I am attempting to reproduce a amooth, but not flat, plaster over stone
appearance as the exterior finish of my home. I am considering using
mortar rather than stucco due to the cracking commonly found in a smooth
stucco finish. I intend to paint the mortar with a rubberized exterior
finish to minimize water absorption. Is this a practical way to get the
finish I am looking for? If so, what would the recommended mix of the
mortar be and can you recommend a paint? Any information that can be
provided on this process will be helpful.
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So what makes you think that a large area of smooth mortar won't also crack?
There are ads on the radio here all the time about some 'new miracle paint' that dries to the thickness of a credit card, never needs repainting, come in 1000 different colors, etc. Maybe you can find an ad for it in the sports section of your local paper...you know "Wanted...25 homes that need to be repainted".
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
What is the substrate you are working over?
Good stucco doesn't crack. Maybe a hairline every 10 or 15 feet here and there, but nothing that would ever admit water, and certainly nothing you'd notice from across the sidewalk. Finding someone who can get you good stucco might be another story.
What about a synthetic stucco? That should never crack at all, and should last a long time.
DRC
You're right...synthetic stucco....eifs...very popular in No Carolina...all the lawyers know it well.
Properly done, it would provide a smooth finish and would be crack resistant. But it's usually installed over a fairly smooth surface like foam board. How would it work over stone?
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
Ed,
I'm not referring to EIFS -- I wouldn't recommend that to anyone. I've built with it, done properly there is nothing wrong with it, but as you know, it isn't always done properly.
There are other ways to use synthetics besides over foam. I'll check for some web sites. What I'm thinking of for a start is STO, like maybe their Flexyl. It was originaly developed as a foundation parging, as it turns out, it's a nearly bomb-proof coating for parapets, too. I don't think you could crack this stuff unless you went at it with a hammer and bad intent.
Seems like that or something like it might work for this guy, no?
DRC
Here's a start;
http://www.stocorp.com/allweb.nsf/stopowerwallsystem
Also;
http://www.stocorp.com/allweb.nsf/prodselectbyname#24
Sto Flexyl - 235
Sto Flexyl is an acrylic-based, fiber reinforced, flexible waterproofer. When combined with Portland cement, Sto Flexyl provides multiple functions, including; waterproof adhesive and base coat in Sto Insulated Wall Claddings, crack repair material as well as a foundation waterproofer.
Material Safety Data Sheet
Product Bulletin
I couldn't tell from the original post if he was actually going over stone or just trying to get the look. That would be worth knowing.
Either way, there are some very good products out there.
DRC
[edited to add Flexl link]
Edited 5/4/2004 1:04 am ET by Dave Crosby
The substrate is plywood, glued and generously nailed, with 30lb felt, and dimpled galvanized stucco lathe.
My local stucco supplier tells me that cntractors will not do a smooth finish because it gets a spider web crazing in wet/humid weather.
What part of the country are you in?
By "smooth" are we talking about a fairly flat sponge-float finish? If so, it's done all the time, no reason why not, especially if you are finishing with an elastomeric.
The 30# felt is not bad, but you'd get a better job with a double layer of Grade D building paper. The two layers of paper give you a definite shear plane behind the lathe.
By "dimpled" do you mean expanded metal lathe? Typically that is used around doors and windows, but I don't think it works so well in the field. You're better off with self-furring lathe, looks a lot like really heavy chicken wire.
DRC
Dave I live in south east Pa.and when I say "smooth" I mean like the plaster in your house smooth.I've always believed that smoother and/or glossier would be more water resistant.
I have been in carpentry for 19 years but I haven't really worked with stucco.The only elastomeric product I am familiar with is dryvit,which,to me,is messy and expensive.
The outside of the house is being done in pieces,making it difficult to simply stucco.Haven't you ever seen the old farm houses with the white-washed plaster finish.
I recently read about the double layer of felte right after I completed my wire. The dimpled lathe is an expanded metal lathe that is self- furring. Isn't chicken wire twisted hexagons?
Eric
P.S. enjoyed your article on rotary hammers. I keep a star drill in my hammer drill case, just in case.
Eric,
OK, now I understand. The advice you received is correct. What is sometimes called a "hard-trowelled" finish, also known as "burning" the stucco (maybe as misunderstanding of "burnished")-- that is to say the smoothest possible troweled finish -- is a very, very difficult finish. I doubt if anyone would guarantee it.
The good news is it isn't needed. Properly mixed and applied stucco is already pretty waterproof. Typically the only leaks you get are at discontinuities, like windows, doors, vents, parapets. These can be addressed effectively with flashing.
Using ordinary methods, a skilled plasterer can get you a wall that is smooth, visually pleasing, and water-tight. If you want to go the extra mile, a little Anti-Hydro won't hurt, and I have had excellent results from acrylic fortifiers.
I agree, Dryvit can be a mess. But there is no reason why you can't get what you want with regular old stucco.
If you have already put the expanded metal lathe on, that's OK, just make sure you use clean ASTM plaster sand. It's only a couple bucks more a ton, and worth every penny. If you use fresh cement, clean sand, mix it a tad bit to the wet side, and force it through the lathe, you can get a good job.
Thanks for the good words on the rotary hammer article. Now I know of two guys who still carry a star drill. <G>
DRC
To "burn" the stucco may not be necessary, but it is the finish that I am looking for.
No one seems to want to answer the question of mortar and paint versus stucco. What did all the masons use before modern stucco, and wouldn't it work better now with expanded lathe and latex additives? The base coat is a modified mortar, why not the finish?
I finish sheet rock quite well and I was hoping to do this myself.
-Eric
Eric,
OK, I'm understanding more about your question as we proceed.
First, yes, you can certainly do this yourself. No reason why not. All it takes is a strong understanding of the basics and a little practice.
Before stucco, lime mortar was the order of the day. There is a reason why we use stucco now, trust me. <G>
Painting masonry is not the best way to go, in my opinion. I've never seen it hold up well over the long haul, and it's really tough to repair.
An acrylic fortified stucco base coat with any good color coat should give you many years of service. If you can finish drywall, you can apply stucco.
Get the lathe detais right, get the moisture control details right, keep your mix consistent, and have at it. Experiment with different floats, you'll get the texture you want.
DRC
The finish that comes close to what you want is the white plaster in swimming pools. They keep it from checking and cracking buy immediately filling it up with water.
FWIW, the glass-smooth finish you seek/sought is known on the left coast as a "Santa Barbara" finish, for reasons unknown to me. It is considered the highest difficulty stucco finish, and only the very best plasterers will even take it on to do. And that is here, where stucco is commonplace (every man and his dog live in a stucco house.) I grew up in the Keystone State, and I would think you are in search of a rare breed in those parts, where true hard stucco is uncommon. Good luck in your quest.
Bugle
Maybe a hairline every 10 or 15 feet here and there
And a judicious use of cut control joints will cure (or isolate) even that.Occupational hazard of my occupation not being around (sorry Bubba)
Yes, good advice. Eric take note.
You can also get a manufactured piece of metal that installs with the lathe that will do the same thing. Less mess, easier, and you can color-caulk it with a urethane caulk. With a little care, the joints can become part of the design, especially if the wall is chopped up with corners, doors, windows, or dissimilar finishes.
DRC