Building a shed...question on base.

[Tim Morton]

I am looking for help here...i am building a shed..10x12...but its going to
be kind of tall with a high roof so it will get heavy by the time i am done. I am building the base using 4"x6" PT as a frame and then using 2"x4" 10' PT joists whihc will be supported by cement blocks. I am not going to pour a pad...I am planning on digging two trenches running the long way and filling with crushed stones and setting a 6"x6" x12' PT beam on each bed of stone. I think this is called a "skid foundation"? Will this be enough of a base? My neighbor came over to look at my idea and suggested running railroad ties on all 4 sides...problem is i do not look forward to lugging those out to the shed site...plus my ground is not real level and I think I can get it level better (re: easier) with just the two skid beams. Just looking for thoughts here.

[Dan Oelke]

Sounds like 6x6 should be plenty.

As a reference point - I have a chicken coop I built (2x4 walls insulated, with 8' walls and sheeted outside with T1-11 and inside with 1/4" osb. ) That coop is a 10x12 and has 3 pressure treated 4x4's 12' long under it. Those in turn are supported in a couple of places each with 2" thick concrete blocks. It has been really pretty solid just floating on top of the soil.

I did spend some time making sure that the tops of all the conrete blocks were level before placing the shed on top of it. Of course I dragged it into place with the help of the neighbor's tractor and then had to jack it up and re-posistion my carefully placed blocks, but it worked pretty well.

[Mark Rios]

You folks over in the North East have different ground temp considerations than we do over here so I can't respond to your floor height needs or if you should lay down a vapor barrier or not but.....I would recommend 2 x 6 for joists. Approximately 10' is the maximum allowable span for a 2 x 6 and even then it's pretty springy. I'm not sure but I think I remember that the allowable span goes down with PT material. This would be from old memories and the new PT treated material may have addressed the lower span rating issue. Even supported in the middle I don't know if I'd go with 2 x 4 for floor joists. I like a nice solid floor. Depends on what you want to put on the floor though I guess.

Even though you are using PT material for your joists, you might also want to consider some sort of moisture protection for the bottom of your floor material, i.e. plywood. They make PT plywood or you can buy copper green and treat it yourself but it's kinda messy and stinky. After buying the one-time use brush and gloves and the copper green you just about have the cost of already treated plywood.

[Ben Grunow]

I think that foundation will be fine. The weight is on the sides where the joists and rafters sit anyway so that's where the support is needed. The only thought I have is that the frost will move that shed around a bit over time so maybe 4 sides for the foundation would be better (w/ ship lap joints at the corners) or at least some long pieces of rebar driven through the 6x into the soil (4' -5' of 5/8" bar 16" o.c.). Just MHO. Good luck

[Robert Mickley]

My $.02 worth, don't set the lumber directly on the concrete blocks, the lumber will wick moisture out of the blocks and when it does rot that will be the first place it goes, an old farm trick is to lay a shingle on the block isolating it from the cement

[Tim Morton]

all great ideas here...thanks.

Yes to the 2x6 joists...
yes to the shingle...
yes to some sort of rebar...
for the floor i am using some sheets of OSB i have laying around that I sealed on both sides...it will have crushed stone under it an about 7" of airspace.

as for the 6x6's....I think i am going to switch those out for railroad ties...and save probably $60 bucks or so...and do 3 of them instead of two.or maybe just use the "drops" in the middle row to support the outside walls, instead of a solid 12ft span of RR ties...I do have to remember this is just a little garden shed and noone is actually going to live in it:D ..although if I could get the red sox games to come in and my wireless router reached that far....hmmmmmm.:cool:

[Ben Grunow]

Spend too much time or money on it and your wife might send you out there for good!

[Tim Morton]

Spend too much time or money on it and your wife might send you out there for good!


The shed is actually for her 45th birthday...she gave me the choice of jewelry or a shed...i'm just not a jewelry kind of guy.:cool:

[Jerry Olexa]

Tim go at least 2X6 if not 2X8 for that span. Also in NE watch the deep frost line of I think 42".. G'Luck

[Randy Meijer]

Don't know what your local situation is; but here in Texas I have seen sheds that size blow over in a big wind. You might be smart to get some of the anchors that are used to tie down mobile homes and tie down your shed so it doesn't blow away.

[Cliff Rohrabacher]

In northern Maine We'd have to consider that during some winters ( snowless) the frost would go 13 feet.

[Tim Morton]

In northern Maine We'd have to consider that during some winters ( snowless) the frost would go 13 feet.

yeah sure... let me get the shovel to dig a few 13ft holes...:D

[Michael Cody]

My 10x20 woodshop/motorshop/shed is built with 3 - 4" x 4" x 20' skid runners, sitting 6" of 1/4"-3/4" 40% dust crushed stone -- then on the skid runners are 2"x6" x 10' 16"OC joists with 3/4 plywood floor. This is barn style w/2x4 walls, 12' high at the peak. It's sheathed w/T1-11, the inside is insulated w/1/2" ply sheathing. I've got all my wood, 2 v8's on stands and a 2 walls of cabinets in it.. plus all my stored stuff and in 5 years all I've had to do is jack up one corner and put a 4" block under it to square it up after that corner settled (it's the corner the v8's are sitting in).. I think you will be fine if you go with 3 runners, your spans on the 2x6's is under 4' (more like 3') and the floor is off the ground by at least 4" if you use 4x4's. The crushed stone keeps the water away from the skids and floor joists ... and 4" is not a lot of room for wind or snow, but will let it keep dry. Might get the odd critter underneath, I put hardware cloth across the ends and down into the stone to dirt.. keeps the animals out in MI anyway.

I feel a lot folks over-think this stuff really.... been folk building like this for 200 years w/o a problem. If you can lay your hands on some black locust, Osage orange or something in that line -- use that instead of 4x4's .. could even use for floor joists and save you a ton of money over PT and last longer too! The floor joists probably don't even need to be PT as they are 4" min off the ground. W/No ground contact and a dry environment, they will last a long time -- particularly up north like Vermont where carpenter ants & termites ain't such a problem. I wouldn't do that in Georgia other more temperate locations.

[Jason Roehl]

Tim go at least 2X6 if not 2X8 for that span. Also in NE watch the deep frost line of I think 42".. G'Luck

He's setting the joists on 6x6s or railroad ties--3 of them. So for a 10x12 shed, depending on which way he runs the joists, that's either a 5' or 6' span. A PT 2x4 is plenty.

[Jerry Olexa]

He's setting the joists on 6x6s or railroad ties--3 of them. So for a 10x12 shed, depending on which way he runs the joists, that's either a 5' or 6' span. A PT 2x4 is plenty.

oops Didn't realize he had a 3rd support. You're right but I'd still go 2X6s but thats my overkill way..

[Peter Stahl]

Don't know what your local situation is; but here in Texas I have seen sheds that size blow over in a big wind. You might be smart to get some of the anchors that are used to tie down mobile homes and tie down your shed so it doesn't blow away.


It's surprising they don't make you strap them down. I had a friend at work who had a lot of damage from a neighbor shed hitting his boat. I my area you can drop a shed anywhere just about (within limits from your property line).

[Peter Stahl]

I am looking for help here...i am building a shed..10x12...but its going to
be kind of tall with a high roof so it will get heavy by the time i am done. I am building the base using 4"x6" PT as a frame and then using 2"x4" 10' PT joists whihc will be supported by cement blocks. I am not going to pour a pad...I am planning on digging two trenches running the long way and filling with crushed stones and setting a 6"x6" x12' PT beam on each bed of stone. I think this is called a "skid foundation"? Will this be enough of a base? My neighbor came over to look at my idea and suggested running railroad ties on all 4 sides...problem is i do not look forward to lugging those out to the shed site...plus my ground is not real level and I think I can get it level better (re: easier) with just the two skid beams. Just looking for thoughts here.

Tim,

If I were doing it I'd close the end off to keep critters from living under there. Had a neighbor who had a skunk family living under there. You don't need 6 X 6's for this, just a 2 X 6 for the end. Probaly put stones under this edge would be a good idea too so water won't sit under the board.

[Tim Morton]

OK..kind of convoluted but I tend to make things up as i go along anyway. But the end result is rock solid and i got to use some wood I already had for the base...I will finish it up in the morning. But what I did is lay 2 RR ties out one in the front and one in the rear. That was my skid foundation. I then built a 10x12 frame using 4x4 PT and this rested on the RR ties.the 12 span is the width and the 10 is the depth. I then took a pair of 4x6 x12' PT that I had and ran those more or less down the center with 16" between them and then ran 2x4x4' out to the 4x6's...I will post a pic once I finish....but it seems to be fine. On top of that will be T&G OSB that i have sealed....tomorrow i will start framing the walls:D

convoluted but effective....thanks for all the help!!!

[Jim Becker]

Tim...you know the rules...if we can't see it, it didn't happen!! ;)

[Jerry Olexa]

Yeah, Tim where are the pics? You're probably watching the BoSox swoon on TV:D :)

[Randy Meijer]

Someone, please!! What is "PT?"

[Jerry Olexa]

pressure treated

[Tim Morton]

Someone, please!! What is "PT?"

Sorry....yes ..what jerry said. i am a lazy typer:D I remeber my first visit here I was going nuts trying to figure out was CS was... And also DAMHIKT:D

Pics will come later today....2 more hours of work till the RS are on:cool:

RS=red sox

[Tim Morton]

Well I got the framing out of the way last night...

[Jerry Olexa]

Well I got the framing out of the way last night...

Looks good, Tim!! You built in w a ridge beam and room for plenty of overhead storage!! Looks solid!!
Yankees-RedSox today @ 12 Noon Dbl header I believe. Wire a set outside while you work on the roof and siding:) :D

[Tim Morton]

Looks good, Tim!! You built in w a ridge beam and room for plenty of overhead storage!! Looks solid!!
Yankees-RedSox today @ 12 Noon Dbl header I believe. Wire a set outside while you work on the roof and siding:) :D

Game time is in 15 minutes...and i am stuck at work...:mad: :mad:

But I feel a cough coming on...*cough* *cough*...yes I may need to go home sick...:cool: