2nd story joist locations

[kkutac001]

Heya. Anyone know how to find where these are located under the floor? I can find studs in walls; do the joists "match up", continuing on under the floor? TIA, Karl

[BigKGlen]

Are you in an apt or home? Do you have any floor vents or returns?

[captexas]

I doubt the wall studs will line up with the floor joists, at least not exactly. Most times these days the wall framing is done laying on the ground and then stood up and nailed to the ground/floor base. Exterior wall studs will typically be 16inch apart on center, but interior will vary greatly depending on the builder. Floor joists will be based on whatever the architect called for. If you have carpet in the room in question, you might be able to pull up a corner to see the wood subfloor that is nailed to the joists. Just look for how far apart the rows of nails are.

[BigKGlen]

If you come away from the wall a foot or so, with a hammer begin a strong tapping on a spot, and begin working either left or right. You will be able to tell a difference in the tone of the 'thump'. the closer to the joist, the cleaner and more solid the sound is. After you feel you have found the joist, measure 16" in the same direction, and begin the tapping again. Once you find that the solid sounds are 16" apart, you can use the 16" rule to find the rest of the joists.

[kkutac001]

BigKGlen -- I live in a two-story house. All vents are in the ceiling. Thanks for the hammer suggestion. It was better than my idea, which was basically, I had no idea. :-)
captexas -- I appreciate your info. It makes sense that they'd not line up, once you put it that way. My house is 35 years old. No telling how far apart the studs or joists are. I really didn't relish the thought of pulling up the carpet, so I think I'll try the hammer idea.
Lastly, I think I remember reading somewhere to put the four legs of the stand on top of (say) 3/4" plywood, so that this will distribute the weight more evenly. I'm remembering correctly, right?
Thanks again, gents! ..Karl

[kkutac001]

Hey. I wanted to re-open this thread for a follow-up. After tapping the floor, it was not immediately obvious where the joists were located. If anything, they seem to run the opposite direction from what I was thinking. This is an A-frame house. Does any carpenter among us know: do they lay the floor joists parallel to the apex of the roofline? Or is there no relation? The reason I wonder is: it would seem the outside wall which lies under the "A" portion would be very much a weight-bearing wall. If so, would they put in the joists perpendicular to the weight-bearing wall?
If all else fails, I'll have to pull up some of the carpet. Yech. Carpet never seems the same after doing that.
If any construction-minded people know, let me know. And thanks!
..Karl

[kkutac001]

An update to close this thread. I spoke with my next door neighbor, an engineer by trade. He said the joists likely run perpendicular to the roof ridge. Moreover, he said the weight of such a small aquarium would not cause trouble for the floor (around 200 pounds). Later,
Karl

[tony]

hey karl, how is my old 100 doing?

[captexas]

Hmm . . . "small aquarium" . . . "200 pounds" . . . "100g" ? What size tank are you putting up on these floor joists? If it's the 100g, it weighs a lot more than 200 pounds when filled!

[kaiser]

You might want to go into the room below and put your studfinder against the ceiling. You'll find out which direction the joists are installed.

[Texreefer]

pm Big Bird but they generally run perpendicular the the main roofline