[Clgmann]

I’m building a porch with exposed rafters from below in which the bearing beams will also be visible. I’m leaning towards Douglass fir to maintain minimal wood check& shrinkage. Any thoughts? Thanks

 

[Half-fast eddie]

If the lumber is within ... i think 18” ... of soil it must be pressure treated.

 

[Nealtw]

I’m building a porch with exposed rafters from below in which the bearing beams will also be visible. I’m leaning towards Douglass fir to maintain minimal wood check& shrinkage. Any thoughts? Thanks

Dry before you buy is the important part about avoiding checks and warped, fir can be as bad as any when you put it up wet.

 

[Nealtw]

If the lumber is within ... i think 18” ... of soil it must be pressure treated.

Rafters

 

[Clgmann]

Dry before you buy is the important part about avoiding checks and warped, fir can be as bad as any when you put it up wet.

I didn’t realize that it has to be installed dry! It will deserve some moisture even after it’s built. Grr!

 

[Clgmann]

It will see some moisture after it’s built.

 

[Nealtw]

It will see some moisture after it’s built.

That isn't what usually causes issues, it is usually when you cut down a tree, cut it into lumber and all the stresses relax as it drys.

 

[Nealtw]

What Is the Most Stable Wood Against Warping and Shrinking? (sfgate.com)

 

[Half-fast eddie]

Rafters

Ah ha. So I see, said the blind man.
However comma he said he is building a porch,and planning to use DF framing. I wasn’t sure how far he was going to go with the DF so its worth noting.

 

[de-nagorg]

It's expensive, but I like DRY Redwood for exposed porch rafters.

And framing.

It is naturally ROT RESISTANT, so it don't need pressure treated,

Just be picky, when selecting your material, no obvious cupping, warped, or twisted stuff, comes on my project sites.

ED

 

[carpdad]

Ambient moisture is fine although not if you're saying it will leak. Drier is better (sometimes if the stock was sitting around long enough) but any lumber, when nailed into a beam, shouldn't twist and warp into an eyesore. I may be mistaken, so search and confirm. I think i read about treating the lumber with wax type preservative makes it dry slower so less damages. You probably will have to hand select all rafters and other lumbers anyway for looks. Rafters will need full blocks to stop the twists.

Bridging can do the same and i think will add interesting design into the rafter bays.

 

[huesmann]

Ah ha. So I see, said the blind man.
However comma he said he is building a porch,and planning to use DF framing. I wasn’t sure how far he was going to go with the DF so its worth noting.

Also, people sometimes use incorrect terminology, so you never know!