16' walls for a pole barn - what post spacing?

[bandtank]

i'm planning to build a 32 x 48 x 16 pole barn (16' is the wall height with clear span trusses on top of the posts). i'm considering using 20' triple 2x6 laminated posts at 8' OC (4' deep with a concrete pad at the bottom, treated 2x6 uplift cleats, and then backfilling the hole with the original dirt and possibly some gravel). i want to be sure i'm not undersizing the posts, but i also want to be sensitive to cost.

i live in the middle of the forest with hills and lots of trees around me. which makes it class B i think. my elevation is 7,100 ft. (colorado springs) and i already have trusses designed that can deal with the snow load.

i'm planning to use 2x8 bookshelf girts at 2' OC all the way up the sides, 4x8 sheets of OSB on the entire external wall surface for wind bracing, metal siding, and a metal roof. there will be various amounts of bracing on the internal walls in addition to the girts. lastly, the trusses will be braced with 2x6s at 2' OC for the top chord and 2x4s at 2' OC for the bottom chords.

any advice would be greatly appreciated.

 

[Cjk]

Re: 16' walls - what post spacing?

My building is 16' sidewalls, 9' on center with 2x6 girts every 24 or 30", then the steel is screwed to the girts. No OSB in the building but they did add 2x bracing in several areas.

 

[bandtank]

Re: 16' walls - what post spacing?

My building is 16' sidewalls, 9' on center with 2x6 girts every 24 or 30", then the steel is screwed to the girts. No OSB in the building but they did add 2x bracing in several areas.

have you had any issues with such 'small' posts with such a 'high' ceiling?

do you have any pictures you could share of your building? i'm very interested to see how yours is built.

thanks for your help.

 

[Cjk]

No issues. We had another buiding put up about 10 years ago. Its only 14' tall and its been fine also.


Will get some pics tonight.

 

[cj7jeep81]

Mine is currently being built. 40x64x16'8" (squeezed out every inch we could). Triple laminated 2x6 posts on permacolumns on 8' centers. 2x4 girts installed every 24" on the outside, and metal screwed onto that. There are 2x6's in each corner (going both ways, so 8 total) for diagonal bracing. No concerns at all about the size of the posts or stength.

 

[bandtank]

Mine is currently being built. 40x64x16'8" (squeezed out every inch we could). Triple laminated 2x6 posts on permacolumns on 8' centers. 2x4 girts installed every 24" on the outside, and metal screwed onto that. There are 2x6's in each corner (going both ways, so 8 total) for diagonal bracing. No concerns at all about the size of the posts or stength.

thanks for the info. could you please explain or post a pic of the diagonal bracing you mentioned? i'm not completely sure i understand the configuration, but it sounds like a good idea to increase the rigidity of the structure.

 

[cj7jeep81]

You can see them in this picture. Basically, in each direction from each corner we ran a 2x6 from the truss carrier (2x10) down to the base of the next post over.

By doing it this way, it won't affect finishing out the interior. They added a lot of strength to keep the walls from racking.

 

[bandtank]

You can see them in this picture. Basically, in each direction from each corner we ran a 2x6 from the truss carrier (2x10) down to the base of the next post over.

By doing it this way, it won't affect finishing out the interior. They added a lot of strength to keep the walls from racking.

do you have a thread detailing your build? it looks great. thanks for the picture.

 

[cj7jeep81]

I updated my signature, but here it is.
http://www.garagejournal.com/forum/showthread.php?t=283468

 

[bandtank]

I updated my signature, but here it is.
http://www.garagejournal.com/forum/showthread.php?t=283468

thanks. your pictures gave me a lot of new ideas.

what do you guys think about making the skirtboard flush with the outside of the posts? it would save me a lot of money because i could use 2x6s instead of 2x8s for the girts. i want the girts to be flush with both sides of the post (bookshelf style) as well. notching the posts is probably out of the question due to bearing capacity reduction, but i was thinking i could cut the skirtboards to fit between the posts and then toe nail them into place.

 

[theoldwizard1]

i'm planning to build a 32 x 48 x 16 pole barn (16' is the wall height with clear span trusses on top of the posts). i'm considering using 20' triple 2x6 laminated posts at 8' OC (4' deep with a concrete pad at the bottom, treated 2x6 uplift cleats, and then backfilling the hole with the original dirt and possibly some gravel). i want to be sure i'm not undersizing the posts, but i also want to be sensitive to cost.

The only change I would make would be using perma-columns or pouring a 4' deep foundation for each post and mounting the column of top. I know this is overkill, but you can use non-pressure treated 2x6 for the posts and never have to worry about rot. The difference in price is about $8-$10 per board (2x6x16 SYP vs 2x6x20 PT).

You original plan is not bad with the concrete pad in the bottom. Use gravel for back fill. It will keep the posts dry.

Keep your posts at 8' OC.

Use 2 - 2x10 "let in" to the posts for the top span between posts.

 

[MagKarl]

Mine is 16-17' eave/wall depending on how you measure. My posts are 6x10 on 12 foot spacing.

Triple 2x6 for posts seems pretty small when you want 2x8 girts both from a strength and fit standpoint. I would go bigger on posts, and 2x6 on the girts if it were me.

 

[bandtank]

The only change I would make would be using perma-columns or pouring a 4' deep foundation for each post and mounting the column of top. I know this is overkill, but you can use non-pressure treated 2x6 for the posts and never have to worry about rot. The difference in price is about $8-$10 per board (2x6x16 SYP vs 2x6x20 PT).

i'm having trouble getting on board with permacolumns because i ran calcs on lateral load scenarios and they fail sooner than solid columns. vertical load capacity isn't an issue, but two bolts and some screws aren't sufficient replacements for the cross section of a structural member. i'm sure they've been used with a lot of success in many buildings, but i'm really interested to know how many buildings with permacolumns have been damaged by a strong gust of wind that wouldn't have happened with a solid wood or metal post. i like the idea, but the implementation doesn't seem that great especially for the price. with that said, i'm open to opinions and corrections.

i'm planning to use pre-built laminated posts so i can't easily create a different size or length.

You original plan is not bad with the concrete pad in the bottom. Use gravel for back fill. It will keep the posts dry.

Keep your posts at 8' OC.

Use 2 - 2x10 "let in" to the posts for the top span between posts.

ok, gravel seems like a better idea than dirt, or maybe i'll mix gravel with the original dirt for each hole to make sure the gaps are filled in. i'm going to tamp every 6" or so.

do you notch the 2x10s into the post? i'm back and forth about whether or not i want to do that. thanks for your help.

 

[bandtank]

Mine is 16-17' eave/wall depending on how you measure. My posts are 6x10 on 12 foot spacing.

Triple 2x6 for posts seems pretty small when you want 2x8 girts both from a strength and fit standpoint. I would go bigger on posts, and 2x6 on the girts if it were me.

i was only planning on using 2x8 girts so they'd stick out enough to be even with the skirtboard and top beam. if i make everything flush, i would downsize the girts to 2x6. my original concern was the other thing you pointed out, though. the first few responders don't seem to have any issues with triple 2x6s, but it still seems thin to me. the other issue is i can't easily get bigger posts without switching to non-laminated lumber, which is significantly weaker than laminated lumber.

 

[Kevin54]

Mortons is building a pole barn down the road from me. They have a concrete and steel portion that goes in the ground that can be turned to level everything exactly. Once set in place and leveled, then the laminated post go on top of it. Chains and binders are used throughout the build to keep things square. I started a thread on it and see if I can find it.

 

[theoldwizard1]

do you notch the 2x10s into the post? i'm back and forth about whether or not i want to do that. thanks for your help.

Notch the post (cut 2 of the 3 2x6 short) so that the 2 - 2x10 rest on top of the 2 shorten boards. Nail or through bolt the 2x10s to the remaining full length 2x6.

If you are going to space your posts further apart than 8', I would use 2 - 2x12s.

 

[mtwaterguy]

I used the book shelf girts on my build and that alone seems to control racking. Adding osb on the outside wouldn't add much. My posts are on 12' centers.

 

[theoldwizard1]

i'm having trouble getting on board with permacolumns because i ran calcs on lateral load scenarios and they fail sooner than solid columns. vertical load capacity isn't an issue, but two bolts and some screws aren't sufficient replacements for the cross section of a structural member.

Simpson Strong Tie makes many different kinds of bracket to connect wood posts to a concrete footing. including ones that are for seismically "active" areas.

The HD3B are made out of 12 gauge galvanized and the HD19B are made out of 3 gauge galvanized.

Mortons is building a pole barn down the road from me. They have a concrete and steel portion that goes in the ground that can be turned to level everything exactly. Once set in place and leveled, then the laminated post go on top of it. Chains and binders are used throughout the build to keep things square. I started a thread on it and see if I can find it.

Chain and binders are the way to go for a square building!

 

[Apex Structures]

Most people overlook the fact that their large garage doors are not rated for high winds and will typically be the first thing to fail if the structure is hit by a tornado or high coastal winds. They collapse inward from the pressure. This failure will happen before the structure itself would lift out of the ground without any anchoring added. The next thing that goes would be horizontal girts on the roof that are nailed to the top chords of the trusses creating the roof panels to peel off in sections. This is largely due to the garage door caving in. If you want to go big, talk to your garage door company about beefing up the struts.

We are talking about a very heavy structure with all that metal and wood. Post anchoring is only needed on open front structures or pavilions in my opinion, or buildings that are located in 120 mph wind zones. On that height, I recommend 40" deep footings, 3-ply 2x6 posts @ 96" o.c., double 2x10 MSR headers, fastened with GRKs, not spliced on the same post, not notched. 48" o.c. truss spacing braced according to mfg specs for desired wind load (90mph-110mph) can be achieved with no uplift blocking or hardware.

 

[Apex Structures]

Check out this post saver product. Won't trap water like the sleeves.

http://www.planetsaverind.com/products.php

 

[MattN03]

Subscribing...

 

[Voi]

Mortons is building a pole barn down the road from me. I started a thread on it and see if I can find it.

This one, right?

http://www.garagejournal.com/forum/showthread.php?p=4784188#post4784188

 

[bandtank]

Notch the post (cut 2 of the 3 2x6 short) so that the 2 - 2x10 rest on top of the 2 shorten boards. Nail or through bolt the 2x10s to the remaining full length 2x6.

If you are going to space your posts further apart than 8', I would use 2 - 2x12s.

how do you connect the trusses to the 2x10s? i was going to orient the posts the other direction to sit the trusses inside the posts. if i do it your way, i'll have to use a metal connector of some sort and i'm not familiar with that method. i'm not against it, but it's new and i would be hesitant to pick something without a recommendation.

 

[bandtank]

We are talking about a very heavy structure with all that metal and wood. Post anchoring is only needed on open front structures or pavilions in my opinion, or buildings that are located in 120 mph wind zones. On that height, I recommend 40" deep footings, 3-ply 2x6 posts @ 96" o.c., double 2x10 MSR headers, fastened with GRKs, not spliced on the same post, not notched. 48" o.c. truss spacing braced according to mfg specs for desired wind load (90mph-110mph) can be achieved with no uplift blocking or hardware.

i already dug the holes to 48", so would you recommend filling up the bottom 8" with concrete and then setting the posts on top of it with dirt/gravel backfill?

if you don't notch for the 2x10s, does that mean they're sticking out 3" from the posts? how do you fasten them to the posts?

similar to my question for someone else, how do you recommend fastening the trusses to the posts and/or headers in the configuration you mentioned above?

 

[theoldwizard1]

how do you connect the trusses to the 2x10s? i was going to orient the posts the other direction to sit the trusses inside the posts. if i do it your way, i'll have to use a metal connector of some sort and i'm not familiar with that method. i'm not against it, but it's new and i would be hesitant to pick something without a recommendation.

The trusses rest on top of the 2x10 and can be just toe nail. Once the purlins are installed they are not going to move. With a 32' span for truss, you might have to go up to 2x12, especially if there is significant snow load.

Speaking of purlins, I would install them between the trusses, not on top, so that the top edge of the purlin is flush with the top edge of the truss. They can be toe nailed in but joist hangers are much stronger.

There are a lot of different types of metal straps/connectors to reinforce that connection. They are typically called "hurricane straps". From simple "up and over straps"

to this style

Download the Simpson Strong-Tie catalog. Lots of ideas !

 

[bandtank]

I plan to use LU24 and LU26 hangers for the purlins exactly as you mentioned. Thanks for mentioning this and for the advice.

To be clear, this is what you're recommending for the 2x10s/post/truss connection, right (see below)? I know the connectors aren't shown, but I understand what you're suggesting. I'll find a connector with the right uplift parameters to match the truss profile.

I'd like for the 2x10s to be flush with the post, so this seems like the best option to achieve that. The girts won't quite be flush as the post is only 4.5" wide in the short dimension, but I can add wood to each post if necessary on the interior side. I probably won't finish the interior surface for a long time, though, so it doesn't really matter. Of course, I could also rotate the post by 90 degrees and cut all 3 plys by 1.5" instead of simply removing two of the plies when the post is oriented the other way, but that seems less strong than leaving an entire ply intact.

 

[theoldwizard1]

Not exactly what I was thinking. Sister the 2x10 (2x12) together and place them inside of the notched post. (See attachment below) Placing the truss directly on top of the post is not mandatory, but will result in a stronger structure.

This is where you need an engineer/architect to "run the numbers" to see if you can have 8' truss spacing with your snow load. They will also tell you if you need 2x10 or 2x12. If you are able to place the trusses directly on top of the posts, you might only need 1 - 2x10 or 2x12 ! Only a pro can tell you for sure.

I like this design for connecting trusses the best

Use the recommended Simpson nails or screws.

The girts won't quite be flush as the post is only 4.5" wide in the short dimension, ...

Use 2x6 (cheap "stud grade") for girts. Cut them to fit between the post and turn them 90°. They should then fit flush to the inside and outside of the posts. The can be toe nailed to the posts because they don't really carry any load.

If you plan on insulating in the future, install the vapor barrier on the outside before you install sheating/siding. You can then use fiberglass rolls/batts between the posts and girts or (cheaper) blown in cellulose insulation. (Cover the inside with scrim cloth, blow in cellulose, than panel/drywall.)

 

[bandtank]

Not exactly what I was thinking. Sister the 2x10 (2x12) together and place them inside of the notched post. (See attachment below) Placing the truss directly on top of the post is not mandatory, but will result in a stronger structure.

This is where you need an engineer/architect to "run the numbers" to see if you can have 8' truss spacing with your snow load. They will also tell you if you need 2x10 or 2x12. If you are able to place the trusses directly on top of the posts, you might only need 1 - 2x10 or 2x12 ! Only a pro can tell you for sure.

I had the trusses redesigned to span 8', which means I won't need any large structural wood between the posts. I'm still planning to use 2x6 purlins and 2x4 braces for the bottom chord, both of which will be mounted with hangers (LUS24 and LUS26) at 2' OC.

I'll lose a little bit of ceiling height by doing this, but I think I'm going to remove two of the post plies for the truss connections. The remaining ply and an additional 4' section of 2x6 will be used to sandwich the trusses at the top of the posts. A few big lag screws will be more than sufficient for uplift.

Use 2x6 (cheap "stud grade") for girts. Cut them to fit between the post and turn them 90°. They should then fit flush to the inside and outside of the posts. The can be toe nailed to the posts because they don't really carry any load.

Thanks. This may save me some money by buying cheaper lumber.

If you plan on insulating in the future, install the vapor barrier on the outside before you install sheating/siding. You can then use fiberglass rolls/batts between the posts and girts or (cheaper) blown in cellulose insulation. (Cover the inside with scrim cloth, blow in cellulose, than panel/drywall.)

I do plan to insulate the barn eventually, so I'll add the vapor barrier to the outside walls as you said.

Thanks for all of the help so far.

 

[bandtank]

Check out this post saver product. Won't trap water like the sleeves.

http://www.planetsaverind.com/products.php

I tried to get pricing from them, but they gave me the runaround longer than I cared to put up with it. I did get a number - $28 per post - but they can't or won't quote the post itself and they won't sell the product to apply on my own. I tried both distributors and neither was very helpful. It seems like a good product, but they apparently don't care to sell it. Permacolumns are rather expensive, but at least you can buy them.

 

[cj7jeep81]

Do you need to have permits for the building? If so, I'd run your questions by the inspector. Would really **** to do all the work and find out he doesn't like the way you attached the trusses, and want's it done differently.

 

[bandtank]

Do you need to have permits for the building? If so, I'd run your questions by the inspector. Would really **** to do all the work and find out he doesn't like the way you attached the trusses, and want's it done differently.

I don't need permits for the actual structure, but I pulled one for the electrical work I plan to do. I am thinking about paying the county to inspect my building regardless of the lack of a permit because I want to "measure twice, cut once" if possible. I asked if they'll do a plan review and I haven't gotten a response yet.

I'm considering these brackets if I end up pouring a significant amount of concrete in the hole.

The pad is flat (mostly), road base has been installed, and holes have been drilled. I covered the holes with plastic yesterday after looking at the forecast because it's now snowing. I'm sure it wouldn't matter that much, but I didn't want to have to clean them again. I'm planning to order all of the materials on Monday for delivery at the end of next week assuming I'm able to get answers from the local building department that make me feel comfortable enough to move forward with my design. Trusses and metal should show up the following week hopefully.

 

[Kevin54]

This one, right?

http://www.garagejournal.com/forum/showthread.php?p=4784188#post4784188

That's it. I searched and searched and couldn't find it. Thanks so much

 

[Kevin54]

how do you connect the trusses to the 2x10s? i was going to orient the posts the other direction to sit the trusses inside the posts. if i do it your way, i'll have to use a metal connector of some sort and i'm not familiar with that method. i'm not against it, but it's new and i would be hesitant to pick something without a recommendation.

The post on the pole barn I posted about and VOI found, are premade. They bolt the post to the adjustable pier post, then the trusses drop between the laminated post. Very nice setup.

BTW......The trusses are bolted and NOT screwed or nailed. 5 bolts through the trusses just like the 5 through the concrete piers.

The second pick shows the adjustable piers that you level and locate first.

 

[kbs2244]

I have posted it before, but the best source I have found about building a pole building is

http://www.easybuildings.com/

 

[bandtank]

The post on the pole barn I posted about and VOI found, are premade. They bolt the post to the adjustable pier post, then the trusses drop between the laminated post. Very nice setup.

BTW......The trusses are bolted and NOT screwed or nailed. 5 bolts through the trusses just like the 5 through the concrete piers.

The second pick shows the adjustable piers that you level and locate first

Pretty cool. I wonder what those adjustable posts are called. I couldn't find them on google.

Do you know what size posts were used? It looks like they used a small piece of lumber (2x6? 2x8?) for the top girts, which makes sense as no trusses are being supported by it. They also didn't use any bottom chord braces.

 

[Voi]

Pretty cool. I wonder what those adjustable posts are called. I couldn't find them on google.

I think they're a proprietary Morton product. Here is a link to their foundation page and a video showing a bit more about them.

http://mortonbuildings.com/why-morton/products/features/foundation-options/

 

[bandtank]

I wish I had a better update, but so far I've had exactly zero time to work on my pole barn. My basement flooded shortly after I started this thread and I've been busy installing a french drain around and inside the house. I should be done in the next week or so and hopefully the weather will let me start on my pole barn again.

 

[buddyboy]

if you're using OSB on the outside for wind bracing, check the requirements for nailing, sometimes it's required to be nailed 16" OC, not 24"