What is this?

[sidney alstad]

Beautiful 7000+ s.f. home today with stone facing at various area's, but what is this efflorescence like substance that was present?....a problem with the mortar? Stone appears to be natural, not cultured.

This can not be good for the wood shake roof.

I look forward to hearing from an experienced mason.

[mike huntzinger]

looks like salts leaching from the stone

[David Bell]

Looks like calcium on the stone, as for the roof, the lead coated copper flashing will cause the discoloring on the wood shake roof.

[John Kogel]

Looks like there are moisture issues around that window in the first pic. Moisture evaporating on the stone may be leaving that salt behind. It could be a sign of trouble.

Just a suggestion. "What is this white powder on stone veneer?" would be a better way to ask this question, maybe get better results.

[Ian Page]

Certainly a moisture issue. You can see further evidence of it staining the upper casement on the window. Being that it is in close proximity to the chimney/roof connection, I suspect faulty flashing allowing moisture to penetrate behind the brick veneer and leach out salts as it percolates down.

[Scott Patterson]

Could be that a soft limestone rock got into the mix and now it is leaching minerals. I would not try and diagnose the problem unless you really know what is going on. I would defer to a masonry expert who works with natural stone.

[H.G. Watson, Sr.]

Obviously there is a problem with moisture infiltration, trapped and drainage plane issues.Improper flashing at chimney/roof junction, faux keystone projections, overall drainage plane, window opening, etc.The faux stacked stone effiect of manufactured stone veneer is a common one. Unfortunately, many builders overlook key general building practice details such as a proper drainage plane behind veneer, use of gyp sheething, reliance on membrane "flashing", and applying "finned" window units, instead of properlly panning and flashing window openings, flashing and counterflashing projections to the roof line, and proper overhangs, dissimilar materials applied overtop the veneer without proper flashiing such as freize board below roof deck at gable end, etc.

I see no wicks, drainage, or lintels so I'm presuming "lick n stick" thin sliced or manufactured veneer on 2x6" frame or SIP construction.

Same issues you might find with poorly installed one or 2 coat stucco, with improper drainage plane, lath, etc. and even efis errors, you can find in poorly prepared and installed applied manufactured stone and faux stone veneer systems.

Not enough viewable in chopped first pic or single distant shot of second to be overly determinative. Unclear if lighter areas on shadow side of roofing materials under chimneys are chalked OR are merely lighter/less discolored from algae/weathering. Both zinc and copper flashing will deter the darkening algae collections on wood roofing, however galv roofing nails can quickly blacken and stain cedar and high tannin wood (reacts) creating a bleeding effect (SS doesn't have that effect). "blue green" algae collections on roofs create a black staining effect, darkening other areas, further contrasting areas sun-bleached - difficult to tell if lighter areas are indeed "chalked" or just brighter than areas darkened due to algae debris. The intersections between veneered chase projection and roofing at gabled end appear improperly flashed/counterflashed as does the long shot of chase to the right on second pic.

Streaking/bleeding on the moulding/trim above window also indicitive of moisture issues. No drip edge anywhere on face of this wall above window.

More on construction details rather than guessing, and better/more plentiful pictures with better detail might have been better.