The Iceland international provided a worthy finish to Jamie O'Hara's delightful pass to level the scores after 54 minutes.
Hallfredsson was then heavily involved as the home side's goal led a charmed life in the final stages. Substitute goalkeeper Dave Lovell parried his shot onto the post and somehow kept out Radwan Hamed and Jacques Maghoma's point-blank efforts both from Hallfredsson crosses.
The first half would have been mildly frustrating for Clive Allen as his side managed to get into numerous promosing positions only for a host of crosses to come to nothing.
That was typified by a break after 15 minutes when Jamie Davis beat the offside trap from John Kyriacou's pass but with Jamie O'Hara and Andy Barcham ready for a tap in, his cross was cut out.
Charlie Daniels dragged a shot wide, home keeper Noel Imber read O'Hara's attempted chip, Barcham flicked a header wide, Imber did well to tip Charlie Lee's downward header over and the closest we came as Barcham prodded Hallfredsson's cross inches wide from six yards.
Despite our territorial advantage, Boreham Wood's work ethic was commendable and they took their sole chance when it arrived after 10 minutes. Joe O'Brien crossed from the left, Paul Burrows nodded back into the danger area and Kieran Adams reacted first to drill the ball under David Button from 12 yards.
We picked up where we left off in the first half as Barcham just failed to get the right connection on Davis' cross.
The equaliser wasn't long in arriving. Nine minutes into the second half O'Hara spotted Hallfredsson's run, delivered the pass and the left midfielder did the rest, controlling well and planting the ball into the corner.
O'Hara then hit the bar with Imber rooted to the spot and Barcham grazed the post one-on-one after Davis won possession.
The next 15 minutes was quieter and the next chance belonged to Boreham Wood as Tommy Forecast, on for David Button, did well to block Ian Cooper's one-on-one chance with his legs.
The final few minutes was all about Hallfredsson. He struck a shot just wide from the angle, saw Lovell deflect another shot onto the post and then cross for first Hamed and then Maghoma to watch in amazement as the keeper denied them from six yards.
Boreham Wood: Imber (Lovell, 65), Burrows (Morgan, 60), Townley, Smith, Harvey (Moran, 60), Adams, O'Brien (Samuel, 45), Black, Archer, Bangura (Cooper, 60), Watters. Unused subs: Hazell, Toyer.
Spurs XI: Button (Forecast, 75), Kyriacou, Daniels, Mills, Lee, Davis (Wells, 70), O'Hara, Lewis, Ziegler (Maghoma, 60), Hallfredsson, Barcham (Hamed, 70).
Emil Hallfredsson was on target as our Spurs XI side drew 1-1 against Boreham Wood at Meadow Park on Thursday night.