See how to install a Torch Down Rubber membrane under the ductwork of an A/C unit. There is no need to hire cranes to lift up air conditioner units on a flat roof you can install roofing material. Using a floor jack and some 2 x 6 planks will do the job
Watch these videos:
Basic principles on How to Torch – https://www.youtube.com/watch?v=t1jALMrWVdY
Learn how to Torch Down a rubber roof – https://www.youtube.com/watch?v=4V1eri1k_cE&t=206s
You can buy a Torch here: https://www.modisystems.com/MagnumTorchKits.php
Type of Torches explained – https://www.youtube.com/watch?v=iuRaXKsJrjA
0:00 Getting Floor jack positioned
0:48 Grab a roll to measure the size
1:16 Torch 2 equal lengths together
3:23 Position double-wide membrane
4:13 Torch membrane to the base