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dolfan 05-27-2013 11:58 AM

sweating in craawl space
House has the vents opened and the water pipes side is out of the late morning /pm sun. The pipes and half of the water tank has sweat on them and places/spots of the plastic does also. Is this ok/normal if not what can I do? I have a small fan 10 or 12 inch I guess I can use sometimes when home. thanks

nealtw 05-27-2013 03:29 PM

The water in the tank and pipes is colder than the air. The air has high water content and when the air comes in contact with the cooler tank the air cools and the moisture in the air condences on the cooler tank and pipes.

drewdin 05-28-2013 08:21 AM

I have been told that if the pipes sweat you need to insulate them, is that correct guys?

nealtw 05-28-2013 09:32 AM

Insulation can help but if this is indicating other problems like high humidity that may need to be addressed too. If the humidy is much higher in the basement than it is outside could indicate small leaks in plumbing somewhere in the house, perimeter drain or foundation waterproofing not doing it's job.

WindowsonWashington 05-31-2013 06:45 AM


What is the vapor control layer like at the floor level? Is it sealed at the wall and piers?

Is there ductwork in the crawl?

dolfan 05-31-2013 05:55 PM

There is black plastic on the ground. Yes there is ductwork there and the dryer vent is close to the water tank/pipes. I have been under there with the dryer on and it is not leaking.

nealtw 05-31-2013 06:58 PM

The crawl space should have good cross ventulation to remove moisture.

WindowsonWashington 06-01-2013 07:13 AM

I would recommend converting the crawlspace to a conditioned type if there is already ductwork in there and the grading is good.

GBR 06-01-2013 04:23 PM

I agree. If no ductwork down there, air seal all gaps/holes in the subfloor; tub drain, plumbing vent stacks, wiring holes, etc, that could add moisture from the crawlspace to the conditioned house areas, pp. 6-11;

Or just used some closed cell pipe insulation on the pipes and foamboard the joists to stop vapor diffusion/leaks through the wood floors. Especially if no plywood sheeting rather than solid wood deck boards; Fig.7;


nealtw 06-02-2013 09:51 PM


Originally Posted by WindowsonWashington (Post 87611)
I would recommend converting the crawlspace to a conditioned type if there is already ductwork in there and the grading is good.

A few years ago we had a few people saying to close up the crawl space and I asked a few questions, as you can see, I got no answers. Perhaps you want to try.

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