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Problems with Roof Insulation

Installing insulation in your house is one of the most effective ways to save energy and make your home more efficient. With the cost of power continually rising, insulating a loft or roof space could save up to £175 per year on heating bills, as well as making your house warmer and more comfortable.

The government is keen to encourage home-owners to implement energy saving measures into their properties and provides grants through energy companies to help with the cost of things like roof insulation.

You can insulate your roof without a problem if you have good materials and access.

With good access to your loft and the right insulation materials you can insulate your own roof.

Their Carbon Emissions Reduction Target (CERT) states that any insulation, whether fitted in a new home or retro-fitted in an older house, should be at least 270mm thick.

If you have some insulation already, rather than replacing it, you can add extra layers to bring it up to the required thickness.

An un-insulated house can lose up to 25% of its heat through the roof, so it is clear that good insulation in the loft will have a positive impact on the efficiency of a home.

However, roof insulation is not without its problems both during and after the installation. Whether you are having it professionally installed or you are taking on the job yourself, there are several pitfalls to avoid in making sure that the insulation is at its most effective.



If you have a relatively new house with good access and a regular beam structure, laying insulation should be an easy job. Rolls of mineral wool insulation, which can be bought from most DIY shops, are the most common type of loft insulation and can be rolled out between beams to the recommended thickness.

If access is difficult or the beams form no consistent pattern, it may not be possible to use roll insulation and you will have to consider alternative options.

If you are unable to get into the loft you should contact a professional installer to insulate for you. They can use specialist equipment to blow insulation materials such as cellulose fibre through pre-drilled holes and into the roof space.

If you can gain access, but the beams are irregular and there are different sized gaps between them, loose-fill insulation is another option. Generally made up of cork granules, cellulose fibre, mineral wool and vermiculite, loose-fill insulation can be bought in bags from DIY shops and poured into the spaces between beams.

It may be difficult to meet the minimum thickness requirements if the beams are shallow, and you may need to supplement loose-fill with extra insulation using rigid boards or roll insulation.


Using a Loft for Living Space

If a loft is to be used for storage or living space there are other considerations to take into account before commencing the installation. Thick insulation may make it difficult to see the beams, and for safety purposes it may be necessary to lay wooden boarding for ease of access.

For a living space in a loft use  pre-insulated wooden boarding to increase the overall thickness

Pre-insulated wooden boarding helps to create a living space in your loft.

This may mean that the insulation between joists is not thick enough; if this is the case, you can use rigid insulation boards or pre-insulated wooden boarding to increase the overall thickness.

If it is a complete conversion and the loft is going to be used as an extra room, it is better to fit the installation to the rafters of the roof rather than to the loft floor.

Rigid insulation boards can be fixed directly to the rafters and then covered with plasterboard. It is important to cut the boards to size so they fit snugly between rafters, and you may need to use insulated plasterboard to reach the required 270mm thickness.


Flat Roofs

It is not usually possible to fit insulation underneath a flat roof, and it is much more common to use rigid insulation boards to insulate from above. These can be fitted to the timber roof surface or the existing weatherproof layer, with another weatherproof layer fitted on top to protect it.

This will prove more costly than standard loft insulation, so it may be best to insulate when the roof is being repaired or replaced anyway.


Damp and Condensation

If fitted correctly, loft insulation shouldn’t cause any particular problems with damp or condensation, but there are a few points worth noting. Any airbricks in the walls should not be covered, and there should be plenty of natural ventilation to avoid condensation.

If you have a water tank and water pipes in the loft, these will also need to be insulated. They are usually prevented from freezing by the heat rising from the house, but once you have stopped the heat escaping by insulating, there is a risk that the water will freeze.

A professional installer is responsible for insulating your water tank and pipes when they carry out the work, but if you are doing it yourself don’t forget to take measures to protect your water supply.



You might have electrical cables running through the loft, and these could present an overheating hazard if the insulation is laid on top of them. While most standard cables will be unaffected, the power supply for an electric shower for example, might carry a load of 30 amps or more and should not be covered with insulation materials.

An installer should re-lay the cable over the top of the insulation if possible, or cut a trench in the insulation if there is not enough flex to run it over the top. Equally, any light fittings which protrude into the loft space should have a gap of approximately 2 inches cut around them to prevent overheating.



Insulating a loft is a very effective way of reducing heat loss and saving money on energy bills. Current government standards recommend that insulation should be at least 270mm thick, and if you already have some insulation you can simply top it up to meet the requirements.

The potential problems range from poor access and irregular joists which make the installation difficult, to issues with damp and condensation if the insulation is badly installed and blocks the loft’s natural ventilation.

Using a professional fitter should counteract any of these problems as they are responsible for ensuring that the insulation is properly installed, but don’t be afraid to go up into the loft and check their work to make sure you are completely happy with it

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