Eifs is fine when installed properly, it's just that there have been a lot of cases where it hasn't been installed proper.  If this was a HUD house, that's kind of where the problems started and I would be leery about buying it.

If it has been there 30  years, any bad spots should be fairly obviously bad.  Look around windows especially.  The bottom 2 corners are most likely to be wrong.  If it look like someone added trim under a window to hide something, pop the trim off.  Next would be if eifs touches the ground.  I don't think it's supposed to do that.  Poke stuff.  If it crumbles or caves in, that means they painted over a problem.

I would NEVER buy a house sheathed in EIFS. Every single one I have seen has been riddled with rotten framing and black mold. It's not an "install" problem, it is fundamental to the design of the product. The exterior insulation creates a dew point at the face of the framing and traps condensation in the wall cavity. This is a national problem and there have been large class action suits across the country going back a dozen years and more.

Later EIFS systems - after numerous class action lawsuits - added a drainage channel to the back of the board to let condensation out (but they adamantly deny that any problems with trapped condensation were the reason for the design change). Even if this fix works, I don't trust it. Too easy for the drainage channels to get plugged up with sawdust, dirt, bugs, etc.

There's really no way to tell if the install is bad until you find a failure. You could yank some outlets and poke around in the cavity, a lot of the problems are in the framing and sheathing near the plate. White mold is a sign of water infiltration, black mold is really bad.

If the floor framing is accessible from a basement or crawl you can look for telltale signs around the box joist and floor sheathing. You could also take an awl and punch a small hole in the EIFS here and there, you should find solid sheathing 2" back. If not ... it's probably rotted away. An awl is a great way to directly check the framing, too.

Dew point / condensation management is always important, but with the original face-sealed EIFS systems, rain / melting snow entry into the wall plus no means of water management  -- and usually no dry-out capability  -- was the main cause of failure.   

I dislike EIFS, but it can be installed correctly, and when it is, it is extremely energy efficient.  If you don't like the channel variety or 3D grid provided by the various manufacturers, plastic spacers are available -- you could even use thin plastic furring....... so, when well executed, EIFS is essentially just another rainscreen.

OP -- many variables in the house scenario you're describing, and IMHO it doesn't sound like you have the necessary experience to advise your friend.  

The Dew point thing is a biggy.  In dry climates though, it isn't as much of an issue because the air just doesn't hold too much moisture.  One thing to look at is take the plate off an outlet.  A vapor barrier on the interior face should be there, and if done correctly, it will be taped and sealed around that junction box.  That helps keep that warm moist air from the interior out of the wall cavity and creating a condensation issue.  It is extremely rare the vapor barrier was installed correctly.

The way to sort of tell if there is a moisture issue.  It is a barrier system.  So look at the base of the system which should be 4" above the grade minimum.  If moisture is in the system, you'll see streaking down the face of the foundation that appears to come from behind the insulation panels.  Looks like efflorescence.  If it has a brownish or blackish color, that's probably the rot of the sheathing as that wood is broken down.

A good way to get a feel for the quality of the install is also at the base of the system.  It is supposed to be backwrapped.  That means at the bottom of the panel, the EIFS will wrap the whole edge.  If you find exposed EPS anywhere, the installer was lazy.  Assume he wasn't any better anywhere else   You should also be seeing proper flashing at all edges as well as proper gaps (3/8" typically against dissimilar materials like windows, trim, banding, etc.).

When push comes to shove, rent a bore scope and observe the interior of the wall cavity, typically near the sill plate below window groupings if there are flashing issues, and general molds on the face of sheathing for condensation/dew point issues.

There are good systems.  But also have her look at the insurance.... damage from this defect is becoming a fairly standard exclusion and you need an additional policy.  That increases the cost.

"A vapor barrier on the interior face should be there, and if done correctly, it will be taped and sealed around that junction box."

 Well, maybe.  Depends what type(s) of barriers were installed on the exterior side -- it's quite to easy create a wall with barriers on both sides that will not allow a wet wall to dry inward or outward.   

Exactly. EIFS is a vapor barrier.

If it was built with EIFS in the 80s, it probably doesn't have a drain mat behind the insulation. Personally, I wouldn't touch it.

However, if they can find out who the original installer of the EIFS was, check to see if they're still in business. If they are, it probably means they did a good job installing the product to spec, in which case the risks are much lower.

Thank you so much for the responses, everyone.  I believe this building is a good candidate for having had a very high quality installation...high quality for the time, of course. I think I'll have the opportunity to see it myself this weekend and will rely on all of your commentary as I do.

EIFS is a vapor barrier... true.  Depends on location though where you want it.  Vapor barriers go on the 'warm side'.  Cooler climate here, so they are always on the interior.  The outside face is pointless because you'll just have the warm, often moist air from humidifiers, hitting a cold surface on the back of the system and within the cavity.  I'd imagine the situation is reversed in someplace hot and muggy all the time.

you should post pics donna!  we could tag-team a punch list

i'm in a temperate climate, so the vapor barrier has to be on the outside half the year, and inside the other half, except for the 6 days a year when it's nice enough to turn off the climate control.  sometimes it seems vapor barriers do more harm than good.  i would prefer to see a vented cavity, so moisture can evaporate the way god and nature intended.  the 'seal you building so you don't air condition the outside' folks get mad at that though.

Mightyaa -- I'm not actually arguing vapor barrier theory, but rather pointing out the potential problems stemming from rule of thumb vapor barrier placement.  If, on a 1980's face-sealed EIFS system a vapor barrier is present on the interior side, as your post called for, how would the wall dry out?  Water always gets in, so it needs to be able to dry one direction or the other. 

In a really tight system, the only moisture is the moisture within the air alone.  Assuming it isn't seriously wet air, the condensation looks more like fog on the glass where it never really gets thick enough that it can bead and roll down.  As the temperature rises again, it evaporates back into the air in there until the next time.  Just like if you breathe onto a cold glass pane... it evaporates back into the air.

Biological growth needs food and water.  So that water has to be there long enough to allow for that growth. 

Worst case scenario is a good vapor barrier AND a barrier system with leaks.  You introduce water into the system.  So it can evaporate to a point into that microclimate, gets back to the top of the assembly, condensates bad enough that it beads, then rolls back down to the puddle below in a never ending cycle keeping everything saturated. 

No system is also perfectly tight.  For instance at the headplate there usually isn't a vapor barrier.  Attic or rafters require ventilation.  So while it's slow, the humidity levels will stabilize with the outside conditions.

And then there's all the things you can't control.  Cooking, cleaning, washing, number of occupants, etc that add humidity.  Here folks install humidifiers.  We also like swamp coolers (evaporative cooling).  So you really can't ever say what the humidity level will be in the interior because it also changes regardless of what's going on outside. 

Vented cavities let unconditioned air into the structure. Really tight systems are unhealthy, and dependence on mechanical air changes is unreliable. Framing does not require exterior ventilation. There is so much moisture in framing materials these days that it can take far longer than the duration of construction for them to dry out. Not every building needs to be built like it's at the South Pole.

/rant off

"In a really tight system, the only moisture is the moisture within the air alone."

Wow.  With the original EIFS system we're discussing?  Don't think so.

You may want to check out the raft of documented historical failures common with the original face sealed EIFS system, which was caulk reliant.  Caulk joints failed at every joint and opening, as they always do.  Rain water and snow melt essentially poured into the system with nowhere to go.  Water migrated around.  And, with the typical rule-of -thumb vapor barriers placed on the inside, coupled with the inherently tight face-selaed original EIFS system on the exterior -- said water stayed in the wall for a very long time.  Walls rotted. 

That's why I put in "in a really tight system"...  The vast majority of problems I see are exactly what you talk about; At the interfaces with other materials.  That I hate to tell you isn't a specific EIFS problem.  Why it's worse in a EIFS system is because it is a barrier system and all that new water in there can't get out.   Put a polymer coating on a stucco and you'll have the same issue....  btw; many manufacturers still required building papers behind their systems (or exterior gypsums which were also rated to be wrb's back then).  Glue had to be trowelled on vertically too; not horizontally.  I did a ton of litigation support on this stuff....

I've seen this on a whole variety of exterior cladding systems.  Screw up the flashing, screw up the watershed, screw up the clearance to grade, screw up pretty much every intersection and you are also going to see lots and lots of mold if water is continually allowed to hit these surfaces.

I thought we were talking vapor barriers.  Are you sure you aren't talking 'weather resistive barriers' like felts or tyvek?  They are completely different things (and different perm ratings).  

EIFS did claim it was a vapor barrier too... but you can't combine them like that in most climates.  Condensation occurs when hot moist air hits a cold surface... so if your shell is also the vapor barrier, there's no buffer zone thus increasing your chances.  The vapor barrier is there to stop the hot moist air from reaching the cold surface.  You can't combine them usually and think it will work.

I actually have seen it in action.  Moldy interior drywall that looked like a shower curtain.  Inside the wall cavity was dry as a bone.  Why?  The vapor barrier behind the drywall.  The lack of a outside air requirement in residential.  And small low income units with lots of occupants, cooking, etc.  humidity levels inside would raise and condensation on the outside wall at the vapor barrier.  The drywall absorbed it... and rotted.