How much weight can the average basement floor (made of concrete) support?

[ ]

[ ]

[ ] <--------- cinder block or concrete wall 8" wide

[ ]

----------------

---------------- <------------ concrete footing 16" wide and 8" thick

o o o o o

o o o o o <----------- 4" of gravel under the entire slab.

THE diagram indicates a typical foundation and footing design. I did this so you would understand that the footing under the foundation sticks into the basement approx 4", and the slab sets on that. If the platform evenly distributes the weight and the platform is right against the wall, it should be fine. If it sets anywhere other then partially on that footing, there is a good chance it will crack the concrete. When the gravel is placed before the slab is poured it is not compacted to any degree, so regardless how well the soil underneath that is compacted, the movement will occur in that 4" of gravel and it will crack under that volume of weight. My suggestion is cut out a section of concrete about 6" bigger then the dimensions of the tank, remove the 4" of concrete and 4" of gravel and pour concrete back at that 8" thickness. Something else to do, is prior to pouring the concrete back, drill 1/2" holes at 4" deep into the existing slab in the middle of the concrete every 24", starting 2" from each corner. Then cut 8" pieces of 1/2"rebar and drive them into each hole so they stick out. Then run pieces of rebar to the 4' protruding making a grid. The bars should overlap the 4" protruding 3" at each point

x x x x x

------------------------------------

x [ ] x

[ ] X= points to dowel in rebar

x [ ] x

-----------------------------------

x x x x x

It may sound like a lot of work. It's really what you should do though. Want you don't want is to take advice from a non professional. I'm in the US so you need to make the transfer to metric. Hope this sheds some light on the situation for you.

Putting down backer board is a waste of time and money when going over a smooth cement floor. Backer board is used to stiffen up an existing wooden floor or wall. It can also be used when planning a shower to allow for build up to slope to a drain. As far as sweating is concerned backer board will not prevent it if it is a problem. It will just make your floor thicker. The sweat comes from the air contact with a cooler floor surface it is not from water seeping through the floor. A dehumidifier will help to solve this problem in the summer months. Make sure you use a sufficient base of thinset (1/4 inch trowel minimum, 1/2 inch if uneven or rough spots). Mixing a latex additive to the grout is also a good idea in below grade and outdoor grouting situations.

That depends on how thick the concrete floor is. a normal 4 to 5 inch thick basement floor should be just fine. a typical garage floor is 5 inches and it can hold a car. if you are still concerned you can find a web site that has a chart ti calculate the weight load or psi on new construction.

There were so many woodworking plans with this collection and you will not believe this but there are over thousands plans in the one package deal. Go here https://tr.im/4YOaC

This is really something to find that many all together. For someone like me who is just really starting to get involved with woodworking this was like letting me loose in a candy store and telling me I could have anything I wanted. That was my dream when I was a kid.