We bought an old, draughty house: How much will it cost to insulate it?
- Got a property question? Email jane.denton@mailonline.co.uk
We recently purchased, and will soon be moving into, a three-bedroom semi-detached house built in the late 1930s.
The property has a loft. Nothing has been updated in the house for decades and it's cold throughout.
Its Energy Performance Certificate rating is F.
What are our options for getting the property insulated from top to bottom and how much could this all cost?
We're keen to bring the energy bills for the house down.
Feeling the chill: A This is Money reader has purchased a draughty 1930s semi (file image)
Jane Denton, of This is Money, replies: An energy performance certificate tells you how energy efficient your home is.
EPCs rate a home from A, meaning it's very efficient, to G at the bottom of the pile. At F, your property has plenty of room for improvement.
More than half of properties in England fall below the C energy performance certificate rating, research by Eurocell showed recently.
Landlords won't be allowed to rent out properties that aren't at least C-rated by 2030.
While that isn't a concern for you, getting your house adequately insulated should still be a priority. As well as making the home more comfortable, it can keep your energy bills down and perhaps even improve its value if you come to sell it in the future.
Changes that could make a home more energy efficient include sealing draughty gaps, installing double glazing, adding loft or cavity wall insulation, upgrading the boiler and replacing it with a heat pump or biomass boiler and putting solar panels on the roof.
The downside, of course, is that many of these renovations will be costly, in some cases in the thousands or even tens of thousands of pounds.
I've spoken to two experts to delve into the detail of how best to insulate your house and outline the potential costs involved.
Andy Simms says older houses were not designed with energy efficiency in mind
Andy Simms, a construction consultant at MyBuilder.com, says: An EPC rating of F is far from ideal, with G being the lowest possible rating, so energy efficiency improvements would be wise.
The age of your property is probably the most significant factor associated with its energy efficiency.
Older houses were not designed with energy efficiency in mind, and are much more likely to get cold due to poor insulation and features, such as sash windows and solid brick walls, rather than cavity insulation.
Getting your home properly insulated is not a cheap job, but it will be worth it. Insulation is great not only for keeping the heat in, but also keeping it out in the summer.
Loft installation is a crucial job as up to a quarter of your home's heat can be lost through the roof. It's also significantly cheaper than other types of insulation, although cost will obviously vary depending on the size.
Average loft installations can start from £500, but you could save up to 25 per cent on your energy bills by getting your loft properly insulated.
It's likely that a property built in the 1930s will have sold brick walls. Insulating these retrospectively involves either adding insulation internally, through building a stud wall with insulation behind, or externally, by fixing a layer of insulation material to the outside wall before covering with render.
The first option reduces living space which is a major consideration, while the second option is considered more effective but takes more work and may require planning permission.
The average cost for internal wall insulation for a semi-detached house would be about £8,200, plus any redecoration costs.
However, it will undoubtedly save you on your bills, create a warmer home, and improve your property's energy efficiency.
Another method to consider is floor insulation. Up to 20 per cent of heat can be lost through the ground floor, especially if your home has wooden flooring.
Timber flooring can be insulated by lifting the floorboards and installing mineral wall insulation between the joists.
Insulating a floor costs around £850, though this can vary depending on a variety of factors. On average, I'd say a wooden floor costs up to £45 per square metre.
Another improvement worth considering is whether your windows need replacing or upgrading.
While complete replacement might not be necessary, it's worth getting advice from a professional to check.
Once you have decided what improvements to make, do some research on whether there are any government grants available to you to help with the costs.
Clive Holland, a broadcaster on Fix Radio, says: An F-rated property from the 1930s can definitely be draughty and inefficient.
However, the good news is that there are several ways to improve insulation and bring those energy bills down from top to bottom.
Loft insulation is usually the best place to start, especially if the loft is accessible and unused.
The recommended depth is 270mm of mineral wool, which can cut heat loss significantly.
For a three-bedroom semi-detached house, you're looking at around £500 to £1,000 for professional installation, depending on the materials used.
If you're comfortable doing it yourself, the cost can drop to around £300 for materials from a good DIY store, however, I would always recommend hiring a trusted tradesperson.
Next, wall insulation is essential, but the right approach depends on whether your home has cavity or solid walls.
Most 1930s properties were built with solid walls, meaning two layers of brick with no cavity in between.
These nine inch thick walls can become very cold and are often prone to damp, making them more challenging to insulate compared to modern cavity walls.
Clive Holland says loft insulation is the best place to start
External wall insulation involves fixing insulating material to the outside of the property and then rendering it. This can cost between £8,000 and £12,000, but it's very effective.
Internal wall insulation is slightly cheaper, at around £5,000 to £7,000, yet it will reduce room sizes slightly and can be disruptive to the installation.
Underfloor insulation is another critical area , particularly if your property has suspended timber floors.
You can insulate beneath the floorboards by accessing the crawl space or lifting the boards themselves. Professionally, this can cost between £1,200 and £2,000.
If you've got a concrete floor, rigid insulation boards can be laid over it, which may be pricier and more invasive.
Windows and doors shouldn't be overlooked either. Double or triple glazing will help, and sealing any gaps with draught-proofing strips or sealants is a cost-effective first step.
Replacing single-glazed units in a three-bed semi could cost £4,000 to £7,000, but it's a long-term investment in both comfort and efficiency.
There are also several grants and schemes available to improve home energy efficiency.
Under the Energy Company Obligation scheme, many energy suppliers offer free insulation and boiler upgrades, including loft and cavity wall insulation and the replacement of old electric heaters with energy-efficient models.
The Boiler Upgrade Scheme also offers up to £7,500 for homeowners in England and Wales to replace their gas, oil, or electric boiler with a heat pump or biomass boiler.
Scotland offers a similar scheme, with grants of up to £9,000, and the option for interest-free loans for additional funding.
Eligibility requirements vary, and homeowners typically need to work with certified installers who apply for the grants on their behalf.
In your case, a full top-to-bottom insulation job could cost anywhere from £10,000 to £20,000, but the savings on energy bills could be up to £600 a year or more, depending on your usage.
