Hot blazing sun or frequent rainy days can make you wish your deck had a roof. With a roof, your deck becomes a shady sanctuary. You would be able to light your grill even if it was rainy. Because you’re wondering how to build a roof over my existing deck, you’ll need to have some good carpentry skills. To complete the project, you’ll design rafters and cut them with a circular saw. You’ll probably want a partner to help you lift heavy boards into place.

Preliminary Investigations

Confirm that your existing deck has been built solidly. You’ll install the support posts for the roof alongside the deck frame. The frame also needs appropriate blocking. How to build a roof over my existing deck involves understanding your local building codes. Visit your local building department and find out what codes must be followed when building a roof in your area.

How to Build a Roof Over My Existing Deck

1. Measure your deck and determine how much lumber needs to be purchased.
2. Dig holes for the new roof support posts.
3. Mix concrete in a wheelbarrow or rented concrete mixer.
4. Position post base connectors in holes and fill with concrete.
5. Slide support posts into base connectors and secure with structural screws.
6. Make sure posts are plumb with the level.
7. Nail temporary lumber braces to the support posts.
8. Notch the tops of the support posts to receive the header beam.
9. Drill holes for through bolts.
10. Connect the header beam to support posts with through bolts.
11. Apply flashing along your home’s wall where the ledger board will connect.
12. Drill holes in the ledger board and the wall.
13. Secure the ledger board against the wall with bolts.
14. Measure from the ledger board to the exterior edge of the support posts for the new deck roof. This figure is your total run.
15. To calculate the rise for your roof, enter the run and the pitch in the calculator. This produces the diagonal.
16. Hit the rise button on the calculator to get the final figure.
17. Set up your saw horses and prepare to cut rafters with a circular saw.
18. With the rafter square, mark the birdsmouth notches where the rafters will set on the header beam.
19. Nail rafters to ledger board.
20. Nail rafters to header.

Nail roof sheathing, like OSB, over the rafters.