DIY Greenhouse Window Reglazing: A Step-by-Step Guide

Updated at: 31/03/2025

Cracked or broken greenhouse window panes can significantly impact the health and productivity of your plants, leading to temperature fluctuations and potential pest infestations. Replacing these panes can be surprisingly affordable and achievable, even for novice DIY enthusiasts. A damaged greenhouse doesn't have to mean a significant financial investment or a call to a costly professional glazier. With the right tools and a little patience, you can breathe new life into your greenhouse and ensure optimal growing conditions.

This guide provides a comprehensive, step-by-step walkthrough for reglazing your greenhouse windows, transforming a frustrating problem into a satisfying DIY project. Whether your damage involves a single cracked pane or multiple broken sections, we'll equip you with the knowledge and confidence to tackle this essential maintenance task, guiding you from safely removing the old glass to securing the new panes securely in place. Let's get started!

Preparation and Safety Guidelines

Tools Needed
  • windows
  • caulk
  • tools for removing caulk
Safety Guidelines
  • Always wear safety glasses to protect your eyes from flying glass fragments.
  • Use appropriate gloves to protect your hands from cuts and chemicals. Dispose of broken glass properly and safely.
  • If working at height, use a stable ladder or platform and follow all safety precautions to prevent falls.

Step-by-Step Instructions

  1. Window Removal

    • Removing old windows from the greenhouse frame.
    • Carefully removing the caulking around the window panes to avoid damaging the glass.
    • Identifying and removing the pins that hold the window panes together.
    • Gently removing the window panes, being cautious not to break them. Note that the pins are staggered, so care is needed around the corners.
    Gently removing the window panes, being cautious not to break them. Note that the pins are staggered, so care is needed around the corners.Gently removing the window panes, being cautious not to break them. Note that the pins are staggered, so care is needed around the corners.Gently removing the window panes, being cautious not to break them. Note that the pins are staggered, so care is needed around the corners.Gently removing the window panes, being cautious not to break them. Note that the pins are staggered, so care is needed around the corners.
    Window Removal

  2. Frame Preparation

    • Cleaning the frame to prepare for the new window panes.
    Cleaning the frame to prepare for the new window panes.
    Frame Preparation

  3. Window Installation

    • Installing the reused or new window panes into the cleaned frame.
    Installing the reused or new window panes into the cleaned frame.
    Window Installation

  4. Reglazing

    • Reglazing the windows (applying new caulk).
    Reglazing the windows (applying new caulk).
    Reglazing

Read more: 3M Thinsulate Window Film Installation: A Step-by-Step Guide

Tips

  • Be extremely careful when removing the window panes, as they are easily broken. Work slowly and gently, especially around the pins.
  • Avoid applying too much pressure when removing the pins, especially near the corners; this can cause cracking. Use a light touch.

Common Mistakes to Avoid

1. Using the wrong type of glazing putty

Reason: Incorrect putty can crack, shrink, or not adhere properly, leading to leaks and a compromised seal.
Solution: Choose a putty specifically designed for glass and exterior applications, ensuring it's compatible with your window frame material.

2. Not cleaning the window frame and glass thoroughly

Reason: Dirt, dust, and old glazing can prevent the new putty from creating a strong bond, resulting in gaps and weak seals.
Solution: Clean the frame and glass surfaces meticulously with a suitable solvent before applying new glazing putty.

FAQs

What type of glass is best for a greenhouse?
While regular glass works, horticultural glass (often slightly thicker and more durable) or polycarbonate sheets are recommended for greenhouses. Polycarbonate offers better insulation and impact resistance, making it a more long-term solution despite a higher initial cost.