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-   -   couple of q's on stucco exterior (http://www.diychatroom.com/f19/couple-qs-stucco-exterior-8347/)

joeyboy 05-09-2007 01:58 PM

couple of q's on stucco exterior
 
I have a concrete block home that I am about to cover in stucco (after removing the current vinyl). I'm going to use a powerwasher to prepare the blocks, and likely use a bonding agent before the first coat of stucco (still unsure on this, kind of depends how well I feel the blocks will accept stucco after they've been power washed).

Anyways, I'm planning to do 2 coats and wanted to know if I should be using the same stucco on both coats. If I should be using a different stucco mix for the base coat than the finish coat, what differences should I be looking for?

Any tips would be great, I've been reading up on stucco for weeks from books and the internet, and am about ready to dive into this, but wanted some recommendations on specific stucco products to use.

joeyboy 05-14-2007 11:26 AM

figured for the public knowledge's sake I figured I'd post what I've found.

I took my measurements for my siding needs, and went and purchased stucco based upon that, which was about 70 bags. Home depot rents a big pickup truck for $20/hr, so I rented that and did 2 runs with 35 bags each. I got 'amerimix' brand stucco. Now, I was planning to do 2 coats (since I'm applying directly to block, if I were applying to wood I'd be using lathe/paper backing first, then 3 layer application. But for my application I was going to do 2 coats (first at about 3/8", second at maybe 1/4") with the same stucco.

The problem I found was with coloring. I wanted to do a tan color, and because I wanted greater color endurance, I decided I'd go with the color powder additives (sakrete makes these, available at home depot as well. It's like $5/box, they come in a few colors). The problem I ran into was that my amerimix stucco was standard color - gray. So, of course, gray + tan powder won't make a light tan (I actually made a bunch of test batches, you can barely tell when there's tan added to gray. *but*, tan added to a white masonry powder, that works real well :)

So, with some extra white mortar I had laying around (from recently tiling a couple bedrooms in this house), I mixed in some of the colored powder. Even at half of the recommended powder level, the tan was very dramatic.

Lesson learned here is that I'm gonna now have to go back to home depot and buy another ~20 bags of WHITE stucco mix that will take this color pigment powder. The white stucco is more expensive, but the good part is that I plan on using the gray amerimix stucco as my thick scratch coat, and then for my thinner finish coat I'll use the white stucco with powder in it.

I like the idea of powder color added in not only for durability, as it won't flake off, but also because I believe it will be cheaper than painting subsequently, it will allow a finished exterior quicker (i'd have to wait for curing before painting the stucco if i were doing it that way), etc

The drawback to not using a paint for the stucco, is that now I'll have to color match paint to the stucco for accent use (I want to paint the cables, pipes, etc on the side of the house to match, but since the stucco's colored with pigment, I'll need to try and match up an exterior paint for use on these details).




I'm planning to begin this week, real soon (basically as soon as I get a power washer to strip the concrete blocks a bit before application). I will post back with pics once it's up and going, but if not, I'll def post pics once it's finished.

concretemasonry 05-14-2007 01:48 PM

Pigmenting any concrete product made in numerous small batches can be difficult if you want uniformity.

I assume the pigment is a synthetic iron oxide, which is a very strong color. Because of this, everything must be absolutely consistant.

Weigh your pigment and do not go by volume. If the pigment fluffs or bulks up, you will be off going by volume. - Weight is more accurate.

After you decide on the proportions, you can bag up all the pigment in plastic bags for each batch so you do not have to weigh when mixing.

Always do everything in the same ORDER and for the same length of TIME to insure uniformity. You may chose to dump the first batch since the mixer will be different than for the subsequent batches (commonly done in concrete products plants).

The one variable that is difficult is the amount of water used. This will effect the darkness/lightness of the stucco mix, but usually not the tint. Wet will be lighter.

Chose you pigment amount based on samples you made up a few days before actually starting. Not as critical with white cement as gray, but still a factor.

Tscarborough 05-14-2007 08:04 PM

Your finish coat will probably only take 50% of what your base coat requires. Your scratch coat over block should be 3/8-1/2" , while the final coat should only be a 1/4" (depending upon finish style).

Also, there are ferrous oxide dyes that will produce a light tan color from grey base, but they are not available from a box store. Note that you can not use a pigment formulated for grey and mix it with white. You will get a different color than you expect (you will get the color of the actual pigment, to be exact). Here is a photo of a dark gray mortar mix with a ferrous oxide pigment that both lightens and turns it tan. Combined with white base, this pigment would make neon orange stucco.

http://72.41.69.75/redonewallmatch.jpg

sflamedic 05-14-2007 10:25 PM

post pics and keep us updated...

joe3534 05-15-2007 06:28 PM

Stucco Questions
 
Hire "Big Joe Stucco" and save yourselves a headache!

joeyboy 05-15-2007 10:12 PM

:huh:

joeyboy 05-19-2007 11:04 AM

Quote:

Originally Posted by sflamedic (Post 45015)
post pics and keep us updated...

Will do! I always post tons of pics when doing new projects, like these I made a few days ago:
http://www.diychatroom.com/f50/any-creative-ideas-how-build-some-legs-bases-my-new-glass-table-7694/

This should be a good project, need to get a powerwasher here before I can start. Seeing that I couldn't find any reputable advice on the lowest sufficient PSI / GPM levels I would need to prep my house, I'm just gonna rent home depot's 3500psi model. They have so much stuff waiting for me there now that I'm gonna need to rent their truck, so monday is hte planned day to go get all that and start prepping the back of hte house (yup, starting out back. I learned that when I tiled the bedrooms, definitely shouldn't have started wiht my bedroom first lol)


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