How Much Space in Ceiling for Expanding Riser Pipe

Frank_63

When my apt was painted, my painter plastered up the space in the ceiling where the riser enters to go up to the next floor. All this winter, I've had expansion noise, and plaster dropping from some of the places where the pipe enters the ceiling. He is coming to repair the ceiling, but I want him to leave sufficient room around the riser pipe for it to expand and not cause the ceiling to crumble. How much space is sufficient?

Mark Eatherton

1/4\" ought to do...

THe expansion of pipes is generally length wise, with minimal expansion diameter wise. If the pipe is being forced side ways due to other lateral expansion stresses, that may have to be taken into consideration.

ME

Frank_63

Yes, Lengthwise . . .

I'm assuming lengthwise expansion is what I'm dealing with, not diameter expansion. The riser is connected to a piece of horizontal pipe underneath my floor, so I assume that expansion of the horizonatal pipe lengthwise is what is causing the riser to move. In fact, the location of the in the ceiling is on one side of the riser, the side that would be consistent with lengthwise expansion of the horizontal piece.

Thanks.

Kool Rod

Hi Frank- I had a similar plaster problem and got an aluminum "puzzle" ring from this company.

http://www.wagnercompanies.com/site/Viewer.aspx?iid=1875&mname=article&rpid=570"

I glued it in place with some panel adhesive and painted over it.
- Rod

bob young

use a floor & ceiling plate split escutcheon.

scrook_2

expansion

Carbon steel pipe expands about 8.4x10^-6 inch per inch/°F (about 0.0001 inch per foot/°F).

For a 150°F (65° to 215°) temperature rise the pipe will expand about 0.015" per ft (a few thousandths in diameter but about 3/4" in length for a 50 ft straight run (0.015"/ft * 50ft = 0.75")!

As we're on the topic: for copper it's roughly 120% of steel (but w/ hot water the temp rise is often less), cast iron (e.g. boiler castings) roughly 70% of steel. For plastics (e.g. PEX tubing, PVC venting) the expansion is often a LOT more.

scrook_2

thermal expansion...

Carbon steel pipe expands about 8.4x10^-6 inch per inch/°F (about 0.0001 inch per foot/°F).

For a 150°F (65° to 215°) temperature rise the pipe will expand about 0.015" per ft (a few thousandths in diameter but about 3/4" in length for a 50 ft straight run (0.015"/ft * 50ft = 0.75")!

As we're on the topic: for copper it's roughly 120% of steel (but w/ hot water the temp rise is often less), cast iron (e.g. boiler castings) roughly 70% of steel. For plastics (e.g. PEX tubing, PVC venting) the expansion is often a LOT more.

As for the plaster, 1/4" clearance sounds reasonable.

Mark Eatherton

Plastic...

1.1" per hundred foot per 10 degree F difference.

Using your example, PEX would grow 8.25 inches.

YEOWser!!

Thanks Steve.

ME