One post used three other terms warp cup and bow to describe various ways in which boards end up twisted.
Floor joist crown up or down.
The board will shrink and warp in the opposite direction of the rings in the wood.
In my son s bedroom there is a raised spot in the floor along one of the joists.
When you are framing a floor system for example you need to look down the edge of the lumber and decide which side has what is called a crown.
Best i can tell this may have been like this when the subfloor went down as the subfloor is well attached to the joists in this area.
Bark side up or down on exterior wood decks stairs.
Always mount the joist and beams bowed upwards.
A board that is correctly installed right side up or bark side down will form a crown and allow water to run off the edges.
The crown will not be the same for each board.
This means using two screws on each end and using two screws towards the outside of the boards at every joist along the way.
A crown will be the edge of the lumber that warps upward in the center when holding it on edge.
This article explains the causes of wood board cupping and gives advice concluding that unless a board is already badly cupped or has a bad side when construction of outdoor decks and wood stairs you should place.
Many people feel that bark side up is always the answer but this is not accurate.
When i use crown i m speaking of the variation from straight that you see when you site down the edge of the board.
Arrange the boards by the amount of crown they have don t put a joist with minimal crown next to a joist with a high crown.
The debate about whether deck boards should be placed bark side up growth rings curving down or bark side down growth rings curving up has raged for years.
The crown of a piece of dimensional rough lumber is the upward arching curvature you see when you look down its narrowest dimensional edge.
The objectives for orienting the decking bark side up or down are to minimize cupping which leaves raised edges for feet to catch on reduce splitting aka checking diminish the chance for rot and have fewer splinters.
I went into the crawlspace with a level and that joist is bowed up about 3 4 to 1 compared to the other joists on either side of it.
The strongest way to secure deck boards to joists is by using the top down face mount screw method.
The result is either a cupping of the wood or a crowning depending on which way you face the board.
Like when you put in floor joists you always try to put the crown up.
In other words a 2 10 would be held up on one end with the 10 dimension being vertical.
Doing this will help keep the boards firmly in place and won t give it the freedom to warp or cup.
Your joist boards will have a crown if you look along the edge the board will swoop in or bow out.
