First thought is that a permeable perimeter would better serve you. Perhaps wood mulch. This would provide drainage. Why do you want to separate your shed from other organics?

thanks for the feedback - mainly I want to keep organics away to help slow the wood rot of the shed. Even with pressure treated I though having wood mulch next to it would cause more moisture retension and speed up the rot of the wood shed.

It seems that you are proposing a mulched area which you are calling "paver base"... not the actual pavers. If this is so, I'd be more inclined to call it a stone/rock mulch. It seems like a reasonable idea IF one makes sure that it is not in contact with any wood of the structure and actually, that there is sufficient clearance from any rot-prone wood. Being for the most part against "landscape fabric" as a weed deterrent, I am nevertheless FOR it as a soil "separator" when one adds stone mulch to soil. If at any time later one attempts to undo their "wrong" of having installed stone mulch, having installed landscape fabric along with it will turn out to be a big help. But, in the case described and making sure that sufficient clearance is maintained, I see stone mulch as having little benefit over plain old wood/bark-based mulch. It would do all the same things and not require a landscape fabric separator. The only other thing I question about the proposed scheme is if 30" from the building wall is sufficient for setting up a ladder. The easiest test is to set up the ladder and see what space it requires and add a small amount for clearance.

Thanks, how is it different from the base of the shed being set on gravel? The wood is contact with the gravel at some points and it seems like the idea of the stone / gravel base was to allow the moisture to filter down, away and into the soil vs a wood mulch that retains more of the moisture towards the surface?

My idea of the paver base was two fold - creating the solid surface for a ladder (30" is sufficient, though I may go to 35" for added comfort - I have a little giant style ladder with a 25" width at the base) and it doubles as improving drainage by moving water through and away rather than a wood mulch that retains more.

Certainly I'm no expert, but that was my logic.

The only area of contact I anticipated with the paver base was with the shed ramp which is pressure treated and contacts the ground at some point regardless of what I do.

When we had the ugly old shed that came with the house torn down and replaced fall 2006/spring 2007, the new shed was built on top of those big concrete squares, set on compacted crushed gravel. The concrete squares became the floor of the shed. The guy who built it for us used that Trex stuff for the bits that are in direct contact with the concrete. Our shed is smaller than yours - 10' wide x 8' deep.

We didn't leave space around the shed, other than at the rear where there is about 15-18" between the shed and the compost bins. The other three sides are planted - but the closest things are either perennials than can be cut back if necessary or shrubs that can also be pruned hard if need be for access. A couple of years after the shed was finished, I changed my mind about the color. DH was able to paint it easily without damaging the plantings.

Any unheated wooden structure is going to deteriorate over time. If we get 20-25 years of use out of the current shed, I'd count that as good. By that time, we're likely to have moved on anyway :-) So think about realistic lifespan for the shed and your likely tenure on the property when thinking about its construction and the planting around it.

Here is a link that might be useful: Shed project

Thanks woodyoak. appreciate the comments. If I got 15 years from the structure I'd be happy. I'd rather not do back breaking labor to get that, but if that is what is necessary then so be it. I have some comments elsewhere telling me to drop in 3 inches of paver base else I risk it being washed away. If's very confusing to say the least, I obviously want it to last but the difference between an inch and 3 inches of base is actually overwhelming. I see neighbors that have done a heck of a lot less than what I plan and they have 10+years. Its difficult to decide what is enough and what is overkill.