Basics of 4ths and 11ths on the Guitar
By far the most common type of 4th chord that you encounter on the guitar is a sus4, where a 4th replaces the 3rd and a chord is stacked 1-4-5. On occasion, a 4th is added and the 3rd is retained, in which case you view the formula as either 1-3-4-5 or 1-3-5-11 and call it either add4 or add11.
Basics of sus4 chords
Here are a handful of sus4 chords in various keys. Sus4 chords naturally occur on chords I and V. You can also move these shapes up the neck and use them as full or partial barre chords. The F shape is one example of a barre chord; it’s actually a partial E form.
In a major scale, sus4 chords occur on the 1st and 5th degrees. For example, the G major scale produces both a Gsus4 and a Dsus4. You may expect the other major chord in the key, C, to also produce a sus4 chord, but it doesn’t. When you count from C in the G major scale, its 4th is Fs, a half step higher than a perfect 4th interval.
The 4th degree in the major scale always has a s4th. You often hear this naturally raised interval in a song’s melody, but you don’t usually hear it in the guitar chords. In fact, even though the 4th chord in a key technically has a s4th, guitarists are far more likely to use a regular (perfect) 4th on it instead, probably not knowing the difference.
Basics of add4 chords
Here are a few examples of add4 chords, which can also be called add11 depending on how the chords are stacked and your preference. Notice that the Cadd4, stacked 1-4-5-1-3, keeps its 3rd, E (the 1st string open). Likewise, the Gadd11, stacked 1-3-5-1-11-1, keeps its 3rd, B (2nd fret of the 5th string). The Dadd4, stacked 1-3-4-1-5, is a type of C form moved up two frets without barring.
Play the Dadd4 with the 1st string open and it becomes Dadd4(add9). The 1st string, E, is a 9th to D.
The following songs feature some form of sus4 or add4:
All Shook Up by Elvis Presley
Brass in Pocket by The Pretenders
Can’t You See by Marshall Tucker Band
Closer to Fine by Indigo Girls
Eye of the Tiger by Survivor
Heaven by Los Lonely Boys
Jack and Diane by John Mellencamp
Little Wing by Jimi Hendrix
Margaritaville by Jimmy Buffet
Signs by Tesla
Stairway to Heaven by Led Zeppelin
Summer of ’69 by Bryan Adams
Tears in Heaven by Eric Clapton
Under the Bridge by Red Hot Chili Peppers
What I Like About You by The Romantics
Yellow Ledbetter by Pearl Jam