Here you go

Resummarizing here because it wont let me edit my main thread, with photos.. plywood is often used for observatory builds because its a smoother surface to seal off, i assumed it was ok..

Summarizing again:

I've tried using some online deck building tools to generate the materials needed for what should really be a simple build for this, but i'm getting weird results and had some questions. I thought home depot had an online one, but only found an offline tool, lowes online did work, but in both cases they generated ridiculous materials lists and prices close to $10k.

I know that a build like this should only cost $300 to $400. (with everything i have below and $69 to ship, its around $480 as of now, so higher than planned)

On top of the deck will be the nexdome with 2 bay (astronomy plastic dome weighs around 300lbs i think).

The first issue is the soil/ground. I have to make things level, so that i dont need extra height on a concrete pier, to keep the whole structure say 12" off the ground and not need a railing.

Here is a shot of my ground so far, i wasnt sure if i should just get a bobcat and push it forward till level, or if tossing the extra dirt that is "high" on the upper part, to the lower part would suffice or cause a settling issue later?

Either way, once down to level, i figure ill either just leave it as just dirt under, or put down plastic to block weeds and cover with a thin layer of gravel.

Back to the deck build itself:

12x6 vs 12x8:

I've seen many do the 12x6 route, but I wasnt sure, so for now i have it figured as roughly 12-13 12x8s?

I have two 4x4x8's figured, but i'm thinking there will be at least 6 posts, with the deck surface at least 12" off ground, may need a few more to go into cement block

Onto the blocks (going with blocks instead of posts in the ground, so when we move, we can just take the whole thing and go, or disassemble):

I think these are the right concrete deck blocks? But now that i'm thinking about these, it looks like they are really meant to go under the 12x6 going longwise? So perhaps for the posts that will be 12-14" tall, i need something else here? (I figured 6-9 of these max)

One of the online builder tools generated the list using these wood to wood triple zinc framing angles, again i'm not sure these are needed?

I know i need joist hangers, unsure on the quantity, but these 2"x2x18 gauge triple zinc face mount joist hangers

**the part on these i'm unsure on, is since this is low to the ground, how ill go about attaching these,since the floor needs in place, so i guess i need to tilt the whole structure to do this

Many regular decking forums dont suggest using plywood for the floor, but i've seen many nexdome floors done with it, i was assuming it was this plywood:

Severe Weather 3/4 inch common square southern yellow pine sheathing 4x8's $39?

I was estimating i need 3 of these.

Then I was figuring using all deck screws and not nails (in case i need to remove them), or maybe nails (which type?) for the hangers. These #8 2" ceramic I thought were the right ones? (or maybe 2.5")

Here is the view of the joists as generated by the home depot offline tool, generally i was figuring a joist every 16, not sure about the extra ones near the pier location:

Another question is on the underside, in the one online generator it shows these things that i'm not sure on, ie: the posts have those brackets and there are i think the right angle brackets:

The other part i think i'm missing here are "toggle?" bolts that go into the posts? With nuts on the other side of some size?

Any thoughts on all this so far, is this a pretty accurate list of things to do this simple deck?

Bottom of the post is a Post Base Connector which attaches the post to the footing.

The 2nd one is a Post to Beam Connector which attaches Post to a beam.

3d is the Hurricane Ties which tie deck joists to the beam to prevent uplift. In your picture that is a cheaper version probably from HD or other box stores. If you located in a hurricane region use the one provided in the link.

That said, 12" above ground you exceeding code compliant riser height, so you should have at least 1 set of steps to get on and get off the deck... In any case, you should get a permit for whatever you trying to build there and submit the drawings so you not violating any local requirements as zoning and everything else goes...unless your local jurisdiction doesn't require that for a ground level deck.

Thanks for the pointers on all that. I checked our local guides, only real requirement i'm seeing is that to avoid a permit the structure must be under 200 square feet. There could be a hidden requirement on the step, so ill try to keep it under 10". I probably dont need the hurricane ties i'm assuming.

Here is a resummary on where i think i am now (exceeded my original budget obviously)

I will omit the extra beams at the top and bottom of the diagram (double beamed) and just attached directly to the 4x4 the 12x8 boards using carriage bolts diagonal above each other.

I wasnt sure though, if i could drop down to 12x6 for the joists portion, while leaving 12x8 for the perimeter. My goal is that the deck floor is around 11" off the ground at most, maybe only 9".

i may just switch that back to 5/4 board instead of the plywood to avoid pooling of the water i've read about.

My list so far is at around $480 shipped (before switching to 5/4 boards), yeah a bit higher than my target, i think a person who hit $300 was using 12x6's etc (re summarizing/adding here)
(after switching to 5/4 boards and adding a few more things here, i'm at more like 670$ shipped, far beyond my original target of $300)

2x8x12 (figuring 16 so far?)

4x4x8 (2 of these)

I guess the screws and nails count depend on hangers or not, so for now 5lb of each to start i guess:

For the deck screws, i'm not sure i recall if ceramaic or polymer matter? And on length, i think 2.5" is ok? (or 3)
Here are 3" Polymer ($26 for 5lb)

For nails, i assume galvanized and 3" as well?
All i'm seeing is a 5lb option: Grip rite 10 gauge hot dipped steel nails 5lb ($15)

If doing hangers i had USP 2" x 8" 18 gauge zinc face joistt hangers (23-28 of them)

For the blocks, the 7" x 11" x 11" concrete deck blocks (9)

I wasnt sure if i need the wood to wood framing angles, here 1.5inch 16 gauge

Do i need these 4x4 triple zinc wood to wood bases for the bottoms of the 4x4 posts into the concrete?

Finally the 5/4 x 6 x 12 foot boards, the one generator indicated 24 of them (the standard grade here not premium but treated)

And two 5/4 x 6 x 10 boards

I don't know if you're still wanting advice, but here's my take. Joist hangers are a pain to install and expensive in the right finish. Those special blocks are expensive. The simplest and cheapest deck to build is a cantilever deck like the attached photo. You don't need the double 2x beams like in the photo. The simplest way is to buy 2 4x4s 12 ft. long. Those replace the 2xs shown. Shim them up with solid concrete block pavers, the cheap ones at HD. Try not to put blocks on soil you've moved (more chance of settling). Place those block supports at 4 ft. on center along the 4x4s. Level it all up. You can shim with scraps of treated 2xs or 1xs. Then screw attach the joists to the 4x4's and the perpendicular rim board to the joists. No hangers. I found that 2x6 was the cheapest deck board. You may be able to go 2 ft. on center with your joists. I built the same deck with the 4x4 base for a temporary stage for a wedding. 8 musicians and their equipment all night. Solid as a rock.

BTW, resting your deck on soil as you have proposed is not an ideal solution. You're bound to have settling and movement especially if you get frost in the ground. But you can level it with shims in the future.

Seabornman, Concrete pier block is about $8 a piece at the box store. joist hangers, ZMAX Galvanized joist hangers are $1,37. for ground level deck that size footings are not required, so frost or no frost that deck is not going anywhere.

Thanks all for the advice.

i had just purchased most everything the other day.

The deck wont sit on the surface. The base of the 2x8's will have about 4" under them, so around 14" to the top of 5/4 x 6 boards ontop.

I have 2x8's for frame/joist (overkill and fine code wise for my area).

I've opted to cement in the posts, ill go with 3 on each side along with one on each side of the pier area. I'm going to just dig down 2 feet and put 1/2" back of high strength quickcrete in each hole and add water, backfill later next day or maybe after 20 mins.

For the other pool deck we only went 3 feet (4 foot is frost line yes), but its held very strong and has much higher posts.

I figure ill use bricks to get things roughly level for the post and use temporary 3" deck screws that i bought to frame/level it until the concrete sets (do one side at a time), then add the cement and wait till it sets 4 hours later and move on to the next part/not add weight to things until then.

I also switched the hangers from triple zinc to galvanized.