Two very different jobs
Roof replacement removes everything down to the deck: shingles, underlayment, and flashing. New materials go on, the old ones go to the landfill, and the job usually involves a large crew, a dumpster, and several days of noise.
A roof coating works with the roof you already have. The shingles are cleaned and a liquid treatment is applied that helps restore flexibility and adds a protective layer against sun and water. Most homes are done in about a day.
When coating is the smarter choice
Coating makes sense when the roof is aging but still sound. Shingles that are faded, a little brittle, and dropping some granules, but still lying flat and attached, are good candidates. So are roofs where the decking is solid and there are no active leaks through it.
In that situation, replacing the whole roof means paying to throw away materials that still have useful life. A coating protects them and pushes the replacement bill further down the road.
When replacement is the right call
If shingles are missing across large areas, the decking is soft or sagging, or water is already coming through the roof deck, a coating is not the answer. Those roofs need repair or replacement. An honest contractor will tell you so during the assessment instead of selling you a product that will not fix the problem.
Comparing cost
Replacement pays for new materials, labor, tear off, and disposal. Coating skips most of that, so it typically costs a fraction of a new roof. The exact price depends on roof size, pitch, and condition, which is why an on site assessment matters.
The bottom line
If your roof is getting older but is not failing, coating can be a practical way to protect it for less money and less disruption. If it is failing, replace it. The key is getting someone on the roof who will tell you which one you actually have.
Related service
Residential Roof Coatings