How to Insulate your Roof

In this video, you will learn how to insulate a roof using wool.

If you are using glass wool, then be sure to equip yourself with the following:

Protective gloves,

A safety mask,

Suitable eye protection

Here, we will be using a bio-based insulating material.

To carry out this job, you will need:

A tape measure

A pencil or felt-tip pen

A reel of construction or string line

A manual or electric saw

A drill driver with screws suitable for plasterboard.

And some cutting pliers.

You will also need:

Some insulation boards,

Some rolls of vapour barrier,

Metal studs

Stud to timber connectors,

Flexible watertight sealing tape,

And double-sided adhesive tape.

This installation is done in three steps which we will outline for you.

Step 1: Preparation

In this example we will be using the sloping rafters of the roof as the basic structure for the installation.

We are going to fix timber connectors onto the rafters, onto which we will then construct the framework which will hold the insulation boards in place.

Begin by marking the points at which you will fix the connectors along the first rafter.

Start a few centimetres from the base of the first rafter, space out your markings every 50cm until you get to the top.

Then do the same along the last rafter.

Measure the width of two layers of insulation boards: here this comes to 28cm.

Position the connector on the rafter

placing the connector notch at the specified measurement.

To make sure the connector is held in place correctly, be sure to screw it in at two different points.

Drill the connector on the highest marking made on the first rafter, then fix another on the lowest marking

Do the same for the rafter on the opposite end of the roof.

Then wind the construction line around the four connectors.

Make sure the line is taught.

Position the other connectors at 50cm intervals along the rafter.

Make sure that their notched edge sits level with the construction line,

And fix them to the rafter.

Do the same for the rafter at the opposite end.

Then remove the construction line.

Next, prepare the installation of the connectors along the middle rafters.

Tie the line between two level connectors,

And fix a connector on every other rafter.

Bring the construction line up to the next level of connectors and continue fixing them on alternating middle rafters so that they are arranged in a staggered, or quincunx pattern.

Take care not to injure yourself on the timber connectors.

Your connectors are now all correctly arranged. You can remove the construction line.

Step 2: Installing the Insulation

The insulation is installed in two successive layers, with a recommended total thickness of at least 20cm.

Measure the distance between the two rafters to give the width to which you will need to cut the insulation boards.

Then measure the height of the surface area you are covering so that you will know how many insulation boards you will need.

Transfer these measurements directly onto your insulation boards, adding 2cm.

This 2cm margin will allow you to press in your insulation boards with a snug fit.

Cut your insulation boards down to size with the help of an electric saw, following the markings you made previously.

For glass wool, a manual saw or box cutter will suffice.

Place your first layer of insulation between the rafters

You can fill up any empty gaps with cut-off scrap pieces of insulation

Next, take the measurement of the total width of the area you are insulating.

Transfer the measurement onto the metal stud.

Cut the stud down to this size using a pair of cutting pliers.

Clip the stud horizontally along the connectors

Then position the second layer of insulation, this time, running horizontally, behind the metal stud.

Step 3: Installing the Vapour Barrier

To complete your installation, we are going to add a sheet of vapour barrier.

This is used for damp-proofing and helps control the migration of vapour into the home.

Start by laying some double-sided, moisture-resistant adhesive tape along the metal studs

Place the double-sided tape on alternate studs.

Measure the height of the space to be covered.

Add 15cm to this length both above and below to ensure that the barrier covers all joints and angles well.

Now, cut the vapour barrier.

Stick the barrier to the double-sided tape, starting from the top.

Make sure that the vapour barrier is kept taught.

Then join up the strips of vapour barrier using the watertight sealing tape,

Now you know how to insulate a roof.