Remove the damaged shingles on the porch roof and inspect the existing wood plank decking. Due to the excessive gaps and cracking between the wood planks, install new OSB roof decking per current code requirements over the existing plank decking to provide a solid and code-compliant nailing surface for the new roofing system. Remove the existing chimney flashing and install new custom-fabricated metal flashing around the chimney area to ensure proper waterproofing and prevent future roof leaks.