Dwarven Reinforcement

You can use your knowledge of engineering and metalwork to temporarily strengthen thick objects and structures. By spending 1 hour working on an item, You can increase the Hardness/Toughness/Durability for 24 hours. [+500 Durability Points]
If you're a master in Crafting, the bonus is +800, and if you're legendary, the bonus is +2,000. You can reinforce a portion of a structure, though 1 hour usually reinforces only a door, a few windows, or another section that fits within a 10-foot cube.