Exactly. Who would barbque inside an enclosed room?

I hope the original question meant that he wanted to know if it is alright to grill in the screened in lanai, not an enclosed lanai. Don't many lanais have outdoor summer kitchens? So what's the problem? Keep the grill away from your house, no problem. Turn your gas off after you finish. I have been doing it for over 10 years, no marks, stains or other problems.

You will have grease and smoke stains on walls and screens as well as the floor. Grills belong out side. Many appartments with balconies have banded all types of grills because of the fire hazard

Not good for the ceiling - heat and discoloring. Don't think it is safe either.

Summer kitchens have a dedicated exhaust vent hood... Well, at least the one's I've seen do...

Much different than a regular portable propane grill...

I don't know anyone who has a grill under their lanai roof. Out in the birdcage area yes if you have one. If not then outside on a patio or concrete pad.

Agree with others, it’s a fire hazard.

Need to be vented, very unsafe !

I would not recommend it.
There’s always a possibility of a grease fire while cooking burgers or chicken.
This can result in a greasy mess on the walls & ceiling of your lania.
If you have a screen door opening to the outside I would suggest a concrete pad large enough for the grill and spare propane bottle.

We had a gas grill outside our lanai about 8-10 feet from the house. Unknown to us, one of the tubes from the tank had a crack in it and in a matter of seconds, the entire grill was engulfed in flames and some siding had melted. We now have a pellet grill and when our landscaping is completed, it will go as far away from the house as possible. I would never put a gas grill in an enclosed area.

I believe the ceiling of our lanais is nothing more than drywall, it's not a masonry product or stuccoed. I'm even hesitant to put a fire table on the lanai?

gas grill indoors
 

I wouldnt try it. There is a danger of carbon monoxice poisoning if there is not enough ventilation. Very sneaky gas and very deadly

Just curious why you would want to?

Grill
 

Nope.

Lanai grilling
 

Great idea if you want smoke to get inside the rest of your home. You might even choke to death. I have not seen a dumber question on here. Sorry!