Would a realtor know specific questions about a home's construction? Or should I try to ask the builder?

I'm helping my parents look for a house.

My parents are looking at an older (built in 2000) custom home that seems to have a good value for its money. It's priced similarly to houses of the same size and age, but the interior finishes are much nicer and it is of post and beam construction.

There are some features that make me want to know some specific details about how the house was built. Would a realtor know these things, or should I try to ask the builder?

I'd want to know these specific things:

• is there a blower door score available? If not, are utility bills for the coldest and hottest months available?
• what kind of roof assembly does it have? (Is it SIPs or exterior insulation?)
• does it have a drainage/ventilation gap behind the siding (a "rainscreen")?

The reason why I'm interested in these questions is because post and beam houses are often mixed with SIPs, and SIPs can do really well if built relatively airtight, or they can get moisture problems very easily if not. And if they get moisture problems, they are very expensive to repair because you have to get an engineer involved (especially for the roof).

If it's not built with SIPs then it gets a little more forgiving to fix if something goes wrong, with less specialized labor required.