Concrete slab for shed on uneven ground

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Old 09-09-19, 10:25 PM
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Concrete slab for shed on uneven ground

Hello - I'm putting together a 4x4x6 Rubbermaid shed. I'm thinking of a concrete base to which I can anchor the shed using bolts (hurricane prone area). But the ground is sloping, please see the attached pic.
1. Given the slope in the ground, how do I go about setting the batter boards? That is, using 2x10 may expose a gap in the lower end when leveled, right? Should I cover that gap with something to prevent gravel/concrete from flowing out?
2. Should the concrete base itself be anchored to the ground in some way? Also, can I just use Quikrete for the concrete?

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Thanks!
 
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Old 09-10-19, 02:50 AM
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Welcome to the forums!

First you want to remove the sod along with any high spots. You want the bottom portion of the perimeter of the slab to be below grade. 3.5" is thick enough for the concrete although it may need to be thicker at the low end to make it work right. Bag concrete is fine.
 
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Old 09-10-19, 04:29 AM
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First check with your local zoning and building inspections departments. Sheds often have setback requirements from property lines. This is often made worse when installing a concrete base as zoning now considers it a permenant structure and it can fall under more restrictions. The space you marked is pretty tight so you very might run into setback issues.
 
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Old 09-14-19, 08:16 AM
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Thank you Pilot Dane and marksr for your responses! I checked the zoning rules and yes the above marked area is utility easement and can't build there. Please see below for the revised location - marked in red arrow (sorry the pic doesn't show the complete view), this is close to the house foundation/wall though. Do you foresee any issues with this placement?
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Old 09-14-19, 09:49 AM
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The biggest issue with building a shed next to the house is the gap in between the 2 creates a great place for trash/leaves to collect.
 
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Old 09-14-19, 10:09 AM
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When you set your frame you will want a little slope to force any water to drain away.

We can't see above that area but if there is any run off from the roof above that will hit that shed it will splash against what ever part of the house is there. Rain will still splash and water off of the shed roof needs to be considered.

Being that close to the house I doubt you will have a frost issue, unless you are in really cold country.

Bud
 
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Old 09-15-19, 09:23 AM
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I would make the base out of pressure treated 2X6 or 2X8 then use shed anchors to hold it down re: hurricane area.

Then if it causes any problems it will be a lot easier to move.

Also you will want the shed roof to slope away from the house if possible.

The gap between the house and the shed will not only collect debris but also moisture so depending where you are located moss/slime etc. could start growing there.
 
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Old 09-17-19, 10:07 PM
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Hi all - here is a better picture of the site - the black plastic base (approx 4 ft x 5 ft) is the floor that came with the Rubbermaid shed and is placed approx. where the shed will be (I can increase the gap between the shed and the wall if that's a better design to avoid moisture build-up etc.) I'm confused whether to go with treated wood or concrete. I'm in Houston, so want to make it as much rain/wind proof as possible. In case of treated wood base, how do I anchor it to the ground - using concrete piers or some other kind of anchors?
manden Bud9051 marksr Pilot Dane
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  #9  
Old 09-18-19, 02:09 AM
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Below is a link that should help
https://plasticinehouse.com/how-to-anchor-shed/

I would use the auger type anchors.
 
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Old 09-18-19, 04:37 AM
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I don't think you have room for a shed there. You can't get the shed far enough away from the house for there not to be some type of problem. So, you'll just have to live with the consequences.

The most important issue will be the roof of your shed. Which way does it slope? You do not want the shed right up next to the house with a roof that will funnel water back towards the house.

As for the problems, you likely will have debris, critters, mold and algae in the small space between the shed and house. Most importantly this might permanently stain the brick and mortar in that area.

For the base I would build it from pressure treated lumber so it can be easily moved or removed in the future. Most 2"x treated lumber is only treated for above ground contact while most 4" x lumber is treated for ground contact. So, make the base frame out of 4x4 or 4x6 timbers. Try to leave as much air gap underneath the base for ventilation. Zoning and building codes may not allow you to have a permenant structure (poured concrete) that close to the house so that might not even be a legal option.
 
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Old 09-18-19, 07:05 AM
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Thanks manden, I will check that out!
 
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Old 09-18-19, 07:33 AM
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Pilot Dane Thanks, please see the picture of the shed below - the roof is sloped to the sides. The requirement here is 5 ft away from the fence so I'll keep the maximum possible gap between the shed and the wall. Will definitely go with treated wood as per all of your comments. Any other comments or recommendations on anchoring the treated wood base (also considering that the ground is slightly sloping)
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Old 09-18-19, 08:58 AM
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I would build a sled style base, using two 4x4 or 4x6 for the runners. Cut bevels on the bottom so it doesn't dig in when you try to slide it around it. I would orient the runners parallel to the long edge of the shed. Then securely attach your shed to the sled base.

Then bore 3 or 4 holes downwards at a 45 degree angle through the sides of each runner. Weld a heavy nut (something big like a 5/8 - 1" nut) to the end of 30-36" long pieces of 1/2" rebar with the hole in the nut sideways (hole through nut open, not blocked). Then drive the rebar stakes through the angled holes to anchor it to the ground. Angling the rebar into the ground does a lot to prevent the shed from being uplifted in heavy winds. The hole through the nut allows you to put a piece of rope through it to pull and remove the stake if you ever want to move the shed. You can also weld a heavy washer onto the end of the rebar or put a 90 degree bend in the end to leave a "handle" though they are harder to get a good grip on to remove. If you don't ever want to move the shed then you can use straight pieces of rebar and pound them in until flush with your wood runners.
 
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Old 09-18-19, 03:08 PM
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Pilot Dane - thanks a lot for the detailed steps!! However, this seems a little complicated for the amateur me . How about using concrete piers like shown below and I build a treated wood base on top of that - any feedback on this method? This will take care of the issue with uneven ground and also provide good anchoring. I'll probably need only 4 (smaller) piers for my small shed
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Last edited by jsgeorge; 09-18-19 at 03:26 PM.
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Old 09-18-19, 04:06 PM
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I would not go to so much trouble for such a small shed and certainly would not do anything so permenant. As another option I might dig to create a level area. Maybe put down 12" square concrete stepping/patio stones, a couple air conditioner base pads, or a layer of crushed stone.

Where are you located? Are you in a high wind coastal area? Right up next to the house and surrounded by the solid fence the shed will be protected against wind pretty well. Depending on what you store in the shed I might not even anchor it or you could use a shed anchor kit.
 
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Old 09-18-19, 04:28 PM
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Pilot Dane Thanks, I'm located in Houston, TX. We have a lot of rain and storms every year, hence the concern with anchoring + also water pooling near the base!
 
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Old 09-19-19, 02:55 AM
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IMO that is too much work for such a small shed and being close to the house the wind won't be as big of an issue as it would be if it was out in the open. Another option to PD's rebar method would be to use a post hole digger to dig a hole on each side of the shed and fill it with concrete embedding a strap that you could nail into the shed's floor framing. You might be overthinking this.
 
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Old 09-19-19, 04:32 AM
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Those sheds aren't the most sturdy. I've seen the upper part ripped completely off the base which was anchored to the ground. So, I'd do something easy. If you really want to anchor it use straps going completely over the top to hold it down which will be ugly and the straps will need to be replaced every year or two because of sun damage. You could also get creative with bracketry inside the shed to try and attach the wall and roof panels together more securely and firmly attach the upper to the base.
 
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Old 09-19-19, 04:47 AM
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Years ago in wind prone areas they'd take a metal tie down strap and go over the roof of a mobile home and connect it to the tie down on each side. Those straps would last decades. Modern day MHs have those straps integrated into the framing hid from view.
 
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