determining floor direction

[nonot8946]

hello, the diy'ers here seem like a very clever bunch. Here is my problem: I live in an apartment and want to set up a tank soon. I have no idea which direction the floor beams run. I cannot rip up the carpet and above me is the roof of the building and not another floor.

How can I determine which direction they go? I am wondering if a stud finder would work through the carpet, floor, and subfloor, but I suspect it will not. I do not want to ask the apartment manager as there is a "no pets policy", but nothing against having a box full of water ;) I've also tried tapping with a hammer, and measuring the floor for level, neither of which are very helpful.

Else, I'm sure someone here is smart enough to have some ideas.

Here are the approximate dimensions or the room, in case they might help

<-12 feet->
_XXX__
|..........|.^
|..........|..|
|..........|..|
|..........|.13 feet
|..........|..|
|..........|..|
|....____|..v
|....|.....|

XXX is a balcony doorway
| are walls

the building continues to the left (another apartment), right, and below

[ErikS]

If you're putting enough weight on the floor to be concerned about structure then I'd be up front with the management. The "no pets" policy is most likely due to the damage they can/will do - i.e. ruined carpets etc. Think of what a tank can do? They may require you to get some renters insurance with a water damage clause.

If you decide to go behind their backs remember that some day a maintanence guy my be in the apt & you could be out on the street in a jiffy.

All that aside generally speaking joists run the shortest span, the short side of the rectangle. Ask a maintanence guy, for all you know the floors are concrete & steel (lots of apts use what's called "gyp-crete" to keep the noise between floors down - subfloors & carpet over top)

[BeanAnimal]

****IMPORTANT****
"joists usually run the shortest span" is TOTALY INCORRECT. There is no general "rule of thumb" There are indications based upon building sytle, age, architecture, height etc.

For example my house is 58 years old, stick built but the rafters and joists run the LONG lenght and ARE PARALLEL TO THE ROOF RIDGE!

The neighbors house has joists the run the long span but rafters the run the short span.

My old apartment building (100 years old) was ballon construction with a central chiminey and the joists "fanned" out from there in all directions.

Modern construction and the use of laminated beams and truss joists makes anything possible.

We won't even get into "prefab" homes.

There are many types of construction and each has different uses and trademarks.

Best bet would be to use the stud finder from the downstairs apartment. Offer the neighbor a six pack or a date with your sister.

If he dislikes beer AND thinks your sister is ugly... Use your stud finder to determine where the ceiling joists in your apartment are. This may give you an indiciation of the building construction... but more clues will need to be looked at to be sure. It is kind of (very) unlikely that the joists from floor to floor alternate directions... but it is possible.

A key indicator would be load bearing wall or a visit to the basement. However depending on the age and location and architecture of the building.... anything is possible.

Take of a few wall vents and see which direction they travel.

Last desperate effort....
Use a small drill bit and drill JUST THROUGH the subfloor (you don't want to pierce any wiring, piping or duct work). THIS SHOULD BE DONE CAREFULLY!!!!

Make sure not to get the carpet twisted in the drill!

If the floor is not insultated, you should be able to use stiff wire to probe around and find which direction the joist run.

WEAR INSULATED GLOVES just in case.

I will leave it to you to determine the best way to probe... but with some thought it should take at most 3 holes. (usualy 1 will suffice).

Just bend the wire as it goes into the hole making sure you know which way it is pointing... then rotate it left and right, it should strike a joist.

Bean

[chawee]

I think you should strongly consider Erik's advice, but...

You might be able to tell from the balcony. Can you see under it? If it’s constructed of wood and cantilevered off the house (without any posts at the far end), your floor joists should run perpendicular to the indicated balcony door… that is to say the same way as the balcony floor joists.

Chalie

[ErikS]

"joists usually run the shortest span"

means

Most often, commonly, usually

it does NOT mean

Always or a certaintyFor example my house is 58 years old, stick built but the rafters and joists run the LONG lenght and ARE PARALLEL TO THE ROOF RIDGE!

building (100 years old) was ballon construction with a central chiminey and the joists "fanned" out from there in all directions.


Both of which lend truth to the statement -

They don't build 'em like they used to.......thank goodness

[RobinsonFam1]

be careful of the balcony idea as well. i think your best bet is yo pull a corner of carpet back a small way to either see the nails in the subfloor or drill diectly into it and not the carpet.

by pulling back the corner you can easily lay it back down and re-tuck it in place. dont pull the whole room back but i would pull back 3'X3'.

HTH

[wasp9166]

really, pull back the carpet look at the nails, done

[wasp9166]

Originally posted by BeanAnimal


For example my house is 58 years old, stick built but the rafters and joists run the LONG lenght and ARE PARALLEL TO THE ROOF RIDGE!



Bean


im curious to know how this is possible, joists yes, rafters parallel to ridge? ummmmmmm

[RobinsonFam1]

ummmm..... ive built an awful lot of homes and office buildings and have never seen then run parallel.

ok ok purlins run parallel, what are the odds of this building starting out a 100 year old barn though.

prolly a typo

[nonot8946]

I figured it out...or not. The problem was that I couldn't pull the carpet, all the corners I tried, I couldn't get it to pull up. So...I did the only thing any fish-nut would do....I moved all the furniture around so that I could get to the one remaining corner....pulled it up...and discovered that I have a concrete floor.

The tank is only 75 gallons, so I wasn't terribly concerned about the weight, but runner it perpendicular to the floor beams seemed the best idea. Now I don't have to worry!

[BeanAnimal]

Wasp...Sorry for the misuse of the word rafter... I typed and did not proofread before I posted.

My ceiling joists run perpandicular to the rafters and parallel with the roof ridge. And yes I know the difference between a rafter and a joist.

Robinson, I live in Pittsburgh and can show you dozens of examples in homes and duplexes. You would be suprised at the huge variations in construction styles you come across. And some of them may been barns :P

In any case my load bearing wall is at a 90 to the ridge. The weight is transfered to a beam in the basement.

[wasp9166]

ya know , i was going to ask if it was concrete but i figured you had allready surmised it was wood , lol

[ErikS]

.I moved all the furniture around so that I could get to the one remaining corner....pulled it up...and discovered that I have a concrete floor.

As I mentioned, lots of new buildings use it, keeps the noise down between floors

(lots of apts use what's called "gyp-crete" to keep the noise between floors down - subfloors & carpet over top)

In any event, it's all good - you can get the tank you want. I'd still check with the management, you'll avoid any issues in the future (FYI - I lived in a no pets apt & the management had no problem with fish).