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Hanging pipes and reducing expansion noises

ChrisJ Member Posts: 15,695
I need some help with this.  When you walk across my living room floor you hear some of the pipes make noise / clunk.  My floor moves a fair amount due to undersized joists and what not.  The noise comes from where the pipes pass through the floor to go up to the radiators more than anything.


right in the center of that is where my boiler sits, so the mains right above the header are hung from a floor that moves.  Is there any easy way to fix this besides stiffening the floor which I may do in the future anyway?  Is there a chance the floor moving will damage the boiler?  I will be adding more hangers as I do my insulation, but I doubt its going to help much with this issue.

What is the easiest way to stop pipes from rubbing where they pass through floors to reduce expansion noises? 
Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment


  • Rod
    Rod Posts: 2,067
    Milk Bottles

    Hi Chris-  Try using a piece of a plastic milk bottle around the pipe as it comes through the floor. I had a expansion squeak  problem on several of my pipes and this seemed to help

    - Rod
  • Jamie Hall
    Jamie Hall Member Posts: 23,313
    Creak, clank...

    This sort of noise is really hard to fix.  Having encouraged you...

    First off, it certainly isn't particularly good to have the mains moving in relation to the boiler.  However, if everything is nice threaded joints, it probably won't do any damage to the boiler -- they're built pretty solidly.  In fact, I would bet that if you were to go down to the boiler and check while someone wandered about upstairs, you might find that the mains -- at least near the boiler -- were being supported by the boiler, not the floor, when the floor deflects, and that at least some of the noise may come from some of the hangars near the boiler being unloaded and then loaded again as the floor moves.

    This may be difficult to fix.  The current more or less standard thinking for timber floors is that the deflection under load should be no more than 1/360 of the span for floors supporting plaster -- or things like pipes.  A typical load would be around 80 pounds per square foot for a residence.  What this means for a span of 12 feet is that the floor should not move more than a quarter inch from no load to full load.  Most older residential floors don't come anywhere near that!  By far the most effective way to reduce excess deflection is to reduce the span with additional columns and beams in the basement.  If the job is well planned, your pipes can be hung from the new beams, instead of the old ceiling, and the deflection problem disappears.

    Another possibility is to support the mains from the floor -- the supports don't have to be that close together (10 feet is more than close enough), and one end can be supported by the boiler in many situations.  This may clutter up the basement, though...

    Reducing of eliminating noise where pipes go through the floor is hard.  There have been several threads on this problem on the Wall over the years -- and, to my recollection, no single good answer.  Try and make sure that the pipes don't actually touch the floor on any side (much easier said than done).  Some folks have suggested putting in a slippery shim between the pipe and the floor where they touch (if they do), such as a piece cut from a milk bottle (don't laugh -- it's been know to work).  Others have tried various lubricant sprays, but not, I think, with much success.

    Other than that, the only other thought I have at the moment is to make sure that where you do have pipe hangers in use that they really are supporting the pipe, and not just sitting there looking decorative.  But if you do adjust hangers, make sure you don't mess up the pitch of the pipe!

    Hope this helps some...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,846
    A couple of suggestions

    In some cases I've been able to wrap a couple of turns of teflon tape around the pipe and slide it into the hole in the woodwork. If you can get it in there it's great because it has a very low static friction coefficient. If that's not practical, try blowing a little talcum powder (real talc, not corn starch) into the gap. It should quiet it down but you might have to repeat it from time to time.

    Have you tried putting a jack post under the center of the floor to stabilize it?
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
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