How to Widen a Concrete Door Opening

Increase the rough opening's width by measuring the appropriate number of inches from either the right or left side of the existing rough opening. Make a mark on the concrete wall with a piece of chalk near the rough opening's top and bottom. Connect these two marks with a chalk line and snap it against the wall.

Increase the rough opening's height by measuring the appropriate number of inches up from the top edge. Mark this new height on the concrete wall with a piece of chalk. Make two measurement marks, connect them with a chalk line, and snap a line across.

Snap a third short chalk line down from the end of the line you just snapped to the rough opening's right or left side -- whichever side you didn't increase the width from -- to form a larger rectangle.

Move to the opposite side of the rough opening and repeat Steps 1 through 3 to create an outline for the larger rough opening on the other side of the wall.

Score along the chalk lines on one side of the wall with a 14-inch diamond saw blade in a masonry saw. Make the score line approximately 1/2-inch deep. Follow the chalk lines as accurately as possible. Move to the wall's other side and repeat this step along those chalk lines.

Cut along the score line with the 14-inch diamond blade saw, this time making the cut depth approximately 3 inches. The score line helps keep your saw blade in place while you apply more pressure for the deeper cut. Repeat this step on the wall's other side.

Hit the portion of wall being removed with a 5-lb. sledgehammer. The wall should break away easily along the cut lines. Place a 1/2-inch chisel behind any rough areas and hit the chisel's handle with a hammer to remove them.