Tongue & Groove cladding how to fix ?

Secret fix was the usual way, like you say, through the tongue, and then the next board put on top.
But for something like this, which is really fencing I think just face fixing would be ok.
Stainless is always the best, but galvanised nails would also be ok.

Most would use brads and nail gun these days.

I think it depends on what kind of look you are going for and what kind of finish you will be using.

 

Not very well up on outdoor wood finishes these days, most tend to be purely decorative, with a bit of wax added so that the water runs off the first time it gets rain on it.
I'm assuming the timber is pressure treated.

You appear to be on a fair slope there or is it the camera angle.

Just one other thing, probably obvious but worth a mention, horizontal t&g should always be applied tongue upwards otherwise water can lay in the grooves.

 

I've used 'Ronseal fencelife plus' water based with a 5 year gaurantee. Spray or brush. After 5 years just apply another coat.
Screwfix or B&Q.

 

You might regret that choice. Secret nailing is fine indoors when you wouldn't expect much movement in the floor boards, but outside those boards are going to shrink and cup, especially with them being 150mm wide, you will probably get quite a bit of cupping.

You might get away with it, but I doubt it, and if I were you I would use two nails at each fixing point.

 

I sell pressure treated t&g to the public, who use it for gates, sheds etc, and I get plenty of feedback and I know that the vast majority use screws and those screws do the job and they also have stood the test of time, ime.

I think people might tell you lost heads are the right thing to use but that's probably from the old timer joiners knowledge bank who didn't have the luxury of impact drivers.

 

Ask @hoofy about ss tongue-tite, lost-tite, etc. screws, all new stuff for me, all I can remember is fixing WR Cedar boards with aluminium alloy nails.


P.S. I am I right in thinking (back about 50 years or so) being told that wood resin can react with steel screws, causing staining?

 

I think those screws would be fine, as would green coated decking screws. I think 40mm screws would be sufficient but no problem if you use 50mm.

The issue people have problems with using t&g outside is the shrinkage and the swell and there's nothing you can do about that except make an allowance when you put the boards on. If they are bone dry now they are only going to swell. If they soaked they will only shrink and if they are somewhere in-between they will do either/both.

The boards you have look like they have a decent length of tongue so you should be fine. Some boards have such a short tongue that when they shrink the tongue comes out of the next groove.

 

I hesitate to show this as it was a job that went wrong, but it does illustrate the power of shrinkage and swelling.

We made 3 pairs of solid oak garage doors out of kiln dried oak, the customer said he wanted to put his own finish on them.
After weeks of driving rain that autumn he rang to say there was a problem.


All the doors had bowed in their width, despite having put 2 mm gaps between all the boards.
The width of the boards had increased in size and because they couldn't force the stiles off, the doors had to bow.
The timber had not been oiled and been in driving rain for a month.

I've always been dubious about putting two fixings across the face off a board as often the boards split at the fixings when the wood shrinks.
Often a nail will allow a small amount of movement to take place, scews less so.

 

Agreed, but you can over think what is an outdoor (fencing) job. The job will never look perfect as the boards shrink you will get gaps between them and you will be able to see the lines, although you shouldn't see daylight because of the tongue.

So, if you put one fixing in the middle of each board you will have less risk of the board splitting, but the cupping and shrinking where the boards fit together could be an issue, or put two fixings in each board and risk splitting but less of a cupping/shrinking problem?

Timber will do what it wants to do and the odd piece might even surprise you. Some jobs last a lifetime while some jobs perish within a few years.

Just go and put the boards on mate, you could have nearly finished the job in the time you've been sat there reading this thread and scratching your head.

 

Well I do agree, you can over think, as with many threads the subject snowballs.
They are only thoughts.

I assume John has almost finished it as we speak.