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