This is one of those projects that every house and every situation will be slightly different. From size and placement of the wall to the actual wood being used. Ours was originally a wall that use to be an outside wall when the house was built over 100 years ago. But over time previous owners have added to and eventually a full conservatory has been added, and it is now our turn as the most recent owners to add to it. So we removed the exterior of the wall (which was rough cast) back to the studs, their also use to be a window there hence the such a large space between the studs.
There i it laid in this state for more than 3 years, and my honest advise is not to let it stay in this state for this long... but but there is not matter you have a little bit of planning involved, what style of wall you are after, and at what stage you are already at.
We had already done the removal of the old wall and just had a little tidy up or touch up work to do. We had to make sure that the rough cast was fully removed and that the metal plating was not going to interfere with the new wall so some final grinding and removal of old material was involved.
The next step was to make sure we had area to attach the ply wood to... this involved adding in a stud and a couple of dwangs so we can screw the sheet of ply to. We used the lowest grade of ply you can get it does not need to be anything special and or does not need to construction grade. These are classed as top sheets of ply used to protect the rest of the goods on a pallet etc. The reason we can get away wit this is because we have not removed any supporting studs or beams we only removed the cladding and re adding cladding with new material.
Once the ply was put up we started the slower process of randomness ... this believe it or not is not as random as it looks and some thought has to go into it. To give it the random look you have to semi plan ahead and make sure nothing is repeating to much you also have to make sure that you don't repeat or over lap to much, but saying this a little is okay to give the random illusion.
Each row is 90mm high. Make sure that your first row is level and and that you random pieces are all the same height when you glue and or brad nail into position. We found that whilst they were sold as 90mm the could range anywhere between 88mm to 92mm the all need to be the same.. I had to re-mill all each row to the same level (I didn't show this in the video but mentioned it)
if you get your first row level(ish) and slowly working your way up keeping it level(ish) you should be fine you as you can hide gaps easily from the average eye level with larger blocks or fatter if looking down on them and smaller or thinner if looking up at them. A trick of the eye. You will get gaps as long as if the are not staringly to big the randomness of the over all wall will hide them.
We used NZ pine because cost and then stained in a teak stain overall we were happy with the look of it all.
The only thing you need to check when doing this is to make sure each row is milled to the same height and getting that first row even...
Over all we were happy with the out come...