How to Measure for Sills — Premium Sills
Each sill is made to fit particular sized openings. Here is how to measure your openings and select the proper size sill.
LENGTH
Measure the width of the inside jamb to jamb of the window opening.
The standard lengths of Sill‑Rite sills are meant to fit standard window widths. The sill should extend 1–1/2 to 3 inches beyond the jambs on each side of the window opening.
EXAMPLE:
| Window Width | Sill Length |
|---|---|
| 10"-14" | 17" |
| 16"-20" | 23" |
| 22"-26" | 29" |
| 28"-32" | 35" |
| 34"-38" | 41" |
| 40"-44" | 47" |
| 46"-50" | 53" |
| 52"-56" | 59" |
| 58"-62" | 65" |
| 64"-68" | 71" |
| 70"-74" | 77" |
| 76"-80" | 83" |
| 82"-86" | 89" |
| 88"-92" | 95" |
| 94"-98" | 101" |
| Custom lengths available | |
If the window opening measures 35-1/2", find the corresponding bracket in the chart. In this case, the bracket is 34"-38". The actual length of the proper sill is 41". In this example, the sill will extend 2-3/4" beyond the jambs on each side: (41 - 35-1/2) ÷ 2 = 2-3/4.
If there is no bracket for the window width, a custom length sill can be ordered. You determine how much the sill extends on either side of the opening (there is no "standard" amount of extension; it's simply a matter of taste). You can also choose the next largest sill if you like the extra extension.
DEPTH
Sill-Rite sills are available in depths from 2 to 8 inches, in one-inch increments, to accommodate various wall thicknesses and window depths.
Measure the depth of the opening from the front of the window to the wall surface. Round up to the nearest full inch to determine the minimum depth of the required sill.
The Sill‑Rite sill will actually protude an inch beyond the stated sill depth. So, even though a 4-inch deep sill fits an existing depth of 4-inches or less, it is actually 5-inches deep.
EXAMPLE:
Depth of window opening: |
3-1/2" |
Round up to the full inch: |
4" |
A 3-1/2" opening depth requires a minimum sill depth of 4". If you want the sill to overhang further, simply choose a deeper sill.
Notes for Replacing Marble Sills
In most cases, Sill‑Rite sills can be installed directly on top of existing marble sills. If the thickness of the existing sill is 5/8" or less, the finished edge of the Sill‑Rite sill will completely cover the marble.
When measuring for sills, the Sill‑Rite sill must be at least least 2-inches longer than the existing marble sill.