Roof to sidewall insulation

MrTransistor · 10-30-2008, 05:25 PM

Hi All,

I know this has been mentioned before but I don't recall anyone having a fix for this problem. I re-caulked the gutter seam by slipping rubber screen door spline between the gutter and the roof fiberglass to hold it pressed in toward the center of the coach while I filled the channel with gold colored RTV silicon caulk. Doing it this way allowed about ¾ inch of bonding surface for both the roof fiberglass and the aluminum gutter. It took 4 tubes of RTV and I have no doubt that it will last as long as I'm still around.

Problem is, that doesn't solve the issue of a cold in the winter and hot in the summer ceiling to sidewall joint. I suspect there is an awful lot of heat transfer in this area since on the coldest days, the ceiling and walls will feel normal but the area from the corner to 6 or 8 inches in on both the ceiling and walls will be freezing cold.

I have looked at the parts breakdown .PDF, http://www.winnebagoind.com/service/...4/4iks40wd.pdf Page 47, and this junction is shown but not in quite the detail that would suggest a fix. There seem to be two if not three separate spaces, one between the fiberglass and aluminum joint, one between the aluminum joint and the inside corner formed by the ceiling and side wall and the other at the top of the wall with no insulation in them. The un-insulated area looks to be a couple of inches at the ceiling sides.

The Winch (affectionate inside joke) suggested two holes, one at the front of the coach and the other at the rear to blow foam beads into the space. This might work for the outside space just under the fiberglass but the thickness of this area wouldn't provide very much insulation. The spaces that really need it and would provide the most effective insulation are the inside spaces between the edge of the ceiling's foam insulation and the top of the wall. My thoughts turned to expandable foam insulation but too little isn't good and too much is bad news since I've seen interior house walls buckle under the pressure of expanding foam.

Anyone out there considered this issue? Better yet anyone have a fix? Your thoughts?

Okay, just found a better cross-sectional view of that joint. It's rotated 90 degrees but has the detail to show the problem. http://www.winnebagoind.com/service/...A/3ikp39wd.pdf Page 134. Oh yes, there's a pretty large area with no insulation!

And here's the picture.

MrTransistor · 10-30-2008, 05:25 PM

Hi All,

I know this has been mentioned before but I don't recall anyone having a fix for this problem. I re-caulked the gutter seam by slipping rubber screen door spline between the gutter and the roof fiberglass to hold it pressed in toward the center of the coach while I filled the channel with gold colored RTV silicon caulk. Doing it this way allowed about ¾ inch of bonding surface for both the roof fiberglass and the aluminum gutter. It took 4 tubes of RTV and I have no doubt that it will last as long as I'm still around.

Problem is, that doesn't solve the issue of a cold in the winter and hot in the summer ceiling to sidewall joint. I suspect there is an awful lot of heat transfer in this area since on the coldest days, the ceiling and walls will feel normal but the area from the corner to 6 or 8 inches in on both the ceiling and walls will be freezing cold.

I have looked at the parts breakdown .PDF, http://www.winnebagoind.com/service/...4/4iks40wd.pdf Page 47, and this junction is shown but not in quite the detail that would suggest a fix. There seem to be two if not three separate spaces, one between the fiberglass and aluminum joint, one between the aluminum joint and the inside corner formed by the ceiling and side wall and the other at the top of the wall with no insulation in them. The un-insulated area looks to be a couple of inches at the ceiling sides.

The Winch (affectionate inside joke) suggested two holes, one at the front of the coach and the other at the rear to blow foam beads into the space. This might work for the outside space just under the fiberglass but the thickness of this area wouldn't provide very much insulation. The spaces that really need it and would provide the most effective insulation are the inside spaces between the edge of the ceiling's foam insulation and the top of the wall. My thoughts turned to expandable foam insulation but too little isn't good and too much is bad news since I've seen interior house walls buckle under the pressure of expanding foam.

Anyone out there considered this issue? Better yet anyone have a fix? Your thoughts?

Okay, just found a better cross-sectional view of that joint. It's rotated 90 degrees but has the detail to show the problem. http://www.winnebagoind.com/service/...A/3ikp39wd.pdf Page 134. Oh yes, there's a pretty large area with no insulation!

And here's the picture.

FrontRangeRVer · 10-31-2008, 05:55 AM

Thanks for the great pics! I have been mentioning this problem area to members here for a couple of years now, and now glad to finally see a good view of the "voids".

I have thought of somehow blowing in some expanding foam, but not sure how to get it all the way from front to back.

In the hot Summer when the Sun is beating down on the roof/sidewall area, that area INSIDE your motorhome is so hot, it almosts burns your hand! This area is where most of our cold in the summer and heat in the winter is lost.

I'm interested in the replies also

rvcarpenter · 10-31-2008, 06:51 AM

Are the 2 big voids aluminum channels? If so it might be safe to use the expanding foam inside of them.

FrontRangeRVer · 10-31-2008, 07:31 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rvcarpenter:
Are the 2 big voids aluminum channels? If so it might be safe to use the expanding foam inside of them. </div></BLOCKQUOTE>

Yes these huge areas....one on the roof that runs from front to back and the other one on the sidewall that runs front to back. There isn't any insulation anywere where the curved parts of our roofs are attached to the sidewalls.

I have thought of using expanding foam, but how to get it in there???

rvcarpenter · 10-31-2008, 08:22 AM

for the expanding foam you'd have to go along and drill holes ever so often and poke the nozzle of the foam can in it.

I was thinking you can buy bags of little stryofoam beans for bean bag chairs. maybe you could dril one hole up front and one in the back and blow them down the length of the chanel.

MrTransistor · 10-31-2008, 10:03 AM

Two excellent suggestions. This one really surprises me. Why Winnebago doesn't pre-fill these Aluminum channels with insulation is a mystery. For that mater, why are the other voids in there not insulated? Can you here us, Winnebago? Maybe a production change is in order and a fix for all of us out there who already have our coaches and would pay for it. I believe that a reasonably priced fix would pay for it's self in reduced heating and cooling bills, for us full timers at least.

Foam beads could be used to fill all the voids but there R-value isn't terribly high. Lots of little gaps around the beads but better than nothing. I first saw this technique used at the Aspen Airport in Co. They had an automatic system that would blow the beads into and out of a double paned glass wall on the south side of the building. That wall was perhaps 6" between the panes and was 6' to 8' high and maybe 19' long with separators every 6'. Foam beads blown in at night, sucked out through the day provided excellent heat control and I'm sure very good economy.

Expanding foam would be much better but the only areas that it could be used in are inside the extrusions. I'm afraid that the fiberglass would pop out of the drip channel or separate from the roof when it expands.

Now for the issue of the holes. How many, what spacing, and how to cover them up. They would have to be drilled through both the fiberglass and the Aluminum extrusions the entire length of the coach. For beads, maybe one in the front and one in the rear would do but they would need to be pretty large. Large enough to almost take a vacuum cleaner hose to draw in the beads. I was thinking for the expandable foam to use a long thin tube (one time use only) inserted through a single hole at the front or the rear, clear to the other end. Then squirt the foam in as the tube is withdrawn. But the timing would be very tough, since you don't want to start pulling till the foam reaches the end and the speed that you pull would be different for each size channel. Can anyone think of a better way?

Additional info; I didn't show the original caulk that was in the seam but it was a very small amount of roof sealant that was put into the quite small area between the fiberglass and the lip of the drip rail. The little area that's seen in the top right drawing. After about a year and a half, it started to pull away and when I removed it there were sections that had just a film of the stuff covering it. Very poor workmanship. My fix is shown in the lower left and center drawings. Quite simple to do, just don't push the spline down too far since the fiberglass in areas doesn't go all the way to the bottom of the channel.

Florida Guy · 10-31-2008, 12:05 PM

How about inside 'Cove Molding'. Place strips of AC copper tubing insulating material up against the wall/ceiling and then place some thin Cove Molding (like what's in some stick houses)over the insulation. I have placed some stained Cove Molding to match the cabinets in areas of our Journey, were the wall meets the ceiling and it looks nice. At the time I Didn't think about adding the insulation first but it would have worked.

PeteB · 10-31-2008, 12:11 PM

Keep in mind that aluminum is an excellent conductor of cold and heat. I am not sure that putting in insulation would accomplish much.

Pete

John_Canfield · 10-31-2008, 01:38 PM

It would certainly be a challenge to fill that void unless there were some major renovations going on coincidentally that would allow access to that channel. There is a huge amount of BTU loss with the metal window frames, vent and shower domes, walls, etc. I used a non-contact thermometer to shoot the interior walls when we were in 110 weather in Gila Bend AZ this year and one inside wall measured something like 85 or 90 degrees - could have been more - I don't remember.

LK23 · 10-31-2008, 02:16 PM

Mark,

There are weep holes in the bottom of the track where you placed the spline. It is my understanding that the weep holes are to allow any water that gets past the caulking to drain out.

Obviously, your fix seals the entire channel and there may not be a need for weep holes, as long as the caulking holds. It will be interesting to see how this works for you.

MrTransistor · 10-31-2008, 07:47 PM

Florida Guy,

Good idea. I assume that you didn't do anything inside the cabinets. How hard would it be to remove the molding to place insulation inside now? If you do, would you also do the same inside the cabinets?

Hi Pete,

Yep, not much can be done for the thermal conductivity of the Aluminum extrusions but stopping the radiant heat transfer as well as convection currents inside them can't hurt.

John,

Stripping that RTV back out of there wouldn't be fun but it's starting to look like that may be the only way. I didn't make thermal blankets for the windows in the living/kitchen area but I did make them for the windshield, bathroom, and bedroom windows. I don't know the R-value but the Warm Window material says they block 80% of the heat flow. So two thick nesses should be 96%. When its 30 degrees Fahrenheit outside, the inside of the windshield will freeze ice but it's warm as toast on the inside of the thermal blankets. I have a picture posted of the windshield blanket.

LK23,

I know about the drip holes and that's why I used the spline, to hold the fiberglass back and keep the RTV from sagging all the way to the bottom of the channel. So even if water could get in there, it can still drain out. So far, I've found one product that is supposed to be slow setting and takes I think around a minute and a half to rise and set. They say it's for the inside of interior walls and isn't supposed to apply enough pressure as to burst the wall. How it would perform for our problem is questionable though, since it's still a mater of using a long tube for injecting as the tube is extracted from the space. Too slow, too much pressure, too fast, leaves voids. Still looking.

Izzyblueye · 11-01-2008, 02:05 AM

All of the above is some of the most intelligent and rational thinking I have seen on this forum, concerning a problem we all have. There are some good minds on here.
I hope Winnebago and other manufacturers are reading this. The best fix is at the factory during manufacture. I hope some one will come up with an after market fix that is feasible.

PeteB · 11-01-2008, 03:20 AM

Mark,

I agree that the void does contribute to some convection but without a thermal break between the outside of the extrusion exposed to the outdoor temps and the inside of the extrusion, heat or cold will transfer around the void and the situation would be almost the same as without added insulation. Think about an aluminum window, with and without an insulation filler, there is very little diffirence in insulation value without the thermal break.

I think the idea of the interior cove insulation is the best direstion to go.

Just my 2 cents.

Pete

Florida Guy · 11-01-2008, 05:42 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Florida Guy,

Good idea. I assume that you didn't do anything inside the cabinets. How hard would it be to remove the molding to place insulation inside now? If you do, would you also do the same inside the cabinets? </div></BLOCKQUOTE>

It wouldn't be hard to remove the existing and insulate. If that was the intention, I probably would get thicker (wider)Cove Molding to allow more room for the insulation. All this could be done inside the cabinets if desired. I just wanted to spruce up the interior a little, plus being retired, am always looking for some handy work. This little job was inexpensive and kept me out of trouble a for couple days.

MrTransistor · 11-01-2008, 10:17 PM

Hi Pete,

I totally agree. I could lean toward the cove molding idea except for the loss of space inside the cabinets and figuring out how to handle the valance around the windows and the slide outs.

Winnebago's roof to sidewall extrusions could include a thermal barrier with a little redesign. I see why they came up with the current design, it's the same concept as the attachment for the bottom of the wall to the floor connection. Problem there is that if the coach is driven on rough roads (as in dirt washboard), the self drill screws loosen and back out causing a separation of the wall. I have pictures up showing the problems we had. One screw every 8 inches didn't cut the mustard, so I installed screws every 2 inches. Also, I didn't use self drill screws. I predrilled every hole for clearance and threads. No problems since.

The roof junction seems to be secured the same way. I sure hope there are no problems there.

Short of a replacement - redesigned roof, I see no alternative to adding insulation to the extrusions, even with the inherent thermal conductivity issue. Anything would be better than what we all have now. I haven't looked extensively yet for some type of foam that will stay runny until it has fully expanded and then sets. This would allow you to inject the foaming agents, and then they would expand and run the length of the voids overflowing out a venting hole at the opposite end, then setting without creating any pressure that would cause the fiberglass to pop out of place. Does anyone know of a product that acts this way?

If we can come up with a workable fix then we can see if the benefits are worth the effort. Who knows, to be truly effective it may require both types of insulation, foam in the channels and insulated cove moldings.

FrontRangeRVer · 11-01-2008, 10:37 PM

The sides of the fiberglass roof are rolled over the uninsulated aluminum connectors along the whole length of the motorhome and connected to the sidewall by the rain gutter trim. Nowhere is there any insulation under this complete rolled edge of the roof. I believe that if someone could insulated UNDER this rolled edge, it would do away with the heat conduction issue with the wall to ceiling connections. A person could always remove the rain gutter aluminum trim along the side and the rolled roof edge would come up and we could get at the wall to ceiling aluminum connections.....Possibly fiberglass insulation between the rolled edge and the roof and side wall connetions.....it would be better than NO insulation as it is now.

The inside ceiling cove is a interesting idea, but since the walls and roof actually flex and twist somewhat as we drive, the cove will eventually work itself loose and that is the reason why ceiling cove isn't installed in motorhomes.

By the way and FYI. The aluminum channels that run the length of our motorhomes that have voids are open at both the front and back.

NeilV · 11-02-2008, 03:14 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by FrontRangeRVer:
The sides of the fiberglass roof are rolled over the uninsulated aluminum connectors along the whole length of the motorhome and connected to the sidewall by the rain gutter trim. Nowhere is there any insulation under this complete rolled edge of the roof. I believe that if someone could insulated UNDER this rolled edge, it would do away with the heat conduction issue with the wall to ceiling connections. A person could always remove the rain gutter aluminum trim along the side and the rolled roof edge would come up and we could get at the wall to ceiling aluminum connections.....Possibly fiberglass insulation between the rolled edge and the roof and side wall connetions.....it would be better than NO insulation as it is now.

The inside ceiling cove is a interesting idea, but since the walls and roof actually flex and twist somewhat as we drive, the cove will eventually work itself loose and that is the reason why ceiling cove isn't installed in motorhomes.

By the way and FYI. The aluminum channels that run the length of our motorhomes that have voids are open at both the front and back. </div></BLOCKQUOTE>

If you fill that area with anything that could wick up the weep water instead of letting it drain you could create more problems then you would solve.

The structural channels as far as I recall from the last time I had the Winnebago sample section of the actual roof joint in my hand if I remember correctly (it has been about two years) have wiring punchouts evenly spaced over the entire length of the channel. The sample was two or three feet long with about six inches of sidewall and about a foot of roof. It was in the sales area of LazyDays in Sefner near the East door to the new rigs.

If you were really determined you could use minimal expansion foam by drilling 1/4 inch holes near the ceiling and then putting white plastick plugs like exterminators do when treating for termites etc. Just remember that this will probably void the warranty on the roof joint just like doing this to any door or window frame in your home will void those warranties also.

ChasA · 11-03-2008, 05:35 PM

Interesting thread. Mostly based on the incorrect assumption that air is a poor insulator. In fact Air space where the air cannot move is one of the best insulators there is. And most insulating materials are nothing more than materials made to stop air from moving. The voids inside the roof area are not the problem,the problem is the thermally conductive aluminum members and air movement between the inside and outside walls/roof. Adding foam or styrofoam balls inside the spaces between the walls may help, but only in as much that they restrict the air flow. If you could completely seal all possible air leaks you would have the best insulation you're going to get.

tderonne · 11-03-2008, 06:53 PM

Air is sort of a good insulator. It doesn't transfer heat well, like water or aluminum. But hot air does rise, so it will convect heat quite well.

The trick is to keep the air from moving. Fiberglass batts actually let air move quite readily. Better than nothing, but not like a closed cell foam. Things like fiberglass are less effective the higher the temperature difference (just when you need it most!).

Back to the topic. It's very important to realize that only hot AIR rises, not heat itself. And that air flow in the form of leakage lets unheated/uncooled air directly in or out. Insulating the floor, the basement, etc, are very important, more important than the roof joint in my opinion, and there's huge paths for both air and heat to escape/enter in our motorhomes.

Love to spray foam my electrical and sewer compartments, as well as the stairwell, and under the driver's area. It'd just cost too much, and make a pretty big mess. I can dream, right?

(I did spray foam the hollow legs of a flimsy ladder about 5' in length, no problem. A 30' extruded tube, probably a problem.)