220 c24 studs, how meticulously should one avoid knots?

[Yrrol]

I will reinforce rafters with additional 45x220 hanbjälkar.
I am out looking for timber and mostly find ones that have a lot of knots and some cracks.

Is the timber weakened by many knots?
Is it weakened by being outdoors under a minimal roof?

 

[Mazen]

Check the grading of the timber, c24 or 30 is recommended for load-bearing structures...
https://woody.se/hus-bygg/traprodukter/konstruktionsvirke/45x220-k-virke-c30-gran

 

[fribygg]

If the timber is graded C24, there should be no problem using it.

 

[Rickard.]

Since K-virke is exclusively spruce in Sweden, it is more often than not that you have both the core and knots in the larger dimensions. Buy the ones that look straight and without any major defects, and there's not much more to do; knot-free can be forgotten.

 

[Workingclasshero]

Since K-lumber is exclusively spruce in Sweden, it is more often than not that you have both the core and knots in the larger dimensions. Buy the ones that look straight and without other major defects as there isn't much more to do, knot-free you can forget about.

Exactly, sometimes it feels like they've taken the worst lumber and classified it just because it's strong enough. When I've built trusses, I've chosen myself, few knots, dense growth rings, and straight. In my 6-sided tower, one of the beams is 45x220 at least 270 years old.... so damn heavy, overkill for roof beams, almost a waste......

 

[Yrrol]

Is the timber of lower quality for having been stored outdoors by the store?

 

[Rickard.]

Does storing the timber outdoors by the store make it worse?

No, but it should have been stored under a roof.

 

[Rickard.]

Exactly, sometimes it feels like they've taken the worst wood and graded it just because it's strong enough. When I've built roof trusses, I've chosen myself, little knot, tight growth rings, and straight. In my 6-sided tower, one of the rafters is 45x220 at least 270 years old... so damn heavy, overkill for rafters, almost wasteful......

From what I understand, we simply don't have a better alternative than spruce here in our country. Knot-free pine is simply not an option, and pine with knots is apparently worse.

 

[justusandersson]

Dense, straight-grained, and knot-free gives the best results. C 24 should not contain many large knots as it should be taken from better, visually sorted timber. An alternative is to use outer paneling of Norrland spruce and screw-gluing. Tie beams used to almost always consist of double boards with spacers. Tie beams are exposed to tensile forces which is good to keep in mind.