Five ledger board techniques to secure your deck

If you are attaching your deck to a ledger board then you must know how to do it properly.  There are some different methods to accomplish this that are well accepted.  A proper connection should be sufficiently strong and water tight.  Both requirements are essential.  If water is allowed to seep in between the band joist and the ledger, it is only a matter of time before rot will set in.

A well built deck ledger board connection

The Two Reasons Why a Deck Collapses

However, the two main reasons for this ever happening are improper fastening or connection means and water damage causing structural weakness.

There is no epidemic of decks falling to the ground despite well publicized accounts of these rare events.  The good news this won't ever happen to you because you are going to study and follow these diagrams faithfully so you build your deck properly.

1/2" Lag screws

This is a side view of the perspective diagram above. 

It is one of the most common ways of connecting the ledger with the band board.  In this instance, minimum 1/2" lags are staggered along the length of the board. The lags should pass through by at least 1/2" on the back side of the band board.

Note: The deck boards have been depicted with a gap between the first board and the house only to emphasize flashing overlapping the ledger.  In the field the first board would be positioned within 1/2" from the wall flashing.

1/2" carriage or cap bolts

In this second method, 1/2" through bolts are used to anchor the band board and ledger together.

This configuration requires access from the basement between the floor joists in order to install the washers and nuts.

Band boards must be solid sawn 2x (1-1/2") dimensional lumber or minimum 1" engineered wood product (EWP).

Pre-drill holes 17/32" to 9/16" diameter.

This is slightly larger than the bolt itself and relieves and pressure or tension in the boards.  The predominant forces in the system will be the tensile compression from the bolts and the bearing weight of the deck.

Wood frame with spacer

The third connection method uses a maximum 1/2" space between the exterior sheathing and the ledger. 

In this diagram the space is created using a 1/2" stack of washers.  Just be sure to verify this stacking method is permitted in your area.

Double layers of metal flashing create a dry air space between the house and the board with plenty of air to circulate further protecting the materials and ensuring maximum longevity.  Consider this if live in wet climate zone.

concrete foundation wall

The fourth technique involves securing the ledger to a concrete foundation wall rather than first floor band board.  One of the benefits of this method is that more rigid minimum and maximum lag screw location configurations associated with mounting to band joists can be avoided.

Then the deck can be set as much as 7-3/4" below the top of the door sill.

This is very desirable in areas with snow fall in the winter or wet climates as it provides an additional level of protection from water entering the home.

Either expansion bolts or epoxy can be used in this scenario. 

For a really durable job, consider applying 30# felt paper or metal flashing between the ledger and the concrete. 

If metal flashing is used, hole must be drilled through the metal prior to drilling out the concrete.  More work but an absolutely bullet proof solution.

Cinder block wall

The fifth ledger board technique involves mounting to a cinder block foundation. 

Cinder blocks are not as common in residential construction today as there were years ago.  And because they are hollow connecting a deck to them requires special attention.

The hollow core inside the blocks must be filled with concrete so that bolts and epoxy have material to be set into. Be sure also to caulk between the first board and the cinder wall.

five ledger board techniques explained and illustrated

Any one of these different ledger connection methods, properly installed, will give you a reliable, long lasting deck that is secure. This is time consuming process and should be done while the house is being constructed to simply and reduce costs.

Installing a ledger connection to a house after it is constructed is a major job.  It is certainly not a job for a weekend carpenter or DIY'er.  It get's complicated in a hurry.

Imagine having to remove courses of masonry, or lap board siding, locating the band board accurately so as not to damage the wrong part of the siding.  You may decide that a free standing deck or floating deck is a simpler less expensive, less complicated option.  That is a different topic for discussion.

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