Why it is always worst near the door
That is where the wheel wells sit and where meltwater pools. It is also the coldest part of the slab, closest to outside air, so it goes through more freeze-thaw cycles per winter than the back of the garage. The pattern is so consistent that it is diagnostic on its own.
Coating over it does not fix it
A coating applied over spalled, salt-contaminated concrete bonds to a surface that is already failing. The damaged layer has to be ground back to sound concrete, rebuilt with a resin-and-sand mortar, and ground flush before anything decorative goes on. That repair is a line on the quote rather than a surprise later.
Why sealing stops it recurring
Once the slab is coated, salt stays at the surface where it mops off instead of soaking in. That is the mechanism that drives the damage, so removing it stops the progression. This is the strongest practical argument for coating a garage in a snow region, and it has nothing to do with appearance.
When the slab is too far gone
Occasionally the damage runs deep enough, or the slab has structural cracking, that a repair-and-coat is not the honest recommendation. We will tell you when that is the case rather than take the job. A coating over a failing slab buys a couple of years and wastes the money.
Want this answered for your slab?
Free site visit with a moisture reading, then a written fixed price. Across the BC Interior.