In article ,
"mr smith" wrote:

house with both vinyl siding and brick (real bricks) exterior.

wash the exterior with a hot water/low pressure power wash.

opinions regarding the long term implications of using
pressurized water streams to clean vinyl siding.

It is LOW pressure, as you said above, or high?

Low pressure shouldn't hurt anything, although one should avoid
directing the spray in such a manner that it might get behind the vinyl
siding.

Do not count on the water to do all the cleaning, especially if it is
applied at LOW pressure, regardless of any detergent. To get the siding
truly clean, a modestly stiff bristle brush should also be used.

also my concern was how fragile is brick to
hot water/low pressure/mild cleaning fluid -
spray streams ?

This is the most critical area. It is the mortar joints that could be
most seriously damaged by such cleaning. Low pressure is obvious given
that high pressure could dislodge weakened mortar. Then you are looking
at tuck-point repairs sooner rather than later. Big bux.

Just how dirty IS the brick? If it were MY brick (I wish), I would
probably avoid using a pressure washer of any kind.

Simply wetting the brick with a garden hose, then scrubbing it gently
with a brush should do all the cleaning necessary. I wouldn't even use
detergent. Again, it's the mortar that should be given the most care.

Remember: One can spot dirty vinyl from the street but has to do a
CLOSE inspection of all but the lightest brick to see dirt.

but you can't tell hidden moisture/mold damage
when it's covered behind siding

You said it. I once attached a box to the side of a vinyl-sided, old
farm house. Water leaked OUT of the holes immediately after I drilled
through the vinyl. One can only imagine the condition of the old, wood
siding underneath.

(or between a brick exterior and a Tyvek covered plywood panel).

That the brick is over Tyvek covered plywood reveals a NEW(er) brick
installation. One could assume that it would drain and/or ventilate
properly, but I wouldn't take the chance that I might cause damage using
a power washer. I'd take it REALLY easy on the brick. Good luck!
--

JR