Exterior Slate Cladding

John-GLGM

CJKarl,

I hate to play devils advocate here, and I am in no way deriding Laticrete products (we use them in a number of applications), However I would argue that using an adhesive method of application alone on this project would create some concerns. The MIA (Marble Institute of America) cautions that "individually set thin tile (nominal 1/4" thick) on vertical surfaces exceeding 8' is not recomended." Since your application is 1/2" slate and you are considering an adhesive system you may be able to avoid issues regarding the fragility of thin tile instalations, but depending on the slate you are using you open yourself to another set of issues including water intrusion.

Even with a waterproffing barrier on the hydrostatic load side of the concrete wall you still have to consider water intrusion on the cladding side of the installation. All but the most dense slate is significantly more porous than other common choices for dimensional stone cladding. Laticrete's own technical design manual cautions that:

• spot bonding is only suitable when
using adhesives with very high bonding
strength and flexibility such as new
technology epoxies and structural
silicone, and may require supplemental
mechanical anchorage.
• spot bonding should not be used in wet
climates with cladding materials that
have high water absorption or water
sensitivity (Figure 7.3-2).
• spot bonding is not suitable for thin
cladding materials that do not have the
cohesive (tensile) or shear strength to

resist the high unit area stress

attachment.
• back-up wall construction must make
provision for waterproofing and flashing
the cavity between the substrate and the
cladding surface.
• spot bonding may not be suitable for

extreme climates or conditions.

If Laticrete is waranting their system and you and the engineer/architect are comfortable with the installation specification than obviously I will defer to your/their expertise. However all the professionals I have talked with at our company would quote this job using a minimum 3/4" dimensional slate with a mechanical anchoring system due to the height of the project, possibility of water intrusion and freeze-thaw environment.

No matter what system you choose I haven't seen any reference in the posts to weepage and control/expansion joints. Make sure that you have provided for venting or weep holes at approximately 5' horizontal and 20' vertical intervals and expansion/control joints at maximum 20' intervals.

Good luck and I'll be looking forward to hearing how the project goes.

__________________
John Hughes
Business Development Manager
Great Lakes Granite & Marble
john@greatlakesgm.com http://www.greatlakesgm.com

gbdesigns

karl contact TEC and ask to be put in contact with henry the north east sales rep. he lives in CT and will set you up with the right products. i wouldn't use any type of sheet membrane. there are all kinds of liquid roll on products to give you waterproofing and crack isolations. ditra is not for vertical use.

angus242

Project is already under way. Products have already been chosen.

__________________
Angus
L+M+O+P=C
"Promise only what you can deliver. Then deliver more than you promise"