How to Install Celotex Insulation Boards

Celotex Insulation Boards Insulation King

If you’re familiar with insulation, you’ll know the name Celotex. Celotex insulation boards are a standout choice when it comes to creating a cosier and more energy-efficient space, and perfect for application in flat roofs, pitched roofs, solid masonry walls and more. Whether you’re a DIYer working on a home improvement project, or a professional looking for efficient insulation solutions, you’re in the right place.  

In this step-by-step and easy-to-read guide, we'll walk you through the process of installing Celotex insulation boards to get a successful installation every time. 

Getting Started  

Before you begin, you must have the necessary safety equipment such as gloves, goggles, a dust mask, and appropriate clothing to protect yourself during the installation process. Then, make sure you have all the tools you need for a successful installation.  

  • Celotex insulation boards 
  • Measuring tape 
  • Utility knife or saw 
  • Straight edge or spirit level 
  • Adhesive suitable for Celotex (if required) 
  • Fixings (screws, nails, or staples) 
  • Hammer or screwdriver 
  • Protective membrane (if necessary) 
  • Jointing tape (if required) 

Step 1: Measure and Prepare 

Start by measuring the area where you intend to install the Celotex insulation boards. Measure both the length and width with the measuring tape, and allow for any obstructions or irregularities in the surface. Be sure to accurately cut the boards to fit the space by using a straight edge or spirit level and a utility knife or saw. 

Step 2: Ensure a Clean and Dry Surface  

Before you start the installation, make sure that the surface where the boards will be placed is clean, dry, and free from any debris or moisture. A clean and dry surface is essential for maximum adhesion and optimal insulation effectiveness. 

Step 3: Fixing the Insulation Boards  

Place the Celotex boards firmly against the surface, ensuring they fit snugly together without any gaps. Check out our 90mm PIR T&G Cavity Wall Sheet Part Fill – 1200x450 or PIR Sheet – 1200x2400 Celotex insulation boards designed for optimal performance.  

You can fix the boards using screws, nails, or staples at regular intervals along the edges and in the centre as needed. Alternatively, you can use an appropriate adhesive.  

Step 4: Cutting and Fitting Around Obstacles  

For areas with obstacles like pipes, outlets, or corners, measure and carefully cut the Celotex boards to fit around them. Use a utility knife or saw to create precise cuts to ensure a tight and secure fit. 

Step 5: Sealing Joints (if required)  

If multiple boards are used and there are gaps between them, use jointing tape, like our Aluminium Foil Tape, to securely seal the joints. This prevents any air leakage and makes sure your insulation is performing at its best.  

Step 6: Adding a Protective Membrane (if necessary)  

In some cases, a protective membrane may be needed, especially in areas prone to moisture. Install this over the insulation boards following the manufacturer's instructions. 

Step 7: Final Check and Evaluation  

Once all the boards are in place, double-check for any gaps or loose fittings. Be sure to check that the installation is secure and effectively covers the intended area. 

Congratulations! You've successfully installed Celotex insulation boards and created a more comfortable and energy-efficient space.  

Final Tips: 

  • Responsibly dispose of any offcuts or waste materials 
  • Consider seeking professional advice or assistance if you encounter any difficulties during the installation process 
  • Always refer to the manufacturer's guidelines and recommendations for specific instructions regarding Celotex insulation board installation 


Remember, proper insulation plays a vital role in energy conservation and maintaining a comfortable environment in your home or building. By following these steps, you're well on your way to achieving efficient insulation for your space with Celotex boards. 

If you’re looking for expert guidance on Celotex installation or choosing the right Celotex insulation, get in touch with our experts today – we're here to help.  

DISCLAIMER: The contents of this guide are intended for information purposes only. Insulation king shall not be liable, answerable or accountable for any loss or damage resulting from the advice given 

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