of an inch, then placing some kind of rubber piece on the bottom for air infiltration. Cutting off the door without raising the threshold may result in an improper seal. You might also like to put masking tape on the jigsaws table itself as this will stop it from scratching the surface of the door. Center masking tape over the marker lines you drew. Plastpro has a “Trimmable” line of doors that can be cut to fit custom openings (1 in. Fiberglass is an incredibly versatile material that can be found in everything from housing insulation to boats. off the bottom!). Cut a Masonite door using a circular saw equipped with a finish blade that has 40 or more teeth. If the door is not clearing interior flooring, the better fix is often to raise the entire door jamb and threshold. By Mark Corke. Shop-Made Sanding Block. The interior of the door is made up of solid wood framing with fillers and some void space. When you must cut into your boat to install equipment, use the right tools and techniques for a neat, professional-looking job. Now the fiberglass needs to be cut by using a fine tooth jigsaw blade. A clean, efficient way to measure, mark, cut, and fill a hollow-core door. How to Cut Fiberglass. On a 3" (fiberglass) cut down, a door will look much better with a 4-1/2" top rail and a 6-1/2" bottom rail than it would with a 3" top rail & an 8" bottom rail. Watch this video and learn why cutting down a fiberglass door is a lot different than cutting a wood door! Replacing a door in your home, such as a cheap hollow-core door, is a fairly simple process with the right tools and a little know-how. If you're going to cut one down, use a solid wood door. Followed by a long string of swear words, and some durable hand tools getting set on the ground rather harshly. Generally, these doors come framed in their own jamb and do not need to be adjusted, but retrofitting may require you shave off an inch or two to make the door fit. I well remember the first time that I had to cut a hole in my new boat. Most of the heat loss from your home comes from the entrance door being of poor quality. Fiberglass doors are filled with foam which helps to insulate the home from the elements. Hell no. Plus, you can choose between 3-, 4-, and 5-inch trimmers. Cutting a frp door is possile but it's an ugly process. Fiberglass doors make for a great choice when you are replacing or installing a new door. A new half-bath is installed with plumbing, wiring, and a macerating toilet to liquefy and expel waste from belowground fixtures. If you decide to cut off an exterior door, make sure you have a plan for sealing the bottom of the door against the threshold when the door is closed.