A Guide to Insulating your Attic

Whether you’ve bought a new home or have been living in your current property for years, it’s always worth checking if you need to get on with insulating your attic.

We all know that energy prices keep going up, but one of the biggest ways you can make savings with them is by ensuring you have the right insulation throughout your home, and the attic is a key part of that.

Not only does this help during the colder months, but it will during warmer weather, too, keeping your home’s temperature regulated and just how you want it.

Before insulating your attic

Before you start insulating your attic, there are plenty of things to think about. From the different materials you can use, the size and shape of your attic, if there’s any insulation already in place and much more.

It can become a big job, but there’s nothing to stop you from installing insulation in your attic if you plan ahead and figure out exactly what you need to do to get the job done.

Learning about insulation

The most important thing to know about insulation is the R-value and what that means.

Different insulation materials perform differently, and all will offer an R-value, normally in inches. Depending on the climate your home experiences, you’ll want to look to reach a certain total number of inches of insulation:

  • An R-value of 30 for hot climates
  • An R-value of 38 for temperate climates
  • An R-value of 49 for cold climates.

This is just a guide, and you can ask an expert for more accurate and local guidance on this matter depending on where you live.

How long it will take to insulate your attic

This will largely depend on the size of your attic, its structure and layout and the materials you plan to use. This kind of project is beginner to intermediate in difficulty, and here are some examples of the differences:

  • Floor insulation between joists
  • Attic insulation with oddly distanced and shaped areas between joists and frame
  • Floor insulation underneath existing floorboards and numerous electrical outlets to box off
  • Floor and wall insulation across the whole attic.

Once you know the area you’re working with, and what’s already in place, you can work out how long insulating your attic will take. This can take from 12 hours to over 100 depending on:

  • The size of the attic
  • The amount of insulation needed
  • What help you have
  • Any previous experience you may have.

The tools you will need

Safety is the first thing to consider when working with any kind of insulation material, as some of it can break into smaller particles and you don’t want to breathe them in or find them under your skin. There are some easy ways to keep yourself safe, though, but read through any and all instructions provided before using anything you’re not confident with.

You’ll find the following tools useful:

Choosing your insulation materials

The biggest decision you’ll make installing insulation in your attic is on the material you’ll use, and there are plenty of options here. There are two different insulation types, and then the materials you can get for each.

Loose fill

Loose fill insulation is packed in bags and can be distributed into gaps as needed, allowing you to easily control thickness and spread. Doing this manually can be quite labour intensive but you can hire machinery to do this evenly without much trouble.

Fiberglass is made from recycled glass or sand that’s spun into fibres. It’s lightweight but you’ll need more of it than other materials as it flattens a lot easier. It has an R-value per inch of 2.2 - 2.7.

Cellulose is made from recycled paper and turned into fibers. It’s treated for heat and insect resistance. It has an R-value per inch of 3.2 - 3.8.

Mineral wool is made from rock and slag materials and turned into fibers. It’s more expensive than other materials but has a natural fire resistance. It has an R-value per inch of 3.0 - 3.3.

Batts (or blanket rolls)

Batts insulation is available in roles of varying thicknesses, lengths and widths. You can easily cut them down to suit the spaces between the joists in your attic and they can be layered over other insulation. A lot also include a vapor barrier, which can take away another task for you to sort later.

Batts fibreglass is made from the same materials as the loose fill, and has an R-value per inch of 2.9 - 4.3.

Batts cellulose is also the same material as the loose fill version and has an R-value per inch of 3.7 - 3.8

Batts mineral wool is the same as the loose fill option and has an R-value per inch of 3.0 - 3.3.

Cotton insulation is made from denim cloth spun into fibers. It’s more expensive than other materials but impacts both airflow and sound. It has an R-value per inch of 3.7 - 3.8.

Steps to Insulating Your Attic

Once you’ve chosen your insulation material, and you know the space you need, you can get to work on insulating your attic, improving the heat regulation of your home and cutting down on those energy bills during the colder months.

Step 1: Clearing the attic

You’ll need:

For a lot of people, the attic is a storage space for things that aren’t needed all the time. It’s a good use of space, but this needs to be cleared before any insulating work can begin.

Clear out any boxes - or if used as a functioning room, any furniture and belongings - to reveal the floor space.

Remove most of the floorboards and flooring laid down, but leave enough to walk on and move around the attic. It’s easier to do this with steady, loose panels that you can move.

Step 2: Finding any leaks and gaps

You’ll need:

We’re insulating the attic to stop heat loss and manage temperature regulation. This will be affected by holes and gaps.

Check for any pipes and wiring moving from the property into the attack. Fill in holes with foam and sealant, depending on the size of the gap.

Check around vents and attic windows for other gaps and fill them in accordingly.

Fix any leaks before laying any insulation. Moisture and damp can react with different materials, and this should play a part in determining which insulation material you choose to use.

Step 3: Box off any electrical fixtures

You’ll need:

Depending on the material you’ve chosen, it might not be suitable to come into contact with electrical points. There is a solution to this, though.

Using small pieces of plywood, box off each electrical fixture. Leave about 3-inches around the fixture for safety.

This will stop any interference of the fixture, whether that’s light or something else, and reduce any risk of fire.

Step 4: Check what insulation you already have

You’ll need:

Before laying any new insulation, check what you already have. This will determine what you need to replace or add to reach the desired R-value.

Measure the gap between joists, and the depth of the joists, so you know what space you’re working with.

Measure how much insulation is already in place, and check for rot and damp. Any compromised insulation will need to be replaced.

It’s worth noting that you can place insulation higher than the height of your joists, if needed. This will affect any measurements you’ve taken, and will change how you replace floor boards once the installation is done.

Step 5: Installing loose fill insulation

You’ll need:


  • Loose fill blower

When using loose fill insulation, you can do this by hand or with a loose fill blower, available to rent from a number of local hardware stores and home improvement retailers.

Manually installing loose fill insulation is a long, labor intensive process, while the blower can help and ensure there’s an even distribution of insulation across the entire attic.

Before starting, install a vapor barrier below where the insulation will go to prevent moisture contaminating the insulation. This goes in between the joists and frame of your attic.

Start in the far corner and work your way back towards the hatch or attic access, filling in any space with insulation. If doing this by hand, take care to ensure it’s as even as possible and beware that some materials will flatten down and need extra layers added on top.

The advantage of loose fill insulation is that you can fill in any gaps, no matter the shape or size, without measuring or cutting anything to size. If you have a lot of odd spaces in your attic that require insulation, this is a good option.

Step 6: Installing Batts insulation

You’ll need:

Double check to make sure the blanket rolls are the right size. You might need to trim down the edges if the gaps between joists are narrow.

Once cut to size, you can start laying the insulation, vapor barrier side down. Start in the far corner and work backwards, always aiming to end up closer to the hatch or entrance to the attic than when you started. This stops you being stranded in the middle of the attic.

You might find some inner joists or connecting beams while laying the insulation. You’ll need to cut the roll at these points and start again on the other side.

At the end of each row, cut the insulation to fill the end and move onto the next one.

Repeat this process for all spaces between the joists.

Once this has been filled, you might find some oddly shaped areas around the eaves or corners. You can measure and fill these areas with the remaining batts insulation now that the majority of spaces between the joists have been filled in.

Step 7: Tidying up loose ends

You’ll need:

Once the insulation has been installed, you can clear up loose pieces or cut away parts that don’t fit properly.

This ensures a neat finish and helps when laying floor boards back down. Loose insulation is a hazard if inhaled, so make sure to continue wearing a mask until the work has been completed and tidied.

Once the flooring is secured, you can return boxes, furniture and belongings back into the attic and it will continue as a storage space or functional room as needed.

You can then reap the benefits of an insulated home and see the benefits in your energy bills!