You may not realise, but this is a very common problem and very difficult to resolve once the concrete is set. As with most job site fixes, the repair method depends on the nature of the problem and when in the construction process it is first noted. The repair method may be even more different if one bolt is out of place or if the entire anchor pattern has been misaligned. 

If the error is discovered before the column base plate has been fabricated, it might be possible to use a different pattern or even a different base plate.

If one or more rods in a pattern are out of alignment after the column has been fabricated, the most common repair is to slot the base plate, and use a plate washer to span the slot. If the entire bolt pattern is off uniformly, it may be possible to to cut the base plate off and offset it on the column to accommodate the out of place bolts.

If the anchor rod or rods are more than a few inches out of position, the best solution may be to cut off the existing rods and install new drilled-in epoxy-type anchor rods. When using these rods, make sure you follow the epoxy manufacturer’s installation recommendations carefully and provide inspection as required in the applicable building code. Take care to locate the holes correctly to avoid any reinforcing steel in the concrete foundation. If any reinforcing steel is cut, a check of the effect on foundation strength should be made.

It is also recommended that your project engineer should be consulted before any of these repairs are undertaken to make sure the best method for the specific application is chosen.

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