Loft Insulation Cost

The cost of loft insulation starts at £2.20 p/m2 for blanket insulation, £7.50 p/m2for loose fill and up to £52 p/m2 for spray foam insulation. The national average cost for insulation is based on insulating a semi-detached house, costs for other properties as well as factors affecting cost are discussed below.
Low Cost £225- £445
National Average Cost £325- £945
High Cost £590- £1125

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According to the Building Regulations 2010 L1B regarding the Conservation of Fuel and Power, a loft must have 270mm of glass mineral wool blanket insulation, or the equivalent. Glass mineral wool insulation is available in rolls of various thicknesses including 100mm, 170mm and 200mm. Many homeowners and tradesmen lay 100mm blankets between ceiling joists and 170mm blankets over the joists at a 90-degree angle to them.

Did you know? Loft insulation is a great investment in your home. Blanket insulation pays for itself in about 2 years through lower heating bills if you install it. If a contractor lays it, the payback time is 3-4 years. After the payback period, you’ll save money with lower costs whether heating or air conditioning your home, you can also be safe in the knowledge that you’re reducing your carbon footprint and making your home more efficient.

See the payback period for other types. We listed them below.

How Much Does Loft Insulation Cost?

Here are your loft insulation options, their pros and cons and loft insulation prices. Let’s start with pricing. You’ll find a table of costs for common home types below.

Glass mineral wool blanket insulation cost is £2.20/m2 to £4.00/m2 depending on how thick the insulation is installed. If you already have 100mm, for example, adding the other 170 will cost about £2.75/m2

Add about £1.20/m2 if blanket insulation is professionally installed.

Pros and Cons: The great thing about blanket glass mineral wood or fiberglass insulation is that it is affordable. Plus, DIY installation is quite easy. Just be sure not to cover vents in the eaves of the loft. Recycled material is used in some blanket installation. Blanket insulation cost is paid back the fastest – in just a few years.

The downside is that the material can cause skin, eye and throat irritation. If you DIY, wear long sleeves and slacks or a cover-all, gloves, a mask and eye protection. Also, if this kind of loft insulation gets wet, it will lose its ability to insulate. If your roof leaks, the insulation will need to dry entirely or be replaced.

Loose Fill or Blown In Loft Insulation

Loose fill loft insulation cost is £4.80/m2 to £6.50/m2 based the amount you add and whether it is dispersed by hand or with the use of a blower. When loose fill insulation is loaded into a machine that blows it through a tube to disperse it, the material is called blown in insulation.

This type is usually installed by a tradesman rather than DIY, but you might be able to hire a blower and buy the insulation from a local building supply store.

Pros and Cons: This insulation is comprised of small, granular particles of cellulose, mostly recycled newspaper. Cork and mineral wool might be included too. It’s a good choice for topping up existing loft insulation, and it is also used throughout the loft.

Loose fill insulation fills every nook and cranny better than blanket insulation. Payback is 3-5 years.

The downside is the higher cost relative to blanket loft insulation. Also, cellulose is very absorbent. If it gets wet, replacement is the only option. It will not dry quickly enough to prevent the growth of mould.

Sheet Foam Loft Insulation

Sheet foam loft insulation cost is £7.75/m2 to £11.00/m2 depending on how thick the sheets are. Contractor use sheet insulation in wall cavities or between loft rafters most often. It’s ideal when you’re converting the loft to living space. However, you can use it on the floor of the loft, laid across the ceiling joists.

Pros and Cons: Foam insulation has a high U-value. That means it does a better job insulating than most other types. The “con” is its significantly higher price. It takes 7-10 years or more to recoup the cost.

Spray Foam Loft Insulation

Spray foam loft insulation cost is £44.00/m2 to £52.00/m2. This type is usually used in hard-to-reach spots in the loft to stop draughts. For example, blown-in insulation might be used as the main loft insulation with spray foam used in spots where needed. It is occasionally sprayed onto the underside of the roof and onto side walls of the loft. However, if not done properly, it can create moisture issues in the loft. Spray foam insulation is installed by professionals.

Pros and Cons: It is very effective with a high U-value. It stops air leaks and is resistant to moisture. The biggest negative issue is its high cost for doing large areas. It is installed by professionals, and you can see the challenge of doing it in this video for a leading brand.

The payback period is much longer, but this loft insulation type isn’t installed for quick payback but for its ability to seal and insulate loft space very effectively to convert it to living space.

Loft Insulation Cost by Project

Those are costs per square metre. What about the price of loft insulation for the whole project?

This table shows loft insulation prices for insulation installed by a professional crew. It covers the three types often used on the floor of the loft – blanket, blown-in and foam sheet insulation.

The average cost is given. When you get loft insulation quotes, the range could be slightly lower or slightly higher.

Your exact cost will depend on the depth/thickness of the insulation needed.

Property Blanket Insulation Loose Fill Foam Sheet
Detached £415 £750 £1,200
Semi-Attached £325 £590 £945
Terrace £300 £525 £875
Bungalow £400 £715 £1,125

Insulation Cost Factors to Consider

The most obvious cost factor is the type of insulation you use. Here are other factors that will affect cost.

  • DIY or Insulation Contractor: Installing blanket and loose fill is quite easy. Follow instructions and/or watch video tutorials before tackling the project.
  • Depth or Thickness of the Insulation: It will cost quite a bit less to install a single 100mm blanket than the full 270mm required.
  • Job Difficulty: Cost is lower for attics easily accessed, empty and rectangular. Cost is higher in crowded, complex settings.
  • Old Insulation Removal: If old insulation has to be removed, that’s really a separate cost. Expect to get quotes of up to £1.75/m2 for removing old insulation. A cost-saving option is to hire a skip and do it yourself.

Time Schedule Required to Install Loft Insulation

  • DIY – 12-24 hours, depending on your experiencing with doing this sort of job
  • Pro – 4-6 hours for most average sized lofts found in semi-detached homes, 6-8 hours for larger detached homes
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Loft Insulation FAQ

Here are common questions and answers we hope you’ll find useful.

Q. How do I know how much insulation I have?

A. Use a ruler to measure its depth. Place the ruler alongside a ceiling joist, and gently push down until you feel the top of the plasterboard beneath the insulation.

Q. What is insulation payback time?

A. That’s the time it will take you to recover the cost of loft insulation through lower heating bills.

Q. Do I need planning permission for installing loft insulation?

A. You do not need planning permission if you are not making structural changes to the property.

Q. How much does it cost for the crew to remove objects from my loft?

A. If you have stored items in the loft, you’ll get one of two answers –

  • “We don’t remove items – you’ll have to do it yourself.” Some companies don’t want the hassle or the potential liability of damaging your belongings or have something turn up missing.
  • “We’ll do it for £30 to £50 per hour.”

Q. How long does the job take?

A. A crew of two pro installers can lay 200mm of blanket insulation in a detached loft in a couple hours. If you do it yourself, expect it to take 3-5 hours. It will go faster as you get the hang of it.

Q. Can I store items on top of insulation?

A. Not directly on it. If you compress insulation, it loses some of its insulating ability. However, you can install a deck above the insulation with legs attached to the ceiling joists. Another option is to install 100mm of blanket insulation between the joists. The blanket won’t be higher than the joists, so won’t get compressed. Then lay insulated polyfoam boards on the joists. The boards are firm enough to hold basic household items. With the polyfoam boards and the 100mm blanket, you’ll get the same insulation value as 270mm of blanket.

Q. Can I get help paying for loft insulation?

A. The government’s Energy Company Obligation (ECO) requires energy suppliers to help customers that need it to get it. Talk to your energy supplier about the scheme.


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