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Water Leaking or Sweating?

Water was either leaking in or sweating near the seams between the upper wall and roof cap, as indicated by brown stains and wetness at two one foot sections. Conditions:

- Six campers in the U270 for three days (my wife's "Girls  Camping Weekend").
- Outside air temperature was 30 degrees F at night.
- Massive sweating on front windshield.
- All vents closed.
- Heated with furnace.
- Light to moderate rain for five hours.
- I just caulked the outside metal seam / strip at the cap.
- Dried out after camping trip. No further water intrusion, even after a rain event.

Could this have this have just been a sweating event due to excessive humidity?

Anyone know if there is a gap in the foam insulation between the roof cap and wall interface?

Should a vent have been opened all weekend to let out the humid air?

Has anyone else seen this?
1997 U270 34FT Build 5140 Cummins 8.3 Allison 3060R
Solar 1920Watts, 14KWH lithium. Orion BMS.

Re: Water Leaking or Sweating?

Reply #1
Lots of people = lots of humidity

Cold outside, propane heat on = more humidity Single pane windows? = lots of sweating windows +1 for Aquahot and dual pane windows

Tim Fiedler
Gen-Pro.biz
630 240-9139
Tim Fiedler    2025 LTV Unity MBL on Order
2000 Chevy Tracker 2 Door Convertible 4WD Now lifted 4.5"
1985 Citroen 2CV6 Charleston
Murphy Rebel on wheels with 175HP Titan
Cessna P337
1980 48' Westport MY (!/4 Share)

Re: Water Leaking or Sweating?

Reply #2
Yes, camping in your conditions you should always open a roof vent a small amount to address excess humidity.
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Water Leaking or Sweating?

Reply #3
1. Could this have this have just been a sweating event due to excessive humidity?
2. Anyone know if there is a gap in the foam insulation between the roof cap and wall interface?
3. Should a vent have been opened all weekend to let out the humid air?
4. Has anyone else seen this?
Tim,
1. Yes
2. There is an extruded aluminium piece that connects the 2,here is a link to a print of what you have. Coax to rear TV Questions
3. Yes
4. Yes

Pamela & Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Water Leaking or Sweating?

Reply #4

Cold outside, propane heat on = more humidity Single pane windows? = lots of sweating windows +1 for Aquahot and dual pane windows


Tim, are you saying propane heat generates more humidity inside a Coach then a Aquahot?
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago

Re: Water Leaking or Sweating?

Reply #5
Tim, are you saying propane heat generates more humidity inside a Coach then a Aquahot?


No, not correct if referring to propane FURNACE, as combustion gases (which do contain moisture) are exhausted outside.

Yes, true if one were to use a propane heater in the coach-- definitely not recommended because of potential Carbon Monoxide issues.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Water Leaking or Sweating?

Reply #6
Why Burning Propane Makes Water | Sciencing

Tim Fiedler

Sure Start Soft Start
630 240-9139
Tim Fiedler    2025 LTV Unity MBL on Order
2000 Chevy Tracker 2 Door Convertible 4WD Now lifted 4.5"
1985 Citroen 2CV6 Charleston
Murphy Rebel on wheels with 175HP Titan
Cessna P337
1980 48' Westport MY (!/4 Share)

Re: Water Leaking or Sweating?

Reply #7
Agree with Brett as always.

Except my U-270 with dual pane windows always seemed wetter inside than my U-320

Tim Fiedler
Gen-Pro.biz
630 240-9139
Tim Fiedler    2025 LTV Unity MBL on Order
2000 Chevy Tracker 2 Door Convertible 4WD Now lifted 4.5"
1985 Citroen 2CV6 Charleston
Murphy Rebel on wheels with 175HP Titan
Cessna P337
1980 48' Westport MY (!/4 Share)

Re: Water Leaking or Sweating?

Reply #8
If your front window is sweating then chances are very good that other things are also. If your coach has the overhead fan above the front window, you can turn that on and it will move .. some... of the air via that long extruded  aluminum connecting front and back caps. If that doesn't solv the window sweating it's time to crack an overhead vent and turn up the heat.  Yes you will push some of that  precious heat right out of the coach thru the vent.  But we've not found any other way to avoid the sweating.        If my DW sees the sweating, she imediatly starts opening things up and UP goes the heat.    Got to move a lot of air to get that water off that front window.      And we've tryed the dryz the air thing. Not good enough. 
Robert and Susan
 1995 36' 280 WTBI 8.3 3060r
 1200 watts on the roof, 720 Ah of lithium's
 Build # 4637. Motorcade # 17599
        FMCA  # 451505
        18  Wrangler JLUR

Re: Water Leaking or Sweating?

Reply #9
Here is my take on this. 

If the humidity is high inside the coach, the cold windshield will start to sweat, just like a glass with ice in has condensation on the glass. 

A dehumidifier in the coach will help lower the humidity level and thus reduce the sweating on the windshield and other cold items.

Cooking, hot showers, washing, & breathing, all help raise the humidity level.
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago

Re: Water Leaking or Sweating?

Reply #10
Make a Camping World run and pick up a dozen Dri Z Air units, will dry you out quick.
1988  40' Grand Villa Cat 3208t

Re: Water Leaking or Sweating?

Reply #11
Make a Camping World run and pick up a dozen Dri Z Air units, will dry you out quick.

How many pints of water does each unit take out of the air?  What is the process for "drying out" the desiccant?

Have always found that if I need a dehumidifier, I use a 30 pint (per 24 hours) small house-type.

But, to address the OP's issue with high humidity and lots of people and cooking, opening a window all the way forward and turning on the vent fan in the bathroom and running the heater to make it comfortable is really the only choice.  Don't see room in the coach for a dehumidifier with that many people.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Water Leaking or Sweating?

Reply #12
Son has a J44 sailboat. Lives aboard in Seattle with a black Lab and his delightful wife. Huge issues with moisture, leading to mold, etc.
Loaned him my large residential dehumidifier.(he has shore power) Takes up a bunch of space. Kept in Port aft cabin. Within 3 days all problems gone. Emptied 3 x a day at first. Once a day now.
Pretty foolproof if you can find the space

Tim Fiedler
Gen-Pro.biz
630 240-9139
Tim Fiedler    2025 LTV Unity MBL on Order
2000 Chevy Tracker 2 Door Convertible 4WD Now lifted 4.5"
1985 Citroen 2CV6 Charleston
Murphy Rebel on wheels with 175HP Titan
Cessna P337
1980 48' Westport MY (!/4 Share)

Re: Water Leaking or Sweating?

Reply #13
Tim,

Yup, residential 30 pint dehumidifier on motorhome when in storage (live/store in a humid area near the Gulf of Mexico) and in boat when not in use.  Done that for the last 30 years.

Never any mold/mildew or smell in any of them.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Water Leaking or Sweating?

Reply #14
Two side effect of a dehumidifier is it heats the air and it makes it easier to breath by removing moisture from the air and leaving more room for O2
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago

Re: Water Leaking or Sweating?

Reply #15
Went to my usual source Ebay to check prices , what a shock those guys want 3 and 4 times more than CW for Dri Z Air products. The bags of salt should be less than $2, the plastic Space Ship device should be around $5.  You simply fill them up per instructions and dump the water and refill as needed.  We tried the electric dryers, not impressed, too spendy to operate.
1988  40' Grand Villa Cat 3208t

Re: Water Leaking or Sweating?

Reply #16
Six persons, 6 X 1.3 qts equals approx 2 gallons of water each day X 5 days, 10 gallons of water.  And so yes, ventilation is important.

from a study of humidity in a home: "it was found that although the activities of the residents may vary, the amount of water vapour produced by metabolic processes such as respiration and perspiration will average about 0.2 litres per hour or five litres per day. This is 1.25 litres per person per day.

A number of activities were also investigated including bathing, showering, cooking, clothes washing and drying, and floor washing"  These would also add water
97 U295 40, Build #5040, 6C8.3 325 HP
Oregon Continuous Traveler
Samsung Residential #RF20HFENBSR,
Xantrex SW2012, (3)AGM8D Hse, (2)AGM Grp24 Eng, Victron BMV-712, 1800w Solar 4 LG & 2 Sunpower
Extreme Full Body Pt w/hdlmps, new furn/floor, 4 down Lexus 2004 GX470 AWD curb weight 4,740 lbs
Prev: 1990 Barth, 10L 300 2 yrs; 91&92 Monaco Signature, 10 yrs, 10L C 300 &  6C8.3 300; 1997 ForeT 6C8.3 325 since May 2017.  Employed by Guaranty RV 14+ yrs.  Former VW New Car Dlr/Service Dlr, Sales Mgr, Rv Sales, and Service Adviser from 1968-2017
"Don't criticize what you can't understand" Bob Dylan

Re: Water Leaking or Sweating?

Reply #17
Thanks for your thoughtful replies. If I had the time, I would design, build and integrate an HRV (Heat Recovery Ventilator) with the rig.  A blower could exhaust some of the air while drawing in outside air. The two air streams would mix in the HRV core, as shown in this Youtube video:

https://www.youtube.com/watch?v=akkhDjxwIu0

A condensate tube would be fed to bottom of the rig. Look at the end of the video for a completed unit hooked to the kitchen window. This is not a sustainable solution but a solid idea. The fan only draws less than 20 watts.

Nothing like fresh air entering the rig.
1997 U270 34FT Build 5140 Cummins 8.3 Allison 3060R
Solar 1920Watts, 14KWH lithium. Orion BMS.

Re: Water Leaking or Sweating?

Reply #18
The first winter we were full-timing we noticed more condensation than what I expected. A neighbor told us about leaving a vent open. Since then the bathroom vent is nearly always open at least some, and usually most of the way. The Kool-O-Matic doesn't really close, but that also means that some air movement is possible there, too. The window over the kitchen sink is also usually open a bit.

We use the electric heat as much as possible, since electricity is usually included in the camping fee. At night we close the pocket door from kitchen to bathroom most of the way, and the sliding door between bath and bedroom most of the way. The heater cat can then perform her duties without disturbing us, and the heat (mostly) stays in the living area. The bedroom furnace is set at a cool enough temperature that we can sleep well, but high enough that it will come on long before any pipes begin to freeze. There is also a small electric heater in the wet bay.

 

Re: Water Leaking or Sweating?

Reply #19
When we lived up in the PNW, a de-humid was a must. Now, down here in the deep desert, it's the opposite!
1993 U-240 "La Villa Grande"..CAT 3116 w/ Pacbrake PRXB...Allison 3060 6-speed..
Previous: 1983 Airstream 310 turbo diesel, 1979 Airstream 280 turbo diesel
                                      Build # 4297
                                      PNW natives
                      Home base:  'Cactus Hug' (Ajo, Arizona)
                        DW Judy & Chet the wonder dog
                        Full-Timers 'Sailing the asphalt sea'