Loft Insulation Costs in 2019

I wonder how many of you have actually been in their loft space more than once in the last 10 years. Not many I expect (except for packing away the Christmas decorations). For many homeowners, the loft beneath their roof (also called a roofspace) is undiscovered country and a place that they never think about from one week to the next. Yet, did you know that with only a small financial outlay, the roof space can be turned into a highly effective layer of insulation saving many hundreds of pounds from your heating bill every year?

Most people know that hot air rises, but have you ever given any thought about where the warm air that is produced by your radiators actually goes to? It rises through the house until it reaches the bedroom ceilings where it eventually finds its way into the roof space, where if there isn’t any insulation it will be wasted. All it needs is for a couple of layers of insulation to separate the cold air from the warm and you won’t lose that precious and expensive heat. Have I whetted your appetite yet? Do you want to save money and use the heat that would otherwise be lost? Carry on reading and find out for yourself how much insulation costs, how much you would save by installing the insulation and the best way to go about insulating your loft or attic.

Available types of loft insulation

In theory, anything that has pockets of air trapped within it will act as an insulating material as motionless air is a very poor conductor of heat. Tn practice however we are limited to materials that are easy to transport and install, materials that will not be a fire hazard, materials that are relatively cheap and those that will be a substantial barrier to heat loss. Bear in mind that the recommended loft insulation thickness is calculated to be about 270mm for minimum heat loss.

Blanket materials. This is probably the most popular choice. It is a fibrous material sold in rolls or slabs (also called batts) and is usually made from mineral or glass fibre, but there are brands made from sheep wool which are non-irritant. The cheap loft insulation of this type comes backed with a vapour barrier paper already attached, but more expensive products come with a foil backing to reflect radiant heat. The advantages of this type of insulation are:

  • DIY friendly. Very easy to install.
  • Easy to install into exposed cavities.
  • Relatively cheap to buy. A roll of loft insulation covering 8.3m2 x 100mm thick will cost about £20. This means that if you use regular fibrous loft insulation you will need about 3 layers.

Disadvantages of blanket insulation include:

  • Some types can irritate the skin and if inhaled, can damage the lungs.
  • Rolls can be very bulky and difficult to fit in small enclosed spaces.
  • Some types, such as sheep’s wool are expensive.
  • Wear suitable protective clothing.

Loose fill insulation.  This type of loft insulation material is made from various lightweight granular materials. Typical raw materials include cork granules, cellulose fibre, mineral wool and recycled newspaper. Remember, naturally flammable materials such as the cork, cellulose and paper are treated to prevent them from becoming a fire hazard. Advantages of loose fill insulation include:

  • Easy to carry and pour into irregular cavities and around obstructions.
  • Can be used as a top-up for existing insulation.

Disadvantages of loose insulation include:

  • Can be blown about in draughty lofts.
  • Although these types are not usually irritant to the skin, they produce dust which can cause problems if inhaled.
  • Use appropriate safety equipment during insulation.

Sheet insulation.  Also known as roof insulation board, this type is designed to insulate between the rafters  (the sloping sides of the roof). There are foam polyurethane or polystyrene sheets sandwiched between foil or other coverings. There are also greener versions that use compressed cork or straw. It is always fire resistant and moisture resistant and can be bought with a decorative finish, however, they are usually covered in plasterboard after installation.

Advantages of sheet insulation include:

  • By insulating the sloping roof, the roof space is brought into the thermal envelope of the house. Great for loft conversions.
  • Can be covered with plasterboard for a decorative finish.
  • Very good insulator for its thickness.

Disadvantages include:

  • Polyurethane and polystyrene sheets use large amounts of energy during manufacture.
  • Sometimes can be expensive compared to other insulation types.

Blown-fibre loft insulation. This is not a DIY method as specialist contractors with equipment are needed to blow this insulation into place. The fibre is blown into gaps between joists.

Advantages  of blown-fibre insulation include:

  • Easy to install by a professional.
  • Other options include wool or paper.
  • Good for insulating difficult to access areas.
  • Light and convenient.

Disadvantages include:

  • Blown-in insulation costs can be very expensive.
  • Can be a problem if the loft is draughty.

Spray foam loft insulation.  Chemical aerated foam can be sprayed between the rafters on the roof. You will need a specialist with equipment to do this job so it will be expensive. However, it brings the roof space into the thermal envelope of the house and allows the floor to be boarded or the loft to be converted into a living area.

Advantages of spray foam insulation include:

  • The roof space will be warmer than using any other type of insulation.
  • Freezing tanks and pipes will be a thing of the past.
  • Even the smallest hole to the outside will be blocked up, preventing draughts.
  • The floor can be boarded without raising the joist level.

Disadvantages include:

  • Needs a professional to do the work.
  • The cost is higher than most other insulating methods.
  • You will need to insulate all the other exposed surfaces as well such as gables, chimney breasts and party walls otherwise the heat will escape through those surfaces.

Loft Insulation Costs

The costs of using loft insulation will vary depending on which type you use, the size of the floor of your roof space and how thick you lay the insulation (remember the recommended thickness is 270mm). The Energy Saving Trust suggests that for a standard gas centrally heated home in the UK using standard fibreglass insulation, the following costs and savings are typical.

  Cost of insulation Heating bill savings per year Payback time
Detached house

(4 bedrooms)

£395 £215 12 to 24 months
Semi-detached house

(3 bedrooms)

£300 £130 12 to 48 months
Terrace house

(3 bedrooms)

£285 £115 24 to 36 months
Detached bungalow

(2 bedrooms)

£375 £185 12 to 24 months

Can I get help paying for insulation?

If you or someone in your home is a member of a vulnerable group or are on certain benefits, then some energy suppliers will help towards the cost of insulation. Apart from this, there are many different schemes that will help with the cost of heating or insulating your home. Loft insulation grants such as these often have a date after which you will be unable to qualify. They often require you to buy the materials first and claim back the loft insulation costs afterwards too.  If this is the case and you are relying on the grant to cover the cost, make sure you check the terms, conditions and the expiry dates before having the work done. Look on this link for information on home grants.

What is the best method of DIY insulation?

If you have an easy to access roofspace, do not have any damp problems and can move around easily in your loft, then insulating is one of the easiest DIY jobs you can do, and one that will save a lot of money too. Remember that if you have damp in a roof, or have a flat roof then you must get a professional assessment before any work is carried out and the work must be done by a professional.

The best roof insulation to use when attempting a DIY project is always going to be blanket material. Try to cover as much of the floor area as possible with this and finish off with loose fill insulation to top up in places that are difficult to reach.

Remember that although insulating your loft will make your living areas warmer, it will also make your roof space colder. This means that if you have any water tanks or water pipes in the loft, they will need to be insulated separately from the rest of the space before you insulate the floor or else the water inside might freeze during a cold winter. Another thing to remember is not to insulate underneath a water tank. Keeping this space clear will also help to prevent the tank from freezing. Do not just lag the water tank and pipes with the same insulation as the floor, buy an insulating jacket specifically designed for your make and size of water tank together with an insulated lid. You can also buy lengths of pipe insulation to suit the diameter of pipes. These can then be cut and fitted to each pipe and then fixed in place with plastic cable ties.

Remember that if you have a water tank or a television antenna inside your roof space you may need access to either one of those at some time in the future. If you don’t intend boarding out the entire loft floor, you should at least provide a walkway from the loft hatch to those two items. If you have laid the recommended depth of insulation (270mm) across the floor then you will need some way of raising the floorboards above the insulation. You can either lay extra joists onto the existing ones until they are at the required level or you can buy adjustable legs that fit the existing joists and provide support for the floorboards at the required height.  If you are fitting additional joists or flooring boards to the loft joists do not nail them into place, use screws of an appropriate length. If nails are used, the impact of the hammer onto the loft joists will be transferred through to the ceiling of the room below. This will cause the plasterboard nails to work loose and may also cause cracks in the ceilings below.

Remember when you are insulating the roof space to pay attention to the loft hatch as well. A colder loft will result in cold seeping through the hatch and cool draughts working their way around the edges of the hatch. Insulate the entire area of the loft hatch and fix draught excluders to the edges. If you have problems fitting the blanket insulation to the top of the hatch, it might be better to glue layers of insulation board instead

Where can I find a contractor to install the loft insulation?

If for any reason you cannot insulate your own loft, then don’t worry there are plenty of contractors out there who will be willing to do the job for you. All that is needed is to contact a reputable professional and ask for a quotation to do the work.

Contact the National Insulation Association (NIA) who have a register of approved insulation installers. Their members agree to abide by a code of conduct so that all their customers are guaranteed a professional standard of work and good customer service. Look on their website to find one of their members who lives near you.

If possible get the contact details on two or three and ask each one for a quotation to do the work. Choose the one that suits you the best. The installer will also be able to advise you on the best type of insulation for your situation so you get the best deal out of it.

To conclude

Insulating your roof space or loft is always going to be worthwhile. It will reduce your heating bills and make living in your home much more comfortable than before. Read this article again and see if it can be of any use to you when you decide to insulate your loft.

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