It does not seem like such a good idea to us, but at least one manufacturer we found has a detail for installing the transition between vertical (or, in this case, semi-vertical) vinyl lap siding and horizontal. Here’s the installation detail recommeded by PlyGem.
Unfortunately, the installation shown in the photo above uses a single J-channel, while the recommended installation diagram specifies two J-channels back-to-back, undersill trim under the lower one, and flashing between them. Here’s a close-up of the transition area, which is definitely less than adequate.
It’s important to note that vinyl siding is not designed to be waterproof. According to the Vinyl Siding Institute, a national trade organization, “vinyl siding, insulated siding, and polypropylene siding are exterior claddings, not water-resistive barriers, and are designed to allow the material underneath to breathe. This factor provides a supplemental rainscreen that reduces the amount of water that reaches an underlying water-resistive barrier.” But sloppy installation means that more than a little water will get behind the “supplemental rainscreen"—and eventually cause a problem.
Also, see our blog posts What do you look for when inspecting vinyl siding? and Can vinyl siding be painted?
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To learn more about exterior walls and structures, see these other blog posts:
• What is the average lifespan of a house foundation?
• What causes vertical cracks in fiber cement siding planks?
• What causes raised white lines of residue on a block wall that are crusty and crumbling?
• What is the difference between soil subsidence, heave, creep, and settlement?
• How much ventilation is required for the under-floor crawl space of a home?
• What causes stair-step cracks in a block or brick wall?
• What causes a horizontal crack in a block or brick wall?
• How can I tell if a diagonal crack in drywall at the corner of a window or door indicates a structural problem?
• What causes the surface of old bricks to erode away into sandy powder?
• What are the pros and cons of concrete block versus wood frame construction?
• Should I buy a house with a crawl space?
• Why is my stucco cracking?
• There's cracks running along the home's concrete tie beam. What's wrong?
• What would cause long horizontal lines of brick mortar to fall out?
• How do I recognize structural problems in a retaining wall?
• What is engineered wood siding?
• Should I buy a house that has had foundation repair?
• What is a "continuous load path”?
• Should I buy a house with asbestos siding?
• How can I tell if cracks in the garage floor are a problem or not?
• What do you look for when inspecting vinyl siding?
• Why is housewrap installed on exterior walls under the siding?
• How do I recognize serious structural problems in a house?
• Why did so many concrete block homes collapse in Mexico Beach during Hurricane Michael?
• How can I tell if the concrete block walls of my house have vertical steel and concrete reinforcement?
• Should I buy a house with structural problems?
• What are those powdery white areas on my brick walls?
• What causes cracks in the walls and floors of a house?
• How can I tell if the exterior walls of a house are concrete block (CBS) or wood or brick?
• What are the common problems of different types of house foundations?
• What are the warning signs of a dangerous deck?
Visit our EXTERIOR WALLS AND STRUCTURE page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.
Photos - Ben Michler, Diagram - PlyGem