Measure all areas below windows, eaves, and any other opening.
Inside Corner Post:
The inside corner post is used when there is an inside 90 degree angle and siding on both sides of the angle, as shown in Figure 6.
Figure 6 - Determining the position of the inside corner post for siding installation
Outside Corner Post:
The outside corner post is used when there is an outside 90 degree angle and siding on both sides of the angle, as shown in Figure 7.
Figure 7 - Determining the position of the outside corner posts for siding installation
The J-channel trim is probably the most versatile trim used to install siding. The J-channel is used anytime the siding stops, hence it is used around all windows, doors, and gables. It is also used when the siding stops on the side of the home and does not carry on to the adjacent wall. It is also used as the wall connecting trim for soffit material.
Figure 8 - Determining the position of the J-channel and starter strip for siding installation
If there was siding on the adjacent walls, the J-channel trim would be replaced with outside corner trim.
Soffit & Fascia:
Most homeowners will cover the fascia boards and eaves when siding the walls of their home, as shown in Figure 9. The soffit is the under part of the eave or the overhang from the roof. The fascia board is the piece of lumber than finishes the front edge of the overhang.
Figure 9 - Determining the position and measuring for the soffit & fascia for siding installation
Following are 5 components or accessories that make up the material that you may need to complete the installation of the siding on the soffit and fascia.
You will definitely require the fascia and soffit material whether you use J-Channels, F-Channels and/or finishing trims is defined by the construction of the eave and fascia and it is very likely that you will need all three trims in different locations.
To calculate the amount of soffit material you will require, measure the perimeter of the area to be covered. If you have a gable roof you will have to measure the distance on the angle of the roof line. Besides the various aesthetic designs of the soffit material, it is also sold as vented and non-vented. Some individuals use a combination of both vented and non-vented soffit depending on where it is to be installed. Others will use vented soffit throughout. To learn more about attic ventilation follow the link.