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Drywall Finishing - Taping Inside Corners

If you have mastered taping a regular drywall joint, you are now ready to try an inside corner. I have a method for inside corners that provides near professional results. It involves a few more steps however than what some others may show you. The steps shown on this page are for a regular 90-degree inside corner.

Do you have a corner that is over 90 degrees? If so, follow this special procedure.

Step 0 - Read the summary given here. It will make it easier to successfully follow the needed steps.

Step 1 - Make sure all drywall is securely fastened on both sides of the corner. There should be proper corner backing to secure the drywall.

Step 2 - Precut your paper tape the length of the joint. Also prefold the paper tape so it is easier to fold when you are ready to apply it. I would avoid metal-backed inside corners available since they are notorious for improperly adhering (and thus causing air pockets) if the corner is not perfectly uniform - stick with plain old paper tape. Are you taping a corner where 2 other corners meet? If so, see this taping guide.

Step 3 - Apply slightly-thinned mud on each side of the corner. You should place adequate mud on each side (and the corner itself) so there will be no voids or bare spots when the paper is applied. The mud should be applied about 2 inches wide on each side of the corner.

Note: The way I "slightly thin" the mud is to wet the tool down in water and place the tool into the mud - I do this a few times if needed. If the mud is already workable this may not be needed. Also, repeat this procedure as needed if you see the mud is starting to dry up.

Step 4 - Quickly pass your paper tape through a bucket of water.

Step 5 - Fold the wet tape and apply to the corner by hand. Press the inside of the corner in as far as possible to avoid any pockets.

Step 6 - Wet your 4 or 4.5 inch knife down with water. Then, hold the tape at the top and draw your 4 or 4.5 inch knife down each side of the corner, applying pressure to squeeze out mud from under the tape. Get as close as possible to the inside of the corner without ripping the tape. You are really just doing the same thing here as you do when applying tape to a regular joint - you are just doing it on two sides. You will notice that the tape will start to "bunch up" a little. When this happens, pull the tape down from below to get rid of the slack. A picture of a dry inside corner is shown here. Use leftover mud to fill screw depressions, discard unused mud, and clean tools thoroughly.

New! - Watch a Video of Me Taping a Corner - Click Here

Step 6 is a critical step! Remember: Use ample amounts of slightly thinned mud, wet tape, & wet tools, and apply enough pressure to cause the majority of the mud to shoot out from under the tape, leaving the tape securely adhered with no bumps or pockets of mud underneath the tape. Excess mud to the sides of the tape is not a problem - you will knock this off in the next step.

Step 7 - Using the 4 or 4.5 inch dry knife, scrape down the surface on each side of the corner as shown here. Often, I use two hands on the tool to exert the pressure needed. There must not be any bumps - the surface must be level for the next coats.

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Step 8 - Use the 4 or 4.5 inch knife, wet down, to place a 2 to 3 inch wide coat of mud on each side of the corner that is about 1/2 inch from the corner as shown here.

Step 9 - Wet the knife down again and draw it up the entire length, exerting enough pressure to make a thin uniform coat as shown here. Do this on both sides of the corner. You now will have a recess at the corner to be filled in with the next coat using the infamous corner tool! Use leftover mud to fill screw depressions, discard unused mud, and clean tools thoroughly.

Step 10 - Let the mud dry. Then, before applying more mud, use your dry 4" or 4.5" knife to level out any mud sticking up. Knock down any washboard surface by scraping perpendicular to the ridges. Don't sand!

Step 11 - Apply another coat that covers the corner and overlaps the last 2 coats you placed on in Step 10. This coat should extend about 2 inches from the corner as shown here.

Step 12- Use the corner tool, well wet down, to firmly draw down the mud. I find it easier to work top to bottom. You should have a fairly nice corner now, although you can place two more very light side coats if needed, slightly overlapping the last 2 side coats.

Step 13 - Let the mud dry. Then, before applying more mud, use your dry 4" or 4.5" knife to level out any mud sticking up. Knock down any washboard surface by scraping perpendicular to the ridges. Don't sand!

Step 14 - Apply 5" to 6" wide coats on each side of the corner keeping about 1/2" to 1" from the corner as shown here.

Step 15 - Use the wet down 10 inch tool to draw down these coats on each side of the corner. Use sufficient pressure so there is not a buildup near the corner. It should look like this.

Step 16 - Let the mud dry. Knock off any high spots. If you have created a new recession at the corner, use the corner tool to fill it in (Steps 11 & 12) although you shouldn't have to if the coat was thin enough and enough pressure was used in drawing down the coat. Otherwise, fill in any drag marks with a small amount of thinned mud by drawing down the knife perpendicular to the mark. Fill in any voids as well. If you are seeing faint washboard-like waves even after knocking down the surface, you can remedy this nicely by applying a very thin coat of thinned mud drawn perpendicular to the waves as shown here (this was an outside corner) - this is a much better move than trying to sand the surface level!

When this step is completed, you should have a wall that would look half-way decent even if you did not sand. Here is a picture of the wall I have been documenting for this site before sanding.

Step 17 - Lightly and sparingly sand with 220 grit paper on a 3" by 8" sanding block. For problem areas such as the meeting of two corners at the ceiling, you may need coarser grit paper but use it with restraint! Vacuum the surface off. Shine a trouble light or lamp at a low angle to see any scratches, voids, or drag marks that need to be filled in. Use small amounts of thinned mud firmly drawn down with the 4.5" or 10" knife (I like to use the 4.5 inch knife for this). If your job passes the low angle light test, you have a completed the job well. Avoid sanding the paper surface of the drywall!

Step 18 - Prime with a latex primer. Don't work the primer around too much - it can lift compound! Paint with a latex paint. Note that some primers require you to paint within 48 hours of priming.

Step 19 - Show your friends the nice job you did. (here's a pic of the painted wall I documented for this site) Tell them about this web site drywallinfo.com !

Have you seen the drywall FAQ's section? Many common questions answered.

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