Couple of years ago I was working on my Granddaughter's room in Georgia and wanted to install our ceiling tiles over popcorn ceiling. This turned out to be a problem because the popcorn texture was not stable enough and we had to remove it. Here are the steps we have taken along with a video and images.

Important Note: be sure your popcorn texture has no asbestos, breathing asbestos dust can be deadly.

Steps to Remove a Popcorn Ceiling

Covering the wooden floor - a brand new wooden floor was installed and finished just days before, in order to protect it we have covered it with a thin plastic.
Wetting the ceiling - it turns out that the multi-purpose sprayer bottle works really well. Be sure to soak the ceiling well and let it sit of a minute. Keep in mind that if the ceiling is protected by coats paint, it will harder to soak it. However if this was the case, it would most likely be stable and you would not have to remove it to install our ceiling tiles, you could simply install our tiles right over the popcorn ceiling.
Scraping popcorn texture - you can purchase popcorn scraper tools at your local hardware store or online. The nice thing is that you can add a bag to it to collect the popcorn but there are other tools that will work. We have found a bagless floor scraper along with another person sucking away the mess with vacuum cleaner works the best.
Clean the ceiling surface from dust - a clean wet cloth or a sponge will do the trick, make sure you have a container with clean water to rinse your cloth or sponge. We have found a floor sponge mop and a plastic storage container with water to be most efficient.

Decorative Ceiling Tile Installation

Now that the popcorn has been removed from the ceiling and the ceiling surface is clean, you can start with ceiling tile installation. There is a complete step by step installation video below.

Finding starting point - Starting in the center of your room with your Styrofoam decorative tiles normally provides the most appealing layout – in many cases you may already have a ceiling fan or light in this spot, but if not, use the string method to determine the room’s center. Stretch two strings across the ceiling at a diagonal from opposite corners and where they cross should be the center – finish nails can be used to secure the ends of the strings or ask a helper to lend a hand. Draw two perpendicular lines where the strings cross to divide the ceiling into four quadrants. Starting in the corner sometimes works better, especially in small rooms and if you are looking to have less waste and do less work. Let's say you have small bathroom, you can start in the most visible corner, this will give the best look and most likely you will have less waste.
Applying adhesive to tiles - The adhesive is applied to the backs of your tiles in small 1 to 1 ½ inch thick mounds. If you happen to have a porous surface such as popcorn, you may want to increase the thickness of the adhesive, but a hard flat surface such as sheetrock or plaster may take a little less – use the first several tiles to determine the ideal amount needed for your ceiling. The adhesive should be placed in mounds approximately two to three inches in diameter and located at each corner of the tile, in the center, and a few other spots as needed. It isn’t necessary to spread the mastic as pressing the tile into place on the ceiling should take care of that task – try to keep the adhesive in from the edges enough so that it doesn’t flow past the tile when installed.
Installing full tiles - Make sure you install the tile straight on your starting point, the rest of the tiles will be affected by this. If you are using layout lines, make sure it is exactly were it needs to be and the same goes for every following tile, the second tile should line up with the first one. The nice thing is that the tiles can be moved around for several minutes.
Cutting the tiles - When you finish installing your full tiles, you will find that you will need to cut the perimeter tiles to fit. Measure both sides of the area from ends of the tile to the wall and transfer the measurements to your tile that is going to be cut. Using a straight edge connect the two sides and cut with a sharp razor knife in a continuous motion. Check the cut tile in the area where it needs to go, this is called a dry fit. if it fits add adhesive and install, if it does trim the tile or cut a new tile.
Caulking - Caulking is optional but recommended. If your tiles are pre-painted you may choose not talk caulk, especially when it comes to two tone finishes, such as Antique Gold because you would not be able to match the caulk. However, if you are choosing tiles in the plain white option, which is unpainted or our ultra pure white finish you can caulk with a white water based caulk and it will match well. Also, if you are painting the tiles after installation, caulking before painting is highly recommended so that you can paint the tiles and caulk at the same time.

Finishing of the edges - Here I am talking about the edge between your cut tiles and the wall. Most people finish of their ceiling project with crown molding, our crown molding is a really good option because it is very easy to install and it comes in matching colors. I have made called Do I need a border for my tiles.

Here is more professional looking video by Ron Hazelton.

Well, I hope you have found value in this article and that you will try to tackle the project on your own. If you are interested in our ceiling tiles that can cover popcorn ceilings, visit our website.