Moisture meter readings Keystone Passport 221BH

mikehoyt

Advanced Member
Joined
Apr 8, 2024
Posts
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I have this MasterCraft pinless moisture meter and used it to check for moisture on our 2022 Keystone Passport 221BH. (Note that this is a captured image from the web. Our readings were not 73% !)
MasterCraftMoistureMeter.jpg


The meter showed elevated reading immediately beside slide on front and back. Am assuming this is some sort of aluminum or other metal framing for the slide? It extends 5 to 6 inches from the side of the slide on both sides. I also see elevated readings forward below where the front cap meets the roof on both left and right sides. Am guessing this is from leak at that joint or perhaps maybe something structural?

Have added Dicor self levelling sealant over entire area of the existing sealant on joint from roof to front cap. The old sealant was showing signs of cracking from exposure to UV and other elements and was beginning to look like a dried up lake bed mud floor. Have not yet addressed the non sag Dicor black sealant on sides of trailer just below this joint

Any comments or wisdom on all of this?

Thanks

Mike Hoyt
2022 Passport 221BH (purchased new in 2024)
 
I used to own a fire & water damage restoration company. What you have is called a non-destructive moisture meter. It uses ultrasound (like a stud finder) to measure variances in material density (wet material is more dense than dry material). Some only read 1/2" deep, some read 1" or more deep. They are really not suitable for measuring moisture on an RV wall due to the framing, glue, insulation, fiberglass exterior, Luan plywood interior, etc. Sometimes even the wall paper will make the readings appear "off". I can be used as a rough guide, but in this application I would not trust it for anything but entertainment.
 
I used to own a fire & water damage restoration company. What you have is called a non-destructive moisture meter. It uses ultrasound (like a stud finder) to measure variances in material density (wet material is more dense than dry material). Some only read 1/2" deep, some read 1" or more deep. They are really not suitable for measuring moisture on an RV wall due to the framing, glue, insulation, fiberglass exterior, Luan plywood interior, etc. Sometimes even the wall paper will make the readings appear "off". I can be used as a rough guide, but in this application I would not trust it for anything but entertainment.
Thank You

I used this from the outside. I have it to test moisture readings on the balsa cored deck of a sailboat. It is more useful there

We have noted an odd odour this year that seems a combination of chemical and mustiness but cannot say exactly. Have not found the source and it goes away when we air out the trailer and comes back when closed up for a couple days. For this reason am looking at all seals on the roof and silicon around openings. Trailer was purchased new June 2024 but sat outside on lot for 2 years so have to check UV damage to self levelling sealant, etc ...

Mike
 
To be clear, is this a new odor or one thats been there from day one? Trailers can often smell "chemical" inside when new because chemical off gassing is occurring. All the carpets, floor coverings, wall coverings, furniture coverings, construction adhesives etc. Will off gass chemicals. It can take quite some time to air out these odors.
 
To be clear, is this a new odor or one thats been there from day one? Trailers can often smell "chemical" inside when new because chemical off gassing is occurring. All the carpets, floor coverings, wall coverings, furniture coverings, construction adhesives etc. Will off gass chemicals. It can take quite some time to air out these odors.
There was no odor last year. Only this Spring after the weather warmed a bit did we notice it. Is faint and we cannot tell which area it is coming from. Suspect could be leak but have not found much evidence of one other than the odor.

Had thought possibly the enclosed underbelly but have not investigated that yet. No odor coming from hot/cold water lines coming from there under kitchen sink. Also considered grey water tank odor? Is a bit of a mystery

Mike
 
Gray tank odors can enter the cabin via air admittance valves but that smell would be evident under the sink.
 
Depending on where you park it and how tight the underbelly is sealed, it is easy to have some small unwanted visitors down there. You can pull up a floor register and pull the metal duct boot out, disconnect the mylar duct (basically a cheap, thin, lightweight dryer vent hose). Then you can look down into the belly area from above for any signs of Mickey Mouse and his friends, or poke your smart phone down there in video mode and pan around and see if there is anything obvious.
 
Musty/chemical? Just from personal experience, my mind always goes to rodents first. Above the ceiling is another possibility.

One of the blessings of living in desert Arizona is that dead rodents "bake off" in about a week, followed by a week of blueflies, then it's like they were never there.
 
Over the weekend I pulled up floor register and looked around with phone on video with flash on. Did not see anything. Could only see a small section of area though. I then took a great big sniff with the register out and my nose in the opening. Nothing.

I do note that when I have this odor it can actually almost sting my eyes at times? It is an odd smell. This was while I had household dehumidifier running continuously and a fan also continuous. Yesterday I ran the AC unit in fan mode on high for 2 hours and then AC on low for two hours in case the odor was that system needing airing. Afterward no real change. This morning when I checked the odor was however reduced noticably.

Note that if I open windows and let air for two days it goes away and is not noticeable while we are using the camper.

It is a weird smell.
 
Glad that you were able to take a peek in the belly. At a minimum, it helps set a baseline in the event of a future issue.

So now it seems to indicate that you may have a chemical off-gassing from the materials used to build the camper as others have noted. There is a reason why every RV made comes with one or more of these labels. It is especially common in the lighter weight campers because they use a majority of composite or manmade wood products and finishes as opposed to natural or solid wood.

For what it's worth, a spider plant happens to do a great job in removing formaldehyde and other airborne toxins. NASA even conducted a study that found that a spider plant could remove 95% of formaldehyde from a sealed space within 24 hours. It couldn't hurt to pick up a spider plant and keep it in the camper between trips and maybe it will help mitigate the odor/irritants.

2025-06-23_09-04-01.jpg
 
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Glad that you were able to take a peek in the belly. At a minimum, it helps set a baseline in the event of a future issue.

So now it seems to indicate that you may have a chemical off-gassing from the materials used to build the camper as others have noted. There is a reason why every RV made comes with one or more of these labels. It is especially common in the lighter weight campers because they use a majority of composite or manmade wood products and finishes as opposed to natural or solid wood.

For what it's worth, a spider plant happens to do a great job in removing formaldehyde and other airborne toxins. NASA even conducted a study that found that a spider plant could remove 95% of formaldehyde from a sealed space within 24 hours. It couldn't hurt to pick up a spider plant and keep it in the camper between trips and maybe it will help mitigate the odor/irritants.

View attachment 1321709
Interesting. I am starting to think is a combination of events. Likely some water ingress and then possibly the off gassing as suggested. Hence the combination of two smells? Running the fan on high with closed up camper likely drives out these smells into the cabin more forcefully.

Note that I applied two full tubes of the self levelling Dicor over the old sealant on roof where it meets front cap. This has fully covered all the old sealant was suggested by dealer to be ok. Have also applied the black non sag sealant over those areas on the sides. If any water was getting in from there in the past it no longer will now

Next is to find a spider plant!

Mike
 
To be clear, is this a new odor or one thats been there from day one? Trailers can often smell "chemical" inside when new because chemical off gassing is occurring. All the carpets, floor coverings, wall coverings, furniture coverings, construction adhesives etc. Will off gass chemicals. It can take quite some time to air out these odors.
There was no discernable odor last year when we purchased. Only noticed this Spring after the weather warmed
 
Port Side moisture.jpg


The attached photo shows where moisture meter shows elevated readings (inside red circle). I realize moisture meters are not always accurate by themselves but I like to think is useful to compare to readings in other areas. In this one area it reads low 20% to high 31%. Surrounding areas 4% to less than 13%. This is measured from the outside. On the other side of the trailer in the same area it had also read higher but as time went on the numbers lowered significantly

To date I have covered the existing self-leveling sealant on the roof where roof meets front cap with a new layer of self leveling dicor product with the blessing of my dealer. Also on the sides in these areas there is black non sag dicor which I touched up any area that looked like could be an entry point for moisture. The black areas did not look degraded. The self leveling on the roof had looked like a cracked dessert floor but the sealant was not loose or crumbly

Inside I closed all windows and ran a floor model household fan on high for 5 days as well as a household full sized dehumidifier for the same five days. Had fan pointed at front of trailer for three days and then the inside of the area in the photo the last day

I noted that initially the odor/whatever was much more noticeable with the fan/dehumidifier running than it was before. After three or four days it diminished considerably. As of today I have turned off dehumidifier and fan and opened all windows. Weather has been mostly sunny during this time with only one overnight rainy period.

Have not detected any strong odor in any cupboard, drawer, cabinet or even when sticking my nose in underbelly (via floor vent removal).

Have not found a spider plant yet but that does sound like a great idea.

Seems odd to have off-gassing now. Trailer was manufactured 2022, sat on lot for 2 years and then purchased new June 2024 and used on a number of weekend trips. Was not discernable odor last year. Trailer was stored beside our house on a section of lawn for the winter. Odor only commenced once the winter ended and temps warmed. My wife did find a potato in the pantry that lived there all winter but it has been removed for nearly 6 weeks now.

Life with an RV is fun. Lots of projects constantly. Takes up almost as much time as my sailboat that was manufactured in 1987

Thanks

Mike
2022 Passport 221BH
1987 Frers 33
 
Did you inspect/reseal UNDER the aluminum molding that is along the top edge of each side of your trailer??? It' covers the "overlapped TPO membrane" to seal the roof to the sidewall. On that aluminum molding is a vinyl "screw cover trim strip" that is an insert that attaches to the aluminum molding strip and covers the screws that hold the aluminum molding to the trailer sidewall. Often times that vinyl trim strip can leak, especially at the forward edge of the trailer where the "gutter drip molding" is attached. Water rolls off the roof near that front cap/roof joiner strip, into the aluminum molding that serves as a gutter, often rolls over the side, around the edges of the vinyl trim strip and then finds the screws holding the molding to the trailer FILON and wicks into the core of the laminated sidewall through those screw threads... If you pull the vinyl trim, look carefully for any signs of moisture under the vinyl and then "one by one" remove any of the screws in those areas, use sealant to fill the hole and reinsert the screw, then cover the screw head with a dab of sealant as a "secondary measure"... Many trailers that I've seen, even those with "gobs and gobs of sealant" around the ends of the front cap/roof joiner strip seem to have some space where water can find its way under the side aluminum molding and then wicks into the screw threads and into the foam core of the sidewalls.....
 
Did you inspect/reseal UNDER the aluminum molding that is along the top edge of each side of your trailer??? It' covers the "overlapped TPO membrane" to seal the roof to the sidewall. On that aluminum molding is a vinyl "screw cover trim strip" that is an insert that attaches to the aluminum molding strip and covers the screws that hold the aluminum molding to the trailer sidewall. Often times that vinyl trim strip can leak, especially at the forward edge of the trailer where the "gutter drip molding" is attached. Water rolls off the roof near that front cap/roof joiner strip, into the aluminum molding that serves as a gutter, often rolls over the side, around the edges of the vinyl trim strip and then finds the screws holding the molding to the trailer FILON and wicks into the core of the laminated sidewall through those screw threads... If you pull the vinyl trim, look carefully for any signs of moisture under the vinyl and then "one by one" remove any of the screws in those areas, use sealant to fill the hole and reinsert the screw, then cover the screw head with a dab of sealant as a "secondary measure"... Many trailers that I've seen, even those with "gobs and gobs of sealant" around the ends of the front cap/roof joiner strip seem to have some space where water can find its way under the side aluminum molding and then wicks into the screw threads and into the foam core of the sidewalls.....
Thank you John

I will look for this. I have not as yet noted any screws so they may be under that mass of black sealant

Mike
 
Thank you John

I will look for this. I have not as yet noted any screws so they may be under that mass of black sealant

Mike
Mike, There is a black vinyl insert strip covering the screws on the aluminum molding strip that runs along the top of each side of the trailer. You have to "squeeze the sides of the vinyl strip to access the screws holding the aluminum molding in place. That "vinyl screw cover" is intended to prevent moisture from reaching the screws, but at the same time, if there's a leak and water is flowing UNDER the vinyl strip, it acts to "assure water reaches the screws"...

ADDED: Here is a photo of a strip of aluminum molding (yours will probably be a little different shape) with the vinyl trim "screw cover" inserted. As you can see, squeeze the edges and it will come out of the aluminum tracks. It's not easy to reinsert, so don't start the project of removing, inspecting and reinserting it at close to dusk on a busy evening....
 

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Mike, There is a black vinyl insert strip covering the screws on the aluminum molding strip that runs along the top of each side of the trailer. You have to "squeeze the sides of the vinyl strip to access the screws holding the aluminum molding in place. That "vinyl screw cover" is intended to prevent moisture from reaching the screws, but at the same time, if there's a leak and water is flowing UNDER the vinyl strip, it acts to "assure water reaches the screws"...

ADDED: Here is a photo of a strip of aluminum molding (yours will probably be a little different shape) with the vinyl trim "screw cover" inserted. As you can see, squeeze the edges and it will come out of the aluminum tracks. It's not easy to reinsert, so don't start the project of removing, inspecting and reinserting it at close to dusk on a busy evening....
Thank you John

Ours is a bit different but now I think I know where to look. This makes a lot of sense

Mike
 
So I temoved the strip. No sealant around the screws. I removed this section of screws, filled holes with Dicor black non sag and coated screws before replacing screws

There is a bead of sealant where top edge of aluminun meets toof (I put there 2 weeks ago).

Next question. Are these staples? Looks like were used to hold strips in place during installation. Then screws to secure. Looks like staples do nothing now but could also leak.

The game continues

Mike hoyt
2022 passport 221bh
 

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