How To Build A Cold Frame

Here are the basic plans for how I built my cold frame. I am not going to go into great detail as details change depending on your window size, materials used etc.

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Materials:

window(s)
2x6 lumber for the frame, spruce, pine or cedar
2x2 lumber, spruce, pine or cedar
outdoor wood screws
outdoor hinges
3 metal handles

Start by finding or making a window, I used a double glazed window that is used in exterior doors. You could also use old wood windows or make your own window with Plexiglass. You can also use multiple windows to make a longer cold frame.

Once the window(s) have been chosen proceed with calculating how much wood you will need to make the frame. I chose to make my frame 3 2x6 high in the back and 2 2x6 high in the front. This will create an angle of approx. 13 degrees to catch the sun.

When you have all your lumber calculated and at hand start by building the front and rear panel of the frame. You will need 5 pieces of 2x6 that are the length of your frame. The 2 top 2x6 will need to have a bevel cut on the top for the window to fit snugly. This can be accomplished by tacking a straight edge on the top 2x6's that will accommodate your saw, set your circular saw to 13 degrees and cut the top edge on an angle. It can also be done on a table saw if you are lucky enough to have one.



Now that your have 2 beveled 2x6 and 3 2x6 cut to the length of your frame you can start to fasten them together. Layout out your 2 bevel cut 2x6 and then add 1 straight 2x6 to the front panel and 2 straight 2x6 to the back panel making sure the bevels are facing forward. When the panels are layed out fasten them together using screws and 2x2's. Cut the 2x2's a 1/2" shorter then each panel with an angle cut on the top so they do not interfere with the window closing.

With the back and front panel completed, I then tacked them together with scrap wood to form the width of the frame. I then attached the window and squared everything up to the window. Doing this helps if you are working by yourself and it also squares the frame to the window which may not be overly square.

When the frame is adjusted and tacked together measure the width and cut 6 2x6 to fit. I then fastened these in place by pre-drilling/screwing through the front and back panels into the side panels. Once you get to the top side pieces, put them in place and use you tacking stripe as a straight edge to transfer the angle to the pieces. Then cut along the line and fasten them in.

Now that your frame is completed add two side handles for transporting the frame and one handle to the window to aid in opening. The only other thing that is need now is a way to keep the window open on hots days. There are many ways of doing this from a simple wedge, to a gas assist lift like the ones used on screen doors or you can use automatic temperature lifts if your window is light enough for them to operate. I will be adding a screen door opener on mine once the weather get warm enough to need one.

One other thing that is a great addition to a cold frame is a min/max thermometer that will show the lowest and highest temperature. I will also be adding one of these in the near future.

Check out my other cold frame posts