A very rough rule of thumb is adding up all the cracks in the wall, and if
they're over 1/4" total, then you have significant settlement. Within this
rule the engineer has given a plausible description.

Vertical & diagonal are usually safer than horizontal cracks; the latter
could indicate a possible wall failure & collapse.

Did the builder perform soil testing on various points of the site,
especially if that neighbourhood is prone to unstable soil conditions.
What is the experience of other owners in that area?

Are the footings adequate for that soil?
Is there adequate rebar in both footings & foundation?

If so, how did the 1/8" crack happen so soon?
I've never heard of 1/8" differential settlement crack being an accepted
part of a "design". Whose design is he referring to? (Mangle-Wood
Construction?) Adequate perfomance on an older structure, yes, but I'd like
to see the passage in an engineering text that says it's normal for a new
foundation. While I haven't been around a lot of recently-constructed
foundations, it seems a little odd to me.

Was the foundation backfilled too soon, with heavy equipment mechanically
damaging the foundation before it cured?

Expansive soil can add typically 10% more pressure than non-expansive soil.
This may have buckled the footing & foundations slightly before they cured.
Is it very wet there, or did it rain much? A high water-table can increase
hydrostatic pressure also.


Good luck with it.


Peter Shepherd
63 Pauline Ave
Toronto


"Zhixin Tang" wrote in message
m...
I'd like to thank all of you who responded. Here are some new
information:

The engineer hired by the builder had a visual inspection. He thinks
it is differential foundation settling that caused the crack. The
differential setting is estimated to be 1/8" and he said this kind of
difference is covered by the design and is normal(?). He said because
of elastic nature of soil initial load caused the crack and the crack
should diminish over time with the current load. When the load changes
(e.g. furniture, snow) it is expected that the crack should be
proportional to load. The foundation is structural sound to support
vertical weight

What are your opinions?