

When replacement windows work best

If you are carrying out work on an existing property and looking for new windows, then replacements are normally the best option. Providing your wall and frame are not damaged, they are simple and less time-consuming to install. The process will not cause any significant disruption to your home and they are often fitted quickly.

It is relatively easy to find a like-for-like replacement window with the same dimensions as your old one, plus, they are designed so that window fitters do not have to work on any other part of the wall or area when installing them. In some cases, you may have to paint over the surrounding areas following installation, or the window trim may need to be removed.

In theory, replacement windows can be used in new constructions. However, there can be issues with this if there is damage to the trims and siding elements. If one of these elements is damaged then it’s likely the other elements will be damaged too.

Cost-wise, replacement windows may look like the more favourable alternative as costs can be lowered due to the minimal labour needed. However, the overall price will depend on the condition of the area around the window, and if your window is not fitted correctly due to unidentified rot, or the opening up of gaps has occurred during installation this can end up being a false economy.

When to use new-construction windows

New-construction windows have nail fin frames which attach to the wall being constructed around your window. This provides a firm attachment during the building process. If you are building a new home then new construction windows are the only choice. Because replacement windows require an existing frame, they cannot be used. Equally, if you are building or adding on a new structure to your home such as an extension, then you will need to use a new-construction window too.

Similarly, if you are carrying out renovation work on your home and you have discovered that your window is not fit for purpose, you will likely discover that its surrounding area is also not suitable. When this is the case, you will not be able to install a replacement window as the framing, siding and wall studs may all be damaged and will need to be removed and replaced. Rather than taking on a big job, using a newly constructed window which comes with nailing fins will be simpler. It usually enables a tighter and more weather-proof fit that may also improve energy efficiency in your home.


Consider the kind of project you are taking on before you decide on which windows will work best for your project. For a new build, or for a straightforward replacement, the choice is clear. If you are doing renovation work, consider the condition of your walls and surrounding window area. Also think what the long-term costs could be, replacements are often cheaper. However, despite a larger initial outlay for new constructed windows, if there are underlying problems, you may end up spending less in the long run.