We have a serious problem recently. We bought a three year old two story house in August. The home inspector didn't notice anything wrong. In autumn we had huge leaks, which damaged our floor. So we asked insurance to help. They paid for the inside wall and floor damage, but they said: if the leak repeats, they won't pay. So, we didn't hurry to fix inside walls, we calked outside horisontal board, which appeared to hide a seam - without flashing. We already thought to complain about flashing absence, but found out that the siding was installed without weather resistive barrier, that is there was no plastic after the siding.

To summarize, our wall consists from outside: siding, insulation, plastic from inside, drywall. The question: is this a builder code violation and if yes what to do? The mold already began forming in the floor under our new parket... Please, help!

What kind of siding is on the house? If it is vinyl, or steel a tyvek like barrier is recommended. Also ,did it leak by windows ,doors etc? Kellyw

It looks like Hardi vertical siding. I am not familiar with the other types.
Leaks were after few hours from the heavy storms, under the top frame of all windows of the wall. After we calked in some time, it decreased, but still, the urge of the floor was wet.

This is the picture of the wall, which has leaking problem.

The siding is T111.

Anybody knows if there is the building requirement to install a weahter barrier behind the T111 siding?

I don't know building codes, but your local building building department does. I would call them. It seems to me to be very shabby construction not to have a layer of sheathing underneath any siding. I have been around long enough to see sheathing go from diagonal one bys to the black pitch coated fiber board to foam board to the OSB popular now. The popular Twick plastic only goes between the sheathing and siding to help reduce air infiltration.

I have to ask how the former owners managed not to have all the leaks.

If you are positive that there is no sheeting beneath the T-111. Siding,I would definitely say you have some legal recourse. I have been a carpenter for 33 years doing all phases of construction and have never heard of t-111 without sheeting and weather barrier of some sort. My 2 cents kellyw.

I called our Marion county person in charge for the building code. She said it is how it is supposed to be: T111, then insolation, then plastic, then drywall. So I can't do anything about that. The only problem left to discuss with the builder is that behind the belly board in the middle of the floors - they have a seam without flashing. That is all...

This is how the seam looks after we took part of the belly board off.

The caulked joint shown should be flashed , as the joint above it is.
Remove the T111 between these joints and flash the horizontal joint . Replace the T111with new material.
The windows do not appear to be flashed .
T111 has a very limited effective life span.
The house should be resided for long term satisfaction