Where to seal with spray foam to keep lizards out of lanai?
 

I've read that they get in from the corner where it meets the siding. Do I just need to seal the hole at the bottom corner and the gaps around that? Or do other areas need to be sealed?

I have attached a photo of mine.

In my opinion, trying to keep lizards out of your lanai by spraying foam is a fool's errand.

No food (no bugs). No lizards (for the most part).

You and your better half could try going out at night with a flashlight, one inside and one outside and look for light coming from the opposite side. I would try with the flashlight inside shining out and outside shining in. If you see light this would be an area to seal. You may want to consider a color matching silicone caulk for inside.
Also, if you have any drains, they can get in that way, but you do not want to seal these.
Look at the sweep on the door, these do wear out and could have gaps.

Been in home for 10 years last month. Never had an Anole, Lizard, Gecko in my lanai. Stucco home. Sealed the door threshold right after we moved in.

My cat owns the lanai. Geckos get in but never get out

I have drain holes in screen frame so water will run out. The lizards occasionally come in. I use my fish net and remove them. Funny some get in and can’t get out. One ran right by hole couple times when I was trying to catch it. Then they’re the ones that just give up and let me evict them. Most probably squeeze in between door perimeter frames, not much do about that?

I put clear silicone caulk all around the bottom of my lanai. They used to squeeze under the lanai.

I don’t recommend foam.

Since then, the only lizards to get inside run through the door when I open it. They are fast!

Same here! We have two Maine Coons, and they act like Velociraptors when they see a gecko. The only problem we have is if only one of them is outside, they will bring it in so they can both play with it.

I put sticky strips in the corners.

that is where they enter/ exit via the screen door threshold in our home, but we haven't sealed it yet. Silcone would be best, expanding foam is a bit uncontrollable.

Cats also guard the lanai, though they taste awful, per Sage, the hunter cat of our two cats. . .

They may be pest but they do serve a purpose when/if they get in. They will eat and take care of any other bugs that get in the patio and save them from getting into the home. Yes they are a nuisance but if they can’t find water and food once they get in they will not make it out.
Good luck as we all moved into their territory LOL

I make pets out of them, I love them.

Mr. Chip....I use steel wool to seal up those areas. Stuff it right up there

I would be concerned that steel wool will rust and stain your concrete and stucco.