Fan is leakiiiing

[honeybee]

Hi! I bought myself a van to go traveling and am working on fixing it up, the fan came pre-installed and while there was watermark on the wood around the fan, the seller lied and said that it was because they had left it open a few times in the rain. Whatever!

It finally started to rain out here and I discovered that the area around my roof fan is indeed leaking. I took apart the fan itself and there was no water inside so I'm both pleased and inclined to believe that the seal around the fan is failing instead. I climbed up on the roof and saw that the seal is roughly intact though there's a crack around one of the screws that may be letting water in and the seal itself looks like it's seen better days.

My question is a very simple one, and sorry if it's something I should've looked up -- am I going to need to remove the pre-existing seal to re-seal and if not, what material would be best to re-seal the area?

Thank you.

 

[rvpopeye]

If you're talking the seal between the fan and roof butyl tape is the stuff you want.
You'll have to remove and remount the fan.

If that sounds too hard you could do repair with Eternabond tape over the flange.

 

[highdesertranger]

yep butyl tape. the RV stuff lasts about 10 years. the marine tape lasts about 20 years. highdesertranger

 

[John61CT]

best Butyl tape http://www.pbase.com/mainecruising/rebedding_hardware

 

[user 37446]

+1 to above. Just don't use pure silicone sealant, you'll regret it. 

http://www.doityourself.com/stry/typesofcaulkseal

Begin quote:

"Water-based Caulk
Generally referred to as latex caulks and sealants, water-based caulks are the easiest to work with because they apply easily, are paintable, have little odor, and clean up with water. They're effective for filling gaps in baseboard and trim, as well as for caulking around interior window and door frames. Most often they come in cartridges ranging from 10 to 12 ounces as well as convenient squeeze tubes ranging from four to six ounces. For latex caulks, your ideal curing conditions are warm (above 40 degrees), dry weather.
Within this category, there are several more specific caulking types with specialized characteristics. Vinyl latex caulk is usually effective for five years and is most effective on small cracks in baseboards and little gaps around windows. Vinyl latex is non-flammable and paintable but not very flexible, and it hardens over time.
Acrylic latex caulk is a general-purpose caulk—more flexible than vinyl latex caulks. It is easy to apply, non-flammable, and cleans with water. It adheres to most surfaces—best on wood and masonry—and it can be painted shortly after application. It is available in pigments as well that allow it to match many surfaces. It remains effective for 10 to 15 years, however, it is not recommended for an area that is subject to excessive water collection like tubs or sinks. It is flexible and maintains that flexibility over time. It should not be applied in temperatures of less than 40° F.

Tub and tile caulk is a specialty performance caulk with added mildewcide to protect against mildew growth in areas prone to moisture (kitchens, bathrooms). Some tub and tile caulks are more flexible and crack-resistant, too. Many formulations include adhesives that combine a sealant and adhesive in one. Like other latex caulks, they apply easily, are non-flammable, clean up with water, and are paintable. They are also available in a variety of colors.

Siliconized Acrylic Caulk
This type of sealant combines silicone with acrylic latex formulas for improved water resistance. This medium-performance, water-based caulk can withstand greater movement than acrylic latex, and it can be used for interior or exterior with good adhesion, even to glass and ceramic tile. This caulk also comes in a variety of colors as well as clear formulas.
Like the former water-based sealants, it applies easily (though best applied in temperatures above 40° F), is non-flammable, paintable, mildew-resistant, and cleans with water. It can endure moderate temperature changes and has a total life expectancy of about 25-35 years.

Silicone Caulk
Silicone caulk is another alternative to using tub and tile latex caulk. It is good for use around bathtubs and sinks because it resists mold and mildew, and it is water resistant with excellent adhesion to smooth surfaces such as metal, glass, and tile. It should be noted, however, that it does not adhere to masonry. Silicone caulk remains flexible after curing and is not affected by UV radiation. Unlike water-based sealants, though, paint will not stick to most silicones and this caulk is more difficult to apply. Silicone does not adhere well to wood, and must be cleaned up with solvents rather than water. It is non-toxic, though, and can be applied at nearly any temperature.

Butyl Rubber Sealants
Butyl rubber sealants are solvent-based with a life expectancy of only two to 10 years. However, be that as it may, this choice is a good one for sealing out water in lap joints, such as gutters, and for metals and masonry as well as outside for chimneys. It's probably the best waterproofing sealant for below-grade applications, such as foundations.

That said, these sealants are also stringy, difficult to apply, and slow curing. They are most efficient when applied to openings between similar surfaces, but are not recommended for openings wider or deeper than 1/4" or in 90° corners. Butyl rubber sealants also offer low to moderate movement capabilities.

Synthetic Rubber Caulk
A relative newcomer to the caulk category, synthetic rubber caulk is perhaps the most flexible product on the market. It cures clear and is ideal for exterior joints that typically expand and contract since it can be applied in adverse weather conditions (wet and cold) and stretches and recovers easily without breaking. It is also great for use on roofs, wood siding, and joints that frequently show movement.
Synthetic rubber caulk can be painted with latex paint. Due to higher VOC content, it can’t be used indoors in some parts of the country, although manufacturers have introduced low VOC formulations to the marketplace."

End of quote

 

[SternWake]

Clean the area around the fan, Apply Eternabond tape, move on to other  things.
I'd not pull the fan just to get new butyl tape under  the flange