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Helping to reduce fuel bills and improving the comfort of your home
Before you start
First of all, you need to decide the thickness of insulation you will need for your loft. For new houses, the recommended depth for mineral wool insulation (fibreglass) in the Building Regulations is 270mm, although 300mm is commonly installed.
However, in existing houses (unless you are undertaking other home improvement works) you are quite free to decide what thickness of insulation to choose.
If you have no insulation in your loft, then installing 300mm could pay for itself in about 2 years through savings in your fuel bill.
If your loft is already insulated with 100mm (4 inches) of insulation, then laying another 200mm could pay for itself in about five years.
Once you have decided on the thickness of insulation then you need to work out how many rolls you will need. This is easy using our the Insulation Calculator.
Check your loft before starting the job
Pitched roofs constructed in the traditional manner, with no living space within, are referred to as “cold roofs” and are normally quite draughty.
This in fact helps to prevent condensation, and as you will make your roof more energy efficient by installing SuperLoft Blanket roof insulation, it is even more essential that there is ventilation of the loft over the top of the insulation.
This will ensure that you will not be creating future damp problems caused by lack of ventilation. Do not attempt to try to reduce the “draughtiness” of your loft once you have laid your insulation.
Before you start, make sure that the loft is free from any obstructions and trip-hazards.
What you will need
Make sure that the loft is well lit, so that you can see what you are doing. Then, even though SuperLoft Blanket completely encloses and entraps the glass wool fibres, it is sensible to wear a simple dust mask, since old lofts are normally dusty places, especially if there is existing fibreglass insulation.
You will need a sharp knife as it is likely that you will need to cut SuperLoft Blanket during the fitting operation, and in this instance, wearing protective gloves is recommended. Wearing safety goggles is always a good idea when undertaking DIY jobs in an enclosed space.
Whilst laying insulation, it is sensible to use temporary support boards which you may need to stand on – and make sure these are wide enough to kneel on, and are firm and stable, ideally spanning at least three joists.
Insulating the loft
Installing the first layer
SuperLoft Blanket is packed in compressed rolls which are lightweight and small enough to fit through even the smallest of loft hatches.
When taking the rolls into the loft before starting the job, it is best to place them on temporary boards spanning the joists, and not on the top of the plasterboard ceiling. When starting the installation, only unpack one roll at a time.
Lay the first layer in between the joists, starting at the eaves (where the sloping roof meets the floor of the loft). This is probably the most difficult part of the job, as it entails crouching into the eaves, where space is restricted.
It is also one of the most important parts of the job for two reasons. First, if all of the plaster ceiling is not covered by insulation, this may result in condensation and ultimately a line of black mould in the room below, where the outside walls meet the ceiling.
Second, it is important not to push the insulation too far into the eaves and block any gaps which provide essential ventilation in the loft space. A gap of at least 25mm should be enough to allow a good free flow of air in the loft space.
Slide one end of the SuperLoft Blanket into the eaves. Lightly press the insulation down between the ceiling joists and continue across the loft, unrolling the insulation as you move towards the centre of the loft.
Before you reach the eaves on the opposite side, cut the insulation. It’s always best to slide ends of rolls into the eaves, and not try to handle and cut rolled up insulation in the confined eaves space. It’s easier meeting-up two ends of insulation in the middle of the loft, where they can be cut to butt-joint into each other.
Carry on fitting the SuperLoft Blanket in this way across the rest of the loft. If there is a cold water tank in the loft, it is important to avoid insulating underneath this, as warm air will rise from the room below and help to stop the tank freezing in the winter.
Any electrical wires should be laid on top of the insulation to stop them overheating. Any light fittings penetrating into the ceiling and into the floor of the loft should have the at least a 75mm insulation-free zone all around them.
Installing the second layer
Once the whole of the loft has been insulated between the joists, you can now install the second layer, which should be cross-laid at right angles to the first layer, and across and covering the wooden joists of the loft floor.
Again, start at the eaves on one side of the loft, but this time you can fully unroll a SuperLoft Blanket roll across the loft and over the joists, as close to the eaves as possible. Then push and position the unrolled insulation so that its long edge is in contact with the wooden rafters. This second layer of SuperLoft Blanket should slide easily over the top of the first layer.
Continue fully opening rolls of insulation and slide them into position, so that the long edges of subsequent rolls are closely butted together, and cross-laid over the first layer. It is important that you work from the eaves and back towards the loft hatch, because you will no longer be able to see the wooden joists, which will make it dangerous to move about the loft.
Once you have laid a second layer from the eaves on one side of the loft to the loft hatch, repeat the process from the opposite side of the loft. You should finish at the loft hatch having completed the job, with the loft fully covered in the double-layer of SuperLoft Blanket.
If you need an insulated storage area in your loft
If you want to keep part of your loft to create a storage area, then you can install Insulated Loft Decking after you have fitted the first layer of SuperLoft Blanket.
If you are fitting a second layer of insulation, then this can be laid around the installed Insulated Loft Decking area.
See the separate area of our website for details of our Insulated Loft Decking and fitting instructions.