How to build a greenhouse from old windows

Greenhouse from Old Windows

Every day of the week, someone is busy replacing their ‘old’ timber framed windows with ‘whiz-bang, no maintenance’ windows. And every day, thousands of glasshouse kits are sold. DIYer Cheft, made the connection and built a greenhouse from other people’s trash.

Greenhouse from Old Windows

This greenhouse project is one of the most inexpensive builds we’ve come across. Although building a greenhouse from old windows is cheaper than buying a quality new kit, you’re still up for the material expenses such as timber for the framing plus the cost of glass. The builder of this greenhouse found a way around this issue by using salvaged windows.

As you can see, the frames and glass in these old windows make perfect building blocks for a greenhouse. You just need to build the frame on which the windows are to be installed on to. You’ll spend very little, if anything, on the windows, depending on where you source them. Craigslist and Gumtree are great sources for these items. You’ll also find lots of timber there so all you have to buy are screws, caulking and latches.

You’ll need these materials:

  • Salvaged Windows
  • 4×4 Timber
  • 2×4 Timber
  • Gravel
  • Cinder Blocks
  • Screws
  • Paint
  • Corrugated Sheets

And these tools:

  • Hand Saw
  • Hammer
  • Power Driver/Drill
  • Shovel
  • Paint Brush
  • Measuring Tape

Click on any image to start lightbox display. Use your Esc key to close the lightbox.8-)


Greenhouse from Old Windows

Look for old windows and save every one you get. After you have enough to build a small greenhouse, lay them out and play a game trying to make two pairs of “walls” of the same height. Two to three inches won’t matter as you can cover the difference with wood. Smaller holes will need to have glass cut for them or filled with something else. Keep in mind that one end will need a door and the other a hole for a fan.

Greenhouse from Old Windows

Using the windows you chose as a guide, construct a frame for each wall. Use good lumber for this, as it is the structure that holds all the weight. I used all 2x4s for the studs and 4x4s for the corner posts. Choose a length that allows at least 14″ of the stud to be placed in the ground for support.

Greenhouse from Old Windows

Start placing the walls up, bracing well so they don’t fall over. Be sure to check that they are level.

Greenhouse from Old Windows

To avoid certain problems with pesky city building permits, I built the structure shed height and did not pour a concrete foundation. Instead I buried cinder blocks to stabilize the 4 x 4 corner posts. They keep it from moving an inch.

Greenhouse from Old Windows

I used some nicely coated deck screws to affix the windows to the frame. This will allow for easy removal and replacement if any should break. This side facing the camera has the empty window for a fan.

Greenhouse from Old Windows

I was able to find someone who needed rocks removed from their yard. Using rocks or stones is good for two reasons: good drainage and heat storage.

Greenhouse from Old Windows

This was tricky. I ended up getting siding from an old shed someone had torn down. Any material you use, look for lightweight and waterproof material. Be sure that you have some that will open for ventilation, at least 20-30% of your floor space. You can get by with less if you use a fan for ventilation. Also build the slant roof with at least a 4 degree pitch, otherwise rain may not sheet off well.

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