How To Properly Measure Your Windows for a SLIP™

The first step in ordering the Slim Line Insulating Pane(SLIP™) system is providing us with an accurate measurement. This is potentially the most important step in the SLIP™ process.  It allows us to build and provide you with a properly fitted product.  It will look and perform optimally for many years.

NOTICE: You only Need to Measure for SLIPs if you intend to Install yourself

‘Daylight Size’

The measurement required is what we call the “Daylight Size.” It is essentially the overall measurement of the width and height of where the glass meets the wood, both width, and height. We understand that there are many types of the vintage sash with a variety of glass configurations; However, the process for obtaining the daylight measurement is identical regardless of the sash/glass setup.

Butt your tape measure to the edge of the sash where it meets the far outside edge of the outermost glass pane (for multi-light configurations).  Or where the profile edge of the sash meets the outside edge of a single light sash configuration. While holding the tape measure end to this point, drag the tape measure all glass panes for multi-light configuration.  Or across the entire pain for single light configurations and read the measurement simultaneously on the opposite side of the sash. For most of the vintage sash, this measurement ends with the fraction 5/8”, but this is not always the case. The same process is repeated for the daylight height. The first measurement we receive must be width, followed by height. These measurements ultimately decide the shape and size of each SLIP™ as well as the hidden balance type for double-hung.

For Double Hung windows, this process needs to be repeated for both top and bottom sash.  They are not always the same size. Repeat this process for all windows you wish to order and install the SLIP™.

Converting from ‘Daylight Size’ to the overall size of the SLIP™

Going from the ‘Daylight Size’ to the overall SLIP™ size. We add additional material sizes to daylight width and height to account for the glazing sealant and the size of the SLIP™ aluminum. Your estimate will show both the customer is given daylight measurements and also the overall conversion size.

Overall Conversion
Top Sash- add 2 ½ to daylight width and height
Bottom- add 2 ½  to daylight width and 1 5/16 to height

Note: on Double hung or single hung window. A bottom slip does not have top aluminum extrusion. This is due to the bevel on the meeting rails. Please watch the full installation video to see more.

Casement/Picture Window/French casement-
Overall Conversion
Add 2 ½ to daylight width and height

NOTE(out of square/sagging windows):

Sometimes windows or sash may be out of square. SLIPs can still be installed on an out-of-square sash. When the sash is out of square, you’ll notice that the daylight will be different measurements at different sash sections. You must take the largest measurement you get from the daylight for your SLIP to fit over the entirety of the glazing. If you requested weatherstripping, we use 1/8″ weatherstripping. The weatherstripping won’t be as effective if a 1/8″ gap around the sash and the frame doesn’t exist.

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