Pressure Treated Mudsill Constrution

The pressure treated mudsill is the beginning of the framing process. This is where the wood meets the concrete. It is usually separated by a vapor barrier and bound tightly with anchor bolts.

Before the Mudsill can be Installed

First things first when it comes to starting the framing process.  Check the dimensions of the foundation to ensure they are in accord with the blue prints.  Finding a mistake with the layout now is much better than discovering it when it is too late.  The most common mistakes are walls that do not line up and walls that are not parallel.  For the most accurate results, chalk lines where applicable.

Many local building codes require the use of a vapor barrier.  Omitting this easy step when it is a requirement will make for an extremely difficult (if not impossible) task to do later.  In order for the entire system to be in compliance with the 2012 International Building Codes, the following criteria must be met:

  • Maximum of 6′ spacing on anchor bolts.
  • Maximum of 12″  from then end of all boards to an anchor bolt.
  • All boards must have two anchor bolts unless it is less than 24″.  In that case, a single bolt close to the center will do.

Laying the Pressure Treated Boards

Be aware of what size boards will go where.  It will be necessary to use a wider board on walls where brick or other masonry stops and wood takes off.  This is commonly referred to as brick to grade and is used extensively on siding homes.

Whenever possible, lay the boards by positioning parallel to their installment and use a speed square to mark the location of the anchor bolts.  Drill the holes with a 5/8″ paddle bit for 1/2″ anchor bolts.  Start the board on one end and move it back and forth to get it to go down over the bolts; watch the fingers!  Use a crescent wrench or similar tools to tighten the nuts down once washers have been slipped over the bolts and the position of the pressure treated lumber is satisfactory.  Remember to use only double dipped galvanized nails when attaching clear wood to the mudsill.

Pressure treated mud sill without a vapor barrier.