What type of stud is installed below a windowsill to support its weight?

The type of stud installed below a windowsill to support its weight is known as a jack stud. Jack studs are shorter members that provide additional support to the header above an opening, such as a window or door, and they distribute the weight to the sole plate or foundation. Their primary function is to bear the load coming from the header and facilitate a proper weight transfer because windows create openings in a wall that can compromise structural integrity if not adequately supported.

Although other types of studs have specific roles in framing, they do not serve the same function as jack studs in this particular context. While king studs run vertically alongside jack studs and help bear the load of the structure, they do not specifically support the windowsill. Stud blocks are used to reinforce areas or provide anchor points but do not directly support the windowsill. Header studs are more commonly associated with the horizontal support above a window or door, rather than below it.