Looking for depth and insurance up front, the Knicks reached an agreement with former Wizards big man Kevin Seraphin Tuesday.

Seraphin will a sign a one-year deal for the $2.8-million room exception, according to league sources.

The 6-9 center/power forward had spent his entire five-year career with Washington, where he averaged 6.4 points and 3.7 rebounds in 16.4 minutes per game. Seraphin, the No. 17 pick in the 2010 draft, had his best season in 2012-13 when he scored 9.1 points and grabbed 4.4 rebounds in 21.8 minutes.

When the Knicks sign Seraphin they will have 13 players with fully guaranteed contracts. Langston Galloway has a partial guarantee, but he's expected to be on the team. The Knicks also have eight players who can play power forward or center.

The Knicks have no more cap space left. Any other signings would have to be for the league minimum.

They used up their nearly $30 million available to them on Robin Lopez, Arron Afflalo, Derrick Williams and Kyle O'Quinn, and also re-signed Lance Thomas and Lou Amundson. The Knicks are expected to announce the signing of veteran guard Sasha Vujacic in the coming days.

With their remaining roster spot, the Knicks could look to add more depth on the wing.

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Last year's second-round pick Thanasis Antetokounmpo, who played for the Knicks' D-League team, could sign a partially guaranteed deal in the near future. The Knicks also are expected to sign former Harvard swingman Wesley Saunders and former Virginia forward Darion Atkins as training camp invites.