How to Install Insulation in a Loft to Save Energy

✔️ Why You'll Love This Project

Here are a handful of reasons why we think you'll enjoy installing your own loft insulation:

• It's cheaper to install your own loft insulation than hiring out
• By improving your EPC rating, you can be eligible for some UK government grants
• Improving the energy efficiency of your home, it will save you money on your energy bills
• Prevents heat loss for comfort and less energy consumption
• Should help keep your home warm in the Winter and cool in the Summer
• It's fairly easy to install, but expect manual labour

UK Grant Benefits:

By upgrading your EPC, for example increasing your mineral wool insulation to 270mmm (which is current building codes for new builds), we knew this could increase our chances of being eligible for a ground source or air source heat pump grant.

These grants can be means tested, but even if this rules you out, it is still worth increasing.

⚒️Tools and Material Notes

You can refer to my shorter printable guide in the how-to card at the bottom of this post. However, I recommend reading the entire post as I have more detailed tips, tricks, and step-by-step images.

Please note that as an Amazon Associate, I earn from qualifying purchases made through affiliate links.

• Tape measure - we used a laser measure for quickness and ease to find out what size square metre we needed to cover
  
• New insulation rolls - We used Knauf's 100mm bottom layer to fit between the joists, and 170mm or 200mm top layer that sits on top of the joists in the opposite direction
  
• Crawl boards - these are very small loft boards which are light enough to carry and move around to areas you're working in, or any small strips of 18mm thick wood
  
• Silicone sealant - this is for sealing up air leaks, gaps and holes around plasterboard joins, cables or pipes. Or you could use expanding foam
  
• Hand saw - to cut up the loft insulation rolls still within their packaging to cut down to the width of the joists
  
• Foam pipe insulation - this is to cover your pipes and prevent freezing if you haven't done so already, fixed with cable ties
  
• Attic lights - or other worklights, head torch or a battery powered LoftLeg light bulbs to see where you are going
  
• PPE - safety equipment and protective clothing such as goggles, gloves, face mask, boiler suit and knee pads are vital as fibreglass insulation is very itchy and can irritate the lungs

📋 Step by Step Instructions

1. Calculate how many loft rolls you need: measure the area of your attic space to determine how much insulation you will need.

I measured mine in 2 stages - one for the 100mm and one for the 200mm top up on any existing insulation.

• Width x Length = sqm
• ÷ by the roll's sqm coverage
• = how many rolls you need

2. Choose the insulation type you prefer: There are different types of insulation material such as mineral wool, glass wool, sheep's wool, eco friendly, etc.

We opted for Knauf's glass wool which has a higher R-value than fibre glass.

3. Prepare the loft: Clear the loft of any debris and remove any old insulation if your budget allows.

Then seal any gaps and holes near pipes, electric cables and plasterboard joins with silicone sealant to prevent heat loss.

4. To fill any areas with no insulation, you must fill with 100mm base layer to the same height as the joists.

Use a tape measure to determine the width of your joists (note that not all are the same).

Transfer the measurement onto an insulation roll without removing the packaging and hand saw it to your desired width.

5. For the first layer, place the base layer between the joists.

Repeat for the rest of them and fill any cavity walls where you need they need extra.

You will need to squish bits in for double joists close to each other where the gaps are very small.

Also, ensure your insulation meets the cavity wall insulation in the eaves, but ensure there is still a 50 mm gap between the insulation and the roof for proper airflow.

6. For the top layer, starting around the eaves, lay at a right angle, in a straight line, running in the opposite direction to the bottom layer.

Where possible, try to slice notches out of the attic insulation with a Stanley knife for the rafters.

Important points: Use light covers over a light fitting to prevent overheating.

Avoid adding insulation under the cold water tank as any heat rising in this area can prevent it from freezing.

⚖️ Project Variations

Here are some different loft insulation ideas you can do:

• Hire a professional installer: tackling this job requires an element of fitness, so you may prefer to hire a professional to do it instead
• Use a thermal camera: find cold spots in your house, and add extra insulation where needed
• Loft hatch insulation: make a DIY insulated loft hatch box as been here
• Different levels of insulation: You can choose to install different levels of insulation depending on your needs and budget. For example, you can install an even thicker layer of insulation for better energy efficiency.
• Different methods of installation: There are several methods of installation available, such as blown-fibre insulation, but always check with a professional as this can cause condensation or fiberglass batts, etc
• Insulating other areas of the house: our EPC assessor said most of a home's heat loss escapes through the roof. Once you've completed this, you could insulate your floor like this

🦺 Safety Tips

• Protective clothing: Always protect yourself while handling loft floor insulation, such as gloves, goggles, and a dust mask to protect yourself from insulation fibres and other debris
• Safe access: Use a sturdy and secure loft ladder to access the loft safely
• Use boards or plants: Use crawl boards as much as possible to prevent any accidents
• Working with a friend: If possible, work with a partner or friend to ensure to speed up the job as it can be tiring

⚡ Care and Maintenance

Check for damage: Inspect the insulation regularly for any signs of damage, from water, rodent droppings etc, and replace it where possible

Avoid compressing the insulation: Do not compress the insulation by placing heavy objects or boards. By compressing, it will reduce its effectiveness as air can't be trapped in the fibres

Ensure proper ventilation: Ensure that the loft is well-ventilated to prevent the buildup of moisture or harmful fumes and gases

Check for dampness: Check the insulation for any signs of dampness or moisture, which may not dry out and cause mould

Replace old insulation: If your insulation is very old, note that it may be worth replacing as it could be less effective

❓ FAQ

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