21st Nov 2022 -

Loft insulation is a cost-effective way to reduce heat loss within a house, whilst saving hundreds of pounds a year in heating bills. If you opt to hire a professional to install your loft insulation, this can add significantly to the costs. Thankfully, installing your own loft insulation is completely within the abilities of a DIY enthusiast. 

In this guide from Building Materials Nationwide, we’ll explain how to insulate a loft using loft rolls within the floor joists, helping to save you money and keep your house warm. We’ll explain the tools and equipment needed, make some product recommendations, and walk you through a step-by-step guide to insulating an attic. While there are other options available to insulate your loft, such as professionally installed spray foam or using insulation boards attached to a pitched roof, installing loft rolls is the most popular method for a good reason, it is easy, affordable, and quick.

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Preparing to Insulate a Loft Room

The most popular way to insulate an attic involves laying rolls of mineral wool or sheep’s wool insulation between the wooden joists of your loft floor. Before you choose what insulation roll to buy, it’s worth checking what is currently in your loft room. You will likely have some insulation already within it and should be looking to have about 270mm total to properly insulate.

Decide Whether to Remove the Old Insulation

Depending on the quality of your current loft insulation, you can either add new insulation to it or remove it before starting. If your current loft insulation is of good quality, measure its height to establish how much insulation you will need to add to reach 270mm. You should also measure the distance between your loft joists, making sure it is consistent. If there are any boards currently fitted to your ceiling joists you will need to remove them.

Check for Wires and Pipes

Before you start work, you’ll need to check your loft space for both wires and pipes. If there are pipes or a cold water tank within your loft space, then you will need to insulate them using pipe insulation and a water tank jacket. Properly insulating your loft will make it much colder, so extra insulation is needed to prevent either your water tank or your pipework from freezing in the winter. 

If you have wiring within your loft space, it must be over your insulation, during and after the installation. The wiring can be clipped or attached to the ceiling before installation. If you cannot easily achieve this, you may need to engage an electrician to rewire your loft. You’ll also need to completely clear your loft of all debris and items before starting. If there is damaged or unsuitable insulation in your house you should remove it, using a Stanley knife to remove any fixings and binning the insulation. Wear a mask with a filter and gloves when handling any insulation. 

Check for Asbestos

If your home is older there may be some risk of it containing asbestos insulation. If you suspect the insulation in your loft is from between the 1920s and the 1980s, do not touch or disturb it. Instead, hire a professional to examine it and remove it. Do not put yourself at risk of handling asbestos.

Pick the Best Insulation for Your Needs

Once you've dealt with wiring and water tanks, cleared old insulation, and removed all debris, it’s time to pick a loft insulation roll. In terms of the type of insulation to buy, Thermafleece Supaloft Recycled Insulation Roll would be a great choice, properly insulating an attic whilst remaining completely safe to handle. Measure out the floor space of your loft, and from there establish how many rolls of Loft Roll you will need to purchase. If installing from nothing you will want to have two layers of insulation, one between the joists and one above that at a right angle. Bear in mind that you are going to need more rolls for the second layer, as there are no joists.

How to Insulate a Loft With Loft Rolls

Tools Needed:

  • Tape measure - Used to Measure your loft roll
  • Large serrated knife (Such as a kitchen knife) - Used to cut single pieces of loft roll
  • Panel saw - Used to cut a wider loft roll into smaller sections for joists
  • Wood offcuts - Used for cutting loft rolls
  • Downlight Covers (Loft caps) - Placed on your loft floor underneath insulation, to insulate over lights installed within the ceiling below. If you are looking to insulate an attic above recessed lights these are vital.
  • Your choice of loft insulation roll
  • Dust mask - To avoid breathing any dust or particles
  • Protective gloves - Mineral wools can irritate the skin when handled
  • Walk board - Balances over the joists to give you a safe space to work from
  • A head torch or hanging light - To allow you to see clearly within the loft

Installation Steps

  1. Get on your walkboard before starting insulation installation. This makes it easy to work within the loft and avoids putting pressure on the floor. Then, lay out your insulated downlights above the location of your lights on the floor below if applicable. Different insulated downlights have different instructions, but they must be placed below the insulation, to absorb the heat of the lights.
  2. To cut your loft roll to the size of your joists, use the tape measure to mark the needed distance, then cut using the panel saw and the wood offcut. If the loft roll you have purchased is the correct width you can simply roll it out.
  3. Lay out the correctly sized loft roll snugly within your joists, leaving a gap of about 25mm between the insulation and the walls (this is to allow ventilation and prevent condensation).
  4. Continue along your loft, cutting and inserting rolls. If a roll is too long, you can use your serrated knife and cut it to size on the wood offcut. You can place two pieces of roll next to each other, ensuring they are joined closely but not compressed. Using this method, cover the entirety of your loft floor, filling each joist whilst leaving small gaps by the walls.
  5. Any cross beams within the wall should be snugly bordered by insulation. The same is true of your loft hatch. Make sure not to compress your insulation, cutting it to exact sizes with your serrated knife. The same is true for any narrower joist widths.
  6. The second layer does not need to be as carefully measured, a full loft roll can simply be rolled at a right angle to the joists. Ensure all rolls are close together and cover your loft space.

This method should give you a brand new level of thermal insulation within your loft. If you are laying loft insulation on top of a previous layer, you can either top it up within a joist or build a second layer at a right angle over it. This will allow you to properly insulate your loft space.

How to Insulate a Loft Hatch

Firstly you should ensure that your loft hatch is a snug fit. If your loft hatch has a draught then the cold air from your loft room will have an easy path into your house. Insulating a loft hatch is a two-stage process, using foam strips to make an airtight seal, and then applying insulation to the top of the hatch. Use self-adhesive foam sealing tape to make a seal around the door. If the door swings down then the seal should be in your loft, and if it swings up the seal should be on the ceiling below. 

To insulate your hatch you will need to attach insulation to the top of it. This can be done using the same insulation rolls you used between joists. Simply attach a plastic bag firmly on the back of the loft door, either with adhesives or a staple gun. Stuff the bag with insulation and seal it shut. Alternatively, you can attach a piece of insulation board, or a layer of insulation foil to the top side of your hatch. It is worth both draught-proofing and insulating your loft hatch, as heat will escape into your loft room through both.

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Loft Insulation Supplies From Building Materials Nationwide

Now that you understand how to insulate a loft, you’ll need to source your materials to begin insulation work. Building Materials Nationwide offers a comprehensive range of loft insulation materials, with delivery options across the UK. We have a wide variety of branded loft insulation rolls, with products from KnaufRockwool, and Isover. We also sell a variety of accessories to help you insulate an attic, from pipe insulation to panel saws to PPE equipment. If you have a different type of loft, such as a flat roof, we have a huge range of roof insulation products, including vapour barriers.

For trade professionals, we offer exclusive trade accounts. Your trade account manager can walk you through the process from start to finish, offering tips to help make the project go smoothly. This includes recommending the right materials and tools for your specific loft layout and climate needs, as well as sourcing materials not stocked on the Building Materials website. Sign up for a trade account through our website today, or tell us what you need through the contact form below.

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