Hi @Hyun,
To install skirting boards to brick, you can simply use an adhesive such as Liquid Nails, however it will not be as strong a hold as if you used both an adhesive and screws.
Your best bet is to use countersunk screws as well as liquid nails.
You can install the screws by cutting your skirting to size and dry fitting it against the wall. Use a 3mm Drill Bit to put a pilot hole through the skirting board and mark the surface of the wall. You can then use a masonry bit to put a hole in the brick where the drill bit has marked and insert a wall plug.
You should then use a countersink bit to countersink the pilot holes in the skirting board.
Once your plugs are installed and the skirting board is ready to go, apply Liquid Nails to the back of the skirting board and screw through the pilot holes into the wall plugs.
Ensure the screws are embedded so that the head sits below the surface of the timber, then cover them up with Spakfilla. Once dry, give them a sand, seal the top edge of the skirting board with No More Gaps and then paint.
This will give you an aesthetically pleasing finish, which will be held strong to your double brick wall.
Let me know what you think and if you have further questions, please don't hesitate to ask.
Jacob
