building/engineering question

[hornadylnl]

I'm building a new steel building and want to put a 2x dividing wall for an office, bathroom, and storage room. It will be 10' off of an exterior wall and 40' long like in this drawing.

I am going to make the 40' wall and 2 divider walls 7' to the ceiling as I want a small storage mezzanine above it.

Here's my question. I was planning to use 2x4x7' studs 16" on center and 2x8 or 2x10x10' for the floor joists. I will put a 2x4 stud wall up against the barn perlins as well and put a bracket about every 3rd stud to anchor the wall to the barn perlins. Do any of you guys know how to calculate pounds per square foot for something like this? I'm wanting to know if 2x4's will be heavy enough. I will put barn siding on one side of the wall and drywall on the other.

My plans for the mezzanine are storing tools, stuff I don't use very much and eventually a 10hp, 120 gallon air compressor up there.

 

[Eddie]

I showed this to my father in law who is a mechanical engineer (Purdue Grad, USAF Lt. Col. Ret.) he says you need to know whether you are going to use 2x8 or 2x10 and the length of your span then look it up in a civil engineering reference book. (Material sales at wherever you buy them should have this data.) He says to look at joists made of 2x4's as they will support more weight than just a straight 2x8 or 2x10. He also says your decking material will make a difference as a more rigid material will spread the weight more evenly.

That all being said, my dad has a similar structure in his pole barn and it is stuffed with lumber and paint and such and shows no sign of collapsing.

 

[hornadylnl]

I was going to go with 2x8 or 2x10 for the joists. They will span 10'. I figured if I went with 16" centers on those, It should hold quite a bit. I will put down either 3/4" OSB or plywood for the decking. I want to keep this as low as possible as the sidewalls are only 14' to the outside. If I can keep it to 8' finished height, I will have about 4' 4" to the bottom side of my trusses. I will be able to stand up most everywhere except for the trusses or right at the edge of the barn.

 

[Eddie]

I am sitting here trying to get him addicted to INGO. He said for a rough comparison your structure should hold as much as an upstairs room in a house, but for an exact pounds per square foot calculation you will need to consult a reference book and he doesn't have one. If you want to eyeball a similar structure though I can let you take a look at one.

 

[hornadylnl]

I am sitting here trying to get him addicted to INGO. He said for a rough comparison your structure should hold as much as an upstairs room in a house, but for an exact pounds per square foot calculation you will need to consult a reference book and he doesn't have one. If you want to eyeball a similar structure though I can let you take a look at one.

Thanks for the help. If he thinks it will be as strong as a second floor of a house, I should be good! I'm too far away to come look at one. I think what I may do is put some extra 2x's in the area where the compressor is going to go. According to the website, is about 1100# and should spread out about 5' or so. I'm wanting the 10hp 120 gallon horizontal model. 3 - 10 HP Air Compressors:

I've got a 6.5hp, 60 gallon now and it won't keep up.

 

[Eddie]

I can't see where some tools and an air compressor would weigh more than the stuff that goes in a normal upstairs bedroom.

 

[Scout]

Here's list of links to shops other people have built. PBB Shop Build Links - Pirate4x4.Com Bulletin Board

 

[Ogre]

Its kinda a different direction, but have you thought about buying a used industrial mezzanine and putting up light duty framed walls below it? I have seen used pallet rack used for this application as well, and it worked quite well.... just a thought. I can't help you on the stick built specs., sorry.

There is one of the nations largest used material handling equipment companies on the south side of Indy, they probably have everything you'd need if you went that direction.

 

[CountryBoy19]

Menards normally carries all the reference/handbooks for construction. I see there is one in your nearest large city. Maybe a quick stop by next time you're in the area to have a look. My future FIL built his own house about 10 years ago with practical knowledge, and anything he didn't know came from the Menards handbooks, and IMHO his house is one of the best stick-built houses around.

 

[hornadylnl]

I'll check at Menards and see what kind of info I can get there. Getting a true #'s per sf may be overboard but it would be better to know then find out after it collapses on me. Thanks for all the info.

 

[jmiller676]

As a mechanical drafting student, thank you for making your dimensions line up, it bothers me when people don't. Other than that I have nothing to add to this thread.

 

[CountryBoy19]

I'll check at Menards and see what kind of info I can get there. Getting a true #'s per sf may be overboard but it would be better to know then find out after it collapses on me. Thanks for all the info.

I know what you're saying. I'm a mechanical engineer but don't have much structural experience so take this with a grain of salt. IMHO your plan for 2x4 studs and 2x8 or 2x10 joists sounds plenty solid to me. And if you're worried about the air compressor then put a couple extra studs/joists in there to be extra sure. If nothing else, it's cheap insurance that it won't sag overtime etc. I would say go down to 12" spacing or even 8" to keep the 16" pattern going properly and it won't be going anywhere.

 

[CountryBoy19]

ETA, I found a calculator online.

Using grade 2 2X8 floor joists on 16" centers, with 20 lb/sf dead load (max the calculator would allow) and 100 lb/sf live-load the max span is 8'8". Grade 1 takes you up to 9'8", and select structural gets you 9'10".

Going to 12" spacing with Grade 2 gets you 10' even.

Now, there are some assumptions I made with this. #1, I know your dead-load is much higher than 20 lb/sf but the calculator wouldn't allow a dead-load higher than that so I tried to "compensate" by using a 100 lb live-load. #2 that is assuming worst case scenario and that the load is acting across the entire span, if you don't have any other heavy objects nearby your span should be able to carry more weight.

Here is the calculator I was using, there may be other/better ones but that turned up on a quick google search: Span Options Calculator for Joists & Rafters

 

[jeffers_mz]

For a normal traffic rule of thumb, use a joist that is X inches tall, for X feet of span. Your 2x10s over a ten foot free span ought to be about right.

If you're going to add point loads up there, like the compressor or anything else, consider adding a small closet or wing wall directly under the point load. Everybody needs closets, and a wingwall next to a lavatory, shower, or even sink won't detract from a bathroom.

Fireblocks (horizontal 2x4s between studs, and joist cutoff scraps between joists above a bearing wall) will stiffen up the studs (against bowing) and the joists (against cupping) even more.

Over enough time, just about any difference in area loading can crack a concrete slab. Too many people look at the compression or puncture rating of concrete, usually 3000 to 4000 PSI, and think they are good to go. Puncturing the slab usually isn't the problem, that a compression issue. Instead what cracks your slab are tensile weaknesses and bending moments.

If I could pick up the compressor without help or mechanical advantage, I'd set it on a slab, or on a joist system bearing on a slab. If I need any kind of help to lift the equipment off the ground, I'd start thinking about a floating concrete pad under the ultimate bearing area for such equipment.

General rules of thumb that I use, hope they help.

 

[CountryBoy19]

For a normal traffic rule of thumb, use a joist that is X inches tall, for X feet of span. Your 2x10s over a ten foot free span ought to be about right.

If you're going to add point loads up there, like the compressor or anything else, consider adding a small closet or wing wall directly under the point load. Everybody needs closets, and a wingwall next to a lavatory, shower, or even sink won't detract from a bathroom.

Fireblocks (horizontal 2x4s between studs, and joist cutoff scraps between joists above a bearing wall) will stiffen up the studs (against bowing) and the joists (against cupping) even more.

Over enough time, just about any difference in area loading can crack a concrete slab. Too many people look at the compression or puncture rating of concrete, usually 3000 to 4000 PSI, and think they are good to go. Puncturing the slab usually isn't the problem, that a compression issue. Instead what cracks your slab are tensile weaknesses and bending moments.

If I could pick up the compressor without help or mechanical advantage, I'd set it on a slab, or on a joist system bearing on a slab. If I need any kind of help to lift the equipment off the ground, I'd start thinking about a floating concrete pad under the ultimate bearing area for such equipment.

General rules of thumb that I use, hope they help.

Several good points! Adding a wing-wall/closet under that area will help out a LOT.

IMHO, in the interest of keeping the overall height and cost down, I think it would be better to do a 2x8 joist and just double them, or go with 8 or 12" spacing in that area rather than doing 2 x 10 for the whole span. I think that would give the desired strength in that area but also give you an extra 2 inches of head-room and lower your cost for the whole thing.

 

[Anonymous]

I don't think 2x4 walls will be a problem at all. It looks like 7' walls will give you 6 1/2' doors, depending exactly how you build it. I know Menards has a deck program that will give you loading. If you can create a 10x10, with no posts in the middle, it should give you a rough idea on loading. My wife packed up all my engineering books yesterday, so I do not have access to them. Disclaimer - this pic was for my reference only. I would not build it this way.

 

[Grux]

I assume the building will be on a concrete slab? If so, and you are in the Indianapolis area let me know. I work for a concrete provider.

 

[hornadylnl]

I just had the slab poured Monday. It is 5" thick so I know it won't be an issue. I don't foresee putting all that much weight up there but 50# here, 100# there, it adds up quick. I want it to be an out of the way place that I can put seasonal type stuff that rarely gets used. I'll check into Menards and see what kind of info I can get there.

I hadn't even given the door height any thought. I will have one exterior door going into it so I will most likely have to go with an 8' sidewall. The height of the roof should be 13' 8" at the sidewall of the barn where there aren't trusses. If I go with an 8' sidewall, I'll still have about 4' 8" after my joist height. I wouldn't be able to walk around standing up but that won't really be an issue no more than I'll be up there.

 

[Grux]

I just had the slab poured Monday. It is 5" thick so I know it won't be an issue. I don't foresee putting all that much weight up there but 50# here, 100# there, it adds up quick. I want it to be an out of the way place that I can put seasonal type stuff that rarely gets used. I'll check into Menards and see what kind of info I can get there.

I hadn't even given the door height any thought. I will have one exterior door going into it so I will most likely have to go with an 8' sidewall. The height of the roof should be 13' 8" at the sidewall of the barn where there aren't trusses. If I go with an 8' sidewall, I'll still have about 4' 8" after my joist height. I wouldn't be able to walk around standing up but that won't really be an issue no more than I'll be up there.

Good deal... I was just going to save you some money if you still needed some concrete!

 

[hornadylnl]

Good deal... I was just going to save you some money if you still needed some concrete!

Thanks, I appreciate it! I'm about an hour from Indy so they may not have been interested in traveling that far though. Concrete definitely isn't cheap!