Framing an Exterior Door in Concrete Blocks

Measure the width of the top of the door opening with a tape measure. Measure the height of the door opening's sides with a tape measure. Subtract the thickness of the lumber, usually 1 1/2 inches, from the height measurement. Mark two pieces of treated lumber with the modified height and one piece with the opening's width.

Put on a dust mask, goggles and gloves. Cut the treated lumber with a circular saw. Select a wood bit equivalent to the diameter of the concrete anchors' shanks. Attach the bit to the power drill. Mark the location of anchor holes on the cut lumber with a tape measure and pencil, typically two at each end and staggered every 12 to 18 inches throughout the field. Drill anchor holes through the cut lumber.

Select a drill bit equivalent to the diameter of the anchors' washers. Attach the bit to the drill. Drill a recess into the top of each anchor hole. This recess is called a countersink hole. The countersink hole must extend into the lumber a depth equal to the thickness of one washer and one nut.

Hold one of the long pieces of lumber against a side of the opening. Place a level against the edge of the lumber. Position the lumber in the desired installation location, usually the center of the opening or flush with outside face of the opening. Use the level to plumb the lumber.

Remove the lumber from the wall. Draw a chalk snap line between the marks that indicate the lumber's edge and snap the string to lay out a plumb line. Use a square to transcribe the plumb line from the side of the opening to the top.

Align the short, top piece of lumber with the transcribed line. Run a pencil along the top piece's edge to lay out its position on the block. Mark the positions of the top piece's anchor holes. Use a square to align the remaining side piece flush with the top piece. Plumb the remaining side piece with a level. Lay out the piece's anchor hole locations on the wall. Mark a plumb line for the piece with a pencil and chalk snap line.

Attach a masonry bit to the drill. Set the drill to the hammer setting. Bore anchor holes at each anchor hole mark on the wall. Attach a washer and nut to each wedge anchor. Align the top piece of lumber with its layout marks. While holding the piece in position, pound wedge anchors through the screw holes to secure the lumber to the wall.

Tighten the anchors' nuts with a socket wrench. Set shims beneath the lumber to adjust the lumber's horizontal level. Slip a side piece between the floor and the top piece. Align the side piece with its layout lines. Secure the side piece to the wall with anchors, tighten the anchors' nuts with a socket wrench and add shims to adjust plumb. Install the remaining side piece beneath the opposite end of the top piece.

Hoist a pre-hung door into the frame. Level, plumb and square the door with a level and square. Adjust the door's position by placing shims between the door frame and the treated lumber. Fasten the door to the treated lumber with a finish nail gun.