David from Tracadi, New Brunswick wants to tear a wall down in his basement and wants to know if it is load bearing or not. He says it runs perpendicular to the floor joists.
If a wall runs parallel to the floor joists, chances are that it is not load bearing, as it is only holding up one floor joist, if that. If there is not a wall just above it, running in the same direction, you can be pretty sure that the one you want to remove is not load bearing.
But when a wall looks like it supports a series of floor joists, it could very well be load bearing --- or not. That's real clear, isn't it.
If there is no wall above this wall, there is less of a chance that it is load bearing, but it still could be. If the floor joists above stop at this wall, or they come from both sides and overlap at this wall, it definitely is load bearing. If the joists pass right over this wall, the only way to be sure is to check with a set of span tables. See just how far the size and spacing of floor joists can properly span without support, and see if you will have that proper support without this wall. Also check if things have been added above. A floor with no special weight on it can span as per the span table, but one with a wall in the middle of it may be carrying a lot more weight and may need support from below. So if it is clear above, and the floor joists are within the safe limits of the span tables without the wall you want to remove, you should be safe to take it out. If at all in doubt, bring in a qualified specialist (construction contractor or structural engineer).
There is a code proposal to solve this problem by requiring structural wall identification signs to be naild to the studs before drywalling. If you think this is a good idea, follow this link to lend your support.