There are many different ways in which an insulation board can be fixed to a wall. The method that will work best for your property will depend on the chosen insulation material. When choosing an insulation material, it is essential to take into account the wall structure and building regulations as well as your budget. Some materials will be much cheaper than other materials.
What is a Masonry wall?
When applying insulation boards to the wall, all finishing such as skirting boards and wallpaper will need to be striped back to expose the masonry wall. Masonry is a term used for construction that uses mortar as the binding material, an example of this is bricks, concrete, stone, and so on. A masonry wall is generally going back to walls foundation. Starting at the masonry wall ensures that there are no pre-existing issues that are being built upon such as cracks, rot, or mould. When properly done, it will also prevent issues developing in the future.
Dot and Dab
The Dot and Dab method is constructed by applying adhesive to the back of the insulation material and applying them directly to the masonry wall. It is a much easier method than applying timber battens to the wall, the adhesive can be used to fill irregularities on the surface however timber battens may be difficult to apply to walls that appear uneven.
Prior to applying adhesive ensure the board is cut to size taking fixtures and fittings into consideration. The board can also be placed against the surface before fixing it to the wall to ensure the fit is accurate. A spirit level can also be used to confirm the walls is straight and level. If the wall is uneven, adhesive can then be applied in the necessary areas to help create a level finish.
To fix insulation boards to a wall using this method, start by applying a continuous band of adhesive with a 15cm thickness around the perimeters and down the centre of the first board. This will coincide with adhesive applied to the walls.
Apply the adhesive the wall in 3 vertical rows with each dab 50 to 75mm wide and 150mm long. Covering a minimum of 20% of each boards surface area. The boards should be fitted starting at the inner corner of the wall. When applied and the adhesive has set, secure the boards with 6 mechanical fixings per board. One fixing in each corner and one on two edges. Do not bridge board joints using adhesive.
Below is a video explaining how to install insulated plasterboard
The dot and dab method is not suitable if:
- The surfaces are at risk of moisture penetration
- Applying to timber frame construction
- Applying to steel frame construction
- If you do not have cavities in the wall
Timber Frame Method
The timber frame method is constructed by applying timber battens to the masonry walls and inserting the insulation boards or batts into the frame. It is a much sturdier method than applying adhesive to the walls and waiting for them to dry. It also means the insulation material is cut into smaller sizes for easier application.
To fix insulation boards to a wall using this method, start by ensuring the wall is clean and dry. Fix battens around the top and bottom of each wall. Be sure to apply a batten to each corner and around window and door frames. Then, fix the battens vertically around the room at a minimum of 600mm centres. When approaching the window, continue to apply the battens in 600mm minimum centre above and below the opening.
This method can be applied when using:
- Insulation boards
- Insulated plasterboard
- Mineral wool
When applying either insulation boards or batts, cut the insulation to size and insert all the way back to the plywood sheathing or masonry surface. Continue until the entire frame has been filled. Ensure the boards are fit flush to the frame with no projections. Use any cut offs to fill gaps left within the frame.
Install a vapour control later over the front of the entire frame – the warm side of the stud work. Lastly, fix plasterboards or insulated plasterboards over the vapour control layer using the required fixings. Ensure the fixings are applied in line with the timer frame and each board is joint at each frame tightly butted together.
Seal any gaps with sealant such as around the perimeter of the floor. Use mesh tape and fill on all boards joins and allow time for the fill to dry. Then go on to apply wall finishings and fixtures.
Always place the unprinted foil facing towards the masonry wall with the printed side facing outwards towards you as you install.
Take into account all fixtures and fittings when installing timber battens and cutting insulation boards or batts such as lights and sockets.
Ensure all boards or batts are tightly butter together when joined.
When applying plasterboard or insulated plasterboard use lifting wedges on the floor.
See the below video on installing mineral wool batts:
Applying PIR insulation boards over timber battens
Insulation boards can be applied over the top of timber battens. Once the battens have been secured to the all edges and corners and at regular vertical intervals around the room, the insulation can be applied. Ensure the battens vertically fitted around the room are in the ideal place for two boards to be joint tightly butted together and fixed at the timber batten.
The boards can then be cut to size if required and fixed to the battens. Ensure when joining boards, they are tightly butted at the centre of the timber battens.
When insulating your walls, always consult a building professional or architect to ensure the correct product for your property is being used in the correct method. You may also require approval when insulating a property. This should also be checked and confirmed prior to installing.