Roof Vent

[Mike Whitney]

Hi all -

I've searched through the forum, but can't seem to find any threads on this.

I'm about to glue in my insulation and wall fabric in my Lil' Bigfoot, but have run into an issue with the roof vent. Stock, there was a 9" with no trim ring. I didn't think anything of it but have recently realized there is no trim ring because the vertical portion of the vent, which extends through the roof/ceiling is too deep to snug up a trim ring. It seems that all roof vents are designed for a thick walled trailer/RV, and not for a 1/8" thick FG trailer.

I purchased a 14" vent, but the vertical flange on the vent is a good 3" deep. The trim ring sits inside of this flange, and can be trimmed on a table saw, but the vent itself can not be cut down in depth.

The issue is, there will be a gap between the vent and the trim ring, vertically of about 2-3". Every RV place I've called says, 'That's the way they all are."

I called Scamp trailers and they indicated that they simply glue in the fabric/insulation and then build a 2" high frame that skirts the hole in the ceiling, sitting over top of the finish fabric. This then occupies the space and gives the top (exterior portion) vent something to screw into. They just stain/finish this trim and call it a day. Not a bad solution, but I'm hoping to find a vent that is built for these trailers.

Another option would be to glue a rough wood frame and tab it into the fiberglass, wrapping it with the interior fabric, but I'm not 100% sold on this method either. The RV place suggested doing a build out on the roof side so as not to lose interior head room. They mentioned using a UV resistant plastic and gluing it to the trailer exterior to build things up 2" or so.

Any ideas out there??! Any better vents?? Any pics?

Thanks in advance,

Mike

[Raya]

Another option would be to glue a rough wood frame and tab it into the fiberglass, wrapping it with the interior fabric, but I'm not 100% sold on this method either. The RV place suggested doing a build out on the roof side so as not to lose interior head room. [b]They mentioned using a UV resistant plastic and gluing it to the trailer exterior to build things up 2" or so.

I'm just adding a note about this last suggestion (if you were to decide to build up the outside of the trailer - not that I'm saying I'd choose this).

I would recommend against using a plastic ring for this job. That's because none of the plastics I know of like to bond to adhesives (such as, for example, Starboard). Also, some of them creep under load. Not that the load is so much, but any creep will make it harder to seal.

I would instead suggest you use pre-made fiberglass board (technically I guess you could say this is a plastic, but I doubt this is what they were suggesting). The FRP board will not be subject to creep, and will happily mate with adhesives. You could paint or gelcoat it to match the trailer (I would choose 2-part paint). It's also more "inert" than wood for outside application.

Here is an example of the board I'm referring to:

http://www.mcmaster.com/param/asp/PSearch2...cMMainWidth=781
************************************

Okay, back to your regularly scheduled thread

Raya

[william russell]

Mike:

When I had a 16' casita, I purchased a powered vent to replace the existing non-powered vent. I found that the manufacturer had "high" profile and "low" profile modles, one for thin roofed trailers and one for trailers with a thicker roof. I forget which model is which but I want to say I needed the "high" profile. The modle I purchased had an additional ring which fitted between the garnish (the part that fits to the ceiling) and the ceiling. The ring was about one half inch thick. After cutting the garnish to the appropriate deminsion and fitting it in place it looked quite good and only had that half inch protrusion into the trailer. Joe Zupa could measure that for the exact protrusion.

Russell

[Larry C Hanson]

Hi Mike,
I had a similar problem with my Trillium when replacing the 9" stock vent
with an after market one. I use 3/4" plywood painted to match trailer
to raise the vent to a suitable level. Good Luck.
Larry H

[floyd]

Hi all -

I've searched through the forum, but can't seem to find any threads on this.

I'm about to glue in my insulation and wall fabric in my Lil' Bigfoot, but have run into an issue with the roof vent. Stock, there was a 9" with no trim ring. I didn't think anything of it but have recently realized there is no trim ring because the vertical portion of the vent, which extends through the roof/ceiling is too deep to snug up a trim ring. It seems that all roof vents are designed for a thick walled trailer/RV, and not for a 1/8" thick FG trailer.

I purchased a 14" vent, but the vertical flange on the vent is a good 3" deep. The trim ring sits inside of this flange, and can be trimmed on a table saw, but the vent itself can not be cut down in depth.

The issue is, there will be a gap between the vent and the trim ring, vertically of about 2-3". Every RV place I've called says, 'That's the way they all are."

I called Scamp trailers and they indicated that they simply glue in the fabric/insulation and then build a 2" high frame that skirts the hole in the ceiling, sitting over top of the finish fabric. This then occupies the space and gives the top (exterior portion) vent something to screw into. They just stain/finish this trim and call it a day. Not a bad solution, but I'm hoping to find a vent that is built for these trailers.

Another option would be to glue a rough wood frame and tab it into the fiberglass, wrapping it with the interior fabric, but I'm not 100% sold on this method either. The RV place suggested doing a build out on the roof side so as not to lose interior head room. They mentioned using a UV resistant plastic and gluing it to the trailer exterior to build things up 2" or so.

Any ideas out there??! Any better vents?? Any pics?

Thanks in advance,

Mike

I used plastic deck material , the 2X2 vertical ballister material. It is actually a little less than 1.5" square. It works great, holds screws firmly, sticks good to adhesives and caulk, and it can't rot here's a picture of one before final touch-up...

[charliej]

I used plastic deck material , the 2X2 vertical ballister material. It is actually a little less than 1.5" square. It works great, holds screws firmly, sticks good to adhesives and caulk, and it can't rot here's a picture of one before final touch-up...

Hi Floyd.....what is plasitc deck material? What is vertical ballister material?

I have the same issue around my fantastic fan....there is no trim.

Charlie

[Mike Whitney]

Thanks for everyone's replies so far - cheers Raya and William

Larry: your solution looks good. As does yours, Floyd. It helps to see the pictures and to get other ideas.

I initially thought of building a wood frame and gluing it to the fiberglass using liquid nails construction adhesive. Does anyone see any issues with this?

Alternately, (as adhering my new 'rat fur' to the ceiling and then conforming it around this wood frame could prove difficult - I'm thinking creases etc..) I was thinking of first adhering the insulation/rat fur, and then simply building the frame and wrapping that separately with the same rat fur material.

Rather than wood, I could use the 2" decking material to avoid water/rot and wrap that instead. I don't know how I would then adhere it to the ceiling, but I'm thinking that if I screwed the vent down from the outside into this 'rat-fur-covered-trim/spacer' that would suck it up tight to the ceiling. For that matter, I could screw through the ceiling with some flush mount screws into the covered trim ring first. These would then be covered with butyl when I install the top portion of the vent .....

Does anyone see any problems with the latter method?

Thank you again,
Mike

[Frederick L. Simson]

...what is plasitc deck material? What is vertical ballister material?

Trex Deck and (vertical ballister) Railing

[Larry C Hanson]

Hi Mike,

The spacer made out of decking material is a great idea. I put my spacer
on the top to the fiberglass to gain mazximum headroom as the vent is directly
over the galley standing area. To mount to the fiberglass I used 5/8 sheet
metal screws installed from inside the trailer. Then the vent was screwed down
to the spacer with the same sort of screws. Butyl tape was used to seal both joints.
Another advantage of putting the spacer on the outside is that the trim ring
that comes with vent can be used to dress up the joint.

I looked at installing a Fantastic fan in the same spot. I would use a similar
spacer to keep the interior headroom, but I would use some sort of plastic
(decking material?) stock if I could find a piece large enough to make the
spacer out a single piece as in the first spacer I built , fewer joints = fewer leaks.


Using liquid nails would make a very strong joint. However, liquid nails dries
to a hard and brittle consistency. To me this means potential leaks if the stuff
ever cracks.

Hope this helps?

Larry H

[RSchleder]

I wonder if simply ordering one from Scamp wouldn't be the simplest? Of course it would need to match the dimensions of your fan.

[floyd]

I wonder if simply ordering one from Scamp wouldn't be the simplest? Of course it would need to match the dimensions of your fan.

Actually , the vent in my photo is a Standard 14X14 fantastic fan. It replaces the original 9X9 by extending two of the sides of the stock opening and cutting the opening to the required size.
The fan Scamp sells is same one generally available and the escutcheon will need to be trimmed for thickness where ever you get it. It comes with great instructions as well.

Note; You can buy fantastik fans with a variety of features ,like three speeds in and out, or various lids , among which is a flat one which hugs the roof and allows for easier entrance through a garage door.