14x20 Shed Construction Questions

[jcook5003]

Hey Guys-

After considering my needs, budget and lot and after asking some other questions here. I've decided to leave my large auto workshop at my moms farm in her 24x80 pale barn.

I would like to get my bike stand and tools at my house. So I can atleast work on my bike projects at home. After a lot of reflection I've decided to build a 14x20 or 16x20 shed on reinforced sonotube piers and a 3/4" plywood T&G floor over joists.

I really used this thread when doing my equipment layouts and choosing a size.
12' x 20' Motorcycle Workshop - Planning Stages - The Garage Journal Board

I've looked over the typical storage sheds built on skids around here, typically a 4x6 skid with 2x6 floor joists, then they block the 4x6 at each end and 8' centers underneath. They seem really overpriced for what you get.

Since this shed wont be moved, I see no advantage to building on skids, I'm envisioning more of what amounts to a "deck" with a shed roof building on top. Are there any advantages to using skids I'm not thinking about?

I'm attaching a drawing I whipped up in CAD, the building drawn is 14x20. Basically the design is a double 2x8 "beam" all the way around on the outside, then another beam on the 20 foot length mid way. Then 2x8 floor joists between them on joist hangers, they only span 7' so a 2x8 should be more than adequate.

As drawn I have the piers on 10' centers length wise. My question is should I drop back and put 4 piers on the 20' length so the double beam is only spanning 5' at a time? I have no idea how to size this beam. It not only carries the floor load but also the roof load between them.

So, how do I size that beam, 10' centers? 5' centers? Obviously less piers is less digging, less sonotubes and rebar, and less concrete, but I dont want something that is built subpar or unsafely.

So can you guys help me out here?



Thanks,
Josh

 

[quicksandfarmer]

Will your building have to be inspected? If so, start with the inspector.

There's basically two loads in this building -- the floor load and the roof load. The center row of piers carries half of the floor load. Each outer row carries one quarter of the floor load and one half of the roof load. Floor load is determined by what you intend to use the building for. Roof load is determined largely by how much snow you get in your climate. Once you figure out your loads, if you google span tables for beams you can see your options for beam sizes.

You also have to size the piers. The middle one carries half of the wall and the outer ones each carry a quarter. You have to make them big enough that they don't sink into the ground. You need to know the bearing capacity of your local soil do determine the proper size.

Depending on your climate/geology you may also have to worry about wind loads, hurricane resistance and earthquake resistance.

There's a lot of detail that goes in, specifics would be helpful.

 

[Sledgie]

Any reason to not have a concrete floor? For about $500 worth of concrete a lot of problems go away. Even if you've never done it, this is a good size to learn on..........

 

[EddieWalker]

I'm also wondering why you want to go to the expense of building a pier and beam foundation when a solid slab is so much better? To support the load of the building, your beams need to be sized according to their span. Google span tables to figure this out. They provide a list of the type of wood available to your area, then how far you can go with each size lumber to get your load rating. 40 lbs per square foot is where you want to be for a home.

At $5 a square foot, which is high here for concrete, but probably a safe number for general guessing on here, you are at $1,400 for a concrete slab. You might come in a bit less for wood, but not enough to make it an attractive alternative to concrete.

The other consideration is getting up to the floor. Do you want to be climbing stairs every time you walk into your shed? Odds are pretty good it will be close to 2 feet above grade when you get it all figured out.

Do you have snakes or rats or skunks or other critters what will want to make their home under your shed? Every shed that I've ever torn down was loaded with dead rats.

 

[Zerk]

I don't agree the she will be to high and need stairs with wood. Sure concrete is nice, but you could buy a table lift or more for the money.

Not based on math or facts, but I might consider 2nd layer of floor. Two 5/8s. Bottom green. Without crawl space close to ground. Maybe pair bottom before laying down, then will last. Though you can't paint fresh green wood.

Put down poly board no mater floor, woodr concrete. For hear and insulation. Extruded is meant for ground contact, pink stuff. Dig down few inches run mesh wire around.

I do lots of bike wrenching. I built my workbench so that. Bottom shelf is high enough for craftsman lift to fit under. Also open at one end to sit and read manuals and can fit a shop vac.

Venting so it does get hot in summer.

Some of my shelves have tall waist height shelve, acts as bench. Back plane to prevent stuff from falling off and can hang stuff.

On sides of shelves I put the metal used to mount garage door openers. Plastic bins hang on it.

They make foam that is supposed to be pest proof, regular stuff they will eat. Get rodents out.

Put some kind of metal flashing or block around perimeter, or green wood, for rotting.

I am hack builder trying to learn, but I enjoy shops and building shelves and benches

 

[quicksandfarmer]

If you must have a wooden floor it would be a lot easier to have the floor sit on the ground, you'd only need 2x4 joists.

The simplest building is a pole building. The poles provide all the lateral strength. With piers you have to have some sort of sheathing to keep the wall from racking. Do a google search for pole barn kits, my impression is you can get the kit for the same money as buying the pieces yourself and it comes all planned for you.

 

[paulharvey]

I don't agree the she will be to high and need stairs with wood. Sure concrete is nice, but you could buy a table lift or more for the money.

Not based on math or facts, but I might consider 2nd layer of floor. Two 5/8s. Bottom green. Without crawl space close to ground. Maybe pair bottom before laying down, then will last. Though you can't paint fresh green wood.

Put down poly board no mater floor, woodr concrete. For hear and insulation. Extruded is meant for ground contact, pink stuff. Dig down few inches run mesh wire around.

I do lots of bike wrenching. I built my workbench so that. Bottom shelf is high enough for craftsman lift to fit under. Also open at one end to sit and read manuals and can fit a shop vac.

Venting so it does get hot in summer.

Some of my shelves have tall waist height shelve, acts as bench. Back plane to prevent stuff from falling off and can hang stuff.

On sides of shelves I put the metal used to mount garage door openers. Plastic bins hang on it.

They make foam that is supposed to be pest proof, regular stuff they will eat. Get rodents out.

Put some kind of metal flashing or block around perimeter, or green wood, for rotting.

I am hack builder trying to learn, but I enjoy shops and building shelves and benches

By the time you buy pressure treated 3/4 plywood, 4" concrete slab with even a 6" thick edge looks every attractive. Concrete for that size could easily be did with you buying beer for 2 buddies.

 

[Zerk]

By the time you buy pressure treated 3/4 plywood, 4" concrete slab with even a 6" thick edge looks every attractive. Concrete for that size could easily be did with you buying beer for 2 buddies.

I disagree.

25 a sheet.

 

[Zerk]

If you must have a wooden floor it would be a lot easier to have the floor sit on the ground, you'd only need 2x4 joists.

The simplest building is a pole building. The poles provide all the lateral strength. With piers you have to have some sort of sheathing to keep the wall from racking. Do a google search for pole barn kits, my impression is you can get the kit for the same money as buying the pieces yourself and it comesu.

Unless I am missing something this sounds awful, like something on an old farm.

Going to rot. You could put few inches of gravel first. Not sure about how stable or level.


I would build on poles or concrete. You can trusses for 24 span.


Homes are 24 across with no support under floors or ceilings.

 

[Zerk]

16x20/24×$30 is 400. You don't have to have 2nd layer but it does make it feel solid, less noise. Cheap Osb on top of that. $200. Not sure cost 2x8s. Should go green, I think code because with in some many inches of ground. People don't though.

A crawl space is not treated.
Bikes are dead weight, 1000 lbs. Though with 2 layers 9f plywood probably ok. Ask a real builders, not people tractor forum. That much weight us the only thing not sure, other wise just a small ranch house

 

[paulharvey]

16x20/24×$30 is 400. You don't have to have 2nd layer but it does make it feel solid, less noise. Cheap Osb on top of that. $200. Not sure cost 2x8s. Should go green, I think code because with in some many inches of ground. People don't though.

A crawl space is not treated.
Bikes are dead weight, 1000 lbs. Though with 2 layers 9f plywood probably ok. Ask a real builders, not people tractor forum. That much weight us the only thing not sure, other wise just a small ranch house

Concrete is only 3.5-4 Cy x $90-110/cy. So 4" of concrete for the price of the plywood, and no need for PT 2x6 or 2x8. Not trying to argue, just pointing out that concrete is not that expensive compared to plywood, joists, fasteners, ect. It's not my shed, and I have no dog in the fight.

 

[quicksandfarmer]

Unless I am missing something this sounds awful, like something on an old farm.

Going to rot. You could put few inches of gravel first. Not sure about how stable or level.


I would build on poles or concrete. You can trusses for 24 span.


Homes are 24 across with no support under floors or ceilings.

What I'm trying to describe is a pole barn with a wooden floor. The poles hold up the walls and the roof. The floor is pressure treated 2x4's directly on grade, clad in plywood. This is based on the assumption that you really want a wooden floor. I agree with others that for a shed a concrete floor is just a better choice.

 

[Zerk]

I've got two pole barns, and three sheds with floors. None on grade. I don't think you will get it level enough to use 2x4s. Putting the floor directly on grade is a poor Idea in my opinion. I same it has be done. I doubt it would fly inspected, not that I am into that.

When floors are near grade I don't think they should use ground for support. Because not level enough and earth moves.

I think it is a bad idea.


I re read your post. You plan on using poles to support floor, which I agree with. But 2x4s are way to small. In my opinion. I would go 2x8 all the way across no support in middle.

2x4s don't have much use other than walls and tie things together. Plus 2x4 walls are not used if you are going to insulate. Though my places were built with 2x4 walls.

 

[Zerk]

Concrete is only 3.5-4 Cy x $90-110/cy. So 4" of concrete for the price of the plywood, and no need for PT 2x6 or 2x8. Not trying to argue, just pointing out that concrete is not that expensive compared to plywood, joists, fasteners, ect. It's not my shed, and I have no dog in the fight.

I should confess I have not priced concrete, because I figured out of my budget. Maybe I am wrong. But it is easy to spend other people's money.


I think it is small but if he only has or two bikes, it is ok. Mine is 20x24, I got 3 bikes and it is tight, attached garage. But my pole barn is 10 feet away with more benches and material. Plus another garden shed. Plus wood shop is in basement though sometimes barn.


If this is where he has to go cause wife has garage, and plans on more then bike work, he will need more sheds. Garden sheds are good for shovels and such.


Sadly these days many man have lost the garage. To secure mine, I bought another harley.

 

[Zerk]

Pricey but I would think about insulating whatever floor you use. You can't do it latter. Insulation and for vapor.


If I had the money I would do concrete with in floor heat, off a boiler, or maybe water heater if insulated good. That would have to get figured by a pro.

My family is in the business and heard stories about pissed off customers who would not insulate. Either lots money every month or unable to heat it. But I am talking UP. Down south different.

 

[buckeyefarmer]

My 12x16 shed is built on pt 4x4s 24"oc with 3/4" flooring direct on top. Framed walls on top w/ osb siding. 4x4s leveled with blocks under them. cost around $1000 to build. truss and shingle roof. now 18 years old.
Parked my small tractor in it for years without a problem. do have groundhogs under it. I built it before owning a tractor. Today i would level a pad first, put gravel down. Then build on top of runners. I would close off access to the underside.

 

[jcook5003]

I would love to build a mega 40x60 shop or even 24' as others have said. My small lot and budget dont work for that though. I've always thought sure a huge shop is nice, I mean I love the 24x80 at my moms farm but I just cant have that where I am.

14 or 16 x 20 is what will fit and what i can afford. It's what I will build.

I agree that motorcycles are a true point load of around 800 pounds on two 3" contact patches, not ideal for a wooden floor. I have gone out and looked at my site again. If I ate up a little backyard I could pour a slab. This gets me into inspections, but I've never had a problem with the barns I've built for other people or myself. So maybe this is best. A 14 or 16 foot wide by 20 foot long slab isnt that much concrete, I know a guy who will finish it for $1/sq.ft. That seems like a good deal to me. Then I only buy material. I think the best option is a footer with CMU stemwall to above grade by 12", gravel backfill after topsoil removal, pour the floating slab inside the CMU wall. I can level the gravel and moisture barrier and lay and tie the remesh.

My queston is, for $1 a sq. ft. is it even worth attempting to finish it myself. I poured a 10x24 pad in my horse barn, but it was only a tack room and wash rack. I worry about getting a much smoother nicer level finish myself on a slightly larger pad. On the 10' wide pour I could screed the concrete with a single board. Not much worry about it being a chore, this will be too wide to screed myself.

 

[paulharvey]

I would love to build a mega 40x60 shop or even 24' as others have said. My small lot and budget dont work for that though. I've always thought sure a huge shop is nice, I mean I love the 24x80 at my moms farm but I just cant have that where I am.

14 or 16 x 20 is what will fit and what i can afford. It's what I will build.

I agree that motorcycles are a true point load of around 800 pounds on two 3" contact patches, not ideal for a wooden floor. I have gone out and looked at my site again. If I ate up a little backyard I could pour a slab. This gets me into inspections, but I've never had a problem with the barns I've built for other people or myself. So maybe this is best. A 14 or 16 foot wide by 20 foot long slab isnt that much concrete, I know a guy who will finish it for $1/sq.ft. That seems like a good deal to me. Then I only buy material. I think the best option is a footer with CMU stemwall to above grade by 12", gravel backfill after topsoil removal, pour the floating slab inside the CMU wall. I can level the gravel and moisture barrier and lay and tie the remesh.

My queston is, for $1 a sq. ft. is it even worth attempting to finish it myself. I poured a 10x24 pad in my horse barn, but it was only a tack room and wash rack. I worry about getting a much smoother nicer level finish myself on a slightly larger pad. On the 10' wide pour I could screed the concrete with a single board. Not much worry about it being a chore, this will be too wide to screed myself.

To me, I would rather be out a sore back and legs, and some beer to a friend or two, then be out $280, but if you would need to buy/rent comalongs, bull float, edgers, and a Fresno, you would probably be about even. Do you want steel trowel funish, or broom; and if broom, can you live with a bull float and broom.

 

[EddieWalker]

I always hire out the finish work. This is how I prefer to do concrete work. I like to set my forms, dig out my footings, run my utilities if I have any, and tie my rebar and set it on chairs myself. I've seen where if you hire a crew to do everything, they sometimes like to skip things, or maybe not do it the way I want it done, and if I'm paying them do to it my way, I don't want to have to also be the supervisor making sure they do it my way.

Getting concrete smooth and nice looking is one of those skills that you have to do it a lot to become good at it. For such a small amount of money, and for something you will have to live with for the rest of your life, there is no question that hiring a pro to finish it is a smart move.

 

[Zerk]

Maybe weight of bike isn't a big deal. Think of a couch with three big people.

I think size will be ok, if you can keep other junk out, or store it well.

I enjoy laying out shops. I would bring 240 out. One of my pole barns only has 1 20 amp circuit, I blow it a bit.

Not to mention air compressor.