I am demolishing an existing 8x11 shed and putting up a 10x10 shed and need to decide on a foundation type. I was originally considering a concrete tube pier footing, but since scanning the posts on this site, I have come across using Dek Blocks, Concrete blocks on grade and precast pier blocks. I live in NJ where it gets really cold in the winter. I have few questions on these methods:

Concrete Blocks on grade - Do I need to fill them with concrete, then anchor a sill plate on top to start the floor system? What would be the best way to anchor the sill plate? Is this method ok for my climate?

Dek Blocks and/or precast Pier Blocks - This is going into my parents yard. They don't really want to have any clearance under the floor so that animals can get access. The Dek Blocks and pier footings end up with some space underneath. Is there a method to building the walls or something to close off that space? What is the required minimum clearance from grade to the bottom of the floor? I read that it is desirable on a non-slab base to have space underneath for ventilation to control moisture.

Thanks in advance - Jerold

 

I refer a poured concrete floor. Its life is forever, its strong, doesnt rot, and is smooth. No animals living under it either.

My eighbor put in a big 15 by 20 foot shed with a treated wood floor.

I tried to get him to go with concrete, he opted for wood and is now very sorry. animals, wasps nest etc. he is talking of replacing wood floor with concrete, now thats a ton of work.

 

I'm with Bob Haller on this one -- a concrete slab. A 10' X 10' slab at 4", with an additional 4" of depth 6" wide footing around the perimeter is only about 2 yards of concrete. $200 for the mud. If you hire somebody to finish it, that's another $150 to $200. It's down, it's done, and it lasts pretty much forever.

 

The poured concrete is an easier route, but the code guy at town hall said not to do a slab and use a post footing. I'll check again why. If the slab is an option, how do I need to prep the ground for the pour? Clear the area, level the ground, ?1"-2" gravel?, 4" concrete? Do I just need to dig an additional 6" deep, 4" wide trench around the perimeter for a footing?

 

WHAT???

Here we are, getting into different codes for different jurisdictions, AGAIN!!

First, find out what set of bldg. codes you are governed by. The left coast operates under the UBC. That states that as long as the shed is less than 120 sq. ft., no bldg. permit is required, and essentially the homeowner can do pretty much whatever they please, so long as it doesn't violate the CC&R's of where they live.(Bldg. Depts. don't enforce CC&R's -- that is up to the residents of the area or a homeowner's assn., if one exists.) But that's the left coast (or at least some of the jurisdictions within the left coast!!) Where you are, things ARE going to be different. I run into that problem DAILY, just going from one county to the next, or one city to the next, or going from a given city out into the county ... There are just way too many ways to interpret a code book, and too many gods doing so!!! (Enough of that soapbox!!)

Go with what YOUR local guy says -- he's the one you are going to have to please.

IF he will let you put it on a slab, then (and this is the left coast way!) dig out 4" of dirt below grade. Dig a footing around the edge that is 2" to 4" deeper and about 6" wide. Add 2" of base under the slab, but not in the footing trenches. Then pour the concrete slab 4" thick, plus filling the footing trenches. (That puts the slab about 2" above grade.) Stick your foundation bolts in the wet mud so that you can bolt the walls to the slab. Once the slab is dry (a couple of days), build the shed.

 

Thanks, Lefty... Tell me about it. Whenever we go to the town hall to get info, the rules change depending on who you talk to at the desk that day. I was researching on the web and came across a site describing the Township code of laws for Utility Sheds for another town in another County from me. They say that they use The New Jersey Uniform Construction Code. I am assuming that since it is the the NJUCC, it applies to the entire state and it stated that anything under 100sf and less than 10' high requires no permits. My town is charging $35.00 for a permit for this thing.

I want to cover the details for a pier post footing with girders supporting the floor for the town hall. My shed's footprint will be 9'x'11'. How far in should I offset the post pier footings from the corners and which direction should the girders be placed (long ways or short ways)? I plan on using fiber form tubes with an EBC 4x4 bracket and 4x4 post on top. I plan on bolting 2x6's to either side of the 4x4 post to form the girders and to minimize the clearance from the bottom of the floor to the dirt below.

Do these lumber dimensions sound sufficient for my needs?

Lastly, should I use only 4 post pier footings or should I add a third set at the midpoint and run the girder in the 9' short direction?

Thanks.

 

I am looking into a similar project, with post/pier questions. would love to hear the answers if you got them (and at this point, how the shed is looking !)

 

You can still pour a slab on top of footings that extend below the frost line to avoid building a wooden floor. A definite overkill for an average size shed, but if the township insists... I don't believe there's a code in the world (even NJ) that won't allow that.

 

So we are trying to decide on whether to do a wood or concrete foundation, sounds like concrete is best. However we will be putting the shed on a concrete patio. Is a foundation needed? if so is pooring the concrete foundation over the concrete patio OK???
Thanks

 

Anchor the shed directly to the existing slab. You'll be fine.

 

Is there any kind of sealer that should go around the bottom to keep out water?

 

A silicon sealant would do OK -- a polyurathane would be better. At $5 a tube for the silicon or $10 a tube for the polyurathane, I would spend the few extra $$.

That will keep the water from coming under the bottom track of the frame -- it will do nothing to stop the moisture from coming up thru the slab, thru the joints in the walls, etc. The shed is an unconditioned space -- don't store anything there that MOISTURE can damage.