This is an accurate list of things you can destroy and the effort you need.
I didn't tried personally to destroy all the things listed, but many that I tried confirm those numbers.
Pratically is important to remember that you can destroy all except pillars, ceilings and foundations.
Credits to user Juper0 / Source
Wood
Wood Shelter: 400 Hits - Metal Hatchet, 167 Hits - Pickaxe, 11-12 - Grenades, 1-2 Charges - C4
Wood Wall: 11-12 - Grenades, 2 - Charges C4
Wood Pillar: Only by decay
Wood Stairs: 54 Hits - Metal Hatchet, 23 Hits - Pickaxe, 11 - Grenades, 1 Charge - C4
Wood Ramp: 84 Hits - Pickaxe, 10 - Grenades, 1 Charge - C4
Wood Ceiling: Only by decay
Wood Foundation: Only by decay
Wood Window: 11-12 - Grenades, 1 Charge
Wood Window w/ Bars: 2 Charges - C4
Wood Doorway: 11-12 - Grenades, 1-2 Charges - C4
Wood Doorway w/Door Attached: 2 Charges - C4
Wood Door: 200 Hits - Metal Hatchet, 84 Hits - Pickaxe, 6 - Grenades, 1 Charge - C4
Wood Gateway: 5 Charges - C4
Wood Gate: 120 Hits - Pickaxe, 32 - Grenades, 3 Charges - C4
Metal
Metal Wall: 4 Charges - C4
Metal Pillar: Only by decay
Metal Stairs: 1 Charge - C4
Metal Ramp: 1 Charge - C4
Metal Ceiling: Only by decay
Metal Foundation: Only by decay
Metal Window: 3 Charges - C4
Metal Window w/Bars: 3 Charges - C4
Metal Doorway: 2 Charges - C4
Metal Doorway w/Door Attached: 3 Charges - C4
Metal Door: 11 - Grenades, 2 Charges - C4 (Metal Doors cannot be damaged by melee weapons or guns. Only through explosives.)
Objects
Wood Barricade: 17 Hits - Pickaxe, 2 Charges - C4
Spike Wall: 25 Hits - Pickaxe, 1 Charge - C4
Large Spike Wall: 100 Hits - Pickaxe, 2 Charges - C4
Small Stash: 5 Hits - Rock, 7 Hits - Stone Hatchet, 4 Hits - Metal Hatchet, 2 Hits - Pickaxe
Small Wood Storage Box: 34 Hits - Stone Hatchet, 20 Hits - Metal Hatchet, 9 Hits - Pickaxe, 1 Charge - C4
Large Wood Storage Box: 67 Hits - Stone Hatchet, 40 Hits - Metal Hatchet, 17 Hits - Pickaxe, 3 Charges - C4
Furnace: 34 Hits - Stone Hatchet, 20 Hits - Metal Hatchet, 9 Hits - Pickaxe, 2 Charges - C4
Workbench: 67 Hits - Stone Hatchet, 40 Hits - Metal Hatchet, 17 Hits - Pickaxe, 3 Charges - C4
Camp Fire: 34 Hits - Stone Hatchet, 20 Hits - Metal Hatchet, 9 Hits - Pickaxe, 1 Charge - C4
Sleeping Bag: 34 Hits - Stone Hatchet, 20 Hits - Metal Hatchet, 9 Hits - Pickaxe, 1 Charge - C4
Resources have certain areas to spawn, although within these areas they spawn in a random location inside the area boundaries. so for example north north-east of split rad there is a location called next valley, in this location i believe it is the most densely spawning location for metal piles and wood piles... it is hard to find a map for these locations seeming how everyone calls areas different things (every makes code names for places within a squad).
in the link below this is a map that shows different locations. on the north of the map you will see next valley if you are looking for a place to make a base this is a good location, although you will have to look out for other people. this place is kinda high traffic.
Click to go to map
hope this helped, this information has come from my experiences in the game, 300+ hours if you were wondering.
Best Answer
You can enter co-ordinates here: https://rustmap.net/