Is Butyl Tape OR QTDG Tape Better For Sealing Water Heater To The Outside Of An Aluminum Trailer?
Updated 05/11/2026 | Published 05/06/2026
Question:
Is butyl tape or QTDG tape better for sealing the water heater to the outside of the aluminum sided travel trailer?
asked by: Aaron S
Expert Reply:
Hey Aaron, thanks for reaching out. For that you'll want to go with butyl tape like part # AL33FJ (3/4" wide 20' roll). That’s the tried-and-true way to seal a water heater flange to aluminum siding. It stays soft, compresses into all those little ridges in the metal, and keeps sealing even as the trailer flexes going down the road. That’s why just about every factory install uses it behind windows, doors, and appliances.
QTDG-type tapes are more for sealing over seams or doing repairs, not for bedding a flange. For your install, lay a continuous strip of butyl behind the water heater flange, tighten it down evenly until you see a little squeeze-out, then trim it clean. Finish it off with a light bead of non-sag RV sealant across the top and upper corners, and you’re set.
What kind of trailer do you have?
(click to enlarge)
Product Page this Question was Asked From
Alpha Systems Butyl Tape for RV Weatherproofing - 20' x 3/4" x 3/16"
- RV Roof Repair
- Tape
- Butyl Tape
- Metal Roof
- Rubber Roof
- TPO Roof
- 20 Feet Long
- Colors May Vary
- Alpha Systems
more information >
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Dave
5/9/2026
Butyl did the trick on sealing my van windows. Been a year and a cold Buffalo winter and no leaks.