I want to cover up some exposed plain, clean, brick internal walls with 4.5mm fibre cement lining sheets
Q. Is using liquid nails a suitable method or do I need a drill/plug/screw fitting also ?
grateful for any feedback / advice please
Welcome to the Bunnings Workshop community @TS. It's fantastic to have you join us, and many thanks for your question.
It's recommended to run a timber batten system over your brickwork that is glued and screwed into position. The battens need to have a max centre of 450mm. You can then hand nail the sheets into position with 2.8 x 30mm fibre cement nails at a spacing of 300mm between fixings. Here's the installation guide for HardieFlex.
A timber batten system is recommended as it allows you to compensate for any variation in the bricks, ensuring that where two sheets meet, they are flush. It's also recommended to have fixings every 300mm, and the timber battens allow you to place those with ease. I note you have a door on that wall and presume you want to fix it directly to the wall so the sheeting is not proud of the door's frame.
I'll include an installation video for a 6mm board below. It shows a method you could use to fix the sheets directly over the bricks. An issue you might run into is being able to countersink the screws below the sheet's surface. As you are using a 4.5mm board, countersinking the screw head fully would likely compromise the board to some extent. This is another reason why nails are preferred.
Please let me know if you need further assistance or have questions.
Thanks for getting MitchellMc
The problem doing that way with battens is that the sheets would sit too proud off the wall and up at the ceiling they would be over the top of the 10mm corner coving moulds
I don't think Liquid Nails will be the best choice for that job. It would work out better using a plaster adhesive (which is also suitable for fibro-cement) designed for drywalls such as Gyprock CSR Drywall Masonry Adhesive
The method is shown and explained well on this video:-
Put small daubs close together so that you don't get large hollow sections in between the daubs.
In case you are anyone else hangs things on the board, you should also nail it (about 300mm apart, as it would be if you had used battens) using masonry nails into the mortar joins (not the brick). It's best to do this as you go, or else mark clearly where the mortar is behind the board so you can do it later. Drill a hole smaller than the nail diameter into the mortar (therefore, through the board) using a small masonry bit. Start the nail by holding it with pliers for as long as possible to absorb excess shock, otherwise it may bend.
(To prevent hammer head dents use a piece of flat board between the nail head and hammer at the end, to finish nailing it in flush to the wall, then nail punch it to hide the head.)
If the nail hole doesn't drill clean and becomes too big, you can fix it by pushing matches or twine into the hole to fill it up then nail into that, - or just drill another hole nearby and fill the extra one.
I hope that gives you the enough clues to do the job....
And I hope you will post pics of the finished project... and any further practical tips that you discover along the way.
Many thanks for the tips / direction given
I will make a start on Sun and post