Please help — Building a shed over an existing concrete slab
I am posting this in the garage/workshop forum but perhaps it belongs in the remodeling forum so please let me know.
We have just bought a house and despite my desires, I am not up to many of the projects the house needs so I am relegated to reach my glory with a new shed.
The shed will go over a concrete slab that once housed a metal shed. The concrete is in good shape and is 11×8. Here is my question. how would I attach a wood floor to the shed? Do I need a power hamnmer to connect the wood to the concrete? And, does my new shed have to fit exactly over the slab or could it be bigger?
I have some shed plans that I will probably use (god help me when i get to the roof) but my first question relates to the floor. Please help if you can add anything to this.
The walls could be on the edge of the concrete slab (assuming slab is square) but not larger. Why do you want a wood floor over a perfectly good concrete surface? It’s only extra work and expense. Anyway you can attach the walls of the shed to the concrete using 3/8″ anchors. They come in different lengths. You will need a masonry bit, drill the required size hole and then pound the stud into the hole. Once tightened it spreads to hold the stud and therefore the wall in place. A very strong method of fasteneing and it’s what I used.
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Thanks Cruise. That makes sense. is that the same concept of using a hammer jack? That’s what a neighbor recommended. So, without a floor the door frame would allow for a seemless entry into the shed (without having to go over the frame. Conceptually I am a little challenged but I want to give this a go.
I’ll try and post pics of mine tomorrow. Maybe that will help.
You could build you shed right on top of the concrete slab, just like they do with a house on a slab. You didn’t say want you wanted to use this shed for but you might want to consider “the lay of the land”. Sometimes when slabs are poured for sheds they aren’t quit as high above grade as they should be. You don’t want to find that the floor of your sheds ends up under water after a heavy rain.
To connect the base plate of the wall to the concrete youÂd need to use an expansion type anchor. There are a couple of variations Â a wedge type and a sleeve type but they all do the same thing Â expand in the hole to make a secure connection to the concrete. Generally speaking things like powder actuated fasteners and “Tapcon” type screws arenÂt sufficient. A hammer drill makes drilling holes in concrete much easier. You can rent one for $20 or so. Any wood that comes in contact with the concrete must be pressure treated. IÂd also run a heavy bead of construction adhesive under the wall base plate to form a seal.
A “jack hammer” is generally used for destruction, not construction.
You didnÂt mention anything about permits. Many communities require permits for this kind of construction and you local building department can be a useful resource if youÂre less than sure of your carpentry skills. Certainly the inspector isnÂt going to help you drive nails but he can make sure you donÂt get into too much trouble.