Installing a new vinyl window in an existing wall. Old House Remodeling:

Installing A New Window
In An Old Wall

In This Article: Related Articles:
Skill Level: 3 (Intermediate) Time Taken: About 8 Hours

By , Editor


Recently I helped a friend remodel two bathrooms in an old 1890's house. The upstairs bath had a tiny 30" square galvanized steel shower stall that looked downright hideous. As far as we could tell, the second-floor bath had been added in the 1930's or 40's. They bumped-out the attic roof with a shed dormer to make some additional space. The bathroom had ancient Masonite paneling with an embossed pattern made to look like ceramic tile, and a previous owners had painted over everything. The toilet and sink were very outdated and in pretty bad shape, so he decided to gut the entire room, a wise decision.

After shopping around for a replacement shower, I discovered that plumbing codes no longer allow shower stalls smaller than 32" square, but I did locate a dealer that could special order a 30" shower. Trouble was, it would take almost a month to get it. The shower stall was positioned right next to the window, so there was no room to install a larger shower.

So the homeowner decided to install a 4-½ foot bath tub instead of the shower. That meant filling in the old window and installing a new window a few feet away.


Bathroom during remodeling, site of new window. This was the bath room after the Masonite paneling had been stripped away. The old window is actually a narrow pair of French doors that open onto the flat roof over the attached garage.

This access to the garage roof made a neat deck, I'll admit, but any deck that has access only via a bathroom is pretty dumb. I could imagine somebody using the bathroom only to be surprised by a sun-bather entering the house. The homeowner decided to nix the deck access from the bathroom.

Removing the old Masonite paneling was easy but there were dozens of tiny nails left in the studs. Many carpenters just pound in these nails, but I contend that this practice is short-sighted and can cause small problems later on. So we removed all of the nails, which probably took a half an hour.

Of course, most rooms will have drywall or plaster. I have never installed a new window in an old wall and left the drywall in place... every window I've installed like this has been in conjunction with a whole-room remodeling job. It may be possible to install the framing for a window opening and leave the drywall intact, but I don't know of any way. I could envision some ways of removing a minimal amount of wallboard around the opening, but it would involve some serious drywall patching.

This is a replacement  window, which the homeowner bought by mistake. After explaining his situation to the staff at Home Depot they steered him to this unit. Uh-huh. Vinyl replacement or remodeling window.

I spent a few minutes trying to figure out a way to make this first window work. I realized that I would need to build a sill and jambs, which could take a few hours, and I didn't have any materials for that. So I just drove to Home Depot and bought the proper window.


The new window:

This is a new construction window, which is distinguished by the nailing flange (right)

Vinyl new construction window.


Cutting The Opening:

The window opening must be carefully laid out to determine the proper places to cut the framing. This layout work is probably the most important element of installing a new window in an existing wall. Please read Framing A Rough Opening For A Window Or Door for some sketches that explain how a window opening is normally framed, and for information on header sizes.



Bracing The Structure:

Note that in many cases the weight of the roof (or floor above) must be supported by braces. If I only need to cut one stud (as was the case in this article), I have usually been able work with no need for support bracing. In an article on cutting an opening for a slider door I explain a few points about bracing.


After I laid out the cut marks on the stud, I made a slice with a circular saw, and finished the cut with a hand saw.


Using a reciprocating, saw I cut the nails at the top of the stud.

When making cuts like these the saw blade may pinch badly. Pinching is a sure sign that the weight of the structure is bearing down on the blade, and that the structure needs to be braced.

I cut the nails that held the solid wood sheathing to the stud.


I removed the unneeded portion of the stud. The red arrow points to the mark where the stud used to be.


I installed a header made from double 2x12's and some plywood spacers to bring the overall thickness to the same dimension as the studs.

Many carpenters make all of their headers this way... 2x12's installed right up against the top plate... because it saves them the time and hassle of cutting the short little jack studs (also called cripple studs) above the header. Such tall headers may be overkill for some windows, but the time savings is often worth it.



I added some trimmer studs (left and right arrows) and then a sill plate (middle arrow). These were all nailed with 16d spiral twist nails, which are less likely to split the wood than fat old common nails.

Sometimes when I'm doing remodeling work on old houses with dry, brittle framing I use 3" deck screws (such as Deck-Mate brand) and pre-drill the holes, especially near the ends of boards. This prevents a lot of the splitting problems that are common with old wood.


The same scene, viewed from farther back.


I installed the upper portions of the trimmer studs. The red arrow points to an extra piece of 2x4 that I installed, to make the window opening a bit narrower.

Often the window opening will not conveniently span from one existing stud to another, as was the case here. Typically another stud (a "king stud") needs to be installed to form one end of the rough opening. In some cases, where the window must be placed at some exact location (such as the precise mid-point of a wall) two new studs might be needed.

Rough opening for new window in existing wall.


The Exterior:

Whenever I install a window I try to do as much work on the inside as possible before I violate the building envelope and invite the weather inside.

The other side of the new window location.


I carefully removed and salvaged as much siding as possible Removing siding to make rough opening for new window.


I removed more siding than I needed. That black stuff is tar paper over top of the wood sheathing.


I drilled 1/2" holes at a couple of corners.


Cutting wall sheathing for new window opening. Then I stuck the reciprocating saw blade through the hole and cut out the solid wood sheathing.



A room with a new view.


I removed the trim around the old door, saving it for later re-use.


Once I cut all around the door jambs, I just leaned the door back and removed it.

Most doors are not fastened through the threshold (the bottom piece), but many newer doors will have a bead of caulking under the threshold.


The Great Wide Open:

Now the weather is coming inside whether I like it or not.


Installing The Window:

I applied a bead of caulking to the back of the window flange.


Tacking vinyl window in place during installation. I placed the window in the opening and tacked one nail in an upper corner.


I made sure the top was level. I only used this small torpedo level because it shows up better. A longer level is best.

After the top corners were tacked in place I measured the diagonals to make sure the window was square.


I nailed the rest of the flanges with 2" galvanized roofing nails, the usual fastener for installing new construction windows.


I filled in the old door opening with studs and oriented strand board (OSB).


Rubberized asphalt flashing around new window to prevent water leaks. I applied tar paper to the bare OSB and 6" wide Ice & Water Shield over the flanges on the sides and top of the window.

This flashing must be applied to the bottom first, then the sides, then the top, so water always flows over the sheet below it.


The view from the inside.


The old door opening was simply filled in with 2x4's nailed to the framing around the old rough opening.


Patching The Siding:

I was not able to find ½" x 4" bevel siding at any local lumberyards, so I made some siding from my own stock of ½" x 6" bevel siding. All I did was rip the siding to 3½" wide on my table saw, discarding the thicker portion. I didn't even sand the cut edge smooth, because this location is so far out of the way that nobody will see the roughness. The siding I made was just a bit thinner at the fat end than the original siding.

I also re-used some of the siding I removed earlier. I pre-primed both sides of the new wood, and pre-painted the faces indoors since the weather was too cold for painting outdoors.

Before installing the siding I made new window casings from the old door casing materials.

Note how some of the siding is mis-matched (red arrow). The siding boards on the left side of the old door were not at the same altitude as the boards on the right side. I had to decide between applying the filler boards on a slope or letting some be out of alignment. I chose the latter because this area is almost impossible to see from the ground, and because I believe that it's almost always wrong to intentionally install something off-level.


The top casing was a special two-piece deal. I just cut it to length, slid the top flange under the siding above, and nailed it in place.


I completed the siding just as dusk fell. I was lucky to be able to do this outdoor work in Northern Michigan in mid-December. Normally there would be at least a foot of snow on the ground.

You can't really see any of the nail heads in the above pictures, but they can be seen from the ground. They aren't really obvious... they make the siding look dirty more than anything. While pre-painting siding is a good idea, the paint still needs to be touched up... when the weather warms up.


The Inside Story:

The finished window from the inside.

After the drywall was installed, finished and painted I installed the window trim.


The wide jamb extensions were made from pieces of ¼" thick by 3½" wide solid red oak, which Home Depot sells. The casing is just ordinary "colonial" casing in red oak.

Jamb extensions can be made from any solid wood, or even plywood with an edge-banding of veneer. For many windows I make extensions from 1x4 clear pine. The ¼" thick wood I used here made installing the casing rather tricky because I could not leave much of a reveal. Usually I would leave about ¼" of reveal from the edge of the jamb to the edge of the casing. If the jambs are not perfectly square I can adjust this reveal and make it look half-decent. But with this very thin wood I had to be extra accurate, which meant placing shims behind the jamb extensions and lots of additional time getting things right.

Since doing this job I have done some cabinet making with oak veneer plywood and adhesive-bonded oak veneer edge-banding, which I bought at Home Depot for about $5 for a 25 foot roll. It worked great. The edge-banding has a hot-melt adhesive on the back of the wood, and all you do is heat the wood strip with a regular clothes iron. Next time I think I'll try making jamb extensions with plywood and edge-banding.



Tools Used:

  • Cordless Drill/Driver
  • Basic Carpentry Tools
  • Levels
  • Circular Saw
  • Reciprocating Saw
  • Power Miter Saw
  • Table Saw

Materials Used:

  • New Construction Window
  • Lumber, 2x4x8'
  • Tar Paper
  • Vycor® 6" Ice and Water Shield
  • 2" Roofing Nails
  • 3" Deck Screws
  • Bevel Siding
  • Oak Casing
  • Solid Oak ¼" x 4"

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Copyright © 2002

Written March 1, 2002