Maybe I'm overthinking this. My wife/we want to install tongue and groove planks over a popcorn ceiling in our vaulted eating area. The area divided into 3 spaces on each side separated by 4x6 rough cedar beams and a beam at the top going across the whole room. Each area is approx 4' x 6.5'.

Plank dimensions are 1/4"x3.5"x4' and weigh 1.5 lbs according to the website.
They would be put up horizontally on the 4' side to avoid butt jointing them together.

There are no (accessible) joists at the bottom and top of the ceiling (the beams may cover them). The joists form a lattice for the dry wall across the whole area. They are not centered within each individual area. Each joist is approximately 1/4 or 1/3 of the way from the end of a section. Meaning that each plank would be nailed once to wood underneath the drywall.

There's a popcorn ceiling currently.

Each plank will have nails at each end and through the joist. The end nails may not be functional since they'll be through drywall only. I think this is sufficient to hold a single plank. Will this be enough to hold all the planks in an area (about 35lbs) once they're put up?

Should liquid nails be used in addition to the nails? If so, does the popcorn ceiling have to be removed for the adhesive to be functional?

Is there anything else I need to consider before putting this stuff up?

Thanks!

 

I would scrape the popcorn down so the wood has a flatter surface to lay against. Use liquid nails on the ends if you can't angle the nail enough to secure the wood to a ceiling joist.

 

Yeah I suspected that. Is dry scraping the popcorn off good enough or do you recommend it be sprayed and removed completely?

 

I would think dry scraping would be good enough for what you intend to do.
How old is your house? Some of the popcorn used prior to the 80s had asbestos in it.

 

it was built in the early 80s. I don't believe there's asbestos in them.

 

If I remember correctly, asbestos was banned from residential use in 1978 although existing stock was allowed to be used up. It's generally thought after 1980 there is no asbestos although the only way to know for sure would be to test it. IMO most of the ill effects of asbestos are overblown. It's only dangerous in dry breathable form. Most folks won't have any ill effects from occasional contact.