Water Pipes located directly under sub-floor normal ???

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Joined: Mon Jun 06, 2011 2:19 am

Tue Sep 29, 2015 2:50 pm

I had a worker cutting out my particleboard floors. Because mobile homes from the 70's were put together in wacky ways, he accidentally cut right through a galvanized water line and we had to replace the pipe.

The pipe wasn't even at the bottom area of the joist. It was actually right under the sub floor at the very top!

Based on what I have seen in my floors in the past, I told him, this was how they originally built it.

But he thinks that someone had actually opened this floor up before and didn't know what they were doing when they added this pipe which runs from the main inlet on one side of home to the water heater on the opposite side.

Now we have a friendly argument as to who is correct.

Can anyone confirm that it's not uncommon to find water lines right under the sub floor (and in some cases running across the top of air ducts) in old mobile homes.

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Tue Sep 29, 2015 5:06 pm

In 70's and earlier mobile homes, it is common to find plumbing, usually polybutylene PB pipe right against the bottom of the particle board subfloor. I have not seen galvanized pipe factory installed, so this may well be a repair. But it makes sense that the person doing the repair would mimic the pipe he is replacing. Be careful with saws on these older floors. You could just as easily find hot romex.

I set my saw just a hair under 5/8" when I cut. The floor will bust out easy from there. Against walls or places where you need to use a sawzall, I will carefully bust out a 6"x6" hole, just using the nailing head of my hammer, then feel around the cut area to be sure there are no pipes or wires. If you do this every time, every single time, after enough years, it will still trick you. :)
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All information and advice given is for entertainment and informational purposes only. The person doing the work is solely responsible to insure that their work complies with their local building code and OSHA safety regulations.