# exterior durarock use



## sorethumbs (Apr 22, 2009)

I've always read that using dura-rock as a base for enginered veneer stone is limited to interior application only. I've got two projects where I'd like to use it outside, and I'm just wondering why not. The first project is skirting for a small deck. This deck is unique in the fact that the outter supporting beam in resting on a framed PT 2x8 wall, 16" oc. 5ft of it is below grade and 3 feet is above. I did not build it, and that is what i'm dealig with. I'd like to apply durarock to the wall as my base, then back-butter and stick the "stone." The size of the skirting is approx. 3'x12'.

I've read the approved applications of durarock from the mfg. and this seems to be an approved use, exterior use is approved. This is in Wisconsin so winter/summer flucuations are a consideration. What do you think about this plan, am I nuts to even try it?


----------



## Tscarborough (Feb 25, 2006)

I have never done it, but I am going to soon with a counter in my outdoor bar. I am going to seal the stone thoroughly is the only thing I plan on doing differently than I would over lath.


----------



## Stone (Mar 23, 2009)

I was always leary of using cement board on the exterior until I did a bridge project three years ago. This thing was fifty foot long and constructed with two huge curved I-beams with substantial concrete pads on either end. The deck was concrete and the bridge was framed with metal studs and covered with cement board. I then covered all the cement board with a sawn thin veneer natural stone which I installed with type S and a bonding agent. So far after a couple of severe winters it is still in great shape and no stones have dived in the creek below. I really questioned the cement board at the time but there were engineers involved who assured me that it was OK. I will try to post a picture.


----------



## jomama (Oct 25, 2008)

I've always been a little apprehensive to use it for stone also. I have used it on a few stubby chimneys under thin brick before though, & they haven't fallen off yet! The resoning then was to snap clearer lines, & the uniform brick thickness will really show an imperfect lathe/plaster beneath.

I bid on a gas station project years ago where durock was speced for thin brick, but I guess I've always trusted lathe more. But now that I see Stone's application of NTV over it on a bridge, I may not be so leary.

The only thing I would add for the OP is consider installing the durock over green ply for added integrity.


----------



## kevjob (Aug 14, 2006)

How about kerdi for the skirt? www.schluter.com


----------



## sorethumbs (Apr 22, 2009)

jomama said:


> The only thing I would add for the OP is consider installing the durock over green ply for added integrity.


Yes, I agree, in fact it's already installed. I also added enough blocking to have created a very stable base structure.


I've never worked with kerdi before, and that is an interesting idea. I don't think I need the waterproofing properties kerdi provides for this project. I do have an upcomming project that involves installing lick-&-sticks as waiscot on a pole barn. That project also has PT for the framing. Maybe I could consider kerdi there.


----------



## S.B. Masonry (May 10, 2009)

I never liked the idea of using durock for exterior veneer either, especially up here in Maine, but I did veneer a fireplace/ chimney about four years ago that the builder had already framed up and durocked. I just make my mud a little stickier and put the K-88 or Acryl 60 to it. Was up there last summer and it still looked fine.


----------



## cleveman (Dec 28, 2007)

Check the product specs for control joints.


----------



## lukachuki (Feb 11, 2005)

Stone said:


> I was always leary of using cement board on the exterior until I did a bridge project three years ago. This thing was fifty foot long and constructed with two huge curved I-beams with substantial concrete pads on either end. The deck was concrete and the bridge was framed with metal studs and covered with cement board. I then covered all the cement board with a sawn thin veneer natural stone which I installed with type S and a bonding agent. So far after a couple of severe winters it is still in great shape and no stones have dived in the creek below. I really questioned the cement board at the time but there were engineers involved who assured me that it was OK. I will try to post a picture.
> View attachment 17984


Beautiful Bridge by the way.


----------



## ClosetPro (Apr 29, 2009)

lukachuki said:


> Beautiful Bridge by the way.


Yes!! That bridge is over troubled waters.


----------



## Morganremodel (Dec 7, 2009)

*Durock as a chimney chase*

I'm working on a job and have proposed and have started building a thirty foot wood framed chimney chase with class A flue behind. I have assumed that Durock can and will support 1" back sawn stone veneer without having to use lathe. The client is nervous about this approach and is insisting on a layer of lathe, screwed to the Durock before the mason backbutters the stone.

Isn't this overkill, more labor intensive, and time consuming. The whole point of durock is to create a backing that eliminates the need for lathe? The client will probably not want to pay for this extra step as well and would like comments on this issue..

Thanks


----------



## TulsaRemodeler (Nov 24, 2009)

Stone said:


> I was always leary of using cement board on the exterior until I did a bridge project three years ago. This thing was fifty foot long and constructed with two huge curved I-beams with substantial concrete pads on either end. The deck was concrete and the bridge was framed with metal studs and covered with cement board. I then covered all the cement board with a sawn thin veneer natural stone which I installed with type S and a bonding agent. So far after a couple of severe winters it is still in great shape and no stones have dived in the creek below. I really questioned the cement board at the time but there were engineers involved who assured me that it was OK. I will try to post a picture.
> View attachment 17984


Thats niice stuff. I'm not a mason but I wonder doesnt whats behind the cement board matter? In your case all seems fine. But over a wood structure wouldnt it be destined for failure?


----------



## Morganremodel (Dec 7, 2009)

*Durarock*

The frame will be waterproofed and heaily fortified, its the lathe as an extra task that seems overkill. If the frame is sturdy then the stone facing should never "pop" off the Durarock..thats the whole point of Durarock I thought - to eliminate the traditional lathe construction???

Confused I am.


----------



## Rockmonster (Nov 15, 2007)

I am going to agree with you Morgan....this is a new world with all the thin stone, robinson brick etc. I have done a number of chimneys, with stout PT frame, felt, durock, brick. They are all in very good shape. Now I will say, I have only done this from the roof up, so usually 4-6 feet or so. But I have seen 30' chimneys happen. I am curious as to the lifespan....Say a real masonry chimney for instance gets you, say 200 years. What are the durock chimneys going to give? 30? 50? 15? I'm going to hope A, because I might still be alive in 15 and I don't want to get up on any roofs at that time. What do the manufacturers say?:wheelchair:


----------

