How do I give others permission to build in my fort?

I've noticed that when playing with friends, they are unable to build anything without my permission. However, I can't seem to find where I can give them permission. It's neither in my Options menu nor in the Settings. Where do I allow my friends to build in my fort?

Solution 1:

As of patch 1.4 that went live on August 4th, 2017, there is now an option to modify build permissions from the menu, rather than going all the way to your Storm Shield.

Though not explicitly mentioned to you (and not exactly intuitive), giving your friends permission to build and gather resources in your storm shield defense missions is not in any of your typical menus. You can find the option in the storm shield generator itself, under the Permissions tab.

You can check each player's name individually to allow or disallow people from building onto* your fortress.

_{*read: "messing up"}