I'm in the process of replacing my old Andersen double hung windows with Pella 250 double hung pocket replacements without the need to fix any siding as they just sit in the original sill and are held in place by the existing external stops.

The question I have is for these side by side windows: How do I secure them to the sides where they are only separated by a 2x4 without the long screws penetrating the window next to it? Can I use shorter screws? Do I secure it at the top of the frame? A combination of both? The middle window may be the one to be more concerned about as I can technically secure it only to the top and use shorter screws to the side.

A mull bar wouldn't work as it would bring the windows too close and siding will need to be redone.



Thank you for your help!

  • 1
    Your pic links don't work. Please try to repost.
    – RMDman
    Apr 3 at 1:26
  • Reposted.. now pics should work!
    – Bill
    Apr 3 at 13:31
  • 1
    What a shame you didn't replace them with a picture window. (If that was possible) Apr 3 at 16:44

1 Answer 1


This scenario is usually anticipated and well covered by the manufacturer. See the document dedicated to exactly that. It outlines various configurations, accessory parts, and clearance and fastening requirements.

See page 7 for combination limitations, and see page 11 for information about fasteners. Note that nowhere does it have you running screws through the sides of the unit. Connection is solely via connector plates at the head and sill. You'll void warranties if you make holes elsewhere.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.