Jamb depth describes the front-to-back depth of a window or door frame through the wall. For an order, distinguish the measured wall depth, the product frame depth and any extension jamb. Record the actual opening and the measuring points, then confirm how the selected frame and mounting accessory will meet the finished interior wall.
Measure through the opening, not across its width. For the window wall-depth measurement shown here, use the interior finished wall face and the exterior wall mounting plane. Decorative casing, brickmould and projecting siding are separate from that measurement. Photograph the start and end points; the required order depth depends on where the selected product mounts.
Where the measuring points are visible and safely accessible, hold the tape straight between them and record the depth at both sides and the head. Label every reading in inches, to the nearest 1/16 inch. If trim conceals an edge, mark the depth unconfirmed and send photos rather than treating the trim edge as the frame or mounting plane.
Keep all readings when depths differ. Do not automatically use the smallest width-and-height rule for jamb depth; have the installer review the wall and finishing arrangement.
There is no single standard jamb depth for every house. Drywall, plaster, sheathing, masonry and renovations can change the required depth. A 2×4 or 2×6 stud description is not a finished-wall measurement. The 4-5/8-inch and 6-5/8-inch depths illustrated here are examples; record the actual opening even if it appears close to one of them.
For the Panes 3-1/4-inch window frame with no fin setback, a confirmed 4-5/8-inch wall depth leaves 1-3/8 inches for an extension. Mounting accessories can change the calculation. Confirm the selected configuration before ordering.
An extension jamb covers the remaining distance between the installed window frame and the interior finish. Panes calculates that distance using the wall depth and the selected mounting arrangement. A standalone snap-in nailing fin sits 1-1/4 inches behind the window face, so less of the frame sits within the wall. Review the resulting extension size, available material and finishing details with the order.
Door suppliers sometimes use jamb width for the front-to-back frame dimension. That is different from the width of the doorway. Label the dimension and show the tape position in a photo so the supplier can confirm what you mean.
There is no universal depth that fits every finished wall. Product frames, wall construction and installation positions vary. Use published sizes to compare available products, then measure the opening and confirm the appropriate extension or frame depth.
No. An extension fills the distance left after the installed frame depth is accounted for. Its size depends on the product and mounting arrangement. Do not enter the full wall measurement as an extension size.
Send clear interior and exterior photos and mark the measurement unconfirmed. Ask the installer or quoting team to identify the required measuring points before final dimensions are approved.