Lumber question beginner

[matsro]

I'm building a frame with a roof over the entrance to the foundation outside. Nothing advanced, but it should withstand moisture outside and be placed near the ground (standing on lecablock). What type of wood is best for this?

I guess I want pressure-treated (decking wood?), but doesn't it risk swelling so that things shift and go wrong?

I was thinking of putting roofing felt on top.

 

[Daniel 109]

The impregnation does not affect the properties of the wood. But it should not be needed in your case.

 

[klaskarlsson]

Well, it depends a bit.
If you want it unpainted, you can use pressure-treated timber.
Where would you put the decking timber though?
Under the roofing felt, it feels better with regular tongue and groove boards, as it's covered anyway.
Against lecablock, it's always best to have sill paper.

Or is it a very low frame (a couple of cm) that's supposed to act as a lid somewhere?

 

[matsro]

Well, it depends a bit.
If you want it unpainted, you can use pressure-treated studs.
Where would you put the decking though?
Under the roofing felt, it's probably better with plain lumber since it's covered anyway.
Against leca blocks, it's always best to use sill paper.

Or is it a very low frame (a few cm) that is supposed to lie as a lid somewhere?

Yes, low frame with a lid. I've made an opening into the crawl space from the side outside, mostly below ground level. So first you go down into a "pit" built with leca blocks, and then you can enter the foundation. What I'm going to build is a frame with a lid on top of this pit. Since it's a small garden, I want it as low as possible and something you can walk on. It's about 10-20 cm above the ground, so it gets damp.

Sill paper is a good tip.

 

[matsro]

The impregnation does not affect the properties of the wood. But it shouldn't be needed in your case.

The decking timber at the lumberyard is still so damp you can feel it. I've heard it can shrink and pull when it dries. But maybe not a big problem in such a small construction as here.

 

[Daniel 109]

Didn't you fear that it would swell just now? Yes, it is true that it is often moist when you buy it. But in practice, there is no difference.

 

[Droynas]

Buy pressure-treated as you think and it will work out
It won't swell, I can promise that, but it will shrink a little. Think of a deck where the gaps become a bit larger over time than when it was first installed.
But it’s nothing major, it will be fine

 

[matsro]

Didn't you fear it would swell just now.
Yes, it's true that it's often moist when you buy it. But then practically there's no difference.

Meant primarily shrink. But well, doesn't sound so relevant then. Good.

 

[klaskarlsson]

I meant primarily shrinking. But well, doesn't sound so relevant then. Good.

With such a small gap on top of a pit, which can become damp, it will probably be good with pressure-treated.