This post contains affiliate links, thank you for supporting this blog.
Today’s post is how to build a cold frame step by step using a door I bought from the Habitat For Humanity Restore Salt Lake City.
Those of you who have been reading, know that I LOVE Habitat For Humanity Restores and with all the garden projects, we frequently head on down there to get supplies. Unfortunately I have not managed to pick up lumber from there yet, so we hit Home Depot and Lowes for the wood for this project and used all off cuts and scrap from the house remodeling projects too.
How much did it cost?
Some estimates are below for the total cost of lumber if buying new and the specialty screws we needed to ensure a flush finish.
Kreg Jig Screws Pack $22 (24 screws used)
Studs x 6 $14.70
Particle board (Plywood) $30
Brad nails $8
It should be noted that the cold frame is the full length of the door and 2 feet deep at the back and sloping to 16 inches at the front, which is larger than many off the shelf cold frames. I wanted something deep which I can line with plastic (to protect the wood on the inside) and fill with compost or make into a hot bed or hot box.
Want to know more about hot beds/hot boxes? Then check out my post Starting Seeds In Winter to find out more about this Victorian growing trick.
Step By Step: How to Build a Cold Frame
When building always remember, safety first and ensure you have appropriate protective equipment for the task you are going to be doing.
Step 1: Measure and Cut Front and Back Panel Pieces
Using the door as the starting point, measure the length and width. If you can get a door with the hinge still attached, it makes putting the lid on the cold frame easier.
Measure and mark out the length (which will match the door) and height of the back piece of particle board or plywood. The height of our cold frame is 2 feet at the back.
Measure and mark out the length and height of the front piece of particle board or plywood, ours is 16 inches high and the length matches the length (height) of the door.
Remember measure twice, cut once!
Cut the pieces out, always line up the saw blade to the line on the scrap/waste side of the line to ensure accurate measurements throughout the building process.
Step 2: Measure and Cut Frame
Measure the length of the stud which should be the same as the length (height) of the door. Mark off the length and draw cutting line, ensuring you are square.
You need to measure 4 length pieces and 4 width pieces. The widths should be the same as the width of the door minus the width of the two length stud pieces for the frame.
Double check the measurements then cut the stud, ensuring you line up the blade on the scrap side of the stud.
Step 3: Put the Frame Together
Nail the top and bottom frames together.
Next, you need to create the risers for the frame. These need to be angled at one end to allow them to fit flush against one frame. The back pieces would give a total height of 2 feet (including the studs the risers are connected to) at the back and 16 inches at the front.
We used a Kreg Jig to create pocket holes on the bottom of the pieces. A total of six pieces were needed, three at the back and three at the front.
We fixed two pieces; one at the back and one at the front of the base frame so we could line up the angle of the top frame.
Using the chalked string marker, one end was held tight at the top corner and the string stretched down to the bottom corner. The string was snapped to give a chalk line and the angle taken to then transfer to the other pieces.
The test pieces were unscrewed and cut, along with the rest of the risers.
Here is a cut riser. These then need to go on the Kreg jig to make the pocket holes to attach to the top frame.
Once all of the pocket holes are made on the lowest side, it’s time to fix the flat edge to the base frame.
The risers are then screwed onto the base frame using Kreg screws. As you can see, the pocket hole method uses smaller screws and fits flush with the base.
Once the risers are attached to the base, place the top frame on the bottom and place the base frame on top.
The angle cut enables a flush join.
Step 4: Nail on Panels
In this picture we’re checking the look of the panels cut not the angle is not flush. I didn’t like it so onto the table saw it went.
The smaller piece is added to cover the stud just above the main panel.
We used a brad gun to nail the particle board/plywood to the stud and frame supports.
Here you can see the small off cut piece attached to the back stud.
The same thing was done on the front of the cold frame.
We actually had some angled off cuts that fit the side panel and a thicker piece of particle board to use and a carrying hold. If you don’t happen to have the right angled pieces cut, use the frame as a guide and mark off the angle to cut out.
The carrying hold isn’t very wide but it serves its purpose.
Step 5: Attach the door for a Lid
Lay the door on top of the frame and check the opening. We needed to flip this door over and cut out some of the hinge to accommodate the width of the stud and particle board on the frame to enable free movement of the door.
String up a handle, we used paracord.
You don’t have to use string as a handle, a door handle will work too.
Here’s the completed cold frame ready to be stained/varnished or painted.
Here’s some tools which we used that were extremely useful in building this cold frame which we think are worth the investment.