7 Soffit and Fascia Installation Tips

When you’re putting new siding on a house, it’s quite common to replace the soffit and fascia at the same time. That doesn’t have to be the case, as they can be done separately, but when completed at the same time, it offers a uniform look to the house. If you can put up siding, you can manage the soffit and fascia. Knowing the best way to do it will make the job much smoother and faster.

Covered Soffit

If the soffit is already covered, then you’ll be putting the new soffit on top of that. This makes for a simple installation. You can to be sure that you use an J-channel to support the soffit.

Uncovered Soffit

Where there has never been a covering on the soffit-hollow, then you’ll need to use a J channel to support the soffit. This will also be the case where a previous soffit has been removed.


With an aluminium soffit, you’re going to have to leave room for expansion. As a general rule, allowing ¼ inch expansion room at each end of the soffit will be ample, although in colder climates, this should be increased to 5/16 inch at each end. This will give ample room to adjust to temperature variations without bending the soffit.


There are two choices with the soffit, going for vented or unvented. The vented soffits have small holes to allow air circulation into the attic, while the unvented are just solid. Most people opt for a combination of the two. This will still allow for ample attic ventilation without drawing in too much cold air from the outside.


Soffit material is sold in lengths. These aren’t meant to make one long length that stretches the entire length of the house. Instead, it should be cut to the width of the soffit, with the pieces locking together. The type of locking mechanism between pieces is going to vary from manufacturer to manufacturer, but the end result is the same in all cases.


When the soffit reaches a corner, you’re faced with two options. You can either miter the corner to 45 degrees or go with a square cut. Although a miter might look better, most people will find the 90 degree square cut much easier to execute. Either way, you’ll need to use a T channel to make the connection.


The fascia is the part that faces outward. Usually, the fascia will need to be cut to the height of the rafter. Make sure you allow enough of an overlap for it to wrap around the underside of the rafter and rest on the soffit or on the channel. At the corner, you should miter the fascia for the best appearance. Do this by cutting a V shape at the bottom and then scribing a line where the fascia meets the corner. Nail the fascia in place every 24 inches using stainless steel nails. The heads should be painted to match the trim.