Level Up (A5E) Stronghold Cost and 'Build time'

[Huntedown]

We are starting to get into stronghold in my game, but I have some question about them.
First of all, how much does it cost to upgrade a lv 1 average training hall to a level 2 average training hall. I have ruled that it is the difference between the two, otherwise it make no sense to get a lower level if it take as much money to build a fresh one.
Second, is there a time constrain on 'building' a stronghold. I try to look if there is a time to actually get a stronghold, or are they just there? Stronghold are already gold sink, but if anyone could tell me if you put time on building/upgrading a stronghold

 

[W'rkncacnter]

i'd assume the cost to upgrade a stronghold is the difference between how much you've already spent on it and the total cost of what it'd be new, yeah. i don't think there's any explicit amount of time that it takes to build or upgrade a stronghold.

 

[xiphumor]

I can only assume there to be a guild of magical contractors who can upgrade your stronghold instantly but charge a massive fee.

 

[Selganor]

Upgrade is just the difference in the costs.

As for time... if "immediately" is too fast for you maybe use the week that it takes to make a "new" stronghold your home ("Multiple Strongholds" sidebar AG p. 362)

That shouldn't be too long but still enough time to have some sort of realistic timeline.

Even if the building was already there, the week might be needed to get all the workers together to put the finishing touches to everything, for equipment to arrive (or be made), ...

I can only assume there to be a guild of magical contractors who can upgrade your stronghold instantly but charge a massive fee.

Fabricate (especially with the rare version that also gives you a tool proficiency) - or a new version that turns it into a ritual could really speed things up.
As could "Wall of Stone" if positioned by someone who knows what to do. Although this might be a bit risky if the Narrator allows a "permanent" Wall of Stone to still be magical and therefore vulnerable to Dispel Magic. (Maybe some Spellcraft to get rid of that could be helpful)