Vinyl siding accessories for protecting roofing and walls

Trim and other vinyl siding accessories

Now we can move on to the flashing and vinyl siding accessories. Flashing is what keeps moisture from entering vulnerable parts of the roof and walls. The flashing is just strips of metal that can be cut to fit anywhere. It needs to be put up before any J-channel goes on.


It’s always a good idea to flash around windows, doors, corners, and any structure attachments. The idea of the flashing is to help the moisture get from the house to the ground with no resistance.

You need to start at the bottom of the window with the first piece, and then do the sides overlapping the bottom. Finally, you’ll do the top piece and it will overlap the two side pieces.

This will keep any moisture that gets in from penetrating the sheathing and causing damage. Attached garages will need flashing where it connects to the house.

vinyl siding trim

After the flashing, comes the installation for the J-channel around windows and doors. The top piece of J-channel needs to overlap the side pieces as shown in the drawing above.

This helps keep water from getting in. The drawing above shows a door lined with J-channel. The windows are the same. The J-channel is one of the vinyl siding accessories that you will use a lot of.

vinyl siding corners

After all the J-channel is put in place, then we can move on to the corner posts and special fittings for exterior outlets. There are outside and inside corner posts as shown above.

The corners should have flashing covering about 10 inches on each side of the corner before the corner posts are put on. The drawing above shows an outside corner and how it is started.

The top nail will be completely to the top of the nail hem hole so that the corner post rests there. All the other nails will be in the center of the nailing slot.

vinyl siding corner

When putting the corner posts on, you need to leave a ¼ inch gap between the top of the corner post and the eave or soffit.

The corner posts will also extend down below the starter strip by about ¾ inch. That will make a neat appearance once the vinyl is in place.

After the corner posts are done, you can put the external outlet fixtures on. These are prefabricated vinyl fittings for outlets, lights, spigots, dryer vents, etc.

These vinyl-siding-accessories will be put on before the vinyl panels because they help hold the panels in place.

vinyl siding equipment

These fittings make the job a lot easier and they are quite inexpensive. They give the exterior a nice finished look.

top of page

Next, nailing the vinyl panels

Back to vinyl siding main page