Are you considering a retrofit renovation of your home? Are you looking to make your home warmer and more comfortable and wondering how much it might cost to make these upgrades?
The answer to this question depends on several factors. Including, what your budget is and what are the drivers for the doing the retrofit renovation? Is it improving the warmth and comfort? Lowering energy bills? Or moving away from carbon based heating systems? Also how much disruption to your home are you able to accept?
In this blog, we’ll break down the costs of some key retrofit measures using two previous case studies.
So whether you’ve been planning your retrofit renovation for a number of years, or maybe you’ve just bought a new home and you’re looking to retrofit? This blog will give you a clearer idea of what to budget for.
How much it cost to retrofit a bungalow in Anglesey
craig eiddew
In this case study, Margaret and John asked us to make their bungalow on the West coast of Anglesey warmer, lower energy and more cost effective to run.
Their home is beautifully situated with lovely views. It’s filled with light and gets lots of sun. However, they wanted to hugely reduce its energy use and increase its comfort.
The retrofit work included new floor insulation, cavity wall insulation, external wall insulation and roof insulation.
In addition to this, they also applied new render, installed triple glazed windows and extensive air-tightness detailing. The heating has switched from oil to an air-source heat pump and they installed solar panels.
Retrofit costs breakdown
- We retrofitted the whole house which was 125/m2. In addition, to the retrofit costs detailed below, the renovation included new bathrooms, kitchen and external landscaping.
- The renovation was completed in 2021 at a total construction cost inc VAT of £170,206.
- We estimate the cost would be around £207,560 at 2025 prices.
- The professional fees budget in 2025 for a project like this would be £31,134 and the HEM Architects fees in 2025 would be £16,768.
Here’s a breakdown of the key retrofit costs
Floors
- Thermal upgrade to existing floors £9,400
- Underfloor heating: £9,500
- Total: £18,900
Walls
- Cavity wall insulation £3,500
- Air tightness works £1,000
- External wall insulation £10,000
- Window structural works £10,000
- Other wall works £1,000
- Total: £25,500
Roofs
- Thermal upgrades to all roofs and wall junctions including new insulation and airtightness works.
- Total: £15,300
New windows and doors
- uPVC PAS 24 certified triple glazed windows and doors. New window sills and cavity closers to existing window openings.
- Total: £5,100
Air source heat pump
- Specified and installed by specialist contractor.
- Total: £12,600
Electric car charge point
- Total: £700
Retrofit: Key result
The result of these changes was that we reduced their heating demand by 81%, from 286 kWh/m2.a to 65 kWh/m2.a.
We estimate this saves Margaret and John around £3,700 each year in energy costs, with annual electricity bills of around £1,100. But with the benefit of their solar panels – it’s likely to be zero.
How much it costs to make DIY retrofit improvements to your home
penmore close
John and Janet live in a 1950s semi-detached home in Chesterfield, that felt cold and was difficult to heat despite its Energy Performance Certificate rating of C.
Hoping to create a warm, comfortable, and energy-efficient home, they approached HEM Architects to carry out a Retrofit Strategy.
With only a limited budget they focused on the recommendations from the ‘Easy DIY Wins’ section of the strategy and carried out the suggested improvements.
The Retrofit Strategy in 2025 costs from £2,495 + VAT.
costs
- Sealed their plasterboard walls with airtight foam
- A window fitter improved the fit of their doors and windows
- Applied fresh sealant around window frames and doors
- Added cavity wall insulation to their external walls
- Total £638
Retrofit: Key result
The impact of our Retrofit Strategy was John and Janet saved £173 on their energy bills for the first 3 months of the year alone. Using 2883kWh less gas than they had done in the same period the previous year.
Since the improvements, their home has also been noticeably warmer and more comfortable.
The huge value of retrofitting your home
These two case studies highlight how retrofit costs can vary, from a few hundred pounds for DIY improvements to hundreds of thousands for a significant retrofit.
The Retrofit Strategy from HEM Architects is the best place to start to provide you with an action plan to start improving your home and to help understand the costs. Also like John and Janet, you want to do the improvements yourself.
If you plan to stay in your home for at least the next 10 years or it already needs renovating, investing in a more comprehensive retrofit can offer great value for money.
Not only can it lower your energy bills and increase your home’s value if you decide to sell. It will make your living space warmer, more comfortable, and healthier for years to come.
Retrofit costs don’t have to be terrifying
Speak to the experts in retrofit who can carefully manage your costs and budget.