Full Frame vs Pocket Replacement Windows

The best product on the market can perform just like the worst if it’s not installed properly.  Most local installers primary do “pocket” replacements and don’t even discuss the option of full frame replacements with their customers.

Look at this “cheap” pocket replacement window and how much glass space is lost.  (A frame within a frame.)


The main way the replacement industry installs today is called a “pocket” replacement. The easiest way to describe it is to think about a wood window. When it was originally installed, the wood window consisted of a frame, tracks for the window sashes to slide along, and the sashes themselves (we are specifically talking about the most popular window type, a double hung). This window was installed into a rough opening, part of the home’s original framing process.

In a pocket replacement, the installer takes out the sashes, removes the sliding tracks and leaves the original wood frame in place. The new replacement window slides into the original frame. Think of it as putting a box inside of another box. Most window installers will then wrap any exterior mold (typically called brick mold) in an aluminum based coil stock.  The advantages to this type of installation method is relative ease, (as compared to a complete removal/reinstall) lower cost to the consumer, and speed. However, if you are putting one box into another, you will sacrifice more glass area. Also, leaving the wood frame naturally means at some time in the future you may have to redo this process because it’s not a question of if wood will go bad, it’s a question of when.  The other opportunity missed here is the ability to determine if there is any other damage or insect infestation in the original rough opening itself. You also won’t know if the original window was ever properly insulated, nor will you have the opportunity to do anything about it.

 A full frame installation as the name implies, the entire window, including the frame is torn out all the way down to the original rough opening. Often this type of installation technique has mainly been recommended when there is visible rotted wood.  When replacing a wood window with a vinyl replacement window in this manner, you’ll also need to understand that you’ll probably have to replace the interior trim as well. This has to do with the difference in the slope of a sill of a wood double hung window, as opposed to its vinyl counterpart.  Wood double hung window sills can have as much as a 15 degree slope, whereas most vinyl windows have around a 5 degree sloped sill. This variation means that the vinyl window will actually sit lower in the rough opening than the original wood window.

You can probably guess that the pros and cons for this method are basically the opposite of the pocket install and you’d be correct. First, you add glass area instead of take it away. Not only do you get about an inch on each side since you’ve removed the whole frame, but you also get as much as two additional inches on the bottom because of the difference in the slopes of the sill.

You are also getting rid of all the wood and replacing it with vinyl making it maintenance free, as well as being able to deal with any moisture and/or insect infestation issues that you can now see.

Additionally, this type of installation will include removing the old wood brick mold as well, and including vinyl brick mold as part of the new installation. Issues have arisen with improperly wrapped brick mold where moisture was allowed to get in and hasten wood rot.

Because we are removing and replacing the interior trim, the other thing we’ll be able to see is whether or not the area surrounding the window frame was ever insulated properly, something you can only do if you remove the interior trim. During the rapid housing build up, many window openings were not properly insulated originally companies expanding, open cell foam to re-insulate here, helping block any air infiltration from around the window when the house was built.   The challenges here are basically two-fold; cost and time.

A full frame installation in and of itself doesn’t take any more time. In this scenario, often a vinyl brick mold has already been attached to the new replacement window. There is opportunity to create an additional air and moisture seal on the exterior of the home before the brick mold is attached to the house. This time and effort replaces the cost and time involved in the wrapping of the exterior brick mold in aluminum coil stock that we mentioned was part of the pocket replacement process. As installers that were used to pocket installs will attest, the full frame install process, given time and experience, can actually be quicker overall.

Most of the additional time and cost comes in because of the necessity to replace the interior trim. A trim carpenter has to get the correct trim type, cut and build and add finish. Think about a stained piece of interior trim. First, stain grade, matching millwork has to be purchased, then the measuring, cutting and installing and then the stain. A good stain job has a minimum of five components with drying time in between each. As you can imagine along with this time component, comes a premium from a cost standpoint as well.

MASTERFIT™ TRIM  For Full Frame Replacment interior trim.

Add the finishing touch to the interior of your home with our MasterFit interior trim system. System includes assembled frame extensions that interlock with mortise and tenon casing. Our MasterFit interior trim system guarantees a long-lasting finish.

Mitered casing with high quality mortise and tenon corner locking system ensures strength and durability without nails.

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