The case that is genuinely strong
A garage floor in a snow region is the clearest one. Road brine soaks into bare concrete, lowers the freezing point of trapped water, and multiplies the freeze-thaw cycles the slab goes through each winter. That is what causes the crumbling patches near the door on almost every ten-year-old garage. A sealed floor stops salt at the surface, so the coating is slab protection rather than decoration.
Where it is the wrong purchase
If the only problem is a warehouse slab that dusts, a lithium silicate densifier at $1.50-$3 per square foot hardens the surface chemically with no film to fail, at a fifth the cost. If the slab is sound and flat and you want no maintenance cycle at all, polished concrete outlives any coating. A contractor who never mentions either option is selling, not specifying.
The resale question
A coated garage floor is a visible, photographable upgrade that shows well in listings, but it is not a renovation that returns its cost the way a kitchen might. Buy it because you will use the space for years, not as an investment. On a house you are selling next spring, the honest answer is that a good clean and a densifier gets most of the visual benefit for a tenth of the cost.
Cost per year is the useful frame
A $5,000 two-car garage floor over a 17-year service life is under $300 a year, and there is no re-coat cycle in a residential garage within that window. Compared against re-pouring a spalled slab, which runs several times the coating cost, the arithmetic is favourable for anyone staying put.
Want this answered for your slab?
Free site visit with a moisture reading, then a written fixed price. Across the BC Interior.