Crown molding is the ultimate trim piece for any space. It immediately transforms a room from blandness to interesting at a great budget.

Yet to achieve this awesome finish, the crown molding needs to be installed just right. Often we assume that the walls are straight and that they meet at perfect, right corners. Sadly, this is not necessarily the case: Ceilings and walls are rarely straight. Corners are rarely ever perfectly 90 degrees.

This then presents the challenge that a lot of DIYers battle with with crown molding installation. What is the correct miter angle? How should the molding rest against the fence when making cuts? How should we make inside and outside corners? 

Truth be told, it would take a bit of practice to get the crown molding installation of your dreams. But with these handy tools and tips, that dream will be closer to you than you think.

Handy tool 1: Measuring tape

This may sound obvious, but the journey to achieving a great crown molding finish starts with correct measurement.

Get your measuring tape and a friend and accurately measure the length of all walls. If you have laser measuring tools, even better!

If, like me, you’re a stickler for visual aids and a whole lot of preparation to get as close to accurate as possible, consider a simple drawing of the room.  Map out these measurements on graph paper. Take it a step further and create a replica of the room in advance, labelling the walls. Note the measurements and add 10-15% to give you an idea of the length of crown molding you will need.


  • When measuring the molding for cuts, measure where the crown hits the wall, rather than the ceiling- Measure the bottom or ‘run’ of the crown.

  • If you’re working with quite a long piece of molding, add about ⅛” to your measurement so you have a leeway to make adjustments. It will be very difficult to cover up a mistake where the molding is even just slightly short.

Handy tool 2: A protractor

I bet you never thought that a geometry set would be useful to you one day. 

One of the most important parts of crown molding installation is making the cuts for mitered joints. If they are not accurately measured, the end result will be a poor installation with ghastly gaps or pieces that do not fit into each other.

For a wall, the standard protractor may not be too easy to work with. Thankfully, there are more flexible options. An angle finder protractor will save you plenty of frustration and guesswork. 


  • The super angle you’re looking for will not be the one you measure on the protractor. Instead, when you measure your angle, subtract it from 180 degrees. Take this new angle and divide it by two to find the mitered angles for the two crown molding pieces.


Say you measure 87 degrees rather than a perfect 90 degrees. The normal next step would be to cut the two crown pieces at 43.5 degrees.

Instead however:

180-87= 93

93/2= 46.5

This is a 3 degree difference. It will separate finished work with a gap from without a gap.

Handy tool 3: A miter saw

You will obviously need this one to make mitered ends. Get a good, sturdy miter saw for your work with crown molding. A smaller saw will get in the way because the fence will be too small, or the blade will not rise high enough to cut through the molding.


  • Change out the factory blade sooner rather than later to keep it from wearing out.

  • For instructions on cutting mitered corners, which are ideal for outside corners, this article will give you great pointers.

Handy tool 4: A coping saw

Coped joints are fantastic for inside corners. A coped joint will be made by having one piece of crown molding without any mitered cuts joined to another bearing the normal mitered cut. 

This mitered cut will then be coped, meaning that all the polyurethane material behind the cut will be sawed away, leaving only the profile to rest on the adjoining molding.

Why is an inside joint better coped than mitered?

  • Coped joints come together more cleanly for a seamless finish

  • Coped joints will be easy to work with for imperfect angles. It will also be easier to hide any gaps arising from an inaccurate cut.


  • To achieve that nice coped cut, hold the saw at an angle behind the edge so that you cut away as much polyurethane as possible. 

  • Use a file or sanding paper to smoothen any ridges.

Handy tool 5: A nail gun

Get a good nail gun that will preferably not require a compressor and that will be easy to load and use.

For crown molding, opt for 2 inch brad nails and mark the studs in advance so you know just where to drive the nails.


  • You can use adhesive at the back of the crown molding to help it rest better against the wall and ceiling. However, do not use too much otherwise it will ooze out and create a mess.

Handy tool 6: A caulk gun

Finder Standard Size 10oz Silicone Caulking Gun, Manual Cartridge Rod  Cradle,Fits 10 oz tube/cartridge (Caulking gun only) - -

With the steps above, you probably won’t need much caulk. Still, it will be useful for any joint that is not glove-fitting. 

Remember, caulk is not some magic potion to camouflage a poorly done fitting. It is great for small gaps and slightly uneven surfaces. Where the wall is too uneven to hide the gaps with caulk, consider changing a few tactics in the installation.


  • Caulk shrinks between applications. When applying it, wet your finger so that it spreads evenly across your surface. A few thin layers of caulk will appear better than one huge blob. 

  • Caulk will not be sandable once it dries but sparkling paste will be. Choose what you will prefer to work with.

There you have it! With these simple, handy tools, you will be on your way to fantastic crown molding installation and plenty more trim work. If at first you do not succeed, cut yourself some slack and try, try again.

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