As an experienced renovator, I know that installing new windows is an expensive process, and so it was really important to my partner and I to get the right style, material and durability for our home. After all, windows hugely impact both our home's kerb appeal, how quiet and spacious it feels as well as its energy efficiency.
And so as part of our mission to save energy at home and create a home that suits our lifestyle and needs, we needed to upgrade some of the glazing. While it would be nice to say I’m talking about upgrading double to triple glazing, our home only had single glazing when we bought it. A lot of the panes were cracked or broken and the timber was rotting from years of damp and high humidity. This also meant draughts, condensation and high energy bills galore. As we live in a Conservation Area too, the process was long and put a huge dent in our limited budget — so, one year on, was it worth it?
Why we upgraded from single to double glazing
A squeegee wouldn't fit between the wooden bars so wiping down condensation every morning was incredibly annoying
When we first visited our renovation project, I made a comprehensive list of everything that needed to be dealt with long-term and short-term, minor to major, with estimated costs to give a rough budget. I’ve renovated before and have worked in home improvement for almost a decade but I’ve never tackled anything on this scale. The roof, the layout, the plasterwork, the electrics. Everything had to be replaced or reimagined. And the windows were the same.
We lived in the house for about nine months before we put the planning application in to change the windows from single to double glazing. This meant we were able to see the humidity issues simply living in it was causing — cooking, breathing and showering — and every morning, we woke up to copious amounts of condensation on the windows. It was also freezing cold, which meant our heating bills were much higher than they needed to be, so we knew something had to change.
Our home is an old cottage with a more modern extension that we think was built in the 1970s. The extension's design was made to fit in with the ‘idea’ of what a cottage would look like without really looking around the village itself. When it comes to the type of windows, each casement was split into eight tiny panes when in reality the traditional style around here is two large panes split horizontally with a single glazing bar.
We made the decision to leave the older cottage section of the house with the original and more characterful single glazing for now (although we have added some temporary secondary glazing to help eliminate draughts and reduce condensation), and focus on replacing the newer single-glazed windows in the extension that somehow were in worse condition.
Securing the design and planning permission for our glazing upgrade
We chose Mizzle by Farrow and Ball for our window colours on the street-facing front
Our house is in a Conservation Area so we needed to comply with certain rules, including applying for planning permission, but the process was far more in-depth that I imagined. If we were swapping like-for-like (so, cottage-style casements in the same white colour) technically we might not have needed the application, but as we were wanting to install rooflights and take down a couple of trees at the same time, we thought it would be best to apply in one fell swoop.
First, we explored if we could save money by installing conservation-style uPVC windows to improve our home's efficiency. They’re not quite as expensive as timber, but overall far more expensive than off-the-shelf units. However, that was outright rejected by our planning officer — hey, it was worth an ask!
I had anticipated this, and was secretly glad about it because I love wooden windows, and had lined up a local company, Redwood Joinery, who specialised in timber windows for the area.
As we progressed with the application, it became apparent the planning officer would not approve the application without specifying that we needed slimline double glazing to give the appearance from the street that the windows were still single-glazed. As well as factoring in the cost of double glazing, this also caused all kinds of back and forth about the design, thickness, energy efficiency and durability of the windows. Interestingly, the planning officer also rejected the original design using a horizontal glazing bar to visually divide the double glazed pane.
Six months after we put in our planning application it was approved and we were able to give the go-ahead to Redwood Joinery.
Has upgrading to double glazing been worth it?
Upgrading the glazing in the extension part of our home has been an absolute game changer! Our windows were installed in August 2024 and almost immediately, I noticed a temperature difference in the house. Don’t forget, double glazed windows don’t just insulate from the cold — they should result in comfortable temperatures all year round, and that was definitely the case for us.
Our first winter with the double glazing was also so much easier to deal with. A squeegee wouldn't fit between the wooden bars on the previous windows, and so wiping down condensation every morning was incredibly annoying and time consuming. While we do still get some condensation now, it is significantly less than before and more occasional rather than constant — usually after long baths, just like any other house.
Although we initially resented having to specify the slimline glazing while the planning application was delaying the rest of the renovation work, I will admit that I know find them more visually appealing. Unlike chunkier double glazing where you can see the metal vacuum chamber, it’s barely visible and the overall effect feels more village-appropriate.
As a shock to no one, the slimline glazing increased the cost for us. We installed seven casement windows and three doors (one back door and two French patio) handmade in Accoya timber with the specialist slimline glazing for £24,656.50. That is, of course, a huge amount of money. Fortunately we factored in rough costs with our purchase price, and we are very much of the view that when it comes to essential upgrades that will increase energy efficiency, solve damp and condensation problems — that’s a great place to spend your money.
With the double glazed windows and doors taking up a huge chunk of our budget, I've also made use of super budget-friendly solutions too. These under £20 draught-proofing measures were really effective.