Greenhouse plans

Doors, windows and lining for your greenhouse

Having a good solid door for easy access is important. We also suggest you install a window at each end for ventilation. When summer comes and the days warm up, opening the window will stop the temperature climbing too high inside the greenhouse.

To make the door, first cut two 1445mm lengths of 50mm by 50mm timber, and two 795mm lengths. Nail the shorter lengths onto the end of the longer lengths to form the outside of the door shown in Figure 3.1.

Now cut the bracing and the 695mm length of timber. Both are cut out of 50mm by 50mm timber. Install the 695mm horizontal brace first, then mark and cut each end of the 1163mm length to the required angle so it fits into the corners as shown in Figure 3.1.

For the windows, the 367mm length sits at an angle of 20 degrees. Use a skill saw for accurate 20 degree cuts.

Shave a couple of millimeters off the lower corner of the 367mm length so it sits comfortably on the bottom piece of timber, as shown in the diagram.

Installing the door

There will be times when you want to close up the greenhouse and keep as much heat in as possible. It is therefore preferable to cut down on draughts around the door.

Before you install the door, install two lengths of 25mm by 75mm timber across the top of the door and on the opposite side to the hinges. Refer to Figure 3.2. This will give the door something to close against and cut down on draughts. We also suggest you install a length of 50mm by 25mm timber along the bottom of the door frame.

Hang the door with heavy duty hinges. We suggest using three hinges to give added stability, but you would probably get away with just two.

A standard door latch set available at hardware stores will complete your door.

Installing the windows

For the windows, first install the window itself, then install the short vertical length of timber shown in Figure 3.3. This short length of timber completes the window frame. Use a small latch to secure the window. A latch that allows the window to be held part way open would be useful, and should be available at your local hardware store.


Line your greenhouse with UV stabilised polythene. Clear polythene is sold by the meter at many hardware stores, or you may need to purchase a roll.

If you have a choice of thickness (usually measured in microns), go for the thicker grade.

To attach the polythene to the frame, we recommend you use hot glue or silicon glue, then staples. The glue will help stop the lining tearing around the staples.

Final notes

Your greenhouse should extend the growing season for tender summer crops such as tomatoes and peppers. It is also a great place to raise a range of seedlings before planting them out in the main garden.

Make sure you keep your greenhouse well ventilated, especially in warmer weather. On very hot days both the door and windows can be left open. Letting the greenhouse get too hot can damage your plants and slow down their growth, which is no doubt the opposite of what you are trying to achieve.