durability 22mm vs 25mm panel ?

[Yrrol]

I have old-fashioned ceiling in several buildings.
From the time when inch-thickness was used. 25mm.

This cannot be bought in regular stores.
I had to take 28mm and have them planed down to 25mm.
Almost 3 times more expensive than 22mm.

Now that everything is going to hell, I'm considering tearing down all the new and old 25mm boards and laying 22mm all the way.

What I'm afraid of is that I might weaken the roof enough to be a danger for me to run around and work on it? There is a beam at the top, one at the bottom, and one in the middle, so it's not drastically much to walk on.

What I'm not planning to do is rebuild trusses, build a new house, and other exciting (costly) proposals I usually get.

 

[öringen]

The difference in durability between 22mm and 25mm is hardly measurable. Why tear it off? Just continue with the usual 22mm, the difference in thickness even if you mix 22 and 25 won't matter when you lay the roof. If you don't want the battens to wave, you can just place a small piece of masonite underneath.

 

[Yrrol]

Experiencing a significant level difference when 3+3= 6mm is missing. The angle is such that I wonder if I need to plane the sharp corners which are angled the wrong way towards the sky before I can lay something on top.

Also, since the old boards have now absorbed so much rain, I hesitate to put a roof on top. If I replace the whole setup with 22mm, I can nail everything in place within one or two days before the rain has a chance to soak the underlayer.

 

[öringen]

I don't think it will be noticeable when you put on the outer roof, break off at a strategic point and continue with 22mm. What kind of roof are you planning to have?

 

[Real7]

Looks pretty airy )), so I think the moisture can dry out.

 

[Yrrol]

I'm going to lay oil-hardened masonite on top, then stringers and battens, and then new slightly shinier concrete tiles.

If I press my thumb on certain spots of the old boards, water seeps out. Not good.

 

[Matti_75]

There is 25mm virke available at small sawmills.

 

[huggan]

Where I bought it, the råsponten was 23.5, so it varies a bit between manufacturers.

 

[Yrrol]

So, does everyone agree that I don't need to be afraid of reducing the thickness of the boards and that the strength is the same in 22mm as in 25mm?

Dropped the top of the chimney on the roof, it just bounced away as if nothing had happened.
I suspect a different outcome on my residential house that only has masonite as an underlay.

When I built storage shelves, I was taught that 22 was a must for the shelves to hold.
So millimeters are sometimes crucial?

 

[mdab]

22mm tongue is approximately 22.5% weaker than a 25mm.