How To Attach A Deck To A House

If you’re planning to install a deck onto the outside of your home, then you are going to need to make sure that your deck is sufficiently supported and fully secure.

Towards that end, you are definitely going to need a deck ledger.

How To Attach A Deck To A House

A deck ledger is a lumber beam that is attached directly to the wall of the existing home and exists as one of the central anchors of the deck’s frame.

With most attached decks the ledger will support half the deck while the beam supports the other half. Which makes the importance of correctly attaching your deck to your house so important.

But in order for it to work properly, you need to ensure that you install it properly. This is why it’s so important to know how to attach your deck correctly, and in a safe manner.,

If you’re looking to build your own deck, then you should start by checking out our guide below. Because knowing how to install your deck ledgerOpens in a new tab. right, will make all the difference.

How Do You Install A Deck Ledger To A House?

There are 2 critical parts of attaching your deck to your house.

  • Strength
  • Water

The first is a given but I have seen more decks fail because of water. Preventing the deck ledger from rotting Opens in a new tab.will ensure your deck is strong for years to come.

This is why we are going to start there. Steps to prevent your ledger from rotting.

Flashing Membrane to Protect the House

For dryer locations this step can be skipped but if there is a potential for lots of water on your deck. A few extra minutes here will save you thousands later.

To start off, you are going to want to ensure that the ledger is able to stay in place no matter what and that none of the elements can alter the ledger, such as rain or wind.

In order to ensure water doesn’t damage the house, you are going to want to install some flashing membrane on the wall before installing the ledger. A self-adhesive flashing membrane is a flexible material designed to adhere to material while preventing water from seeping in. 

Joist Membrane Tape

Think tape but thicker and waterproof.

Installation is as simple as peel and stick.

To see my recommended joists flashing tapeOpens in a new tab., click the link.

Find out the height you want your ledger to be installed on the wall. A deck should generally be between 2″ and 6″ (50-150mm) below the door threshold. To ensure water and snow doesn’t get into the house.

Make a mark on the wall at that point. Aim to stick the flashing material to the wall around 4 to 6 inches above the marking you made, so that the flashing material will extend higher than the deck ledger. Ensuring any water running off the house will not wick up the wall. Rotting the house wall.

You may need to take a row of siding off to ensure the membrane is high enough on the wall. Tucking it under the building paper will further enhance water runoff.

Installing The Ledger

Now that you have installed your self-adhesive flashing material, you are ready to attach the ledger to the house.

Snapping a chalk line on the wall at the height of the top of the ledger.

*Builder Tip*

The ledger material must be the same height as the deck joist or larger. If installing 2×8 joists the ledger should be a 2×8 or bigger.

Get some assistance from a friend and hold the ledger board up to the wall around where you want it.

Check that it is level and fits perfectly on the wall.

If the ledger does not follow the straight chalk line you can start fastening from one end and end just the board up and down. To straighten out the board along the house.

*Builders Tip*

Do the layout for the joists on the ledger before attaching the ledger to the house.

Use nails or screws to tack the ledger in place on the wall.

Then there is an easy way and a hard way to attach the deck to the house.

Hard Way to Attach the deck to the House

  1. Once you have temporarily tacked the ledger to the house straighten it as you go.
  2. Mark out lag bolt locations. The amount of spacing between each bolt will depend on the size of the decking, and the eventual load that it will bear.
  3. Ensure bolts are a minimum 2″ (50mm) from the top and bottom of the material. Adjust as required to avoid having bolts behind hangers or joists.
  4. Drill holes slightly smaller (1/16″) than the lag bolt’s shank diameter as required for lag bolts.
  5. Slip a single washer on each bolt before installing.
  6. Twist the bolts into the holes with a drill or socket wrench.
  7. Tighten the bolts till the ledger is pulled tight to the house.

Easy Way to Attach The Deck Securely to the House

  1. Once you have temporarily tacked the ledger to the house straighten it as you go.
  2. Mark out screw locations. The amount of spacing between each screw will depend on the size of the decking, and the eventual load that it will bear.
  3. Ensure screws are a minimum 2″ (50mm) from the top and bottom of the material. Adjust as required to avoid having bolts behind hangers or joists.
  4. Drive GRK Star Drive Washer Head CoatedOpens in a new tab. Steel RSS Structural Screws into the ledger.
GRK screws in Ledger board

Extra Flashing

Once you have attached the deck ledger to the wall, you will then want to add a little bit of extra flashing material across the top of the newly installed ledger board.

Take a smaller section of the flashing material and lay it out over the top section of the ledger board with a small section of the flashing touching the ledger, and the majority attached to the wall above.

This ensures that no water whatsoever can get between the ledger board and the wall.

Installing Joists Building the Deck Substructure

Build the rest of the deck’s substructure. Installing the beams and joists as required but don’t forget there is one more step before installing the decking.

Metal Flashing

We fully recommend investing time and money in additional flashing.

Purchase metal or vinyl flashing which is treated so as not to react to the wood treatment.

Form flashing is folded to sit on top of the ledger with one side going up the wall.

Types of deck flashing

Acting as the first line of defence against damage from rain, the flashing against the wall directing the water over the ledger, rather than behind it.

If water does get under the metal, then the adhesive flashing will act as the second line of defence. 


If installing cladding on the wall under the deck we recommend doing this before installing the joists. This will give you room to work especially if the deck is low to the ground.

Cladding under the deck may not be required but will increase the protection of the house material.

This may seem pointless because you won’t see it once the deck is finished, but it does help to prevent bugs and other creatures from nesting under your decking. Plus protecting the house against rain.

To Conclude

We hope this guide has proven useful.

Though the task of installing a deck ledger can be daunting, due to how important it is, provided you follow this guide, you will be able to install your ledger perfectly and enjoy your new deck problem-free for years to come. 

Some deck ledgers will have slightly different requirements, but these simple steps will get you started attaching most decks to the house. Below are a few additional tips and answers for attaching your deck to your house.

Frequently Asked Questions

Does Deck Ledger Need To Be One Piece?

No. The deck ledger can be in multiple smaller pieces, but no part should be less than 4′ (1.2m). A minimum length to properly anchor the board to the house.

Do Decks Need To Be Attached To The House?

Though it is possible to construct free-standing decks, it is generally recommended to attach a deck to a house, because it is more secure, especially in bad weather.

To read why and when you will not want to attach a deck to the houseOpens in a new tab., click the link.

Can Ledger Board Extends Past House?

Yes. Your ledger board definitely can extend past the length of the house, however, you should ensure that it has extra support to make up for not being attached directly to the

Ryan Nickel

A Red Seal carpenter, passionate about building decks to be enjoyed.

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