How to use backer boards

What is a backer board?

Traditionally you have would have used either plasterboard or plywood as your substrate when tiling wet areas in your home.

But in recent years these have been replaced by cement-based backer boards. They have proven to be the perfect base on which to tile in your bathroom or kitchen thanks to their waterproof qualities and the fact that they don’t need to be treated before tiling your floor or wall.

They can also hold more weight, in terms of your adhesive, grout and tiles, compared with other popular surfaces such as plastered walls, plasterboard or Wedi boards, up to 10 times more in some instances.

What are the weight limits for wall substrates?

Gypsum Plaster – up to 20KG/m2
Gypsum Plasterboard – direct without a plaster skim up to 32KG/m2
XPS Boards (Wedi) – up to 120KG/m2
Cement Boards (HardieBacker) – up to 200KG/m2

Our favourite at Tile Warehouse is HardieBacker. Not only are they easy to install but they can be fitted directly onto a stud wall or onto a wooden or timber floor.

They have been ingeniously designed thanks to products such as Portland Cement to make them all-weather resilience. These give HardiBacker unique characteristics such as resistance to fire and water damage well as rotting, warping and UV – making them far more longer lasting than other brands. As a bonus, they come with a 10-year limited guarantee.

HardieBackier Board

How to fit backer board to floorboards

The ideal support for floorboards is the 6mm HardieBacker boards (although you can use a 12mm boards if additional height is required).

The HardieBacker should be installed onto a clean and smooth surface, so make sure to remove any debris or dust. Also remove or fix any floor damages such as uneven, warped or loose floorboards. To avoid excessive movement, which can lead to tile cracks, we would also recommend using a 15mm WBP plywood or an 18mm T&G flooring grade chipboard.

The board joints should be staggered in a brick pattern and should not align with subfloor joints. You will find that the boards can be easily scored and snapped using a HardieBacker scoring knife. If there are any gaps of 3mm or more between the wall edges and the floor these should be filled with a moisture resistant sealant.

Then simply apply a gap filing bed of tile adhesive using a 6mm notched trowel and slowly embed your boards into the wet adhesive with a sliding motion. The boards will then need to be fixed to the subfloor using a minimum of 12 screws into the board (4 rows of 3). And, wherever possible try and keep your screws 15mm from your board edges and 50mm from board corners. Alkaline-resistant tape should also be placed over the joints.

The last thing you will need to do before you start tiling is to prime the face of the board with a suitable primer if you are planning on tiling using a cement-based tile adhesive.

How to fit backer board to masonry walls

The good news is that both 6mm and 12mm HardieBacker cement boards can be used on masonry walls. Plus, as previously mentioned, they can take up to 200kg of tile hanging weight per m2 so almost any tile can be fixed.

The backer boards should be installed onto a clean and smooth surface and all dry lining removed prior to installation. Place three vertical beads of high strength adhesive evenly down the back of the board and press firmly against the wall.

The board joints should always be staggered in a brick pattern and fastened with 9 (6mm x 60mm) stainless steel screws into brown wall plugs. Ensure you do not overdrive the screws and the screw remains flush with the front of the board. Once secured cover the joints with an alkaline resistant tape.

Just like the floor, prime the face of the board with a suitable primer if you are planning on using a cement-based adhesive. No priming is needed if you are going to be using a ready-mixed adhesive.

Prime Time

How to fit backer board to plaster or plasterboard

The process for boarding onto plaster or plasterboard is very similar to masonry walls – with a few slight differences.

The first thing to do is locate any existing studs and mark the plasterboard or plaster. The boards can be installed either vertically or horizontally as long as you ensure all vertical joints are made in the centre of the studs.

Make sure to leave a 3mm gap between the floor and wall edges and fill this with a good quality silicone sealant. Then fix stainless steel screws (a minimum of 45mm in length) at 200mm centres and every 200mm down each stud. Once secured, cover the joints with an alkaline resistant tape.

Don’t forget to prime the face of the board with a suitable primer if you are planning on using a cement-based adhesive. No priming is needed if you are going to be using a ready-mixed adhesive.

How to fit backer board onto stud walls

We would recommend using 12mm HardieBacker boards when fixing tiles to stud walls. The backer boards can be installed either vertically or horizontally ensuring all vertical joints are made on the centre of the studs. Don’t forget to leave a 3mm gap between the floor and wall edges and fill this with a good quality silicone sealant.

Then fix stainless steel screws (a minimum of 45mm in length) at 200mm centres and every 200mm down each stud. Once secured, cover the joints with an alkaline resistant tape. Don’t forget to prime the face of the board with a suitable primer if you are planning on using a cement-based adhesive. No priming is needed if you are going to be using a ready-mixed adhesive.

Backer board in wet rooms

Thanks to its all-weather resilience products such as HardieBacker can be used in wet rooms. However, prior to applying your backer board you will need to tank the area using either a liquid membrane or a matting system to ensure it is fully waterproof.

Factor Beige

Need more information?

If you have any questions regarding selecting the right tiles for your home, then feel free to contact our Customer Services team using our web chat facility.