Granite Staircase Grout Failure
Granite Staircase Grout Failure
(OP)
Ok all, I have just come across a problem on a project that I did not personally work on, but wanted to see if others have had similar issues and how they resolved them.
Problem: There is a concrete staircase with granite treads for a University in the Northeast US. The construction was completed approximately 2 years ago, and within the past 6 months they have started noticing significant grout failure in the steps.
Design: Steps were designed with concrete slab and piers, and5.5" x 6" x 16" 5.5" x 16" x 48" granite treads that are grouted onto concrete steps and doweled in with stainless steel dowels into the concrete slab. I am working on getting some design drawings and photos right now, but this is all I have to go off of at this point.
Thoughts: Initial thought is that the grout was not spec'd out properly, and the constant rain, snow, and salting the steps have encountered the past couple years have sped up the failure process.
Any thoughts?
Thanks in advance.
Problem: There is a concrete staircase with granite treads for a University in the Northeast US. The construction was completed approximately 2 years ago, and within the past 6 months they have started noticing significant grout failure in the steps.
Design: Steps were designed with concrete slab and piers, and
Thoughts: Initial thought is that the grout was not spec'd out properly, and the constant rain, snow, and salting the steps have encountered the past couple years have sped up the failure process.
Any thoughts?
Thanks in advance.






RE: Granite Staircase Grout Failure
Dik
RE: Granite Staircase Grout Failure
They sound like exterior steps. Water management, and like you said, salt/de-icer can be real tough. The profile of the finished grout can make a big difference in how it sheds water too. Shed roof vs bird bath.
Cementitious grout? Was some kind of sealer included in the specification? For the grout and even the granite?
I don't really know anything about this, but as a practical matter I don't have much faith in cementitious grout in easy indoor industrial machine installation applications.
I'd think superb surface preparation and a highly flexible grout would be needed to have a chance of long term survival.
RE: Granite Staircase Grout Failure
RE: Granite Staircase Grout Failure
Dik
RE: Granite Staircase Grout Failure
RE: Granite Staircase Grout Failure
Please see attached for the photo and a detail for the stairs. It appears that they are calling out 1/2" mortar on the detail, with no real specific "water repellent" described.
RE: Granite Staircase Grout Failure
RE: Granite Staircase Grout Failure
You indicated that the pavers are 16" x 5.5" x 6", but the treads are long blocks. Maybe those are the ones in the landing.
RE: Granite Staircase Grout Failure
I am planning to get out to the site in the next couple days to ensure that the steps were built properly and have a pitch to them. The more I look at the photo, the more I'm thinking that the water is not running off the step, and just sitting in the crevice at the horizontal intersection.
RE: Granite Staircase Grout Failure
RE: Granite Staircase Grout Failure
Where there was no gap to grout, along the horizontal lines at the bottom of the risers, grout will not work. What remains should be raked out and that corner joint sealed. Sikaflex 11FC comes to mind.
RE: Granite Staircase Grout Failure
Any water getting into the grout and down behind/under the granite treads will be subject to freezing and thawing action, and will concentrate at that horiz. joint from inside and outside. I wonder if those horiz. grout joints at the tread/riser juncture shouldn’t be raked back so a proper caulked joint can be applied. The butt joints btwn. treads are probably o.k. as shown. Also, they appear to be draining the whole upper plaza onto those steps. You can see drainage stains on the treads and the risers on the left of the photo. Should there be a drain at the top of the steps?
RE: Granite Staircase Grout Failure
Dik
RE: Granite Staircase Grout Failure
First and foremost, I am going to confirm that the slope was constructed as designed, and does not have a negative pitch back to the horizontal joint.
Thanks for all the valuable insight.
RE: Granite Staircase Grout Failure
Dik
RE: Granite Staircase Grout Failure