Laying WPC terrace planks: Instructions in 11 steps
In the following instructions, we assume a WPC terrace with aluminium substructure on a level grass surface.
Step 1: Mark out the terrace with a spirit level and line. In this step, allow for a 2% incline away from the house. The line indicates the top of the WPC planks.
Step 2: Remove the earth as deep as you need to for the planned subsurface layers. Measure down from the line to transfer the planned incline. Also plan edging. To do this, remove earth 50 centimetres wider on all sides and insert the edging.
Step 3: Rake the surface even, remove stones, wood and plants and compact the subsurface. Use a plate compactor and go over the area at least twice across and lengthways.
Step 4: Now it's time for the gravel. Spread it evenly over the complete surface in 5 to 10 centimetre layers. Compact each layer individually. The final layer of gravel should finish about 15 centimetres below the line.
Step 5: Spread fine gravel as a compensating layer. This layer should be about 4 centimetres thick. In other words, measure 11 centimetres down from the line. This layer is not compacted but simply spread evenly with the wooden lath.
Step 6: Lay weed control mat over the entire area. Overlap the individual lengths by 10 centimetres.
Step 7: To create a solid surface for the substructure, lay concrete slabs with a 40 centimetre gap between them – measured from the centre of the slabs. However, pay attention to the instructions from the manufacturer of your WPC planks. Lightly tap the slabs with a rubber mallet. Pay attention to the drainage at the house wall if the terrace is to finish directly at the door threshold.
Step 8: Now it’s time to install the substructure. Drill holes for the fixing material in the middle of the rails. Lay the profiles at the planned positions. Leave an expansion gap of 3 centimetres between the rails. Mark the position of the profiles and drill fixing holes.
Step 9: Place anchors in the holes, position the supporting pads and screw on the profiles.
Step 10: Lay the first plank flush with the construction beam and fix it in place with an end clip. Drill all fixing holes and screw the planks tightly. Place a normal clip on the other side of the plank.
Step 11: Now lay all the planks. Slide the second plank into the clip of the first plank and screw it tightly as described above. Place another clip on the other side of the plank. Lay all the planks in this manner and fix the last one in place with an end clip.