Question about barn design.

[Mjdubya]

Hello fellas,

I'm starting a 30x40 pole barn this weekend that I plan on pouring a concrete floor in next year. I turned a gravel pad over for it last weekend. Here's my plan. I'm using 16'- 6x6 treated posts 8' on center. I plan on putting 4 feet in the ground. I'm wondering about the header? I have enough 2x12s to use for the the header and am thinking about notching the posts enough to fit BOTH 2x12s on top of the posts. Which I then plan on bolting. Then I have 4/12 trusses that I will place on 2' centers. I'm going to sheet the roof with osb and it will be a metal roof. I want to get it that far before winter. I live in Alaska. I plan on framing in all the walls with 2x6 lumber and will set anchor bolts in the bottom plate and pour a floor and a footing in it next summer. Also I'm going to sheet the building with t1-11 or osb I haven't decided yet. Does this plan sound good? I've never built a building this size before. Thanks guys for your input.

 

[rburke65]

Welcome to TGJ! You'll get better answers to your questions if you update your profile to include your location. And I see nothing wrong with your pan. Good luck......from Ohio!

 

[Mjdubya]

Thanks I appreciate your reply! And I updated my location.

 

[tjdux]

Sounds fine. Osb sheathing may be overkill. Since you're going with metal siding (ribbed tin i assume) you could just use purlins instead of full sheets.

Nothing wrong with full sheets anr may insulate better just throwning my 2 cents out.

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[tjdux]

Also google perma columns

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[Mjdubya]

Thanks! The perma columns look like a good idea, rot is one of my concerns which is why I'm framing it all in and pouring a floor up to the bottom plate anchor bolted together. In theory I could cut all of the 6x6s off at ground level and the building should be solid. I was thinking about metal siding but was worried about condensation getting into the insulation. Up here a sheet of osb is about 18 bucks and a 12 foot sheet of metal 3 feet wide is around 45 (if i remember) at the local home depot.

 

[matt_i]

Something doesnt seem to fit, if you are going to frame the walls so the posts don't do any work (from a moment standpoint), why not just stick build. You should still be able to build a frost protected shallow foundation even though it would take more insulation.

 

[Mjdubya]

I'm hoping to build it out of pocket and I don't think I would be able to swing the cash to get it up before winter if I had to pay for a foundation that would eat up alot of my funds. I know it seems backwards but it's just the best way for me to do it. The summer is short here.

 

[matt_i]

You could also potentially do the reverse, build the foundation/floor this year, then be ready to frame and build a year from now. I don't know if you are going to heat this, that would make a big difference to me. If its just a cold storage then you are probably fine with post-frame. But, if you are going to heat + insulate the frost protected foundation has the advantage of insulation under the floor. I feel like the stud cavities are easier to insulate as well with more common materials.

 

[ddawg16]

Personally, I'd do CDX plywood for the roof vs OSB

 

[AVIVIII]

I wouldn't bother notching, it's not going to gain you anything.

I use 2x12 truss supports (header) inside and outside, but I also add a 2x10 cap on the flat on top. It might be overkill for 8' centers, but maybe stretch it out to 10' and save yourself some digging!

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[Mjdubya]

You could also potentially do the reverse, build the foundation/floor this year, then be ready to frame and build a year from now. I don't know if you are going to heat this, that would make a big difference to me. If its just a cold storage then you are probably fine with post-frame. But, if you are going to heat + insulate the frost protected foundation has the advantage of insulation under the floor. I feel like the stud cavities are easier to insulate as well with more common materials.

I am hoping to be able to use it to store my boat and other junk this coming winter. The building will be cold storage for the most part but if I need to use it I'm planning on a wood stove inside just in case. By frost protected you mean insulated with foam? I hadn't considered that but probably should. I'm planning on digging footing and doing a monolithic pour next summer.

 

[Mjdubya]

What's the longevity of treated posts? These posts I bought are rated for direct burial. And they will be high and dry in pure gravel backfill.

 

[rburke65]

I've had 4"x6"s in the ground for 33+ years......still looks structurally ok.

 

[AVIVIII]

I've had 4"x6"s in the ground for 33+ years......still looks structurally ok.

With the old treatment...

I don't trust the new environmentally friendly stuff, so I tarred all of my poles 6" above grade to the bottom. Just don't coat the very bottom so any trapped moisture can drain.

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[Mjdubya]

With the old treatment...

I don't trust the new environmentally friendly stuff, so I tarred all of my poles 6" above grade to the bottom. Just don't coat the very bottom so any trapped moisture can drain.

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That's a great idea!!

 

[Chris705]

Lots of manufactured plastic boots also available to slip over the ends of the posts to eliminate contact with wet soils....just want to be sure building gets enclosed fairly quickly.

 

[Jayhem]

We just built a 40x60 pavillion with 6x6 posts on 9 foot centers and they didn't need to notch the headers in either. Just 5" galvanized nails, 3 per header 2x12 end were all the engineered design required. Our snow load is only 30 though. 2 headers one on each side of the posts.

 

[seanc_mt]

I supportted my 2x12 the entire way down the post. I started from the bottom pressure treated 2x6, on top of it running vertically measured and cut 2x6 spacers nailed all those on with 2.5" framing nails. Then placed the next girt on. When i got to the to top measured the last spacer so the 2x12 sat on it. That way the entire post holds the weight of the roof. I live in Montana where the snow load is 65 lbs sq ft. Held up great with a 4x12 roof pitch. And the nice thing about this is, i could do all it myself because no measuring to keep the girt sapcing equal with the pre cut spacers.

 

[seanc_mt]

I also sheeted the entire roof with 5/8 OSB and the walls with 7/16 osb. The added cost was less than $2k for all the sheeting. Seems like a small investment that makes the entire building stronger, compared to screwing metal right to purlins and girts.

 

[Mjdubya]

This is all really good ideas and advice guys, I really appreciate it.

 

[Mjdubya]

I also sheeted the entire roof with 5/8 OSB and the walls with 7/16 osb. The added cost was less than $2k for all the sheeting. Seems like a small investment that makes the entire building stronger, compared to screwing metal right to purlins and girts.

This is kind of what I'm thinking. The added cost of plywood or osb isn't really that much. As far as the header I think I'm just gonna notch the post so my sheets of plywood lay flush. I just like the idea of the post carrying the weight. Not the bolts or nails holding the header on. I can't really see the picture very good on my phone but will look when I get home from work.

 

[Mjdubya]

View media item 71082 so here's what I ended up doing. Seems pretty strong with the double 2x12 and 1/2 inch galvanized bolts.

 

[Mjdubya]

View media item 71081

 

[Mjdubya]

I'm not sure if these pictures are uploading? If not go to my profile and I have a album. It was a hectic weekend and now back to work. Need to finish the eves and have the metal ordered for the roof.