Need Outside Coal Bin Advice.

So I'm going to be making a coal bin for under my deck. I have plenty of room for a 10 x 6 x 6, but would probably cut the 10' down to 9'. And was thinking I would slope the floor long ways. Was thinking I could go 2' higher on the back end. I'm thinking I will have a auger on the low end. I calculate the slope will cost me about 54 cu ft. I think I would still have like 5.4 ton of coal if they fill to about 5' high. I think 5 ton would be plenty of coal for the year.
What materials would you recommend? I think I would make slide out boards on the front and back to have access if needed. 2 x 4 frame strong enough? I think a metal roof would be best.

Thanks

Lot of food for thought in the "Pictures of your bin" thread.

COAL BIN Pics

Steel cable or two through the middle could help.
Good drainage and ventilation...don't want it to freeze or ice up.

Make it sloped and/or add a low point drain.

Couple ideas for you....
I put a couple 5" round vents at the high side of the walls of my bin so there would be airflow across the top of the coal stash.

I used three 4 x 4 runners spaced across the 4' width and used 5/4 deck boards spaced slightly for the floor so that water could drain out and airflow could come up.

Since I had a partial roll left over, I put tyvek on the sloped boards to 'slippery' them up and keep the coal sliding toward the intake pipe. If you don't have it on hand, big box stores sell it in small sizes and it will be cheaper than any metal flashing material.

I made a hinged hatch on the roof that I could swing open and it is wide enough to dump the loader bucket of coal into the bin. Hindsight says I should have made it 6" wider and I wouldn't have to be so exact when lining up the bucket. I use flashing across the top where the hinges are and along the sides to keep rain out.

My bin is 8' long and I have the long sides sloped the 3.5' toward the middle where the intake pipe is. This summer I will be adding a sloped board on the one short side and shortening the intake pipe to be more toward the one wall. The coal will be pushed from three sides toward the intake pipe rather than just two sides. That will cause more dead space in the bin, but will keep more coal within reach of the intake pipe.

Do you have any pictures of your bin?

I made my bin 4'X4'X4' that way I could get away with using 2 sheets of plywood, and all of the 2"X4"s I bought were 8', so a had little waste. I made the front of it with 5/4"X 6" slats that are can be removed and the bottom two slope into the bin with a 12" gap to let the coal flow out so it can be shoveled out.

My suggestion for the walls of a coal bin is use dry stacked concrete blocks. The kind of block to use depends on how high you need the walls. You could use hollow core 8 or 12 inch block, lower courses could be 12 inch, upper 8". It's surprising how high you can go, especially if you put a re-bar in the open core, to tie each course to the next. Fill the core voids with coal. What's nice about this approach is it's easy to change, enlarge, move etc. Works well on a concrete pad. If you are going to have high walls consider the interlocking retaining wall blocks commonly used in landscaping. Want more stability? Use the dry stack block method that bonds the wall together by a surface plaster of portland cement with embedded fiberglass. In all cases an exterior banding strap can hold it all together for even more security.