atNorth signs YIT for second FIN04 building as campus grows to 430MW

atNorth has signed YIT to build another data center building at its FIN04 campus in Myllykoski, Finland, adding a phase to a project that has grown from a 60MW opening plan to a 430MW site while the power and permitting decisions that will determine its final size remain unresolved. Data Center Dynamics first reported the contract, which covers mechanical, electrical and plumbing work on a facility designated FIN04A1; neither the value nor the construction timeline was disclosed.

The award is YIT's second at the campus, following a July 2026 selection for another building, and it extends a project atNorth first announced in late 2023 as a 23-hectare site that would open with 60MW and eventually hold several hundred megawatts. The company now lists 430MW across 45 hectares and a path to "several hundred additional megawatts," with two buildings approaching completion as of March, when atNorth began hiring to run the site.

YIT's Aleksi Laine, executive vice president for the infrastructure segment, described the campus as "one of the most significant data center developments in Finland," and the contractor, which has operated in the country for more than 110 years, said its strength in technically demanding projects fits the industry's requirements for quality, safety and security of supply.

Construction agreements at this scale are the visible end of a longer sequence. Grid capacity and permitting are the scarce inputs in the Finnish data center buildout, and this publication has argued that grid position is now the deal currency in digital infrastructure. FIN04 makes the case plainly: a campus that began at 60MW and now lists 430MW, with a path to more, is being built out in stages rather than all at once.

atNorth is ordering buildings one at a time and filing permits for three more, sequencing that suggests construction is running ahead of confirmed demand, a defensible strategy in a market where power access and approvals are the long lead items, not cranes. The February permit filing, made even as those buildings neared completion, looks like a deliberate effort to hold land and options before demand is locked in.

Whether the campus reaches its 430MW ceiling depends less on YIT's schedule than on Finnish grid capacity and the pace of approvals, variables a contractor cannot fix. The undisclosed contract value keeps the economics of this building private, so the number worth watching is the gap between the original 60MW and today's 430MW listing.

Each new contract narrows that gap, and each permit filing widens the site's optionality. The February permit application is the next variable. If it clears, YIT's two contracts at Myllykoski are unlikely to be the last.