During Summer it gets very hot under the pergola. Any ideas of how to insulate and reduce the heat please. Thank you
Welcome to the Bunnings Workshop community @rameshm. It's great to have you join us, and thank you for sharing your question about how to insulate your pergola.
One of the best ways to reduce the sun's heat is to use a Pillar 1.83 x 5m Cream 90% Shade Cloth. The Cover Shade Cloth is designed to shade living and entertaining areas from heat and UV. You can attach the Shade Cloth to your pergola frame by using Trojan 10mm 13 Piece Grommet Tool Kit, in combination with Everhang 25mm Zinc Cup Hooks - 100 Pack. However, if you want to permanently attach it to your pergola, you can use an Arrow T50 Heavy Duty Staple Gun All-Purpose.
Please keep us updated with your progress, we look forward to seeing your pergola covered and ready for use.
You might like to consider swapping the sheets out to something that doesn't have near 100% light transmission. Once the UV rays penetrate the sheeting they'll strike hard surfaces and heat them up. They'll then radiate that heat increasing the air temperature within the pergola. I like @EricL's idea, but my preference would be to have the shadecloth on top of the roof sheeting instead of below.