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How to Dot and Dab Like a Pro

Last modified: 08.08.2024
Prepared slab of Rockwool Dual Density mineral wool insulation with EWI Pro Premium Basecoat applied using the perimeter and dab method. This non-combustible insulation board, available at EWI Store, provides outstanding thermal and acoustic performance, making it ideal for use in high-performance EWI systems.

There are generally two approved methods for attaching plasterboard and insulation boards. For plasterboard, in particular, the dot and dab method is favoured by most. This method changes slightly for insulation boards as the attachment parameters change. The secondary method tends to be reserved for insulation boards, which we call full coverage. Both methods have their merits, and we'll discuss the process and benefits in today's blog.

Dot and dab are often referred to as drylining. In simple terms, it is a method for attaching plasterboard to a solid brick or concrete wall. The technique involved dabbing dots of adhesive across a wall surface and then simply pressing the plasterboard into place. Brick walls can often be uneven, but a layer of plasterboard can create a smooth surface quickly and efficiently. Crucially, it removed the need for wet plaster, which is far more time-consuming and more messy. The technique is only suitable for solid brick, block or concrete walls.

  1. Preparation: Apply a PVA sealer mixed with water to the wall. This prevents the bare masonry from absorbing moisture from the adhesive. Ensure the wall is clean, dry, and free of dust.
  2. Measuring and Marking: Measure the wall and mark where the plasterboard will be placed. This helps in cutting the plasterboard to the correct size.
  3. Cutting Plasterboard: Cut the plasterboard to the required sizes before applying the adhesive.
  4. Mixing Adhesive: Mix the plasterboard adhesive according to the manufacturer's instructions. Mix only enough for one board at a time to prevent it from drying out.
  5. Applying Adhesive: Using a plasterer's trowel, apply fist-sized dabs of adhesive approximately 10mm thick to the wall. Space the dabs about eight inches apart, ensuring they adhere firmly to the wall. The perimeter of where the board is placed also receives a layer of adhesive.
  6. Fixing Plasterboard: Lift the plasterboard and press it firmly onto the wall, ensuring it is level and evenly attached. Use a spirit level to check for straightness.
  7. Repeating the Process: Continue the process until all plasterboard sheets are fixed to the wall. Once dry, seal the joints between the boards and skim the wall to prepare for decorating.
Diagram showing correct dot-and-dab application of adhesive for plasterboard installation. Proper adhesive placement ensures strong fixing and reduces thermal bridging. EWI Store supplies a range of compatible adhesives and accessories for reliable internal insulation systems.

The dot and dab method varies slightly for insulation boards. Despite still being referred to as a dot and dab method, it requires a perimeter of adhesive around the insulation board. In contrast to plasterboard, the adhesive is applied to the insulation boards instead of the wall.

  1. Preparation: As with plasterboard, ensure the wall is clean, dry, and free of debris. Measure and mark where the insulation boards will be placed.
  2. Applying Adhesive: The key difference here is the pattern of the adhesive. For insulation boards, you must apply a continuous adhesive band around the board's perimeter. This creates a seal and prevents air movement behind the board.
  3. Dotting the Board: In addition to the perimeter band, apply adhesive dots evenly across the board's surface. Ensure these dots cover at least 40% of the board’s area. This provides sufficient bonding and prevents the board from bowing or flexing. There will often be 3 or 4 dots on an insulation board. However, when boards are cut smaller to fit into patterns, you'll use fewer dots across the board; the number is left to the installer's discretion as long as the 40% coverage rate is maintained.
  4. Fixing the Insulation Board: Press the insulation board firmly onto the wall, ensuring the perimeter adhesive creates a tight seal. Check for alignment with a spirit level and adjust as necessary.
  5. Securing the Board: For added security, mechanical fixings should be either hammered or screwed in. This step is especially important for thicker or heavier boards; however, we recommend it for all insulation projects. Wet and dry fixing insulation boards are always more secure and will ensure that there is no delamination due to the failure of one of the fixing mechanisms.
Close-up of mineral wool insulation board with fresh adhesive applied using the perimeter and dabs method. This technique ensures secure adhesion and thermal performance, ideal for fixing mineral wool boards in EWI systems. Available from EWI Store, our adhesives offer strong bonding and ease of use for all insulation applications.

The full coverage method does exactly what it says on the tin. A layer of adhesive, usually around 5-8mm, is applied to the whole back surface of the insulation board. A full coverage adhesive method is recommended to ensure the highest level of thermal efficiency and structural integrity.

  1. Preparation: Again, start with a clean, dry wall. Measure and mark the positions of the insulation boards.
  2. Applying Adhesive: Instead of dabs, spread a continuous layer of adhesive over the entire surface of the board using a notched trowel. The adhesive should be evenly distributed to avoid any gaps or air pockets.
  3. Fixing the Insulation Board: Carefully press the board onto the wall, ensuring full contact with the adhesive. Use a straight edge to smooth out any air pockets and ensure the board is fully bonded. We also recommend slightly sliding the board around to eliminate any spots of lower coverage or air pockets. The movement will equalise all of the adhesives and ensure a stronger bond.
  4. Securing the Board: As with the dot and dab method, mechanical fixings are used for additional security, especially for larger or heavier boards.
Application of EWI Pro Premium Basecoat to Rockwool insulation board using a stainless steel notched trowel. Available from EWI Store, this versatile and breathable basecoat ensures excellent mechanical strength and is ideal for use in mineral wool systems.

It's also possible to see the application of a full coverage method alongside a dot and dab method. The most likely scenario for this is the application of mineral wool; the surface of mineral wool boards can be fluffy. Therefore, the adhesive coverage layer acts as a smoothing parge coat and should be as thin as possible. This step is not essential. The patterns for insulation boards will look similar to the diagram below:

The dot and dab method for plasterboard is both efficient and cost-effective. It requires less adhesive than full coverage, making it a budget-friendly option. This method is quick to apply, allowing for rapid installation, which is ideal for large projects or tight schedules. The technique also provides some flexibility in adjusting the plasterboard position before the adhesive sets, ensuring a perfect alignment. Additionally, the gaps between the dabs allow for slight movement of the walls without cracking the plasterboard, providing a durable finish.

Applying dot and dab for insulation boards with a perimeter adhesive ensures a robust thermal barrier. This method significantly reduces thermal bridging and air leakage, enhancing the building's overall energy efficiency. The adhesive perimeter acts as a sealant, preventing moisture ingress, while the evenly spaced dots provide strong adhesion and stability. This technique is especially beneficial for thicker insulation boards requiring firm hold and stability, ensuring long-lasting performance.

The full coverage method for insulation boards offers maximum thermal efficiency by eliminating air gaps between the board and the wall. This ensures consistent insulation performance across the entire surface. Full coverage adhesive provides superior bonding strength, making it ideal for heavy or large boards that need strong support. This method also minimises the risk of moisture penetration behind the insulation, protecting both the board and the wall structure. While more time-consuming and requires more adhesive, the full coverage method delivers the best long-term energy efficiency and structural integrity results.