New House sagging floors 1

[tonydutt]

First time poster...
I am a mechanical PE, but, need some structural advice for my house...

4 year old, 2-story house with a crawl space in eastern VA. Crawl is dry, tested girders and joists for moisture, no issues.

House is supported with concrete block piers. Girders are 6x6 treated lumber (not sure exactly which type of pine) and joists are 2X12 regular untreated pine.

My issue is on the first floor tile is cracking, wood floors are wavy, and drywall on a load bearing wall has cracked. second floor has several areas (above the load bearing wall from 1st floor) where drywall is cracking.

From my inspection of the crawl (random sample of 3 areas) the joists which are above the pier are high and the joists not above a pier are low (not all). So, I put a level on the girders in between the piers (on the bottom obviously) - totally level.

So, what I think I need is to do is to support the joists somehow. I have found a bunch of solutions including jack systems - which seem easy to install given the correct footing. But, then I read some posts here which discuss metal straps and whole bunch of other ideas, including sistering joists.
I could use some thoughts and ideas on possible solutions, possible downfalls, and things to avoid so I don't get taken when I get an estimate later this week.
I want to be econmical, too. The jacking system seems to be the best, but, probably the most expensive.

All the best, Tony

 

[Stillerz]

What does sitting for the PE have to do with anything here?

Small drywall cracks are perfectly normal in new construction as the building materials dry out or acclimate to the humidity in the house. Usually a one-time fix.

The tile cracking could just as well be a shoddy job.
In the 12 years or so that I was building homes, the way tile was laid changed five times or more. It seems like once a year a new material comes out and people start to think that this new way is the only way to go.
I have tiled many floors and I have never been called back for cracking tile. From my experience the most important thing to mitigating floor cracks is to be sure that all plies of the floor are fastened tightly together (sub floor, backer board and any membrane).
I, for one, always use(d) a modified thinset mortar that has a latex additive for adhesion and flexibilty to adhere the tiles and also to adhere the backer-board (whatever kind it may be) to the sub floor.

I have seen many hardwood floors that were wavy even in new construction. Hardwoods absolutely need to acclimate to the house before being installed. They will absolutely expand. If they expand and have no room to grow from being installed improperly, you'll have a wavy bumpy floor from the wood buckling ever so slightly.

Your problems may well be from poor finish work.
I would at least investigate the broken tiles by pulling a few up and looking to see how the tile and substrates were installed.