One job move filled an opening in Washington while creating another in San Francisco.
To replace Foerster, the 49ers hired Mike Solari, marking his return to San Francisco.
Solari served as the 49ers tight ends/assistant offensive line coach from 1992 to 1996 before moving to Kansas City. He was the offensive line coach with the Seahawks the past two seasons.
The Redskins also added two other assistants to coach Mike Shanahan's staff Thursday: defensive line coach Jacob Burney and defensive backs coach Bob Slowik.
Foerster coached San Francisco's offensive line the past two years. He takes over a Redskins unit that was constantly shuffled last season because of injuries and ineffectiveness.
Foerster joined the 49ers in 2008 after working for the Baltimore Ravens from 2005 to 2007; the Miami Dolphins in 2004; the Indianapolis Colts in 2002 to 2003; the Tampa Bay Buccaneers from 1998 to 2001; and the Minnesota Vikings from 1993 to 1995.
Foerster's hire in Washington nearly completes the Redskins' offensive coaching staff, though the team still is looking to hire a receivers coach.
Sean McVay was hired as the Redskins offensive assistant on Friday. McVay worked for new Redskins defensive coordinator Jim Haslett last year with the Florida Tuskers of the United Football League.
The Redskins also formally announced Friday that Steve Jackson will remain with the team as safeties coach. Jackson has been on the Redskins staff since 2004.
Information from ESPN NFL Insider Adam Schefter and the Associated Press was used in this report.