Concrete Piers or Full Foundation for Firewood Storage

[SPIKER]

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Mysfyt, like most northern places, we have frost heaves, my road becomes an obstacle course each winter! I'm planning this as a permanent addition to the garage, so I want to do it once and do it right. I don't want the posts heaving which would raise and lower the roof and solar panels.

How far down below the slab should I dig out for a gravel and sand base? How many inches of gravel and how many inches of sand? I have access to a small gas powered plate compactor. I'll talk to the concrete contractor as well, but want to go into that conversation with a basic idea of what I'll be doing.

Problem about digging down is that opens up the area for water to flow into, when it does freeze it has a greater amount of water than the surrounding regular earth so it heaves much worse. It s better to keep it all with same ground moisture content in high frost areas than have one area able to run in and then freeze. Similar issues building roads some areas where freeze thaw cycles are regular it is best to not create a bowl that channels water into that area. Once channeled into the drive or barn base it has a mini underground lake that freezes and pushes everything up.

The past two winters were really bad about deep frost here, my barn did have one spot heave right at the corner where cut lines let water flow under the slab. finished sealing those cut lines up this week for next winter and expect that there will be 0 heave. Remove only the organics on top inch or two (grass and active soil) then back fill with fine sand/stone/clay and compact heck out of it and build on top. If you can give it a year or two after removing the organics off top that helps, but still compact it often... if it seems to move much hit it again.

M

 

[EddieWalker]

Thanks LD1. I tend to go for overkill when building things! Code here is for 50psf snow load. Thanks for the info on not connecting the slab to the piers, I'll make sure they are separated with foam or similar. I was going with the 6x6 beam (3 2x6's bolted together) as it is cheaper than 2 2x12's. Plus it seemed to make sense putting a 6" beam on 6" posts.

This would be a very bad idea. There are times when you can get away with cutting corners, but in this case, you will regret using the smaller lumber. Spend the extra and use the 2x12's. The cost difference isn't significant, and never having to do it again, or deal with a sagging beam is more then worth the small additional cost.

 

[LD1]

3 2x6's bolted together is better than a 6x6 I thought you were gonna use. But I would use lumber large enough to only need 2 boards instead of 3.

I know they make fancy brackets and there are different ways it "Can" be done, but I dont like setting a beam "on top" of the posts. I would rather notch the posts and set the header on the notch, then thru-bolt. One board on the inside, one on the outside.

USe this chart for minimum sizing requirements. http://www.southernpine.com/app/uploads/AL_27-32L.pdf

Your header has to support half of the roof, so 5 square feet for each lineal foot of the header. At 50psf code, your header needs to support 250PLF.

With 4 posts for 22', you are spanning 5.5' each. (actually a tad less since that is post center to center.)
Using the 6' span colum, a single 2x8 #1 is good for 335Plf
Your 3 2x6's are good for 726plf
A pair of 2x8's is good for 671plf and is probably cheaper than 3 2x6's.
Even a pair of #2 2x8's is twice what you need.

USing 3 posts, 12' span colum (even though your actual span is gonna be closer to 10') a pair of 2x12's is good for 323#. Which is still a nice safety factor.

Lets look at cost now.
USing double 2x12's, you will need (4) 12' 2x12's. They are $16.35 ea around me. Thats a ~$50 header.

Using a double 2x8 with an extra post, you will need (6) 8' 2x8's @ ~$5ea, so thats ~$30 header
Using a triple 2x6, you need (9) 8' boards. Those are $4.60ea (almost as much as 2x8's). SO that would be a ~$40 header

But either of those last two are gonna require an extra post, extra hole, extra concrete footing or pier, which is gonna negate the $20 savings and more i the long run. Not to mention One less post in the way (assuming you are leaving that side open and not enclosing it.) a few knee braces also shortens the effective span of the header and makes things a good bit more rigid.

Now what are you planning for rafters?

50psf and 10' span here is what I show you would need

#2 SPF lumber
2x8's will span 24" OC
2x6 will work up to 12" spacing

For #1 SYP
2x6's will work up to 16" centers
2x8's for 24" centers.

Not sure what stores you have around, but I would shop for #1 SYP lumber for everything. Menards stocks it in larger sizes and can special order it in the smaller stuff. It is nice clean straight lumber and stronger than the #2 SPF stuff they ormally stock. ANd cheaper alot of times too.

IE: right now I can order 2x8x12' #1 SYP for $7.24 (good rafter board with overhang)
They stock #2 and better SPF for $8.09

The SYP is a WAY better board and cheaper.

Sorry for the long post. Just some ideas to think about. There is more than one way to build and build successfully. I wouldnt say one way is better than others. Just different ways to get the same end result. If it were mine, I'd do 3 posts, notched at the top, a 2x12 inside and out, 5 degree knee braces approx 2' down the post (and 2' out the header). And I'd use #1 SYP 2x6's on 16" centers if sheathing and shingles, or 2x8's on 24" centers if purlins and metal.

 

[BoylermanCT]

Thanks Eddie and LD1. On the header, I still want to use 3 2x? for the header. My posts will all be 3 2x6's bolted together, so it makes the most sense to keep the header the same thickness, so when it comes time to add exterior siding (which will be log siding to match the rest of the garage), everything is in the same plane. LD1, the span on the beam will be 7.33' from post to post, not 5.5'. Knowing this span, and that I will do triple 2x? for the header, do I need a triple 2x8's instead of 2x6's?

For the rafters, I was planning 2x6's on 16" centers. The span is 10'. The charts I've been using say this is good for a 11' span at 50 snow load. I will be re-roofing the garage with galvalum metal roofing, so I will be putting down purlins every two feet to attach the metal roof to.

I get my lumber from a local lumber yard. We don't have any Menards in the area, only Home Depot and Lowes so I will ask about the yellow pine.

 

[LD1]

Your right. Dont know what I was thinking, I was figuring 3 mid posts, not 3 openings....

IF you notch the posts, everything will still be in the same plane. And I am not sure how you are orienting the laminated colums, but 3 2x6's only make 4.5-4.75" thickness, and a 2x6 is 5.5" wide. Assuming you are putting the posts how most are even a 3 ply header isnt the same thickness without two sheets of 1/2" plywood. So I would still notch but thats personal preference

Looking at the chart I linked, a triple 2x6 spanning 8' is good for 410plf. So still well above the 250plf you will have with a 50psf snow load. Thats for #1 SYP.

#2's cut it a bit closer at 303plf

I dont mind helping out at all, and neither do others. But it would really benefit you to understand those charts for span tables. It will help you make more efficient building decisions.

Sometimes upsizing and going with more span or downsizing and shortening the spans makes a big difference in material costs.

 

[boggen]

sounds like a pain in the rear to deal with moving pallets back and forth via pallet jack. a chunk falls, and snags up between pallet you want and another pallet. and you climbing over stuff and moving chunks here and there to get to the chunk that fell and jamming things up.

i think it would be easier... just to build a long "lean to" mini shed for pallets of firewood. were you could simply back up tractor adjust 3pt hitch and drop pallet. (double checking foot on brake pedals to get pallet up under the mini lean to.)

getting all the ants, and mice and critters that can come along with firewood... along with getting good air circulation through the stacked lumber to help it dry out... i am kinda scratching my head why you would want all that firewood up inside and against the shed.

other issue is moving pallets around. the further back pallet most likely end up going to be the dryest. but you will have a bunch of extra pallets in front of it you would need to move. to get back to the dry pallet of firewood.

goal of firewood it is suppose to be cheaper... but sounds like you are paying more for firewood vs some other fuel to heat with.

 

[BoylermanCT]

Boggen, as you know, the biggest hassle of heating with wood is how many time you handle it. Before using pallets, I would split and stack the wood on the sunny side of the barn, which is farthest from the house. Then before winter, I would throw it all in a 4x8 trailer, and make many trips to stack it in the woodshed in the barn. Last year I decided to stack it on pallets, and then moving the wood in bulk would be easy with the tractor. Last year once the wood was seasoned, I moved the pallets into the barn. All of them had to be put in via a 5' door, and dropped there since the tractor is too big to fit in woodshed area. So I use the pallet jack to move the pallet from the doorway into its final storage space. I can fit 16 pallets in the current woodshed. But the concrete floor is not the best, and moving the pallets around was difficult. So I figured I could build a new woodshed next to the garage, which is even closer to the house than the barn, and make this process as efficient as possible. Unfortunately the location of the barn and garage prevent me from getting easy access with the tractor, and my access to the new 10x22 woodshed is via one 10' end. I can't access it via the long side or the back.



Oh, and the main reason for building a new woodshed is not the woodshed! I am putting solar panels on my garage roof next year, and the current roof is not large enough to hold 28 panels. I need an additional 6' of roof. So if I add more roof, I might as well use the space under it for something useful!

 

[BoylermanCT]

Your right. Dont know what I was thinking, I was figuring 3 mid posts, not 3 openings....

IF you notch the posts, everything will still be in the same plane. And I am not sure how you are orienting the laminated colums, but 3 2x6's only make 4.5-4.75" thickness, and a 2x6 is 5.5" wide. Assuming you are putting the posts how most are even a 3 ply header isnt the same thickness without two sheets of 1/2" plywood. So I would still notch but thats personal preference

Looking at the chart I linked, a triple 2x6 spanning 8' is good for 410plf. So still well above the 250plf you will have with a 50psf snow load. Thats for #1 SYP.

#2's cut it a bit closer at 303plf

I dont mind helping out at all, and neither do others. But it would really benefit you to understand those charts for span tables. It will help you make more efficient building decisions.

Sometimes upsizing and going with more span or downsizing and shortening the spans makes a big difference in material costs.

LD1, on the chart you sent, if my snow load is 50, is my dead load standard at 10? So snow + dead = 60. So a 6' span would be 360? Does 1 ply, 2 ply etc indicate the number of 2x's in the header / beam? So if a 6' span as a load factor of 360, then a single 2x8 at 335 is not enough, but a single 2x10 at 453 would be fine. Or 2 2x6's at 422 would be fine too. Am I understanding this right?

What is the BL or bearing length? I know it is inches, is it the # of inches resting on the post?

This chart is for yellow pine. Are there charts for douglas fir? That seems to be the most common 2x around here.

Thanks for your time, and dealing with a novice builder!

 

[LD1]

Not sure what you are asking about 6' span and 360#. The PLF is pounds per lineal foot along the beam. Your "lean-to" is only 10', meaning 5' of that is supported by however you are tying into the building, and the remaining 5' is resting on the header. So for every lineal foot across the beam, you have to carry 5 square foot of roof. Even at 60psf total load, thats still only 300plf. And ground snow load is different than roof live load. And 10psf for a dead load is for sheathing and shingles. Are you going that route or purlins and metal. You see, there are a ton of variables to iron out.

Its all in how you read the tables.

In that particular table, live load (50 psf snow) is using l/240 deflection, while total load is using l/180 but same loading capacity. Also, those tables are 1.15 duration factor.

If in doubt, error on the side of caution. A single 2x10 run across 22' might add a whole whopping $20 bill to the whole project vs a 2x8. But look at how much stronger it is.

And yes, 1-ply is a single board, 2-ply is 2 boards side by side, etc

BL you are correct on. That is the bearing length that needs to rest on the post. If you are notching the post or properly attaching to top of post you need not worry. But for something like a garage door header or window header, that is referring to the number of jack studs needed on each side. 1.5 would need to rest on at least 1 2x stud. 3" BL would need to rest on 2 studs on each end, etc.

I have never searched for doug-fir tables. Around here, SPF or SYP is about it. american wood council, I think their website is something like AWC.org has a calculator that can select different species, grades, spans, etc. But I dont think they have one for headers. Just joists, rafters, etc. You can google for some tables.

Hope that helps and didnt further confuse you. Again, if in doubt, error on the side of caution, or see how other things are built i the area. Your original plan of using 3 2x6's and 2 intermediate posts is pleanty strong since the "beam" is only spanning ~7.5'. I just dislike trying to attach a triple header directly to the top of the post. I would rather see a notched post.

 

[BuilderML]

Hello from across the state, Let me start by saying that you have one of the greatest fly fishing rivers around,"farmington river". I was flying fishing it one time and 2 guys had come from Ireland just to fish that river.
Now to your post, I did not read every post but i did catch pieces. You'll be fine using piers to carry your roof load. I would advise you to use what they call "big foots" 24" round footing at the bottom of your piers. Yes as others have said make sure you isolate your piers from your floating slab or you will have issues. Let me add to that make sure you isolate your floating slab from any surroundings that are frost protected. One concern i have is that you said later one you will be closing it in with walls. It can be done but you need to keep your walls isolated from your slab also which will be tougher to do seeing how you will want to build ontop of your slab. If you plan on closing it in later on which will be attached to your house/garage which is frost protect i advise you to also have your new shed frost protected. What your doing is not the same as a pole barn. You need to plan on your slab moving so once you start locking it in place with walls if not done correctly will create problems in the future. Just not something i would do or recommend. Your roof needs to be designed to 30psf not the 50lbs you talk of. 50 psf is the design of floor loads. 40psf/live load, 10psf/dead load. Let me add nothing wrong with over building figured i would say that before i get yelled at by some.:laughing: When it comes to your beam to post method of construction you have manys ways you skin a cat, my method would be a 3" notch in the front of a 6X6 with a 2ply beam resting together in the notch. This will allow you to keep your outside face of the building flush to give you an even plane for exterior finishes/siding. Its tougher for me to get onto TBN these days with now 2 boys under 3 years old but if you have any questions just ask and i will respond as soon as i can. Have fun with your build.:drink: