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Window Assemblies & Accessories

Learn how to install all Pella assemblies and accessories for wood, fiberglass and vinyl windows from our knowledgeable team of product experts.

Select Assemblies & Accessories

Mullion Installation Instructions

Mullions - Architect Series® and Pella® Lifestyle Series

Select a mullion assembly/combination instruction from the list below.

Instructions

Joining Mullion Assembly
1/2" Mullion Assembly for Nail Fin
1/2" Mullion Assembly for Subsill
Wood Blocking Spread Mullion Assembly
EnduraClad Trim End Anchor
Expansion Mullions
3" and 4 1/4" Tube Mullions

Mullions - Pella® Impervia®

Select a mullion assembly/combination instruction from the list below.

Instructions

Pella Impervia Structural Mullion Assembly
Combination Assembly Using 1/2" or 1" Mullion Reinforcement and Subsill
Joining Mullion - 3- and 4-Way Joints for Pella Impervia Awning, Casement and Large Awning
Joining Mullion - 2-Way Joints for Pella® Impervia Windows and/or Joining Window to Special Shape Windows
3" and 4 1/4" Tube Mullions

Mullions - Pella® 350 Series

Select a mullion assembly/combination instruction from the list below.

Instructions

1/2" and 1" Mullion for Windows with Nail Fin
Joining Mullion for Windows with 5/8" Flange or Flush Flange
Joining Mullion for Block Frame Windows

Mullions - Encompass by Pella® and ThermaStar by Pella®

Select a mullion assembly/combination instruction from the list below.

Instructions

1/2" Mullion
Flange Frame Structural Mullion - Eastern US only
15 Series Joining Mullion Easter US Only
3" and 4 1/4" Tube Mullions
H-Bar Vertical Mullion

Mullions - Pella® 250 Series

Select a mullion assembly/combination instruction from the list below.

Instructions

1/2" Standard and Aluminum Reinforced Mullion
3" and 4 1/4" Tube Mullions
1" Tube Mullion

Wood Jamb Extension - Pella® Impervia®

Instructions

Wood Jamb Extension

Trim - Architect Series® and Pella® Lifestyle Series

Select an exterior trim or subframe/panning instruction from the list below.

Instructions

Frame Expander and Receptor
Subframe Installation
Clad Wood Subsill
Flush Flange Accessory Installation
Subframe Installation Length and KnockDown Assembly
Traditional Trim Installation
Traditional Trim Assembly

Trim - Pella® 350 Series and Pella® 250 Series

Select an exterior trim or subframe/panning instruction from the list below.

Instructions

Flush Flange Accessory Installation

Trim - Encompass by Pella® and ThermaStar by Pella®

Select an exterior trim or subframe/panning instruction from the list below.

Instructions

Sloped Sill Adapter and Head Expander for Single-Hung, Fixed and Sliding Windows
Sloped Sill Adapter including 3 3/8" Wall Depth (Western US Only) for Single-Hung, Fixed and Sliding Windows
Flush Flange Accessory Installation

Construction Hardware Removal for Architect Series®, Designer Series® and Pella® 450 Series

Instructions

Construction Lock Lever Removal
Construction Lock Lever Removal - Alternate Method
Roto Cover, Crank and Lock Lever Installation

Exterior Sash Lug Instructions for Architect Series® Traditional and Architect Series® Reserve™

Instructions

Monumental Hung
Exterior Sash Lug for Architect Series Aluminum-Clad Hung

Hinged Panel Operations and Blinds and Shades

Instructions

Pella Lifestyle Series only

Removable Grilles on Circlehead Units

Instructions

Architect Series® and Pella® Lifestyle Series

Helpful Resources

Pella Contractor Program

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Support Center

Contact us if you have questions about windows, patio doors or entry doors.

Installation Guides

Find everything you need in one packet for your construction type.

Product Warranties

Always read the Pella warranty before purchasing or installing a Pella® product.