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Install lap siding over existing stucco. OK?


luvtorekord
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Hello,

My wife and I are smack in the middle of a terribly long remodel / addition in Southern California. We are adding a second level to our single story home. We want to use siding vs. stucco.

The second level is all new so the lap siding can be nailed directly into the plywood sheets (It's my understanding that this is how it would usually be installed) However the existing first floor exterior has a very thick layer of concrete or cement (Not sure which) coated in a bumpy stucco. (Do I sound newbie enough for ya?!)

My question is this:

Is it OK (I know it's not ideal) to install lap siding using drywall screws and construction adhesive over the existing stucco on the first floor only or do we have to "prepare" the first floor exterior some other way in order to install the siding?

My contractor has started installing the lap siding in the area where the A/C compressors are going to go this way and it looks as though it's grabbing really well but how would this perform in the long term? Anyone have any ideas on this? Thanks in advance for your help!

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The Hardiplank install instructions don't say you can do this--it doesn't mean you can't. I'd call James Hardie direct and talk with a techy, (assuming you're using Hardiplank)

I can't figure any reason why it wouldn't work. You'll have to contend with how it terminates at the window, door, hose bibb and other miscellaneous penetrations. It may not be pretty.

If you're in a high wind area, using your invented method, the boards may not hold like they're supposed to. I'm sure they've never been tested using your criteria.

Of course, if there's any inherent problems with the original stucco install including flashing, weeps etc. you'll just be covering it all up and making a bigger mess.

I wouldn't use drywall screws. Use some type of decking screw and make sure its long enough to get in to the sheathing behind the stucco.

Check the overlap on the boards. From your photo it looks like its too small. Hardi requires a 1 1/4" overlap.

It all seems a bit squirley to me and I wouldn't want to risk an unknown.

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It looks like a mess to me. Not that it can't work, but it's pretty far outside any mfg. or industry recognized & approved approach.

Which, BTW, is the minimum standard, meaning you got yourself a buckethead job.

If I found this on a job, I'd probably have to sit down and catch my breath.

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Yeah I suppose that your replies are right on the money! lol

Randy:

We're doing a 1" overhang which I heard is fairly typical but what do I know. We're not in a high-wind area so that shouldn't come into play much. Not sure if it's "Hardiplank" but it is a cement board of some type. I will find out what this is and post my finding.

I DO like the idea of decking screws or something similar and the length is certainly something that I'll have to look into. I believe that he's started with 1-5/8" drywall screws.

"Kurt" and "inspecthistoric:"

Your replies were both amusing and helpful, thanks!

What are my options here then and what would be the "ideal" way to install this on the first floor? Take down every bit of first floor cement and stucco and then do what? Install sheeting, wrap it, then nail the siding on?

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We're doing a 1" overhang which I heard is fairly typical but what do I know. We're not in a high-wind area so that shouldn't come into play much. Not sure if it's "Hardiplank" but it is a cement board of some type. I will find out what this is and post my finding.

Every manufacturer of fiber cement siding specifies 1-1/4" laps.

I'm sorry mate, but you've engaged the services of a hack.

BTW: when I was deciding between grained and smooth fiber cement I screwed a dozen boards of each over my poplar siding w/ drywall screws. The screws lasted just under the two years it took me to side my house. By the time I got to the "sample" area, all the screws were rusted through.

I wouldn't attach fiber cement w/ anything but stainless.

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Hi,

I'd be concerned about the fact that he's using too short an overlap. I don't think drywall screws are appropriate for the reasons stated. Other than that, if the stucco was weathertight before, this really shouldn't allow any water in.Still, I think it would have been wiser to apply it as a rainscreen over the stucco by first applying pressure-treated battens. That way, you could nail it directly to the battens using nails and the back of that siding can dry out.

Don't forget, when Hardiplank is installed over most other sheathing and underlayment systems it is able to dry to the interior through diffusion like wood does. If you've got a layer of painted stucco in front of it, you've essentially placed an impermeable barrier there. I think it's going to have a harder time drying out after hard rains. What's he planning to do at the base of the wall?

ONE TEAM - ONE FIGHT!!!

Mike

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When and if you have a problem down the road you might ask yourself why you choose not to follow the standard method of installation as set forth by the normal instrutions. When all else fails read the instructions and follow them. There is a warrenty issue also involved. It may be voided by short cuts.

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  • 1 year later...

I recently install HardiPlank over Real Stucco, but to do so I attached firring strips to the stucco (pressure treated 5/4) on 16" centers using 3" deck screws. This required pilot holes for the screws. Lots of work but worth it. I the installed the HardiPlank siding following the 1 1/4" overlap. To top things off I used 1" brad nails along the bottom edges to pull the overlap tight. Oh... before doing this project I installed new windows and added an extra 1 3/4" trim to bring out the vinyl brick mold so they weren't sunken into the siding. The whole darn project took a while but my heat kicks on a whole lot less often and runs a great deal less when it does kick on. I'm looking forward to the summer for similar results with the air conditioner.

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  • 5 years later...

I recently install HardiPlank over Real Stucco, but to do so I attached firring strips to the stucco (pressure treated 5/4) on 16" centers using 3" deck screws. This required pilot holes for the screws. Lots of work but worth it. I the installed the HardiPlank siding following the 1 1/4" overlap. To top things off I used 1" brad nails along the bottom edges to pull the overlap tight. Oh... before doing this project I installed new windows and added an extra 1 3/4" trim to bring out the vinyl brick mold so they weren't sunken into the siding. The whole darn project took a while but my heat kicks on a whole lot less often and runs a great deal less when it does kick on. I'm looking forward to the summer for similar results with the air conditioner.

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I recently install HardiPlank over Real Stucco, but to do so I attached firring strips to the stucco (pressure treated 5/4) on 16" centers using 3" deck screws. This required pilot holes for the screws. Lots of work but worth it. I the installed the HardiPlank siding following the 1 1/4" overlap. To top things off I used 1" brad nails along the bottom edges to pull the overlap tight. Oh... before doing this project I installed new windows and added an extra 1 3/4" trim to bring out the vinyl brick mold so they weren't sunken into the siding. The whole darn project took a while but my heat kicks on a whole lot less often and runs a great deal less when it does kick on. I'm looking forward to the summer for similar results with the air conditioner.

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Drywall screw are not corrosion resistant. Maybe you could get away with this in a dry climate, but otherwise think rust streaks on the siding at a minimum. Also, if it starts to fall off I'm sure the contractor will tell you it is out of his one year warranty.

The proper way to do this would be to attach furring strips. That should have been planned for when the addition was constructed. Also, if the stucco is bumpy then the siding will probably look wavy.

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