Flagstone Restoration Project: The Untold Story

PHASE I OF THE FLAGSTONE RESTORATION PROJECT is a great reminder of what such efforts can accomplish. Last spring, the flagstone pavement in front of our sanctuary’s steps was looking pretty darn decrepit. Happily, by November, it had been restored to the point where routine maintenance should be able to keep it in decent condition for a couple of decades. Here is an overview of how the project proceeded.…

First of all, for a summary of why this work was undertaken, see my Messenger article from July 5, 2021:

Restoration Project Underway: Flagstone on Main Street

“Before” photos from May 2021

Honestly, it’s hard to remember just how awful the front entrance of Mishkon looked by the time this project began. Time and the lack of regular maintenance had taken a huge toll on the sandstone. Glancing back at these photos now, what stands out for me is how mottled and uneven the surfaces had become.

Lower steps at central handrails, with stubs of old handrails

Two depressions in front of the central handrails 

had been filled in with white plaster 

(shown here mostly shaded by nearby tree).

Front patio at northern end of steps

Southern end of patio, under the shade tree

Defining the Job Specifications

It took some careful thinking in order to decide — and to describe — what exactly ought to be altered, versus what was best left alone. After consultation with an expert, the basic job specs were spelled out as follows:

1. Remove grime and even out the mottled appearance by low-power washing, acid washing, and applying an alkaline pH balancer to all sandstone surfaces (including grout): portico, steps, planter walls, wall caps, and flagstone pavement.
2. Replace the unstable and damaged stones (to be specified), particularly those that pose a tripping hazard.
3. Repoint the damaged or missing grout and fill in damaged concrete.
4. Seal the horizontal stone-and-grout surfaces with 2 coats of an invisible penetrating sealer.

An estimator for one of the bidders made a very instructive 4-minute VIDEO, in which he describes to his company’s work crew the agreed-upon scope of work. He’s talking not only prospectively to them, but also enabling the customer (me) to ratify in advance what we’re agreeing to address. 

Then, just after the contract for Phase I had been prepared and was about to be signed — and 2 days before the work was supposed to start — I happened to visit Mishkon right after Ruben had hosed down the patio area. Upon noticing the puddles that remained…

…I suddenly realized that there was a series of low spots in the patio (a couple of them are marked in red in the photo below). Water then collected there and would soak into the stones. And given that water eventually disintegrates sandstone, it was no surprise that those pieces tended to be in the most deteriorated condition.

In order for this project to succeed in arresting the ongoing deterioration flagstone, we needed to have those low spots leveled out. Therefore I added this task to the scope of work at the last minute. The contractor insisted on counting it as a change order, even though no actual work had begun on the project yet. Thus this part of the work was relatively expensive, but also the most valuable.

The Work Begins

As soon as the most deteriorated stones were removed, it was discovered that they had all been laid directly on the sandy dirt, without any concrete pad below, which would have provided a stable base. No wonder they shifted over time! 

A concrete base was poured underneath each replaced piece of stone. The photo below shows such stones before an acid wash was applied to even out the coloration—both within and across the flagstones. (Sorry, I don’t have a good picture handy of the finished surface. Go and see for yourself!)

In a few places, however, the acid wash was not sufficient to clean up the accumulated grime. In the spot shown below, for example, at the edge of the southern planter, the dark surface was apparently the result of many years’ worth of passing dogs that had left their mark.

So I agreed to pay extra for grinding away the top surface of the stone—not only on the flagstone walkway but also on the planter’s face. An interim photo is below. It now looks a whole lot better than before!

One final detail that makes me smile is how Ruben and I took steps to protect these newly spiffed-up surfaces from passing dogs until the masons came and applied their sealer. (Ruben told me that he watched as dogs would approach but then give up before leaving their mark.) Such are the details that make a difference in the overall success of a project!  😉