Stucco on Hardiboard

[deejayoh]

I searched the forum for guidance on this but couldn't find a good thread, so thought I would put it up for the group

I want to do a stucco finish on my oven housing, which made of metal stud/hardiboard. I need some input on the correct approach here.

Some places I read that the right way to do this is

• Tarpaper
• Metal lath
• Stucco (scratch/brown/final coats)

Other places I have read that it's ok to apply the stucco straight to the hardiboard.

Then there is also synthetic stucco, which I guess is an option

What's the right way to do this?

thanks
Dennis

[Gulf]

Re: Stucco on Hardiboard

Dennis,
I looked at this stuff by quikrete at my local Home Depot today. Scroll down to Quikwall. They had a broken bag and as it is my nature to investigate. It appears to be made of white portland has fibres in it. I have never worked with it. Just thought I would throw that out there .
I am more familur with latheing.

[Tscarborough]

Re: Stucco on Hardiboard

Unless you can live with cracking at the joints and corners, you have to lathe it. Quickwall is a product used for drystacked block walls, it is just good stucco with fibers. Synthetic is an option, but will still crack at the joints and corners.

[Pdiff]

Re: Stucco on Hardiboard

Unless you can live with cracking at the joints and corners, you have to lathe it.

I'd second this. I used metal lathe over everything, including block. It came out great and hasn't cracked at all. The block probably wasn't necessary and required a hammer drill, but it made the transitions easier.

I used Tscarborough's mix posted here a while back. Thanks, BTW! Worked great (but I'm glad that job's done!),

For Base:
1 part Portland
1/2 part type S Lime
3 parts sand

For Finish:
1 Portland
1 S Lime
2-4 Sand

[deejayoh]

Re: Stucco on Hardiboard

Tscar and Pdiff

Thanks for the responses! That's what I was looking for.

Pdiff - great spot for that oven! That is beautiful. And the stucco look you have is just what I want for my oven house

[jeeppiper]

Re: Stucco on Hardiboard

gut feeling is that you need the metal lathe to give the stucco some back-bone. Otherwise I can see it peeling off the cement board in chuncks....

however I have no experience.

[Pdiff]

Re: Stucco on Hardiboard

Tscar and Pdiff

Thanks for the responses! That's what I was looking for.

Pdiff - great spot for that oven! That is beautiful. And the stucco look you have is just what I want for my oven house

Thanks. I picked up a rounded cornering tool for the edges and flat trowel for the rest. I also did not tint the stucco, but painted at the end. Too many small batches (innumerable 5 gal bucket mixes) to keep a tint consistent.

Yes, the placement is nice, in the country side, but I haven't been able to fire for many weeks. That grass you see is now tinder dry (no rain for 2 1/2 months) and I'm scared of starting a fire I have several placements of screening on the chimney, but sparks can still fly out. Not worth the chance. Hope it rains or at least gets a heavy dew soon!

[ironpony]

Re: Stucco on Hardiboard

I applied stucco directly over Duroc backer., same as applying over scratch coat. You can tape the seams with fiberglass tape like drywall finishing and nothing will crack. Prepare similar to prepping for tile. I have some areas that are several years old, even some with cultured stone applied to it, again mine is Duroc brand not hardi backer.

[Tscarborough]

Re: Stucco on Hardiboard

Ironpony, there are 2 types of advice given on the internet:

Anecdotal

and

Best practice

Anecdotally, I am sure your experience is valid. As a professional in the industry, I can not give other than Best Practice advice. There are many ways to do any particular project, and sometimes or even often the anecdotal advice will work. The issue is when it doesn't. That is why the acceptable industry practice is to apply lath over cement board or hardibacker when when coating with stucco or faux stone on broken planes.

The choice is up to the individual, but unless best practices are followed, there will be no warranty (not that they warrant cracking anyway). Normally the investment in time and money to do it to specification is well spent when the alternative to remove and redo will be several times the initial cost of doing the project to Best Practice.

It all boils down to your willingness to assume that risk.

[deejayoh]

Re: Stucco on Hardiboard

Tscar -
What about the moisture barrier (e.g. felt paper). Is that not necessary?

[Tscarborough]

Re: Stucco on Hardiboard

It is cheap and it is effective, so required or not it is Best Practice.

[ironpony]

Re: Stucco on Hardiboard

answered his question. just another forum with to many experts. I will never post again.
over and out.

[Tscarborough]

Re: Stucco on Hardiboard

No need to get mad.

[WJW]

Re: Stucco on Hardiboard

I don't get the thin-skinned thing.

Bill

[Cheesesteak]

Re: Stucco on Hardiboard

I applied stucco (3-coat) to my oven directly to the cement board. I used woven fiberglass mesh in the brown coat. I used a concrete bonding adhesive on the cement board prior to the scratch coat. Same process used on my CMU walls for the base and island areas. Not a crack to speak of, hairline or otherwise.