Lumber Grade Specifications
Just like any other product, lumber is graded. Different species have
different systems but they are basically the same in many respects. The lumber
is graded from the worst quality to the best. The grades will take into account
the size and frequency of knots and the location of where the lumber comes from
the tree. Grades often take into account the grain of the lumber as well.
Grain of lumber is called either vertical or flat. Flat grained lumber is
generally considered lower quality. It has a greater tendency to cup or curl.
You can easily spot a flat grained piece of lumber when you look at the cut end.
If the growth bands are slightly curved or somewhat parallel with the width of
the piece of lumber it is flat grained.
If the growth bands are parallel with the thickness the lumber is considered
vertical grained.
Flat grained lumber should be used for the decking surface and stair treads.
Always install it so the growth bands hump upwards towards the sky.
Vertical grained lumber is excellent for trellises and other things where
warpage will cause appearance problems.
Redwood Lumber Grades
- Construction Heart
This lumber is taken from the center of the tree
(heart) and can contain knots. It is great for trellis posts or beams. The knots
are usually small and tight.
- Construction Common
This grade contains knots and can be taken from both
the center or the outer fringes of the tree. If it is from the outer edges, it
will be lighter (blond) and it is called sapwood. This grade should not be used
where it might come into contact with the ground.
- Merchantable Heart
This is an economical grade of heartwood. It can
contain larger knots and knot holes.
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- Clear All Heart
This is is the second best grade. It contains no knots
and is taken from the heart of the tree. This lumber has the highest amount of
natural preservatives.
- Architectural Grade
This is the absolute best grade. It is unequaled in
beauty. If you want a piece of wood that has exquisite graining, will be warp
and twist resistant, this is the one to purchase. It is expensive - don't waste
it!
