josephhanson wrote:For internal lumber, see if you can get any finger joined boards, they don't warp, twist and they don't have any knots in them. The glued finger joints are stronger than the plane board.
My experience with finger jointed boards has not been so great when it comes to bending resistance. (A board being any lumber up to 1" actual thickness.) Finger jointed boards of 1x thickness or less are not graded structural lumber. It is usually meant for indoor use because of the adhesives most often not being water resistant. Trim, mouldings, door frames are the usual tasks it is used for. Finger jointed boards are most often more straight than plain sawn wood. The lack of knots is a blessing at times too. However I have broken joints with no great effort on occasion. I would be careful of where and how it is used.
In dimensional lumber (2 to 4 inch nominal thickness) there are 2 varieties of finger jointed wood; one marked "CERT EXT JNTS" and the other marked "VERTICAL USE ONLY".
That marked "VERTICAL USE ONLY" is appropriate for carrying loads in compression as vertical framing members. These products are grade stamped VERTICAL USE ONLY and is manufactured to meet the performance capabilities of solid sawn, end-loaded bearing members where short-term bending or tension loads from lateral forces such as wind, seismic and impact may be present, but where forces from the conditions of long-term, sustained-bending or tension loading are not present. This used to be marked as "STUD USE ONLY". The adhesive used typically contains polyvinyl compounds,
That marked "CERT EXT JNTS" is intended for all structural applications. CERT EXT JNTS products may be used interchangeably with any solid-sawn lumber product of the same species and grades. The lumber may be used as beams, joists, rafters, studs, plates, or in any other exterior or interior framing application. The adhesives used generally contain phenolic resins and are heat and water resistant.