Installing deck flashing on an existing deck can help protect the structure from water damage and extend its lifespan. Deck flashing is a thin metal strip that is installed between the deck and the house to prevent water from seeping into the house through the ledger board. Here is a step-by-step guide on how to install deck flashing on an deck.

Gather the Materials

To install deck flashing, you will need the following materials:

Deck flashing

Metal snips

Tape measure


Nails or screws


Caulking gun

Measure the Length of the Ledger Board

Use a tape measure to measure the length of the ledger board where the flashing will install. Be sure to measure the length accurately to ensure that you purchase the correct amount of flashing.

Cut the Deck Flashing

Using metal snips, cut the deck flashing to the length of the ledger board that you measured in Step 2. The flashing should be long enough to extend at least 2 inches past the edge of the ledger board on each side.

Prepare the Ledger Board

Clean the area of the ledger board where the flashing will install. Remove any debris or dirt, and make sure the area is dry. If there are any nails or screws that are protruding from the ledger board, remove them or hammer them in so that they are flush with the surface.

Install the Deck Flashing

Place the deck flashing over the ledger board, making sure that it extends at least 2 inches past the edge of the ledger board on each side. Secure the flashing to the ledger board with nails or screws. The nails or screws should be long enough to penetrate the ledger board and extend into the framing of the deck. Space the nails or screws about 6 inches apart.

Seal the Deck Flashing

Using a caulking gun and caulk, seal the top edge of the flashing where it meets the house. Be sure to use a high-quality caulk that design for use on metal and is compatible with the material of your house.

Inspect the Deck Flashing

After the caulking has dried, inspect the deck flashing to make sure it securely install and there are no gaps or holes where water can seep through. If you notice any gaps or holes, seal them with additional caulk.

Additional Tips for Installing Deck Flashing

It is important to choose the right type of deck flashing for your deck. The most common types of deck flashing are made from aluminum galvanize steel. Both materials are durable and long-lasting, but galvanized steel is more resistant to rust and corrosion.

If your ledger board already install and you are unable to access the back of the ledger board, consider using a self-adhesive deck flashing tape. This type of flashing design to install without removing the ledger board and can applie directly to the surface of the ledger board.

If you are unsure about how to install deck flashing, consider hiring a professional contractor to do the job. A professional can ensure that the flashing is installed correctly and will provide long-lasting protection for your deck.

In addition to installing deck flashing, it is important to maintain your deck by regularly cleaning and sealing it. This will help prevent water damage and extend the life of your deck.

In conclusion

installing deck flashing on an existing deck is a simple and effective way to protect the structure from water damage. By following these steps and tips, you can ensure that your deck is properly protected and will last for many years to come.