Window manufacturers offer a variety of window frames for the variety of different new and retrofit window installations. Choose the right window frame. In most types of window installation, exterior window trim is an unnecessary and expensive extra to be avoided.
Nailing Fin Window Frames
The most popular type of window frame is the nailing fin. Manufacturers designed the nailing fin for the most common type of new installation. The nailing fin attaches flush to the structural sheathing of the building. The frame of the nailing fin window protrudes beyond the nailing fin about an inch. The protrusion provides a place where the siding can dead-end into the window frame without needing exterior window trim.
The nailing fin works fine for this type of application, unless you plan on adding insulated foam sheathing to the wall. Some window manufacturers now provide nailing-fin window frames with jamb extensions to accommodate exterior foam insulation.
Brick Mold Window Frames
The brick-mold window frame has been popular for new and retrofit windows for many decades.
Manufacturers designed brick mold window frames to give a finished look to a window installation surrounded by brick. However, many builders use the brick-mold frame for wood frame construction and window replacement. Vinyl windows with vinyl brick mold are popular for retrofits.
The best vinyl brick mold has a removable slat that conceals the screws that hold the brick mold in the window in place.
Flush Flange Window Frames
Builders use flush-flange window frames with stucco exterior finishes. Flush-flange window frames are also appropriate for any kind of cladding that produces a flat surface.
Block Frame Windows
A block frame window uses no added nail fin, brick mold, or flush flange. Therefore, installers fasten the window through the frame into the rough opening. Specialty screws, plates, or clips attached the window frame to the rough opening. The block frame window installation is the most versatile window installation option. Also the block frame allows installers to install windows from indoors.
You can save time and money if you select the right window frame. And just as important, the right window frame provides the best-looking and most durable exterior finish.
I like how vinyl brick molds hide the screws that hold the window in place like you mentioned. I’m building a home and have to choose out the windows. I really like vinyl because it’s so durable.
I like how you went into detail about the various types of window frames. I personally didn’t know that you can install block-frame windows from inside. This post is very insightful and I learned a lot! Thanks.
I have a wood frame house and I am having impact windows put in- they appear to be block frame windows and lack the fin for a nail in application – there were also 1/4 inch gaps they calked- I don’t think this is correct- they called them retrofit windows but on a wood frame house I think they still need to build out wood to butt up to the lip to secure it and prevent leaking- is there such a thing as not finned impact windows for a wood framed house?
Selecting the correct window frame for your installation can significantly impact both the appearance and the durability of your exterior finish. Nail-fin frames are commonly used in new wood-frame constructions, fitting flush against the structural sheathing. Brick-mold frames, often made of vinyl, are suited to both new installations and retrofits, especially those surrounded by brick. Flush-flange frames are preferred for flat exterior surfaces such as stucco, while block frame windows offer versatility and indoor installation options. The right choice can save you time and money while enhancing the overall look of your property.