The north wall of my house (new construction) is out of sight and mostly out of the bad weather (in our area, Seattle, wind blows prevalently from the south). We are getting real stucco all around, but have considered different alternatives for the north side (trying to save some money). Given we don’t like using hardiplanks or similar siding, the only alternative currently on the table is to use a slightly thinner coat on that wall.
The exterior walls are plywood, with 2 layers of 60 minute paper, chicken wire (and necessary metal lath reinforcement). The stucco installer suggests using a slightly thinner coat both for the scratch and brown coat, then finish it as the other walls. The resulting thickness is 1/2″ instead of 3/4″ as everywhere else. Saving is roughly 20% for that wall.
Looking on the internet, I found references to stucco system thicknesses of 1/2″ to 3/4″ (for plywood sheathing), so it seems to be within the stucco parameters.
Am I looking for trouble? Do you have any first hand experience of how a 1/2″ coat performs?
The other alternative is something like this (http://www.multicoat.com/mts-is.htm), but it seems too close to EIFS
Thanks in advance, Rob
Replies
how thick is your plywood? 1/2 or 3/4? what is the stud spacing? 16 or 24?
it's 1/2" plywood on 16" spacing (2x6 studs). In most places (windows, bump outs, etc, it's much less than 16" on average. According to the engineer, stucco has no structural function (we didn't decide on the siding system until after the engineer ran the numbers, so shearwalls have been designed with only the framing elements and the plywood sheathing)
we use only 1/2" here in PA for side walls.
no problems.
make sure you create a drainage plane to allow water to escape at the bottom of the stucco.
carpenter in transition
Thanks for the good news :-)
My stucco installer says that the 2 layers of paper will shrink and detach, creating a drainage plane. At the bottom of every wall he's using metal lath (L shaped) with holes on the bottom to allow water to escape. He said that he's never had a problem with drainage using the 2 layers of 60 minute paper. Would you consider that enough of a drainage plane, or would you add something else (somebody in the past suggested thin vertical cedar strips, but my installer seems to think it would cause more problems with getting the stucco to properly attach to the walls)
i don't know what 60 minute felt is. we use 30lb felt, and i would bet that there is a 60lb, but 60 minute ??
i would feel comfortable with this. the cedar rippings would be nice also, but would be a lot of extra labor.
but my installer seems to think it would cause more problems with getting the stucco to properly attach to the walls
normally, i wouldn't agree with this, but when i saw that he puts most of his fasteners in the plywood, not the studs, then i understood. personally, i think nailing the lath into framing members is important. i would expect that the lath would be fastened every 4"-6" into the framing members and approximately the same in the field.
carpenter in transition
the slight added flex in 1/2 plywood will tend to cause more hairline cracks than you will see in 3/4 inch plywood. Not a problem with the thicker stucco but an area of concern with the thinner stucco. Does that mean it will fail? No! Please, I didn't say that! It means that when you pay less and get less there is less safety margin to cover mistakes.. I don't know of anyone who can consistantly make their stucco exactly a 1/2 inch thick. if you should get some on the thin side, say 3/8ths and that should get a real big blast of wind hitting it could you have a pop out? I honestly don't know. I know that workmanship and other details will cause more failures than how thick the stucco or even the plywood is.
Nailholding can be an issue with 1/2 plywood over 3/4 inch. the nail holding I'm refering to is the nails used to hold the screen on.. In a perfect world the guys will always hit the studswith their nails, but if the studs are hidden under the tarpaper/ building wrap, that's pretty hard to do..
I guess what I'm saying is you always cut corners at your own risk.. Now maybe you need to save some or you can't afford to build the house, maybe you have other priorities for your funds.
I refuse to make a judgement about that.
Don't get me wrong: I know I'm cutting corners, and I'm prepared to see minor problems. The north side of the house is hidden from view, and relatively protected from any weather (wind or rain), due to the location and how close it is to another house. And, yes, it's about hitting a budget after having had quite a few overruns, without resorting to hardiplank on the north wall (probably functionally good, but estetically very unpleasant)
As for your comment on nails, I noticed that my installer is using a lot of thick staples instead of nails to hold the 17 gauge chicken wire (roughly 20-30 staples per sqft). The staples are driven by a pneumatic staple gun, all the way in. Most of the staples are in the plywood, not the studs (due to the density of the stapling and th eimpossibility to find studs with the tarpaper, as you say)
Based on what I found on the dryvit website (traditional stucco, not EIFS):
Fasteners: 15/16” wide crown staples; 1-1/4” on studs, 5/8” in field
it seems to be standard installation
Lookin' fer trouble again, are ya?
I ran the numbers on your savings at the outrageous cost of $200/yard for stucco mix.
Mind you there is either no labor savings or there is a labor upgrade ($$$.)
For a 30' long 10' tall wall, you would save the meager sum of $55.00. That's only 7.5 cu ft saved.
That's a lot of hassle for little savings. Get the unconveeentional technique past the inspector, gotta disclose to any prospective buyers, gotta find or convince the mason, etc.
Don't do it.
SamT
Edited 3/22/2005 7:57 pm ET by SamT
Well, I'm basing my numbers on what the installer is telling me: $6.50 a sqft versus $8 a sqft. Over 2,000 sqft, it's a 3,000$. Granted, it's only ~20% savings on just one side, so in the big picture it's not that significant. But it's 3,000$ that can be used on something else (and that wall is the biggest/most expensive part of the house, due to the property layout and grade). yes, in percent it's trivial, but if I can save 3,000 10 times over, in the end it's significant (alas, more commonly, I seem to add 3,000$ here and there, many times)
I'm not sure how the installer figured out his cost, but that's what it's going to cost me...
Intuitively, it's not just about the material savings... the labor to move and apply less material (haul up all those lbs of stucco mix) has to figure out somehow. Paper, chicken wire, stress joints and metal lath around windows is the same, obviously.
I asked the inspector, and 1/2" meets code. No need for disclosure, as it's still traditional stucco (yeah, well, I'll probably mention it to the buyer, but it's not a requirement), and the mason is the one who suggested it originally: he's actually done a lot of tract homes with 1/2" everywhere, and still provides the same warranty (I have the impression that he's happier to do 1/2" at $6.50 than 3/4" at $8, for whatever reason)
So, as far as I'm concerned, the savings are real (I would not do it for 55$ :-). The only reason not to do it, would be if I had to spend more in the future to fix problems. Given it's the least exposed wall, minor cracks would be easy to conceal and deal with, and water problems are not as likely to develop
I'm not looking for trouble, just trying to understand the tradeoffs (as everything else in life, nothing is free, but once the tradeoffs are understood, some solution might be perfectly acceptable)
In another post people asked about the "60 minutes" paper... that's what I saw when looked at it (60 minutes, 10 years warranty). Here's the paper they are using http://www.fortifiber.com/FBSG/pdf/data_sheets/super_jumbo_tex_60.pdf. What do you think?
Thanks, Rob
Rob,
See. That's the difference between asking the man on site and asking the REMFs back in Washington. WE get to make up our own numbers that have nothing to do with the reality of the situation.
If i was a kid, I'ld just say "Made you look."
It now sounds like you've covered all the bases and don't have any reasons not to use 1/2".
'Course I was talking a 10' wall 30' long. You have a 20' wall 100' long.
Biiiig house.
SamT
Been following your thread - seems to me you should consider the "one coat" system. The following excerpt is from the Exterior Design Institute
The One Coat Stucco System can be applied over virtually any type of wall construction, new or retrofit. The One Coat Stucco System can be applied as follows:
2-coat application for a total of 3/8" thick base coat and a finish coat applied over a vapor barrier and minimum 20 ga stucco netting or expanded metal lath attached over solid backing. (i.e.: foam board, plywood, exterior gypsum sheathing, fiberboard.)
OR
3-coat application consisting of 3/8" scratch coat, 3/8" base coat and a finish coat applied over a vapor barrier and expanded metal lath attached to framing.
NOTE: 3-coat method may be applied directly to open framing. However, stucco cracking is better controlled when sheathing such as foam board, plywood, exterior gypsum sheathing or fiberboard is applied to the framing members and stucco to buffer the expansion, contraction and warpage that occurs in wood or steel framing.
Expansion joints in the One Coat Stucco System provide expansion relief through the substrate. Control joints provide expansion relief in the coating only.
Expansion joints are required: At structural expansion joints. At the abutment of dissimilar materials.
Control joints are required:
At corners of doors, windows, or any wall openings.
At floor lines in the frame construction. In frame construction to create panels no larger that 144 square feet. Maximum distance between joints not to exceed 12' in any direction. Length to width ratio not to exceed 2-1/2 to 1.Where aesthetic reveals are desired in coating, pre-formed trim or accessories may be used. Where architectural moldings, copings, or popouts are desired, foam shapes with Stuc-o-lite coatings may be used.
When using wood sheathings:
Provide minimum 1/8" gap between sheets to allow for swelling of sheathing.
Avoid sheathing joints at floor lines in multi-story construction.When the One Coat Stucco System is applied to horizontal areas where standing water might occur, a minimum 6" on 12" slope is required.
Sealing of cementitious finishes prior to painting or finish application is recommended to prevent efflorescence.
Sealant and foam backer rod for all details must be compatible with the One Coat Stucco System. Consult system manufacturer for information concerning applications and approved sealants.
SamT: yes, you made me look :-) that's what I love of this board: people with real experience not afraid to calling a spade a spade. Usually if an idea doesn't get hopelessly shot down here, it works beautifully. A grudgingly "might work" here, means more than a "I can guarantee it will last you a lifetime" somewhere else, given the levelof hard-core scrutiny. (REMFs? ... [googling]... got it now. Vietnam-era slang. Funny). And, yes, on that side the house is 3 stories, so the square footage goes up (still a very big house, no questions there :-)
John: thanks for the pointer. I think, though, I'll go with what my stucco sub suggests. One thing I learned building my house, is that I can (and should) ask all the questions and try to understand the tradeoffs but, in the end, go with what the person installing it feel more comfortable with. They are the ones with the experience, and they are the ones that need to do the work and provide warranty. A "good enough" solution, properly installed, it's much better than the perfect one installed poorly (due to lack of experience). I have a really good general contractor, and he has a pool of really good subs, so I'm usually well served by following their suggestions (but asking a ton of questions served me well, especially thanks to this board)
Thanks so much. 1/2" it will be (I should probably use part of the savings to offer you guys a drink... well, if you ever are in Seattle, let me know: drinks will be on me :-)
Being in Seattle, you probably have some earthquake considerations. IMHO, 1/2" is a better seismic choice. The plywood sheathing gives you your shear strength. The felt keeps the water out. The stucco just makes it look nice and gives the felt some protection. Other than that, it's just dead weight. The less dead weight, the better, for earthquakes.
-- J.S.