A few years ago, the section of a chimney that rose above the roof had crumbled, and that was, he said, "the moment that we came within a whisker of losing the entire ceiling."
In 2012, the six trustees - Martinez, his wife, Leah and four others who often constitute the Sunday congregation - added several roof supports.
Crutches, so to speak.
But like a lady of considerable age, he said, the meeting house is fragile.
Though the estimated $20,000 for that 2012 work has been paid, the trustees will hold a fund-raiser for further work at 1 p.m. April 14 at the meeting house.
One morning last week, Martinez walked about the one-story stone building, showing off its weathered wounds, the setting evocative of a quieter era.
Standing at Caln Meetinghouse Road, its south side looked across King's Highway, better known as Route 340, to an undeveloped wooded slope, and to the north lay a broad treeless field of low Quaker gravestones.
"There's still a lot more work to be done up there," Martinez said, pointing to the 1995 moss-spotted northern roof, which must be replaced within five years.
There are lesser needs.
"Windows are in pretty critical condition," he said, prying too easily at loose woodwork. "Some have to be completely restored."
Martinez, 63, should have a sense of what matters to the site, artistically.
The Downingtown painter of portraits, landscapes, and such is the former exhibit designer for the Kimbell Art Museum in Fort Worth, Texas.
His website notes that he designed the 2001 Bush White House Christmas card and in 2003 completed a White House commission of a 10-by-18-foot landscape.
It is now in the family quarters there.
But why an Old Caln congregation of only six on many Sundays?
Because the meeting house is not an active worship site, decommissioned decades ago. "Laid down," is the Quaker phrase.
It's totally open to the public" for Quaker worship, he said, and sometimes does attract worshipers.
For its six trustees - all members of the Downingtown Friends Meeting - Old Caln is where they worship.
Except on the last Sunday of each month, when they tend to the business affairs of their Downingtown congregation, worshipping there.
On cold winter mornings, there may be another reason for the worshipers to number only six.
Only an old wood stove in the middle of the 1726 worship space, which one of them shows up early to stoke on Sundays, warmed by a small space heater against the north wall.
The trustees share the building's austerity with the larger community.
A lawn sign notes that it harbors the Old Caln Historical Society Museum, whose artifacts - flax comb, branding iron, sausage stuffer, and such - are in one of the structure's three rooms.
And for the curious passerby, a plaque on an outside wall testifies that it is on the National Register of Historic Places.
But the place has not been lost to the past.
"We're dedicated," Martinez said, "to eventually bringing it back" to a fully functioning worship site.
Contact Walter F. Naedele at 610-313-8134, firstname.lastname@example.org, or follow @WNaedele on Twitter.