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Old 05-07-2015, 06:34 PM   #1
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THOR #1469
Insulating A Pillars - Condensation?

For all of you that have posted on threads about insulating the A pillars on your motorhomes by stuffing them with mat insulation, or some other form of insulating material, have you given any consideration to the possibility of condensation buildup on or in the A pillar as a result of the reduced air circulation through the pillar?

If so, what if any issues/risks did you identify and how do you plan to mitigate those risks?

Right now I see the potential for a condensation build up due to uneven temps between the inside and outside sections of the pillars and with the elimination of air circulation the potential for corrosion working inside out on the pillars.

You thoughts would be welcome. I am thinking about how best to tackle the A pillars in an attempt to decrease noise levels inside the coach while travelling and have some concerns about just "stuffing insulation inside the A pillars".
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Old 05-07-2015, 07:54 PM   #2
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Gee, thanks. Hadn't considered that.

I've stuffed a camera up both sides on the Axis and there is nothing there other than the radio antenna cable on the driver's side so there's not much that a little moisture would hurt. It's all glass, plastic, and fiberglass.

I'm going to guess ('cause I want it to be true ) that filling the voids will actually reduce air infiltration from the coach and maybe reduce condensation a bit? It may be worth tugging the stuff out and replacing it every couple of years though.

In the Axis the pillars rattle terribly as well as channeling wind and engine noise into the cab. They are only attached on one edge; the other edge is free to clatter and bang against the windshield. Packing the insulation has nearly eliminated that. I really don't want to go back to the din!

Randy
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Old 05-07-2015, 10:08 PM   #3
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Originally Posted by groswald View Post
Gee, thanks. Hadn't considered that.

I've stuffed a camera up both sides on the Axis and there is nothing there other than the radio antenna cable on the driver's side so there's not much that a little moisture would hurt. It's all glass, plastic, and fiberglass.

I'm going to guess ('cause I want it to be true ) that filling the voids will actually reduce air infiltration from the coach and maybe reduce condensation a bit? It may be worth tugging the stuff out and replacing it every couple of years though.

In the Axis the pillars rattle terribly as well as channeling wind and engine noise into the cab. They are only attached on one edge; the other edge is free to clatter and bang against the windshield. Packing the insulation has nearly eliminated that. I really don't want to go back to the din!

Randy
I'm not positive but I imagine my A pillars are similar to yours in that the bottoms are outside the cab and the tops are inside the cab, basically coming through the front corners of the dash. This in and of itself concerns me in that under normal operating there will be a difference in temperatures between the inside and outside section of the pillars creating the perfect situation for condensation. It could cause a condition where condensation builds up on the outside of the inside cab section of the pillars and you start seeing moisture on the inside trim pieces. Albeit, this may not occur during short trips or trips not requiring inside heat or AC use etc... but since I do go out in sub freezing temps early and late in the year, I can see where this may be an issue especially rolling down the road with the front window defroster running on high temp.

Also, although I did not yet look, you confirmed one suspicion that the A pillars must have holes for cables, unused bolt hoes etc.. which will allow air to enter into the pillars. My concern here is the build up of condensation over time and the infiltration of oxygen may allow the build up of corrosion on the inside of the pillars, thereby weakening their structural integrity over time.

I agree from just looking at the pillars that they are a funnel for noise wind and everything else. I wonder if anyone has found a birds nest in theirs yet?

Since I am not an expert in the area of insulation and condensation maybe my concerns are unfounded, but I don't think so. Just look at what happens with a cold beer after a minute out of the refrigerator or a container of warm food placed in the fridge. Also, in houses they put soffit vents and air channels in before insulating in an attempt to minimize condensation from being absorbed by the wood.

Bottom line for me is to not implement a short term or hasty fix that results in long term or expensive issues with corrosion of the A pillars.

Heck, maybe I'm over thinking this.
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Old 05-07-2015, 11:22 PM   #4
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Originally Posted by dstankov
Just look at what happens with a cold beer after a minute out of the refrigerator or a container of warm food placed in the fridge.
Except that a cold beer can is made out of aluminum: Aluminum transmits heat very efficiently (which is why pots & pans are made out of metal). Fiberglass is an insulator and thus you won't get the inside or outside temperatures "transmitted" across the fiberglass that would cause condensation in the first place.

I would think that even in sub-zero temps the engine compartment will still be heated by the engine and thus you won't get sub-zero temp air going up into the A-pillar. Especially if you close off the end with some fatmat: no airflow going in to introduce any humidity to cause condensation. In addition: if the end is closed off the A-pillar will probably just assume the temp that is inside the cab and thus the gradient across it won't be near freezing anywhere enough to cause condensation.

I'm no expert but my gut is telling me this is no worse an issue than simply camping in cold weather where you get tons of condensation simply because the unit is closed up and everyone's breath introduces humidity in the air (the few time's we've camped in cold weather the windows were dripping wet in the morning due to us & the furnace).
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Old 05-08-2015, 01:04 AM   #5
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Originally Posted by JamieGeek View Post
Except that a cold beer can is made out of aluminum: Aluminum transmits heat very efficiently (which is why pots & pans are made out of metal). Fiberglass is an insulator and thus you won't get the inside or outside temperatures "transmitted" across the fiberglass that would cause condensation in the first place.
Just brain storming here

Beer bottles, as well as soda bottles (which condense with temp changes) are also made from glass and plastic. Pots and pans are also made from steel, cast iron, and copper. If I am not mistaken when aluminum and steel are heated to the same temperature steel holds a higher temperature longer than aluminum during the cool down cycle.

On my coach the A pillar is not in what I would consider the engine compartment. My A pillars are 2 feet to the sides of the leading edge of the AC condenser mounted on the front of the radiator. Any cold air coming in the grill or through the wheel wells is being blown on the A pillars sections exposed to the elements. If I were a betting man I would wager on after an 8 hour drive the temp of the outside sections of the A pillar being closer to the outside ambient temperature than they are to the temp around the engine or inside the coach.

Fiberglass does not absorb moisture. Moisture will sit on fiberglass until it is channeled away or is absorbed by surrounding materials. Since steel does not absorb moisture there is the potential for moisture to collect on densely packed insulation if that is what is stuffed inside the A pillar. That moisture in contact with steel and in the presence of air has the ability to cause corrosion. There is a reason why, at least in Virginia, the building codes require an air channel between the roof sheathing and fiberglass bat insulation or an air channel from the soffit going higher than the level of blown insulation and blown insulation cannot be in direct contact with the roof sheathing. It all has to do with air circulation and moisture control.

Maybe the solution for the A pillars is some type of foam that will add in sound deadening, provide some level of insulation but allow for moisture to wick through and out. Maybe the solution is to install some type of setup that can be installed while traveling yet be removed when parked to allow for air circulation.

Maybe the solution is to wrap the A pillars with sound deadening and then cap the ends to eliminate wind without the use of insulation.

Maybe the solution is as simple as stuffing the A pillar full of fiberglass.

What I do know is that when I think about the cost of replacing an A pillar, I want to get it right or at least as close to right as possible. I plan on doing something but I do not want to create a mountain of trouble for a mound of comfort.
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Old 05-08-2015, 02:10 AM   #6
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Quote:
Originally Posted by dstankov
On my coach the A pillar is not in what I would consider the engine compartment. My A pillars are 2 feet to the sides of the leading edge of the AC condenser mounted on the front of the radiator.
That could be the difference between your F53 chassis and my E-350 chassis. Our pillars seem to be about even with the radiator.

Another thought: Find someone with an older Class A Thor built on the same chassis--Thor has been doing this for a while. They may have some insight...
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Old 05-08-2015, 02:11 AM   #7
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My Axis pillars appear to be quite sealed off from the factory.

Many other sealed tube/hollow areas in a typical RV structure unless it's all wood.
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Old 05-08-2015, 02:53 AM   #8
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Originally Posted by JamieGeek View Post
That could be the difference between your F53 chassis and my E-350 chassis. Our pillars seem to be about even with the radiator.
My pillars are about 6 to 12 inches behind the headlights and sit about midway between the headlights and leading edge of the front tires and in line with the coach battery. To put that in perspective my radiator is about 18 to 24 inches away from the front grill. I can actually climb inside and somewhat stand inside the front clip between the grill and radiator.

I believe any sound coming through my A pillars would be tire or road whine more than engine noise.

Another difference I believe is that only the top one or two inches of the engine protrudes through the floor in my coach. As you can see from the attached photo even the valve covers are below the level of the floor. I believe they could cut my doghouse in half (height) and still clear the top of the engine. This could be why my initial sound level readings seem to be lower than what others have experienced and why the Challenger seems to be a quieter ride than other coach models. I do believe however, there is room for improvement.

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Quote:
Originally Posted by JamieGeek View Post
Another thought: Find someone with an older Class A Thor built on the same chassis--Thor has been doing this for a while. They may have some insight...
Thanks for the suggestion. There is an individual who is a member of one of my FMCA chapters that buys restores/remodels and sells used motorhomes for a hobby/second income. He winters in Florida but his shop is at the other end of my county so I may give him a call or visit and see what he has found in the past. He has dealt with everything from the smallest class Cs to the largest diesel pushers so he may have some suggestions or "best practices".
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Old 05-08-2015, 03:09 AM   #9
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Your engine is much more exposed than ours is. Ours appears further forward:

The front "hood" on the Axis/Vegas units pretty much touches the radiator:

A big difference between the larger F53 units and our smaller E350 units.

Another difference: Sitting in the driver's seat you are pretty much sitting on top of the front wheel. In the Axis/Vegas units we are behind the front wheel.

I'm sure both of those differences changes the noise a bit, for example: since our engine is further forward it may not make as much sense for us to insulate the floor from noise.
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Old 05-08-2015, 12:38 PM   #10
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Originally Posted by JamieGeek View Post
Your engine is much more exposed than ours is. Ours appears further forward:

The front "hood" on the Axis/Vegas units pretty much touches the radiator:

A big difference between the larger F53 units and our smaller E350 units.

Another difference: Sitting in the driver's seat you are pretty much sitting on top of the front wheel. In the Axis/Vegas units we are behind the front wheel.

I'm sure both of those differences changes the noise a bit, for example: since our engine is further forward it may not make as much sense for us to insulate the floor from noise.
Yeah, when I'm driving down the road I can access the control panel for my leveling jacks easier than I can reach the controls for heat and AC. Sitting in the drivers seat at full arm extension my finger tip are a good 12 inches from reaching the heater controls. I am 5 foot 11 tall and wear 34 inch shirt sleeves.

One of the major differences I immediately see is the majority of noise making engine components (e.g. valve train, exhaust manifolds, etc... are level with or higher than your floor and are contained/confined within the doghouse. In my coach all of these areas are lower than the floor and as you stated why it may be more beneficial for me to sound deaden the underside of the floor pans than it would be for you.

A suggestion for you to consider, in you engine compartment the flat panel that runs from side to side and has the air ducting attached, just from looking at the picture I can see where, if that is below your dash panel, you may get a transference of vibration or wind related noise going inside the cab. It's hard to tell from the picture but I'd look for hard mounting points between that panel and the interior surfaces and if I found any I'd use some sound deadening material to cut the vibration. In my house, I learned this trick when re-mounting a garage door opener where there was a bedroom above the garage. The addition of a rubber seal between the mounting bracket and the ceiling and some rubber washers for the lag bolts allowed my daughter to sleep through me going to work at 5:30 every morning and allowed me to park the car in the garage on weeknights. In that case the noise of the garage door opener was transferred to the room above through the vibration of the mount on the ceiling and lag bolts in the joints (garage ceiling joists were the bedroom floor joists.

In the case of my doghouse I expect to gain additional benefit from tackling vibration as well as reducing engine noise. Not only am I going to add insulation to the interior of the doghouse but I am going to tackle where the doghouse mounts to the coach (in my case 4 screws) and the surface area where the doghouse comes in contact with the floor. I believe that will reduce the vibration related noise of the doghouse itself and reduce rattling of things thrown in the tray and cup holders on top of the doghouse.

As a side note, another area I plan to tackle are the mounting points for the converter/charger and the inverter. I noticed fan related noise from these components and since they are outside I believe the noise is being transferred inside from vibration on or around the mounting points. By tackling these two items maybe (operative word) I can increase the noise level comfort while parked as well as while driving (primarily the inverter). My inverter is right below the drivers seat.
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Old 05-08-2015, 01:46 PM   #11
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Quote:
Originally Posted by dstankov
A suggestion for you to consider, in you engine compartment the flat panel that runs from side to side and has the air ducting attached, just from looking at the picture I can see where, if that is below your dash panel, you may get a transference of vibration or wind related noise going inside the cab. It's hard to tell from the picture but I'd look for hard mounting points between that panel and the interior surfaces and if I found any I'd use some sound deadening material to cut the vibration.
Good point. That piece of plastic is rather flimsy and may vibrate while going down the road. The dash panel is above that by about a foot. The ducting is the intake for the automotive climate system.

In our Axis we do have a good amount of wind noise that sounds like some is getting around the dash panel--something I hope I've already fixed with the fatmat sealing off the sides of the dash panel.

This has been a very interesting discussion.
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Old 05-08-2015, 03:33 PM   #12
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Originally Posted by JamieGeek View Post
Good point. That piece of plastic is rather flimsy and may vibrate while going down the road. The dash panel is above that by about a foot. The ducting is the intake for the automotive climate system.

In our Axis we do have a good amount of wind noise that sounds like some is getting around the dash panel--something I hope I've already fixed with the fatmat sealing off the sides of the dash panel.

This has been a very interesting discussion.
Another interesting example of the effects of vibration and sound. In my house I have a relatively open floor plan. One day my wife, myself and some friends gathered for a movie night. In my family room I have my television connected to an AV receiver with full surround sound. During the movie I noticed an on again - off again rattling noise in the room and it drove me nuts. I spent three days trying to figure out what was happening and blamed everything from the TV to the receiver and the wife's knick knacks. Turns out I needed to blame my wife. The day of movie night she pulled the refrigerator and stove away from the walls for cleaning. When she pushed the refrigerator back she went too far and the plastic water line for the water dispenser was resting against the wall. When the refrig motor would kick in it would cause the water line to vibrate against the wall and cause the vibration related sound to carry through the interior (non-insulated) walls into the family room. The solution to the problem, pull the refrigerator out from the wall 1/4 inch. The moral to that story, never tell my wife something is her fault. Since then I have always had to move the frig and stove for cleaning because in her words "she can't do it right".

Insulating the side of the dash may not completely solve your problem if there are other components connected from that panel to the dash if those components are not "vibration proofed".

As a note, as proven during many hearing tests while on active duty and since retirement, there are many sound levels that I cannot hear through the ear canal but I can hear through vibrations hitting the base of the skull and traveling to the inner ear. My wife likes to say I am deaf in one ear and can't hear out the other (too many years around things going boom in the night). She now suspects my hearing aid has an on/off switch and she has started watching my left hand while talking to me. She thinks the back of my left ear itching whenever she is talking is too coincidental. Hey, it took over 25 years for her to become suspicious of that little trick, and she's still not certain. BTW, no on/off switch but there is a volume control which serves the same purpose.
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Old 05-09-2015, 04:22 PM   #13
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TyCreek's picture got me thinking. Here's a similar shot of my coach (on the other side). Notice anything missing - besides insulation, that is? Sorry it's a bit blurry.



How about now?



That lonely self-tapping sheet metal screw should be securing an angle bracket that itself secures the dash to the nice steel structural member. It's now clear why my dash bounces any time there is a gusty headwind.

I've got some FatMat on order, but this will have to be fixed before I can install that.

TyCreek - thanks for posting that picture!

Regards,

Randy
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