FWC Single Sheet Roof "Tin Canning"...Why?

[Wallowa]

Casa,

Yes indeed I bought the Hawk new in 2016....first off FWC does not believe this issue of oil canning in those FWCs with single top sheets is 'significant'. They do not believe enough owners are having this problem to warrant them addressing it. I understand them blindsiding this problem because there is no apparent correction possible for the deformed top sheet.

Aside from that; I do not believe there is a retro-remedy to remove the slack waves in the aluminum sheet generating the oil canning noise. Replace all top sheets that are oil canning? With what? Not a viable option unless there is a design or materials alteration before the top sheets are replaced. I think FWC makes a great product but they screwed up in not considering the consequences of oil canning with the single top sheet.

We have some very bright folks [not me...them] on this forum, including material engineers and as of yet a true correction for this deformation has not been discovered. In other applications a quilting of ridges may prevent the deforming of the top sheet, but who knows? Tough call of balancing weight by adding cross struts and VHB or adding ridges against the ability of owners to lift the top into place as weight is added. Still uncertain if top sheet is stretching [highly possible since deformation is seen] and if so, by how much and will it continue.

Hey, noise canceling ear plugs are an option!

Phil

Ps...How many FWC owners with single top sheets are experiencing this problem of oil canning and the booming racket in high winds? Who knows, but a better question is how many with this problem does it take for FWC to address this issue? It comes down to future sales and potential cost of rectifying those campers with this problem versus turning a blind eye and saying the issue is insignificant. Perhaps "it ain't no big deal", unless you are trying to sleep with the rifle shoots of oil canning just over your head.

 

[Vic Harder]

Phil, has FWC not said that during manufacture, the one piece roof sheet is glued to the roof members with VHB? And you can clearly see that they are NOT presently adhering to said structure? If so, sounds like a manufacturing flaw.

 

[Wallowa]

Phil, has FWC not said that during manufacture, the one piece roof sheet is glued to the roof members with VHB? And you can clearly see that they are NOT presently adhering to said structure? If so, sounds like a manufacturing flaw.

True Vic...but design or material flaw and or manufacturing errors?

How would the top sheet deform and produce the slack seen in the top sheet? Flopping up and down unattached to struts should not stretch the top sheet material if that material was of correct thickness and design. Even if VHB failed or was insufficient to anchor the top sheet.

 

[Vic Harder]

Who cares why the problem has happened? You say the top sheet is not attached, and that it is supposed to be attached. Have we got confirmation that IF still attached, oil canning does not occur? If so, the best bet might be to take it the factory and have them take your roof off and restore it to factory condition.

 

[BBZ]

IMO.. they aren't going to fix all the roofs that are not attached anymore, there would hundreds at the very least.. Mine, 2013 is unattached all over the roof, looks like a wave.. mostly, not a big issue unless in windy conditions.. but its kind of a bummer that they won't acknowledge its a problem.. ( had a 80s grandby with a 2 piece roof and a million screws and there were no issues ever)

Clearly a design flaw..

 

[Wallowa]

Who cares why the problem has happened? You say the top sheet is not attached, and that it is supposed to be attached. Have we got confirmation that IF still attached, oil canning does not occur? If so, the best bet might be to take it the factory and have them take your roof off and restore it to factory condition.

Exactly...at this point why is not the question...but how to remedy the problem....simply replacing a defective top sheet with another defective design/manufacturing identical to one that failed is not a solution but a "ground hog day" which will just again repeat the oil canning issue. "Factory condition" is the 'condition' that failed in the first place.

 

[ckent323]

Vic, I think you asked a reasonable question "Have we got confirmation that IF still attached, oil canning does not occur?"

I am wondering if there is photographic evidence of a roof (or several roofs) experiencing oil canning for which detachment of the roof from the rafters (or roof support beams) has been documented? Is there a documented cause and effect for the oil canning or is it just guesses and assumptions?

I realize answering that question requires exposing the roof to rafter interface by some means - maybe by removing the headliner and insulation in the ceiling. I don't recall reading that anyone has done that.

If there are photos they need to be sent to FWC.

Other questions:

Do any two piece roofs have oil caning problems? If not why not?

Are the one piece roofs the only models with the roof not being screwed down and held by VHB tape?

 

[Casa Escarlata Robles Too]

I would think that the roof material used by ATC (two piece) shouldn't have the oil canning problem
due to 1 they are screwed down , 2 they have a corrugated surface,and 3 the insulation used by ATC
is fiberglass batting,which IMO help deaden any sound if the roof did flex.
Frank

 

[Wallowa]

In researching the causes of oil canning, reduction of the areas of the unsupported flat surfaces reduces the chance of these areas generating waves/bubbles due to stressors such as temperature fluctuations and movement. Less area to flex, less waves and less oil canning.

The distance between the struts/stringers on a top sheet is significant and especially so if the top sheet is not securely fastened to the frame on these support members. Does VHB do as good a job as screws in securing the top sheet to the frame? All depends on the stresses on the top sheet, distance between supporting frame and thickness/design of metal top sheet.

Will mention that many FWCs with single sheet top sheets have a wide variety of roof top mounted items that can significantly affect whether or not the slack, stretched waves will generate and over what area of the top. And the extent of oil canning noise can be due to these variances in what is on the roof. Tough to generalize what will stop oil canning with the existing single sheet top sheets because of numerous variables in camper use and configuration of installed items on roof. Thicker single sheet top sheet aluminum, ridged/patterned top sheet and more frame attachments would be a good starting point at stopping oil canning, but that is not a reasonable expectation for a remedial fix of this problem by FWC.

Fiberglass or noise reducing foams is not thick enough to sufficient reduce the booming of oil canning in the top sheet. In my Hawk it is not a distant popping sound but thunder like booming and akin to a rifle firing right over your head when you are in the bed just below the ceiling top sheet. Given the right wind velocity and direction, sleeping is impossible.

Distortion of metal, especially aluminum, top sheets over time is inevitable. How to reduce the areas of flexing and oil canning noise to an acceptable level is the conundrum. My two 6 foot aluminum flat bars arrive today and I will place them on top sheet tomorrow; how to actually test them in a variety of wind conditions is any bodies guess.

 

[Wallowa]

2016 Hawk

These are the two 6 foot 3" wide and .313" thick bars positioned between longitudinal frame members. 6.5 lbs. each.

They are not yet secured with VHB but only there to determine if they stop the top sheet from flexing and creating oil canning. For both sections between the longitudinal frame members these bars stopped all oil canning that I tried to create by hand pressure; the top sheet was secured vertically and it appears deformed slack was depressed and non-moving.

Next will be to duct tape them in place and lift the top to assure that I could handle the extra 13 lbs. on the top sheet.

My only worry is that once installed and driving on our choice of rough off roading the mass of the bars will generate a bouncing of the top sheet and further deform the top sheet. I will try to locate the transverse frame members and secure the aluminum bars such as to maximize positioning over these frame supports to lessen the probability of the bars bouncing.

Phil

Ps...Thanks Sage for describing how to post a photo

 

[kmcintyre]

Great work! If this resolves the issue, I wonder what FWC will say about it?

Kevin

Top Shhet Al Bars.jpg

2016 Hawk

These are the two 6 foot 3" wide and .313" thick bars positioned between longitudinal frame members. 6.5 lbs. each.

They are not yet secured with VHB but only there to determine if they stop the top sheet from flexing and creating oil canning. For both sections between the longitudinal frame members these bars stopped all oil canning that I tried to create by hand pressure; the top sheet was secured vertically and it appears deformed slack was depressed and non-moving.

Next will be to duct tape them in place and lift the top to assure that I could handle the extra 13 lbs. on the top sheet.

My only worry is that once installed and driving on our choice of rough off roading the mass of the bars will generate a bouncing of the top sheet and further deform the top sheet. I will try to locate the transverse frame members and secure the aluminum bars such as to maximize positioning over these frame supports to lessen the probability of the bars bouncing.

Phil

Ps...Thanks Sage for describing how to post a photo

 

[Wallowa]

Great work! If this resolves the issue, I wonder what FWC will say about it?

Kevin

Yes, hope so too..."proof of the pudding is in the eating"...where my attempt at a solution intersects reality is the question....not all winds and from all directions generated oil canning, but over time oil canning under a wider and wider variety of conditions became the norm. So...time will tell..sleepless night are not an option.

Phil

 

[Casa Escarlata Robles Too]

Hope this works out for you Phil.The extra 16# shouldn't be an issue to lift the roof.
I could lift the roof with the #60 weight of a canoe plus the 2 solar panels.

Frank

 

[Wallowa]

Hope this works out for you Phil.The extra 16# shouldn't be an issue to lift the roof.
I could lift the roof with the #60 weight of a canoe plus the 2 solar panels.

Frank

True that...I tried lifting with 16 lbs. prior to ordering the aluminum...but the wild card is that I am an old man who's muscles seem to have dissolved! Old age is not for the weak and weary !

 

[Jon R]

Might want to round the corners and bottom edges of those bars if you aren’t using a pad layer of some kind.

Idea for testing: Leave the roof down and all windows/vents closed, and make a plate for one of your turnbuckle doors with a round hole to use a shop vacuum to pressurize the camper. Use the entry door as your pressure control to apply and remove interior pressure. I suspect a shop vac will generate enough pressure to push the sheet metal up (maybe too much), so start with the door open and push it closed carefully while watching the roof. You might not need full closure to pop the roof up, and you don’t want to pop more of the sheet metal free of the frame.

 

[Wallowa]

Might want to round the corners and bottom edges of those bars if you aren’t using a pad layer of some kind.

Idea for testing: Leave the roof down and all windows/vents closed, and make a plate for one of your turnbuckle doors with a round hole to use a shop vacuum to pressurize the camper. Use the entry door as your pressure control to apply and remove interior pressure. I suspect a shop vac will generate enough pressure to push the sheet metal up (maybe too much), so start with the door open and push it closed carefully while watching the roof. You might not need full closure to pop the roof up, and you don’t want to pop more of the sheet metal free of the frame.

Interesting approach...I can see how that might push the top up and perhaps deformed areas of the top sheet...but my camper is permanently mounted on the Tundra so access to out side of the turnbuckle door is a non-starter..i could reverse both Fantastic fans with door closed and try that approach.

I did take sand paper to the edges and corners and will give it a better sanding before mounting them..thanks, surprisingly sharp spots!

Phil

 

[Casa Escarlata Robles Too]

Jon R is on to something ,but why not use the power fan of the camper set on high to pull air in.
Then use the door to quickly change interior pressure.

Seems like that would work.
Frank

 

[Wallowa]

Jon R is on to something ,but why not use the power fan of the camper set on high to pull air in.
Then use the door to quickly change interior pressure.

Seems like that would work.
Frank

Yes I mentioned reversing the fans and pressurizing the interior....then opening the door and shutting off fans could potentially drop the pressure quickly...either event might produce oil canning; up or down...anyone can try that and so will I....two fans like I have may be needed....this might be a method of testing if I have really stopped the oil canning...once without bars and then with bars in place..

Thanks..Phil

 

[Jon R]

I had tried this with my MaxxAire fan and, while it raised the whole roof surface a little, it didn’t lift the sagged areas and oil can them. My roof is relatively new though and I have not experienced oil canning or high winds. The camper is very airtight with the roof down, so flow from one fan is adequate and a second identical fan won’t raise the pressure significantly. The fan aerodynamically stalls when I close the door fully (you can hear its speed increase from unloading). Peak pressure is achieved with the door cracked open and the fan not stalled.

 

[Ted]

This has been an interesting thread just to learn so much from the engineers and see the brainstorming for solutions evolve. Vic asked if we have confirmed that the roof needs to be detached for the oil canning to occur. I would say the answer is no. In my case and that of Wandering Sagebrush we had this problem from the start with new campers. I also know my roof was attached as FWC did take my roof apart and Stan stated they had to chisel the aluminum from the frame. And these being new campers also would indicate that the aluminum does not have to be stretched from snow load, vibration, or anything else. And since it was still attached to the rafters, I don't see how adding screws would help.
It appears a solution or two may be at hand, whether adding aluminum pieces as Phil is doing or arcing the roof by pushing it up from the inside. Hopefully those with this problem will soon be able to sleep well in their campers. Why only some campers are experiencing this is a mystery. But, IMO, the smooth aluminum will still be a problem for new campers yet to be built until FWC replaces it with a different product, such as the diamond stamped door a few pages back.