The Tesla Model 3 glass roof makes mounting a roof rack more difficult than on other vehicles.
Some aftermarket companies have now come out with options for roof racks, and Tesla also has their own version of it.
Tesla Roof Rails
Due to the fragility of the glass roof, and the potential for stress cracks, some mechanics don’t recommend a DIY install of the Tesla roof rack on the Model 3. Reddit user WntrWltr says this:
Off the top of my head I believe [the torque specification] was approximately 5-8 newton meters, and when I installed my roof rack I used a calibrated torque wrench (aircraft mechanic here, every 30 days they get calibrated), and I only reached 2 or 3 Nm before stopping and calling it a day due to my mechanics intuition. The key to installation is going little by little and making sure the rack is seated properly in the rubber foot pads, this enables the rack to seat down evenly and prevents it from being uneven laterally and placing too much stress on the J-hooks. After going back and forth tightening in approximately 0.5 Nm increments, once I got to about 3 Nm I stopped and left it be. The rack is incredible secure and I have carried my bicycles on it without any issues. I do believe that unless you have a low-torque torque wrench and a fair amount of mechanical aptitude, you should not be installing this rack yourself, the risk of over tightening and cracking the roof is way too high.
Roof Rack Cracking glass roof
Some Model 3 owners have had their glass roofs crack from roof racks. In some cases the cracks are caused by over tightening of the roofrack or other similar problems, but in other cases the actual cause of the cracks are unknown.
In this photo, you can see the Tesla supplied roof rack, and a crack in the glass roof right near the mounting point.
Another Model 3 owner had spider web cracks in his roof from the stress and Tesla replaced it for no charge src