A patio canopy offers advantages all year round, as the shelter of a roof over the terrace not only keeps the rain out but also creates a more pleasant microclimate for the terrace. A canopy restricts the flow of the outside air, making it comfortable for longer on the terrace. Moreover, your barbecues will never have to be cancelled because of threatening weather, while in the winter months the terrace can be used as an extra storage place. Creating a patio cover is fairly simple, and when you use polycarbonate hollow core panels, it is also extremely durable.

Step 1: Determine the size of the roof

Before you can start creating your DIY polycarbonate patio canopy, the format must be determined, here three things are decisive:

  • The height of the exterior – Important if the high side is placed against the house wall
  • Doors opening outwards – If the slope is too steep, the top of a sliding door can touch the roof or the structure
  • The minimum clearance height – The underside of the structure may not be less than 2.20 high on the lowest side.

You can calculate the format on the basis of these criteria. First, determine where the end of the polycarbonate patio cover comes (the low side). You then calculate how high the high side meets the exterior, the roofing must have a slope of approximately 5 degrees for rainwater drainage. This corresponds to an incline of approximately 10 centimetres per metre.

For the frame material, you use posts of at least 6 * 6, beams of 7 * 17 (exterior and crossbeam) and side member beams measuring 4,5 * 14,5.

Step 2: Starting the construction

Once the size of the terrace covering is determined, you can begin the construction. At the edge (the low side) the roof is supported by at least three poles, on which a transverse beam lies across the entire width of the roof. Determine the location where the poles will be set in the ground and drill holes of at least 60 centimetres deep.

The exterior beam must then be fixed, it can most easily be attached to the house wall with wall plugs. We recommend using a plug every 40 centimetres. Drill the holes in the beam first and then mark the positions of the holes on the wall. Next, drill the holes in the wall.

Step 3: Set up the basic construction

The construction of the patio canopy starts with the installation of the wall beam against the wall. Ensure that the beam is flat and level against the wall. Then position the posts for the low side in the ground. For a long service life, treat the underside of the piles with bitumen or a preservative. Make sure that the tops of the posts are in line during installation and that this line is level. You can fix the posts with struts temporarily, then fill the holes with concrete mortar. As soon as the concrete mortar has hardened, the structure can be built up further.

As soon as the posts are firmly set, the front crossbeam can be placed in position. This is a beam of the same size as the wall beam. This beam is screwed onto the posts from above using thick screws. For stability, the sleeper must also be attached to the posts with struts. You can also choose to use metal brackets, these are less visible than wooden braces.

Now the longitudinal beams can be placed. Do not be fooled by the light weight of the polycarbonate hollow core plates that will lie on top of the cover. Because of the weight of rainwater, snow and wind force, the construction is heavily loaded: this is the reason why you use one longitudinal beam per linear metre as well as two longitudinal beams for each side. This means that for a four-metre wide roof, a total of six longitudinal beams must be used.

The longitudinal beams are attached to the wall beam and crossbar with metal brackets (available at every DIY store). Use sturdy screws of at least 4-millimetre diameter and as long as possible.

Step 4: Fix the polycarbonate panels

Polycarbonate channel sheet is very strong and virtually unbreakable. In fact, this sheet is the strongest link of the entire patio cover. Despite the enormous material strength, polycarbonate is easy to machine. We recommend using polycarbonate hollow-core sheet at least 16 millimetres thick. In fact, cutting is not needed as you can order polycarbonate channel sheets cut to size in our webshop. However, drilling the screw holes is still necessary.

Place the first panel on the side beams, keeping 2-3 cm distance between the edge of the polycarbonate and the wall. Now drill the first screw hole at the side edge of the panel, the screw should come out in the corner of the wall beam. Now fix the first panel with one screw. You can now align the polycarbonate panel with the construction. If the panel is correctly positioned, drill the second hole, again on the corner of the wall beam, and screw the plate with the second screw. Check that the panel is aligned completely parallel to the side members. If this is the case, the panel can now be permanently secured. Use a wide washer under each screw head. Do not tighten the screw too tightly, as soon as the washer comes to rest firmly against the panel, the screw is tight enough. Start with screws on the wall beam, and then on the side members. Work from the house wall to the low side and fix the polycarbonate channel sheets with a screw every 50 centimetres.

Step 5: Finish the patio cover and make it waterproof

To make the roof waterproof, it is necessary to use an H-profile between the polycarbonate panels. You can install a U-profile along the side edges to prevent moisture and dirt from entering the hollow-core sheets. These are available at the hardware store; a suitable profile can be found for each sheet thickness. Profiles are available with rubber lips that ensure a waterproof seal. If you choose profiles that do not have this option, the edges must be sealed along the profiles. Before sealing, the polycarbonate must be thoroughly degreased.

To prevent rain from getting in at the wall, a lip seal must be applied. There are various products in the market for this: the best thing to use is an aluminium L-shaped profile that you fix to the wall with screws and plugs. The edges must then be sealed along the wall and the polycarbonate channel sheet.

Finally, you can install a gutter on the low side as a patio canopy will catch a lot of rain. You fix the gutter to the transverse beam with gutter brackets and the drain pipe can be neatly attached to one of the posts. Then all that remains is to enjoy your DIY patio cover.