Plywood on the sanctuary roof: seismic integrity (Condition Report)

PLYWOOD IS THE KEY to the seismic integrity of our sanctuary building, according to three structural engineers I have spoken with. Although no plywood seems to have been employed in its original construction, a layer was added overhead in 2004 during a re-roofing effort, as discussed elsewhere in this blog. 

As of this past week, I can say with confidence that the roof’s plywood is adequate to ensure that our building provides at least a minimum life safety level of performance in the event of a serious earthquake. 

Cross-section in a cut at the walkway alongside the roof's barrel,
showing 3 layers: plywood, sheathing, and rafter.
(I added a typical nail for comparison—but placed it too low.)

Last month, in the process of making structural repairs to the roof, enough plywood was exposed that I was able both to see the size of the nails employed and to measure the nailing pattern used. Those two factors affect the seismic integrity of the roof. 

Below the jump, I show and discuss my findings, while looking ahead to similarly strengthening the walls.…

Repair of concrete retaining wall in stairwell, below school building (Activity Report)

WHILE A CONCRETE-REPAIR CRAFTSMAN was doing repair work elsewhere on the premises in mid-September, he redid this old patch, as well. 

November 2023 
(As usual, click/tap on an image to enlarge it.)

For a description of the problem, see HERE.

Below the jump, this post documents what was done, as well as how one resulting concern was handled.…

Repairing the concrete retaining wall of the stairwell below the school building (rev. 5-16-24)

TO THE WEST of the school building is a below-grade, concrete retaining wall, which forms one side of the emergency-exit stairwell that leads from the Social Hall up to our “Ruben Alley” and then to the public alley. There is a large (6-foot-wide) cement patch on this wall—evincing a previous problem in that spot. That patch has some rough edges that I find troubling, for the concrete there is actively degrading. And the longer that we wait to repair it, the more costly it will be.

November 2023
(As usual, click/tap on an image to enlarge it.)

I mention this now because we are contemplating concrete repair work elsewhere on the premises. Handling all of it at the same time would be prudent. So below the jump, this post discusses the stairwell situation. It closes with a suggested remedy.…

Revisiting seismic strengthening as a goal

STRUCTURAL ENGINEERS prepared one of the modules in the 2003 Historic Structure Report (HSR). Among other things, it assessed the sanctuary’s seismic integrity and offered a plan for improvement. 

(As usual, click/tap on an image to enlarge it.)

Below the jump, this post summarizes the seismic portion of the structural module, in light of more recent developments, while ending with a recommended plan for the future. That is, it compiles and updates my various prior posts about seismic issues.

South Wall Discovery Project: Initial Report

ON THREE OCCASIONS during the past two decades, structural engineers have recommended that we do test cuts into the south wall of our sanctuary. The goal: to enable more reliable cost estimates for waterproofing and possible structural repair work, hopefully later this year. Given more than two decades of known water intrusion and termite activity in that area, the engineers were concerned that there might be significant structural damage in the wall. They told us that there was only one way to find out: to look beneath the plaster surface.

Prep work, as viewed from bimah:
Marking the locations, and placing air purifiers to catch plaster dust.
(As usual, click/tap on a photo to enlarge it.)

This past week, we finally undertook that adventure in discovery. Although the board had approved this work in May 2021, it took until now to arrange for the proper alignment of funding and expertise. Careful planning (described HERE) was needed to ensure that we would get useful and reliable answers to our questions, given our limited budget. 

This post reports on what was done, and the initial findings.

Summary: Pending Project: Tie-Rod Connection Check

WE PLAN TO OPEN UP one of the tie-rod connections, on the outside, at the 2nd column on the north wall, to ensure the sanctuary’s structural integrity. Here is a view from the inside.…

(The function of the tie rods is to hold the walls in a vertical position, while the load of the vaulted roof is, in effect, pushing those walls apart.) 

Upper Side Chambers: The Rest of the Story

EARLIER THIS MONTH, I described my plan to open up two normally enclosed chambers at the junction between the sanctuary roof, ceiling, and walls. Well, that plan was enacted yesterday. We learned a few things, and we took some action! This post describes what happened, and the outcome.…

Looking eastward toward the viewing port
that Ruben and I had peeked through last week

Safety Improvement Made This Week

BACK IN DECEMBER, the board had voted to approve the installation of 2 seismic gas shut-off valves: one for the school, and the other for the sanctuary. I’m pleased to announce that the first one was installed today! (Hopefully the second one will be done tomorrow.) This is a capital improvement, in that it has resulted in a betterment to the facility: a safer synagogue. Thus it’s to be paid for from our Capital Improvements Fund.

The new inlet pipe downstream from the meter
features a bright red earthquake valve.

This post treats the history of this issue and its resolution.…

How Much $$ to Ensure the Long-Term Viability of Our Facilities?

GIVEN THE AMOUNT OF FUNDING that the board’s policy has allocated from dues for maintenance and repair purposes, it is more than sufficient to pay for Mishkon’s regular, periodic maintenance needs.

A typical annual termite inspection

And enough additional funds are likely to accumulate from these sources (as well as from the regular Building assessment, the Kleinman Family Fund, and any bequests) to fund the future replacement or restoration of worn components, as well. 

Replaced patio flagstone, ready for grouting (Oct. 2021)

However, there are three aspects of facilities care that are not provided for by regular funding: (1) the present replacement or restoration of worn components—that is, catching up on deferred maintenance and arresting the processes of degradation; (2) several new capital improvements worth doing soon; and (3) a cash cushion to allow big-ticket items to be paid for when the need arises. In other words, we need a sizable infusion of funds to get us over the hump of our present humble condition.

Sanctuary roof, looking westward

In this post, I will discuss the target funding levels both for our urgent present facilities needs and for our future ones—and the prospects for achieving those.

The Restoration Plan, as It Stands

AS MY LOYAL READERS KNOW WELL, last June, the board approved a facilities restoration plan. Its execution is of course subject to the availability of funding, which I have little control over. Yet at least we have a plan, regarding our priorities and how to go about meeting our goals. Here is a status update.…

Details about the Roofs and Their Condition

Sources

These sources are cited in the material that follows.

• Historic Structure Report (HSR) 7/03; prepared by Historic Resources Group, incl. structural system assessment by John A. Martin and Associates
• Property Condition Report (PCR) 1/8/19; prepared by Partner Engineering and Science
• Field Inspection Report (FIR) [on water intrusion] 10/5/20, prepared by Spiegel Property Damage Consulting and Forensics
• Assessment by Chuck Jewett, President, Hull Bros. Roofing 2/24/21 
• Synopsis (photos with captions) by Rich Radenbaugh, Bilt-Well Roofing and Solar 3/15/21

(Thanks are due to Sue Kaplan, Johanna Schmidt, and past boards and staff for having arranged for the above reports.)