Step by Step: Replacing OEM skylights with new Custom Maxim Skylights

[66Overlander]

Originally Posted by WGreg

I have a 2005 model which I believe is older than what your AS is. I ordered two skylights from Maxim in February and completed installing them in March (it was warmer then). I called Maxim with my measurements and ended up with their standard 17.25" x 25.25" and 22.25" x 22.25" skylights which fit fine. Good luck.

Thank you! Those are the dimensions I am planning to order.

[66Overlander]

Well, glad I haven't ordered our Maxim skylights yet. Made a trip to measure the skylight curbs on our 2016 Classic over the weekend and found the approximate dimensions of the outsides of the curbs to be significantly larger than expected and larger than the skylight dimensions I had expected to order:

Front Skylight:
22.5" x 22.5" *

Rear Skylight:
26.0" x 17.5" *

* In both cases the curbs might actually be 1/16" larger in each dimension. It was hard to make precise measurements through the existing skylight and double sided tape that was used on the top of the curbs to attach the skylights to the trailer.

It sort of scares me how much larger these skylight curb dimensions are than anyone else has reported here, but I tripled checked the measurements, so I believe them to be correct. Airstream must have made quite a dimension change in recent years.

I will call David at Maxim with these dimensions and see what he recommends. I might expect order the new Maxim skylights at 1/8" to 1/4" larger than the above curb dimensions.

[switz]

He will say, take the old ones off and exactly measure what you have on the roof. Based on the non-square construction of the frame, I would make the unit about 1/16' larger as we had a corner that was not truly vertical as compared the relatively square top edge of the frame.

[66Overlander]

Thanks for the 1/16" suggestion. Is that about what everyone else has done? I was thinking 1/16" or 1/8". Thanks in advance for any other feedback.

P.S. I went back to the trailer again and re-measured the curbs from the top and sides. They are definitely 22.5" x 22.5" and 26.0" x 17.5".

[carl2591]

this is in response to question about double sided tape for removal of skylights if needed..

so my question would be about using butyl tape under skylight frame or on top of installed curb on roof.

its the perfect width, you roll the butyl tape out on the existing skylight curb, set the skylight on top, press down and install SS screws with gaskets on sides and done. if you use proper length screw it goes into the roof curb not creating a leak spot. am i missing something with all the caulking, etc mentioned.

maybe put a strip of tape on front facing(leading edge) side of curb, push the assembly back to make sure leading edge of skylight is better sealed?

Originally Posted by lsbrodsky

David does not recommend tape.
Larry

[TheDuke]

I finally got my new Maxim skylights ordered for my 2016 Classic a couple of weeks ago. I ordered a 18" X 26.5" and a 23" X 23". I asked about sealants and was told that they liked the "OSI" brand. So that is what I am going to use when I install mine.

[Wingeezer]

Originally Posted by switz

He will say, take the old ones off and exactly measure what you have on the roof. Based on the non-square construction of the frame, I would make the unit about 1/16' larger as we had a corner that was not truly vertical as compared the relatively square top edge of the frame.

No doubt that is teh best way but not too practical in the sense that the old skylight flange may well come off in many pieces, so once off, you'd have to close the opening with some sort of plywood panel or something unti you got your new skylight.

I did contemplate doing just that because I found that I could not really measure the curb accurately with the old skylight in place.

I did measure close enough to know that mine were similar in dimensions to those others had been ordering, and Maxim assured me that they knew what I needed.

Despite their assurance, because we live many miles from Dallas, I didn't want to risk finding that perhaps my curbs were slightly out of square ore maybe sloped so that the new skylight wouldn't fit.

And if it doesn't fit, it would not be an easy fix!

Looking at the design and the way the skylight is secured and seals I couldn't see any downside to ordering one to be made a little on the large side.

So I decided to add 1/4" to the suggested dimensions for the skylights I bought - worked out fine but still a pretty close fit to drop them on over the curb.

I'll never know if they would still have fitted if I went with their standard dimensions - it sure would have been close though!

Brian.

[66Overlander]

Originally Posted by TheDuke

I finally got my new Maxim skylights ordered for my 2016 Classic a couple of weeks ago. I ordered a 18" X 26.5" and a 23" X 23". I asked about sealants and was told that they liked the "OSI" brand. So that is what I am going to use when I install mine.

I was going to write you back when I finally got my order in. I am assuming your curbs were the same size as mine and you went a full half inch larger in each dimension. Is this correct?

[66Overlander]

Originally Posted by Wingeezer

So I decided to add 1/4" to the suggested dimensions for the skylights I bought - worked out fine but still a pretty close fit to drop them on over the curb.

I'll never know if they would still have fitted if I went with their standard dimensions - it sure would have been close though!

Brian.

I am/was planning to go with 1/8" over. Do you think that would have worked on yours?

So far here I've seen that people went 1/16", 1/4", and apparently 1/2" over. 1/8" seems like a good middle value the I think should work on mine.

[Wingeezer]

Originally Posted by 66Overlander

I am/was planning to go with 1/8" over. Do you think that would have worked on yours?

So far here I've seen that people went 1/16", 1/4", and apparently 1/2" over. 1/8" seems like a good middle value the I think should work on mine.

Joe.

I'd like to be able to give you a definitive answer, but have no way of knowing!

The fit did seem pretty close on mine at 1/4" over nominal dimensions.

As I say though, I couldn't really see any downside to going larger, becasue as far as I could judge, the securement and weather sealing have nothing to do with how loose the fit over the curb is when you drop it in place- within reason of course!


Brian.

[66Overlander]

Originally Posted by carl2591

this is in response to question about double sided tape for removal of skylights if needed..

so my question would be about using butyl tape under skylight frame or on top of installed curb on roof.

its the perfect width, you roll the butyl tape out on the existing skylight curb, set the skylight on top, press down and install SS screws with gaskets on sides and done. if you use proper length screw it goes into the roof curb not creating a leak spot. am i missing something with all the caulking, etc mentioned.

maybe put a strip of tape on front facing(leading edge) side of curb, push the assembly back to make sure leading edge of skylight is better sealed?

Interesting idea. Butyl tape is more of a putty in tape form than a real double sided tape. Airstream used it for decades to seal panel seams and window and door frames. It would definitely make the skylight easier to remove if that ever became necessary.

I tend to agree that sealing on top of the curb flange is not likely to be a leak path except while driving or possibly in a rain storm with a driving wind.

We'll see if anyone else has tried this or has other feedback.

[polarlyse]

I had intended to use some butyl tape when I installed mine this past January. BUT, when we left home I left IT at home so I used caulk. Seemed to work fine, no leaks. I had lost the rear, original, skylight last summer and covered the opening with a piece of
1/4" plywood. Worked great and was watertight. Before leaving our AS in Georgia stored for a few months I climbed up and got a good measurement on the curbs and ordered the new Maxims when we got home. My measurements were consistent with those that Maxim had on file and the lights fit nicely. We were in some serious rain storms while in Louisiana during March so I feel comfortable that we've survived the best leak tests without any leaks. So far so good.

[Larry C]

Originally Posted by 66Overlander

Interesting idea. Butyl tape is more of a putty in tape form than a real double sided tape. Airstream used it for decades to seal panel seams and window and door frames. It would definitely make the skylight easier to remove if that ever became necessary.

I tend to agree that sealing on top of the curb flange is not likely to be a leak path except while driving or possibly in a rain storm with a driving wind.

We'll see if anyone else has tried this or has other feedback.

Butyl tape has been used for 50 or more years in the RV industry, because it is cheap, and fast for production line assembly. That being said, eventually, it will dry out, shrink, and leak.

I've installed the Maxim skylights on 2 Airstreams, using Sikaflex sealant, and have never had a leak. It is true it could make removing the Maxims a problem, but the chances of having to remove them is pretty remote....

Usually, it's best to stay with a proven way of doing something....

For whatever it's worth.

Larry

[Wingeezer]

Originally Posted by Larry C

I've installed the Maxim skylights on 2 Airstreams, using Sikaflex sealant, and have never had a leak. It is true it could make removing the Maxims a problem, but the chances of having to remove them is pretty remote....

Usually, it's best to stay with a proven way of doing something....

For whatever it's worth.

Larry

Larry,

I have had my Maxims installed now for a few years and did the same as you - that is, I used Sikaflex, mainly because I had it on hand and at that time, Maxim offered no suggestion as to what I should use.

However - a year or so later, one of my skylights developed condensation between the upper two polycarbonate layers. The seal between those layers had visibly bulged inwards a little and apparently failed.

I happened to be in the area of Dallas and showed it to the people at Maxim. They agreed with my diagnosis and without hesitation agreed to provide me a replacement skylight. I brought the new one home with me to Canada.

However, when I tried to get the old skylight off - no dice!

I tried prying up using plywood to spread the load over the Airstream roof but that Sikaflex just would not give. So I put the screws back in the skylight to think further about the dilemma!

As luck would have it, somehow, the condensation between the polycarbonates evaporated and has yet to return after several years, and so I have not had to pursue this further ......... yet! I suspect it will just be a matter of time.

I contacted Maxim and explained my situation and asked if it would be possible for me to just dismantle the frame of the new skylight and swap the polycarbonate "sandwich." They said I would not be able to do this so I didn't try and still have done nothing further!

So at this point, if, or when the condensate re-appears and I decide to do what I must do to get the old skylight off, I really think that the only way to do it will by by cutting the old skylight in place into pieces with a dremel tool or similar!

In fact, in doing so, I might may even leave that portion of the aluminum frame that is bonded to the curb by the Sikaflex in place, trim it to size so I can just drop the new skylight over it! That might just be the simplest remedy - but will probably not be a quick and easy task!

So if I had it to do again, I think I'd be looking for something a little less tenacious than Sikaflex to use when installing Maxim skylights! Not sure what - maybe butyl tape.

Just my experience!

Brian

[carl2591]

never say never.. Butyl on the exterior around the black and gray tank vents lasted some 10 yrs with exposure to sun, wind, rain etc and while it did crack a bit was not all that hard to remove..

The sikaflex, from what i have heard, is a fricken BEAR to remove which could cause more damage. If I put in place a reminder to remove and replace the butyl every 8 yrs or so years, or in event of unforeseen damage, I think I would go with butyl tape.

It protected from the elements for the most part it seems.

this is from the vintage supply guys on the butyl tape

"This pliable non-hardening 100% butyl mastic is a superior replacement for the original non-butyl putty tape used on vintage travel trailers. It is tacky and, unlike old fashioned putty tape, does not harden over time. Also, it is safe for contact with EPDM rubber roofs because it does not leach petroleum residue.

It is used when installing moldings, windows, doors and vents. It waterproofs overlapping metal and seals around fasteners when they are inserted through the tape.
Can be trimmed to width with a utility knife."


sounds like the new stuff is better than the old stuff.. figures right..

Originally Posted by Larry C

I've installed the Maxim skylights on 2 Airstreams, using Sikaflex sealant, and have never had a leak. It is true it could make removing the Maxims a problem, but the chances of having to remove them is pretty remote....

Larry

[TheDuke]

Originally Posted by 66Overlander

I was going to write you back when I finally got my order in. I am assuming your curbs were the same size as mine and you went a full half inch larger in each dimension. Is this correct?

Yes Joe, you are correct. I decided to go 1/2" larger than my best measurement. When you think about it, that is only 1/4" on each side. This is the size that I know has been installed and works fine. It is also the size that Dave at Maxim recommended. I hope to have mine in a couple of weeks? I went with the white powder coated frame, which Maxim does not do in house, that added another week or so.

[switz]

Was in a "severe thunderstorm" or squall line last night at the KOA camp ground in Amarillo, TX. Festivities included 30 mph wind gusting to 60 which hit the 23D broadside (hitched to car and no stabilizers down, just on tires) and really rocked the boat and was not a pleasant experience. The waves of rain were interspersed with ½" to ¾" hail which resounded loudly on the aluminum skin and five solar panels. There was no failure of the Maxim Skylight, the two Maxxfans or other stuff on my roof. The windshield did crack on the Mercedes. The campground was flooded briefly much to the dismay of the tent campers.

Several less expensive trailers around me had failures of their skylights. I think the original Airstream skylight would also have failed from the hail.

YMMV

[btowntincan]

Wow, Switz. That doesn't sound fun at all. Glad everyone seems to have made it thru OK. Did the hail dent your AS?

[asv2]

Hello,
I have a new Maxim just installed in April and researched the thread up-and-down before installing, trying to determine what kind of sealant to use.

In Post #200, David at Maxim cautions against using butyl tapes as they have a tendency to ooze. He says heat mixed with contraction and expansion of the polycarbonate may cause the butyl tape to become so hot it will literally melt and therefore render the seal ineffective and possibly become visible from the interior........
Post 134 mentions that David does NOT recommend solvent based sealants as they can attack the skylight components.

I finally settled on Sikaflex 715. (Note there are several different numbered Sikaflex sealants) Sikaflex 715 is not solvent based, but is a "Silane Terminated Polymer" or "STP". Hopefully the Sikaflex 715 will do well.

My Maxim is gray with anodized aluminum frame, looks great! Also, I provided Maxim the exact measurements (22 X 22) and did not add anything. It's a perfect fit.

[switz]

There were no dents in either the Airstream or the car. Just the windshield let go with long a crack developing. Needed to be replaced anyway, but this just accelerated the timing for this project.