How do I find out who built my house?

The fastest way is to search your county's property appraiser or building department website for the original building permits or Certificate of Occupancy.

Trempealeau County should have history of building permits that were pulled, and it should provide the answer. At a minimum it will tell you who pulled building, plumbing, electrical and HVAC permits

Tax records or assessor records will show that info. Get on Google, run your county and state "Blablah county, State assessor office". That's give you a list, then you can run your home by name or address and the list of transfer will be found.