When constructing a deck, it is important to consider the spacing between the ledger and the wall, as well as the spacing between the joists. Many deck builders prefer to leave a gap of around half an inch between the ledger and the wall to allow for water drainage. This can be difficult to achieve when constructing a deck on an existing home with an interior roof that is already finished. The code only recognizes transverse bolts as a way to separate the ledger from the wall, which would require opening up the roof and patching it afterwards.
However, structural screws are now available, as long as the local building official accepts engineering letters from manufacturers. The spacing between joists depends on the type of wood used. Most sawn timber manufacturers recommend that the ledger should be placed every two feet. For most DIY projects, measuring tools such as tape measures and mass tables, along with simple calculations, are enough to determine the space between the joists.
Ledgers are usually installed during construction in an alternate or straight line between the joists and are hidden under a single platform. If you need help determining the distance between joists, you can use a base and beam calculator. You can also learn to use pegs and ropes to locate the joists and establish the correct spacing between them at the bottom of the deck. This will help ensure that your deck is structurally sound and safe for use.