Powerful build and reach weapons

[Melvin the Mediocre]

A medium creature wielding a lance has a reach of 10 feet.
Under the effects of enlarge person, he threatens 15 or 20 feet away.

If the same creature has the powerful build adjustment, and is wielding a large lance, do the reach values change? I would suspect that a medium creature wielding a large lance threatens 15 or 20 feet away, and when enlarged threatens 30 to 40 feet away. But I am not finding any rules along those lines.

[AspectVoid]

Melvin the Mediocre wrote:

A medium creature wielding a lance has a reach of 10 feet.

Under the effects of enlarge person, he threatens 15 or 20 feet away.

If the same creature has the powerful build adjustment, and is wielding a large lance, do the reach values change? I would suspect that a medium creature wielding a large lance threatens 15 or 20 feet away, and when enlarged threatens 30 to 40 feet away. But I am not finding any rules along those lines.

Powerful Build states: However, his space and reach remain those of a creature of his actual size.

This means that a medium HalfGiant only threatens 5ft naturally. Reach weapons double your natural reach. Size category of the weapon does not factor in. Thus, a medium Powerful Build creature with a large reach weapon will still only hit foes 10ft away.

[Ansel Krulwich]

Given that the rules for weapon size or the Titan Mauler archetype don't give any sort of reach enhancement for larger than normal weapons, I wouldn't grant a large lance any additional reach because of a powerful build adjustment. They still have medium sized arms and a medium sized frame. But that's just my opinion.

Edit: I couldn't find Powerful Build in the PRD. Where is that ability from?

[Claxon]

Ansel Krulwich wrote:

Given that the rules for weapon size or the Titan Mauler archetype don't give any sort of reach enhancement for larger than normal weapons, I wouldn't grant a large lance any additional reach because of a powerful build adjustment. They still have medium sized arms and a medium sized frame. But that's just my opinion.

Edit: I couldn't find Powerful Build in the PRD. Where is that ability from?

Its from a 3rd party psionics book, specifically for the half-giant race.

As noted powerful build doesn't affect reach of the medium half-giant, his reach will be whatever it normally would be. As a lance is a reach weapon it doubles your reach. If you use enlarge person it makes you large and again double your reach. A large half-giant with powerful build and a lance will have 20ft reach.