Any DIY enthusiast ought to be able to lay loft insulation but there are some safety considerations that you must be aware of first. For the purposes of this article we’re going to assume that the insulation being laid is a mineral wool, glass wool or natural wool roll (sometimes called a quilt).
There are other forms of insulation. Blown insulation is a foam that is forced in by a blower, but this must be installed by competent contractors. There are granules that can be laid between the roof joists and also solid boards that are cut to fit. But by far the most popular and easiest insulation to fit is the blanket or quilt type that comes in rolls.
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Types of Loft Insulation Quilt
There are three main types of blanket or quilt insulation. They are all referred to as ‘wool’ but only one is actual wool and it’s usually labelled ‘natural’ wool. This is the preferred choice for those who want to use natural products throughout the home but it does cost more.
Mineral and glass (actually fibreglass) wools are extruded into a format that looks like wool, hence the name. These are both highly irritating to the skin and throat so it’s vital to cover up and wear gloves and a mask. Disposable overalls are a good idea
Preparation for Laying Loft Insulation
Get up into your loft and take a look around. You’ll need good access to the roof void to lay quilt insulation, particularly in the areas between the joists, as this is where the insulation will be laid. Clear away any obstructions or debris between all the joists and if you’re thinking of boarding the loft, do it after the insulation has been put in.
Get a plank or board up in the loft and put it down across the joists. This is for you to kneel or lay on while laying the insulation. The joists should take your weight but if you rely on them alone you will inevitable slip and put your foot through the ceiling. So use the plank or board, moving it around to suit.
Fitting Insulation in the Joist Gaps
Most rolls of loft insulation are made in widths to suit most joists but if your house is over forty years old you may not have standard, or even regular gaps between the joists. The wool can be split quite easily just by pulling it apart, so you can make it fit any width and any length.
Some loft insulation comes in long rolls which makes them easier to transfer between the DIY store and the car, and mean fewer trips up into the loft. These are marked with standard joist widths so that you can separate the rolls into smaller rolls of the correct width once you are up in the loft. Of course, pushing all this work onto you makes it cheaper for the manufacturers too!
Laying Loft Insulation
Laying loft insulation is simply that: laying it down, there are no fixings. Start from one end and work toward the loft hatch, then do the other end and work back to the hatch again, leaving the area around the hatch till last.
With each roll push the end of the insulation roll into the eaves but not right up to them. It’s vital to leave a ventilation gap to prevent condensation build up in the roof void, which can lead to rot and structural problems.
Then unroll the insulation until you reach the other end or the roll finishes, in which case just start a new one. Don’t stretch the insulation to make it fit as this will decrease its efficiency. Just tear off a small strip to fit on the end instead.
Water Tank Warning
When you get to any water tanks place insulation all around them and on top but DO NOT lay insulation underneath. The tanks need the heat rising from the house below to stop the water freezing in cold weather.
Take it Easy
That’s it. A fairly simple job but it can be a bit messy and take a long time, depending on the insulation you choose and how straightforward your loft space is. Just make sure that you wear all the right protective clothing and take plenty of rest stops. It can get very hot up in the roof void.
These days it is recommended to double-layer the insulation (cross lay) to get up to modern u-values. You can also find encapsulated loft insulation which makes the whole job less irritating.