Road frontage generally does add value, for a couple of practical reasons. Frontage typically means easier, more clearly legal access, without needing to rely on an easement or a shared driveway arrangement with a neighbor. It also usually means lower development cost down the line, since utilities and a driveway cut can often run directly from the road rather than needing to cross another owner's land.
Within frontage itself, the type of road matters too. Paved road frontage generally commands more than frontage on a dirt or gravel road, since paved access tends to signal easier year round use and can matter for financing or future development plans.
On the how much question, there isn't a reliable universal figure. The premium varies by county, by how tight the local buyer pool is for that type of access, and by what comps in the immediate area show. Rather than looking for a flat percentage or dollar amount, the more reliable approach is a direct comparison:
- Find comps with frontage and comps without it, in the same general area and similar size range
- Compare price per acre between the two groups
- Adjust for any other differences, topography, utilities, proximity to town, before drawing a conclusion
That kind of side by side comparison, using actual local sales, will give a far more accurate read on the frontage premium for a specific area than any general rule of thumb would.