Measuring for Xtend Porch Windows is pretty straightforward once you know exactly what you are measuring.
The key is this:
Measure the finished opening that the window frame will insert into.
Xtend windows have a 1" mounting flange around all four sides. Xtend doors have a 1" flange on the top and both sides, but not along the bottom.
So your measurement is the clear opening between solid mounting surfaces — not the outside edge of the flange.
How to Measure
Measure the width in several places:
- Near the top
- In the middle
- Near the bottom
Then measure the height:
- Near the left side
- In the center
- Near the right side
Use the smallest width and smallest height.
Older porch openings are not always perfectly square or parallel, so using the smallest measurement helps make sure the finished window fits properly.
Provide all measurements in inches, not feet and inches, and measure to the nearest 1/8".
For example:
41 3/8" × 67 1/2"
Give us the actual finished opening size. Xtend windows are built slightly smaller than the dimensions provided, so there is no need to make your own deductions.
Measure Between Solid Surfaces
Measure from one solid mounting surface to the other.
If trim, screening channels, old window frames, or other materials will be removed before installation, do not include them in the final measurement.
Also watch for anything protruding into the opening, including:
- Plates
- Brackets
- Screw heads
- Bolts
- Other hardware
If those items need to stay, the final window size needs to account for them.
Your Existing Openings Do Not Have to Stay the Same
Just because an existing screened porch is divided into a certain number of openings does not mean the finished porch has to use those same openings.
Before taking final measurements, think about:
- Structural support posts
- Door location
- Railings
- Fall-protection needs
- Window width and center bars
- The overall window layout
Sometimes a small framing change can create a much better finished porch.
Our window sizing and layout guide can help if you are still deciding how the openings should be divided.
Know Which Posts Need to Stay
Some porch posts simply support screen framing or railings. Others support the roof.
Structural posts need to remain unless the porch is properly reframed to carry the load another way.
Xtend windows and mulled window assemblies are not structural.
If you are unsure whether a post or header is structural, consult a qualified contractor or engineer before changing it.
Think About the Door
Door placement can affect the entire layout.
Our 36" × 80" Xtend door opening is our standard size and is less expensive than a custom-sized door. If an existing opening can reasonably be modified to that size, it may save money.
Some screened porches also have a transom above the door simply because of the original screen framing. If that framing is not structural, a full-height door opening may create a simpler, cleaner layout.
Consider Railings and Fall Protection
Xtend windows extend approximately 2" into the opening, so make sure railings, drink rails, brackets, and other interior obstructions have enough clearance.
If fall protection is needed, we often recommend single fixed-glass units below single vertical 4-track windows. Keeping support posts closer together can make this type of layout easier, since our recommended maximum opening width for a single Xtend window is 48".
Our fall-protection guide explains those options in more detail.
Existing Metal Framing May Be Usable
Some screened porches already have aluminum or other metal framing around the openings.
That framing may be able to remain if it is solid, properly supported, and provides enough flat mounting surface for the window flange.
We can provide self-tapping screws for installations into metal.
Take Final Measurements After Framing Is Done
Preliminary measurements are great for planning and quoting.
Final measurements should be taken after any framing repairs or layout changes are complete.
Before ordering, make sure you have:
- Measured between solid mounting surfaces
- Measured in several places
- Used the smallest width and height
- Recorded everything in inches
- Measured to the nearest 1/8"
- Accounted for any hardware protruding into the opening
- Double-checked every opening
You can also watch our measuring video for a visual walkthrough.
Need a Little Help? That's What We're Here For
A lot of our customers install their own Xtend windows, and we understand that measuring custom windows can feel like the part you really don't want to get wrong.
If you are unsure about an opening, send us pictures or a sketch. We can also walk through the porch with you by phone or FaceTime and help make sure you are measuring the right places before you place the order.
You do not have to figure it all out by yourself.
