On Wed, 21 Oct 2015 13:01:53 -0400, Micky
wrote:

On Wed, 21 Oct 2015 05:44:56 -0700 (PDT), Compromise
wrote:

On Wednesday, 21 October 2015 08:38:17 UTC-4, TimR wrote:
On Wednesday, October 21, 2015 at 12:13:04 AM UTC-4, HerHusband wrote:

A roof truss is usually designed to be supported only by the two outside
walls, and the interior walls are just partitions that don't support any of
the structure above.

However, before you tear it out, you may want to investigate a bit more.

Climb up into the attic and see if there are any posts, walls, or other
structures that might rest on the wall below. If so, the wall may be
holding up that load, even if the trusses support the roof itself.

What would the purpose of the crawl space piers be, if that is not a load bearing wall? Just support of the floor? I'd be cautious here.

It is also is not certain that he actually has a truss. That's a technical term and he may or may not be interpreting what he sees in the attic correctly.

Hi Tim,

I have a house inspection report that says truss. From all I've read I think they call it a double cantilever. I am concerned about those piers in the crawl space as well. Will check it out further. P.S. He is a she

I don't know if it matters to the basic question of your posts, but
why do you think it is a cantilever, and why double? You may have a
good reason, so I'm interested.

But, cantilever does not refer to the geometric pattern of the pieces
of the truss, but to how the whole thing is supported. "A cantilever
bridge is a bridge built using cantilevers, structures that project
horizontally into space, supported on only one end." In practice,
there are usually two pieces to such a bridge that meet above the
middle of a river.

But the trusses supporting a roof, like the ones I have, are supported
at each end. If the truss were cut half way across, there is no way
its attachment at just one wall could support even that one half.

Contrast that with https://en.wikipedia.org/wiki/Cantilever_bridge

Dictionary.com for cantilever

1. any rigid structural member projecting from a vertical support,
especially one in which the projection is great in relation to the
depth, so that the upper part is in tension and the lower part in
compression.
2. Building Trades, Civil Engineering. any rigid construction
extending horizontally well beyond its vertical support, used as a
structural element of a bridge (cantilever bridge) building
foundation, etc.
3. Aeronautics. a form of wing construction in which no external
bracing is used.
4. Architecture. a bracket for supporting a balcony, cornice, etc.

In a roof truss, the upper part is in compression and the lower part
is in tension, the opposite.

Well, you could, I suppose, use roof trusses like two awnings, facing
opposite directions from where they are supported in the middle.
Possibly for a fairground pavilion, so from the side the building
looked sort of like a tree. with no outside walls, just something in
the midline, maybe 3 or 4 feet wide to hold up the middle of the
trusses.

Then the upper part would be in tension and the lower part in
compression. I've never seen this, and it's conceivable the metal
plates, with nail equivalents, wouldn't work so well when the tension
was in the opposite direction (though I think they are symmetric, in
result, even though the "nails" are possibly bent only from one
direction. I haven't paid enough attention.).

But if it did work, in that case they would be balanced cantilevers,
sort of like a teeter-totter that doesn't teeter.

But I suspect your trusses are supported at the ends and not in the
middle.

OTOH, I don't accept there speculative etymology. I think the origin
of the word may be counter lever. The weight at or on the other side
of the support provides leverage to hold up the unsupported end.