Hang Sprinkler Pipe to Hollow Block Structure?

8/8/2025

We have a project where they are retrofitting a sprinkler system in an old building. The structure is hollow block with lathe & plaster applied to the exposed side of the hollow block.

Does anyone know an approved method to hang pipe greater than 1"?

Thanks in advance.

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6 Comments

Anthony

8/8/2025 08:20:26 am

Toggles go up to to 1 1/2'' I believe. I've run in to this before and the solution was to get the project structural engineer to sign off on 2'' pipe with toggles and hang our mains to the concrete 'beams' that span between the columns. Older building columns are usually less than 15' apart.

Chad

8/8/2025 09:05:35 am

Agreed 1-1/2" max on the loading of toggles like that with out an engineering judgement.

And make sure there isn't asbestos insulation in/above the beam!

Glenn Berger

8/8/2025 09:25:42 am

Verify with a Structural Engineer before proceeding.

Is the piping going to be exposed? Or is the existing ceiling going to be removed to allow ensuring proper attachments.

David Kendrick

8/8/2025 09:30:45 am

Possibly the hollow clay tile were laid out in a pattern that was infill to structural beams. Akin to pan construction used today.
If you can establish a pattern to the structure related to the columns, well we had a project where we measured out the steel beams and cleared enough plaster to weld studs on the steel and spanners where we had to.
I’m concerned about a system attached to hollow clay tiles alone. We had an entire hallway drop. The concrete poured on top of those tiles, circa 1900, didn’t tooth in and form a secure enough connection to support the pipe. Bu then we had the concrete and steel completely exposed after the collapse of the old ceiling.

Tough project.

Jack G

8/8/2025 10:27:21 am

Yes. In Philadelphia it is called Terra-cotta tile, big thick hollow tubes with walls up to 2 inches thick moartered together criss cross and in layers, , usually floors between columns ( several layers thick, and walls too, and every building built before 1959 was built with it.
Please run whatever you do with the city construction department and the engineer if record.
Most projects include a test for weight, and pull out test.,if not order and present to the A&E, city engineers. Hilton does it for free in Phillie to sell hangers and bits.
Carbide tipped bits and hole saws should be used ( especially core bits) and pull out and clean several times while using them.
Regular ones burn out quickly,
I try ( using toggles ) to ho up several tubes into the hollow, and use a nut and washer to steady / set the rod.
If thick walled , a us case/ double expansion case works fine and a pull out test satisfies the 5 times/etc rule.
The concrete on top is usually a thin slab (4-4.5 inches) and sometimes it’s mixed with gypsum and is not ysuall great to hang to.( Wanamaker bldg in Phillie);
I do not go 15 ft between hangers , ends up about 8 - 9: feet ( at
least 1 hanger for every piece of pipe, double up on full lengths);
And 57 years of this no one has had a pullout ( any trade ) here.
So—- 8-9 feet on center, hang in at least an intermediate tube, use a nut and washer at ceiling, carbide bits and hole saws, test hangers with city and project engineers.

Jeff

8/12/2025 09:35:07 am

Drill 3/4” hole using carbide hole saw thru the plaster and lathe. If the ceiling is concrete, we were able to use a long sds bit, with a 1/2” copper pipe on it to set the depth. Then our welder welded the set tool to a long piece of 1/2” rod. Use a double nut on the end for the hammer to set the drop in anchor. Works great. The skill is in “fishing” the anchor tool to find the drilled hole in the dark.

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Hang Sprinkler Pipe to Hollow Block Structure?

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