Pole barn loft joist size

[Dstyduhar]

Hey guys,

I finished framing the office in my pole barn and needed some advice on joist size for storage above. I have 14' sidewalls and scissor trusses so I'm trying to do everything I can (within reason) to maximize the headroom. This is important to me.

Info

- The joist span distance is 12'1"

- Joists will sit on top of 8' 2x6 framed walls with double top plate. No hanger brackets

- I'm in NC so likely would be getting #2 Southern Yellow Pine

- Want to be able store some heavier stuff up in the loft....not fully assembled engines or anything but maybe a spare engine block or two I have, spare cranks, boxes of junk I have collected over the years. Just long term storage stuff.

- Plan on midspan joist blocking and 3/4" decking

- Ceiling material for office will be metal panel, nothing heavy like drywall or osb.

My initial gut feeling was 2x10 @ 16" center but would 2x8 on 12" center work? The span tables show 2x8 on 16" center up to 11'10" for SYP so that falls a bit short, hence why I'm thinking on 12". How does a deeper joist on 16" compare to a shallower floor on 12"?

Thanks,

Drew

 

[Jeff C]

I would personally do the 2x10 @ 16” OC. It will be a better floor than 2x8 stretched close to their limit. Are you really going to notice 2“ extra headroom if you do 2x8?

Spruce and/or hem-fir is readily available at about every lumber yard in NC too. Noticeable weight savings every time you have to move it, cut it or carry it up a ladder compared to pine. May not be a concern for you but now that I’m getting up into my middle age years that matters more and more to me.

 

[MegaVan]

Another option to consider is finding #1/DSS/MSR lumber if you want to stretch farther.

I'm digging through my shed build. I did a small loft.



12' 8" span
2"x8" SYP
Designed for 30 lbs dead 10 lbs live (loft light duty storage) - I'm confident it could hold an engine block on a pallet.

I would be very uncomfortable at 2x6 - even at 12" on center. Another thing to consider is if you can get a nail gun between the joists at 12" on center.

 

[billconner]

Using tables in IRC, some 2x6snon 12" centers are OK. Lots of 2x8 on 16" centers are fine.

You could halve the span with an lvl in the middle and probably use 2x6s easily, if not 2x4s.

 

[FordTruckWench]

The span tables show 2x8 on 16" center up to 11'10" for SYP so that falls a bit short, hence why I'm thinking on 12".

Mom's house has 2x8 joists in the main part. At first I was shocked, but then noticed that the house is only 24' wide (um, deep?) in that part. So, 24' minus two CMU walls, minus a central beam/wall, creates two spans of 11' something". Anyway, she has a grand piano in the living room, i.e. supported by those 2x8's.

 

[NUTTSGT]

I'd rather spend the extra bucks now and know it's right then spend some bucks only to find out later, you need to spend more bucks to make it right.

 

[dfiler2]

I would look at using I-Joists they are lighter and easier to work with, 9 1/2" would work fine on 12'.

2-1/2" x 9-1/2" x 16' I-Joist 40 Series

I-joists are prefabricated I-shaped structural members that are designed for residential and commercial floor and roof rafter applications. I-joists are comprised of solid sawn flanges and structural panel webs that provide strength and versatility. Their lightweight construction, ease of...

www.menards.com

 

[HaiKarate]

My loft is is similar in size. I did the calcs but then went overboard with 2x12" every 12" and decked it with 3/4" ply. If I ever want to put a car body or pool table up top I should be gtg.

 

[Dstyduhar]

Hi guys,

I settled on #1 grade 2x10 syp for the joists on 16" center. Still torn on what to do for the decking though. 3/4 plywood is so so expensive. Looked at tongue and groove 3/4 OSB since its cheaper but worried about the flooring chipping up from foot traffic....even with the smooth side up. I feel like sheet goods will be the best bang for the buck but have some concerns that 3/4" might not be thick enough (16" center joists) wit me wanting to have the ability to store heavier stuff up in the loft. Crazy?? Put the joists tighter than 16"? Go thicker on decking?

Thanks,

Drew

 

[billconner]

1" rough sawn pine. I love my garage attic done this way. Strong as hell.

 

[Dstyduhar]

1" x what? no tongue and groove or anything? Do tell

 

[loganb]

If you want stronger, look at AdvanTech subfloor from Huber or the other similar products from LP and others. You can get it up to 1-1/8" thickness for higher strength values and it is rated for exterior exposure during construction....but be aware....its not cheap but buy once cry once product

 

[Dstyduhar]

If you want stronger, look at AdvanTech subfloor from Huber or the other similar products from LP and others. You can get it up to 1-1/8" thickness for higher strength values and it is rated for exterior exposure during construction....but be aware....its not cheap but buy once cry once product

Is that what folks refer to as Sturd i floor?

 

[loganb]

Is that what folks refer to as Sturd i floor?

Similar but different, Sturdy-I-Floor is a Georgia Pacific product and is plywood but has some thicker options that include an 1-1/8" thickness. The AdvanTech is more similar to OSB in terms of construction but performs far better than the standard OSB sheathing They're both upgrade options over the traditional subfloor options in residential construction.

 

[mike93lx]

Advantech is what I would get. Although probably not 1-1/8 for just storage.

Glue and screw. It will be rock solid

 

[loganb]

I'd agree with Mike, for storage like this the 1-1/8" is overkill, especially if going 16" OC with studs. Glue and screw it...enjoy the hell out of it

 

[Dstyduhar]

Im trying to be forward thinking with the decking. Yes, its for storage right now but I have scissor trusses and the majority of the loft space has 6' or more height...8' in the center. Would just hate to later decide to turn it into a hangout area or something and have the flooring be inadequate. of course, I could just lay down another layer of sheeting but trying to be smart w/$$.

 

[mike93lx]

Im trying to be forward thinking with the decking. Yes, its for storage right now but I have scissor trusses and the majority of the loft space has 6' or more height...8' in the center. Would just hate to later decide to turn it into a hangout area or something and have the flooring be inadequate. of course, I could just lay down another layer of sheeting but trying to be smart w/$$.

Regular Advantech is plenty.

1-1/8 is an upgrade and is not what would normally get used in anything but a high end home build

 

[Dstyduhar]

Gotcha. How about advantech vs regular 3/4 osb t&g? Assuming there is cost difference (going to call to check today).

Thanks,

Drew

 

[billconner]

1" x what? no tongue and groove or anything? Do tell

I used plain 1x8. 60 cents a board foot, so less than $20 for 4x8 area.

Sturd-I-Floor is an APA product standard and available from multiple mills (manufacturers). Designed to be subfloor and underlayment in one, for padding and carpet. It is used under other floor finishes as well.

 

[mike93lx]

Structurally, it's likely basically the same. Advantech has a significant advantage in weather resistance, which is not relevant in your case. The surface on the Advantech may be a little nicer, but a coat of paint probably fixes that

 

[firebirdparts]

You can find 12" span tables, so really, you don't have to ask us. When you do Trex outside, it's fairly common to have 2 by 8's on 12. Maybe very common.

Joist Span Table

Joist Span Table - Use this table to determine floor joist spans, deck joist span, and floor joist spacing.

www.mycarpentry.com

According to this it's adequate.

 

[Dstyduhar]

You can find 12" span tables, so really, you don't have to ask us. When you do Trex outside, it's fairly common to have 2 by 8's on 12. Maybe very common.

Joist Span Table

Joist Span Table - Use this table to determine floor joist spans, deck joist span, and floor joist spacing.

www.mycarpentry.com

According to this it's adequate.

Already stated info above about joists...was discussing how to deck the top now. Thanks