spacing distances and flange widths may be used as determined by one of ordinary skill in the art and should be considered within the scope of this disclosure the adjustable masonry form 10 further comprises at least one horizontal breakaway element 19 on the planar base 12 the horizontal breakaway element 19 may be positioned on the lower surface 17 the upper surface 18 or both as desired the horizontal breakaway element 19 allows a user to configure the adjustable masonry form 10 to a particular installation by altering the width u201c w u201d of the planar base 12 in this manner the width of the planar base 12 of the adjustable masonry form 10 can be custom tailored to each masonry construction if desired in one embodiment the horizontal breakaway element 19 is a groove designated 19 a fig1 a and 1b and 4 a and 4 b in an alternate embodiment the horizontal breakaway element is a scored line designated 19 b fig1 c other horizontal breakaway elements may be used as is known in the art the horizontal breakaway element 19 runs at least partially down the length of the planar base 12 in one embodiment the horizontal breakaway element runs the entire length or substantially the entire length of the planar base 12 the horizontal breakaway element 19 may be parallel to the longitudinal axis 14 of the planar base 12 a plurality of horizontal.