How To Install New Construction Windows (In an existing home)

GETTING STARTED

 

Installing new construction windows in an existing home may sound like an intimidating task. But if you follow these step-by-step instructions, you'll be a window installation wiz in no time.

This tutorial is for installing windows with integral nailing flanges with sheetrock return interiors. Wood windows with brickmould or flanged windows with wood interior casing have a slightly different process. The basics are the same however. So let's get started.

 

The Finished Product.
The Finished Product.

TOOLS & SUPPLIES NEEDED

  • Cat's claw/nail puller
  • Framing hammer
  • Pry bar
  • 2 foot level
  • 4 foot level (doubles as a straight edge)
  • Tape measure
  • Circular saw
  • ½" or ¾" chisel
  • Caulk gun
  • 8d or 10d galvanized nails
  • Nail set
  • Siliconized acrylic caulk
  • Exterior trim boards (i.e. cedar, smart siding, or PVC)
  • Standard window flashing
  • Power miter saw
  • Table saw
  • Jigsaw (not on every application)
  • Flexible window wrap tape (tar backed & self-adhesive)
  • Utility knife
  • Pencil
  • A positive attitude and gumption

GOING BUH, BYE

Click thumbnail to view full-size
THE OLD WINDOW WITH THE SIDING CUT BACKREADY TO PREP THE OPENINGA CLOSER VIEW OF THE OLD FLANGE WITH THE SIDING CUT BACK
THE OLD WINDOW WITH THE SIDING CUT BACK
THE OLD WINDOW WITH THE SIDING CUT BACK
READY TO PREP THE OPENING
READY TO PREP THE OPENING
A CLOSER VIEW OF THE OLD FLANGE WITH THE SIDING CUT BACK
A CLOSER VIEW OF THE OLD FLANGE WITH THE SIDING CUT BACK

STEP ONE: REMOVING THE EXISTING WINDOW

Let's assume the new window has been measured for and purchased.

  • Using the cat's claw, remove the existing nails from the current trim boards framing the window.
  • Cut any existing caulk beads around the trim boards.
  • Pry the trim boards slowly from the exterior and remove.

You should now be able to see the existing siding and complete frame of the old window

  • With the circular saw, set the blade depth just deep enough to cut the thickness of the siding. Setting the blade too deep will make cutting more difficult; too shallow and it won't clear.
  • Make your cuts as straight as possible and about 1" beyond the edge of the existing window's nailing flange.
  • Remove all nails between your cut and the edge of the siding.
  • Remove the old siding keeping as much intact as possible. You may wish to re-use it later.

You should now be able to see the entire window and flange with securing nails exposed.

  • Begin removing all nails from the existing window's nailing flange. I usually pull the bottom and sides first and finish with the top. You should probably have someone assist you once the final nail is pulled to keep the window from falling on you.
  • Remove the old window from the rough opening. A gentle nudging might be needed, but the unit should come out easily.

PREPARATION, PREPARATION!

Click thumbnail to view full-size
MEASURE THE DISTANCE FROM THE FLANGE TO THE INTERIOR FRAMEMARKING YOUR LINE TO THE SHEETROCKAFTER THE SHEETROCK HAS BEEN TRIMMED BACKWINDOW TAPE ALONG THE SILL AND SIDES
MEASURE THE DISTANCE FROM THE FLANGE TO THE INTERIOR FRAME
MEASURE THE DISTANCE FROM THE FLANGE TO THE INTERIOR FRAME
MARKING YOUR LINE TO THE SHEETROCK
MARKING YOUR LINE TO THE SHEETROCK
AFTER THE SHEETROCK HAS BEEN TRIMMED BACK
AFTER THE SHEETROCK HAS BEEN TRIMMED BACK
WINDOW TAPE ALONG THE SILL AND SIDES
WINDOW TAPE ALONG THE SILL AND SIDES

STEP TWO: PREPARING THE ROUGH OPENING

  • Measure the distance from the backside of the new window's nailing flange to the edge of the new window's frame. Our window has a measurement of 1 7/8".
  • Measure the distance from the outside of the rough opening's framing stud to the edge of the interior sheetrock return. The difference between these two measurements determines how much sheetrock needs to be removed. Our installation needed 1 1/8" removed from the interior sheetrock.
  • Using your tape measure, mark this distance on the sheetrock at various points and mark a line with a straight edge.
  • With your straight edge as a guide, score the line a few times with your utility knife.
  • Remove the excess sheetrock from all sides and clean up the edges.
  • With the window wrap tape, cover the entire length of the bottom sill plate and about 3-4" up each side. This will provide a waterproof dam on the sill in case of any water infiltration.

You're now ready to install the new window.

PLUMB, LEVEL, & SQUARE!

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OUR WINDOW AFTER SQUARING AND SOFT NAILINGCHECKING FOR PLUMBCHECKING FOR LEVEL (Note the sheetrock mud) :)
OUR WINDOW AFTER SQUARING AND SOFT NAILING
OUR WINDOW AFTER SQUARING AND SOFT NAILING
CHECKING FOR PLUMB
CHECKING FOR PLUMB
CHECKING FOR LEVEL (Note the sheetrock mud) :)
CHECKING FOR LEVEL (Note the sheetrock mud) :)

STEP THREE: INSTALLING THE NEW WINDOW: PART 1

  • With assistance, (and the window locked) center the new window in the rough opening and check for square. This is done by placing your tape measure on the top left outside corner of the window frame and measuring the distance to the bottom right corner. Record this measurement.
  • Next, take a similar measurement from the top right outside corner to the bottom left corner.
  • These two measurements should be within 1/8" of each other. If not, you'll have to adjust accordingly by shifting the window right or left in the opening. I tend to shift in increments of 1/8" with good success.
  • Once the unit is square, soft nail the top left corner to secure.

NOTE: DO NOT HARD SET ANY NAILS UNTIL THE WINDOW IS PLUMB, LEVEL, AND SQUARE!

  • With the 2 foot level, check the sill plate for level and shim if necessary.
  • Check for plumb on the side you soft nailed and adjust accordingly.
  • Check for plumb on the right side and adjust accordingly.
  • Recheck for square.
  • Once both sides are plumb and the sill level, you can soft nail the sill. I usually put nails in each corner and the center.

NOTE: Chances are pretty good if you properly squared the window, the sides and sill will be plumb and level.

Click thumbnail to view full-size
TAPING OVER THE NEW FLANGES TO THE SIDINGTAPING OVER THE NEW SIDING AND BEYONDBACK CAULKING THE TAPE TO THE NEW WINDOWTHE FINISHED PRODUCT... AGAIN!
TAPING OVER THE NEW FLANGES TO THE SIDING
TAPING OVER THE NEW FLANGES TO THE SIDING
TAPING OVER THE NEW SIDING AND BEYOND
TAPING OVER THE NEW SIDING AND BEYOND
BACK CAULKING THE TAPE TO THE NEW WINDOW
BACK CAULKING THE TAPE TO THE NEW WINDOW
THE FINISHED PRODUCT... AGAIN!
THE FINISHED PRODUCT... AGAIN!

STEP FOUR: INSTALLING THE NEW WINDOW: PART 2

  • Recheck both sides for plumb, the sill for level, and the unit for square. (Sounds like I'm beating a dead horse, but this is the key to proper operation of the window).
  • Once all the measurements are correct, you can hard set each nail and add additional nails. Nail every 8" on each side, every 6" on the sill, and allow the top to float.
  • With window tape, cover the new flange and extend to the edge of old siding.
  • Nail into place, either new siding (ripped to size with your table saw), or the existing siding if not overly damaged, and install over the new window's flange to the edge of the existing siding.
  • Caulk any major voids.
  • With window tape, cover up all seams; to the edge of the window to about 1" past the outside seam.
  • Back caulk the tape to the edge of the window on all four sides. This is done as prevention against any water that may infiltrate the primary trim boards and caulking.

WE'RE GETTING CLOSE.

  • Flash the entire top of the new window with standard window flashing. Make sure you extend the flashing the width of each side trim board. (If your new window rests directly under a wide soffit, you can usually skip this step).
  • Cut your trim boards to size and notch as needed; as if in under a soffit.
  • Nail the trim boards in the following order: 1) Top 2) Sides 3) Bottom.
  • Nail each trim board into place.
  • Caulk the top and sides of each trim board but not the bottom edges. This is done to ensure proper drainage.

YOU'RE DONE!

Give yourself and your help a nice high five and move on to the next window.

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Comments 35 comments

solarshingles profile image

solarshingles 8 years ago from london

Rob, thank you for this wonderful, very precise and highly practical hub! I also like how you use your tags about this particular niche market. Try to add them many more(long tail ones).


Rob Jundt profile image

Rob Jundt 8 years ago from Midwest USA Author

Thanks solar for your kind comment. I like reading hubs like this so I thought I'd start writing a few.


Morris Streak profile image

Morris Streak 7 years ago from UK

Quite detailed your instructions are. Removes the fears, I imagine, in the minds of those who want to do these themselves. Good stuff. I'm into home improvement, too.


Jennifer 6 years ago

Thank you so much for this helpful article it was instrumental in our window project.


baylegg 6 years ago

I need to replace the three windows on the back of my house. It's north-facing with no eave. The sills have rotted. I've purchased Andersen TW 400 series - new construction windows with nailing fins.

If I have T-111 siding and foam board sheathing under that - no existing nailing fins or flashing, would you cut the siding and foam board down to the framing and then install as you've said?

Could I just apply flex sheathing to the bottom of the rough opening and nail directly to the siding, apply flex sheathing all around and a drip cap and then just use extension jambs inside?


Rob Jundt profile image

Rob Jundt 6 years ago from Midwest USA Author

baylegg:

Thanks for dropping by. It sounds as though your application is fairly similar to the one described in my hub. One thing I would not do, however, is cut back the foam board. I would leave it flush to your RO. And, if at all possible, leave the T-111 intact as well simply by loosening its nails and sliding the new window, flanges and all, underneath. This, of course, would be more difficult if the T-111 was a solid piece with no seams. So, to make a long description longer, if you can keep the existing siding without cutting it, do so. If not, remove as little as possible, install the new window over the foam board, flash if necessary (NOTE: you can also flash under the foam board prior to nailing the new window to it if you have the right size drip cap that will cover the entire window frame), then you can tape the seams, replace siding and caulk, and then follow the remaining steps in the hub. By all means flex wrap the sill as noted, and finish caulk all trim boards. Jamb extensions on the interior can be easily installed after the windows are in place. Hope this helps.

RJ


whitton profile image

whitton 5 years ago

Nice Hub. Very detailed and precise.


michael 5 years ago

fantastic schooling !

You're helping to make the world go round.

Thanks man !


Rob Jundt profile image

Rob Jundt 5 years ago from Midwest USA Author

Thank you whitton and michael. Your comments are too kind and appreciated. Have a great day!

RJ


Peggy 5 years ago

Thank you so much Rob for the instructions. I am a novice for sure. I am building small cabin . I closed it up for winter and am now spending time learning how to install windows for the spring. I am really grateful for all the time and effort you put into this. Peggy


Jim 5 years ago

This the by far the best how to article on installing nail fin windows for replacement. I have house wrap under my t 111 it was impossible to cut the siding without cutting house wrap. I've read that house wrap joints must be taped. I found that it was impossible to tape joint between the existing house wrap and new window flashing. I did the next best thing which is to use 6'' wide paper flashing and tuck it under the existing flashing. I also taped the nail flanges with flashing tape. Does anyone know a better way to join the house flashing with new flashing or better way to cut the t 111 without damaging the house wrap?


Rob Jundt profile image

Rob Jundt 5 years ago from Midwest USA Author

Peggy and Jim:

Thanks for the nice comments! For Jim, the manner that you taped over all house wrap, as long as the new tape is behind a primary drainage plane, should work. A good rule of thumb for flashing is to always make sure to place the new UNDER the old. When in doubt, you can always tape these joints as well. In a perfect world all flashing should go directly onto the framed wall panels (without siding installed) with at least a 1/4" overlap above the opening, window, or door below. Flashing should also extend at least 1/2" beyond the edge of all openings (casing included) below. As far as being careful not to damage house wrap while cutting t111, I would set the saw blade about 1/8" shy of the siding's OA thickness and then carefully use a chisel to remove the excess. As you alluded to, once you penetrate that house wrap, it's essentially useless. Good luck in your window endeavors.

RJ


Pete 5 years ago

RE:Make your cuts as straight as possible and about 1" beyond the edge of the existing window's nailing flange."

I have removed the exterior trim and the T1-11 runs right up to the egdge of the window. How do I know how far the flange extends so I can cut 1" beyond that?

Thanks!


Rob Jundt profile image

Rob Jundt 5 years ago from Midwest USA Author

Pete:

I would make a test cut with a small blade (possibly a utility knife) to see where the window's existing flange is. From there, it is just a matter of marking a line, setting the correct blade depth, and making the cuts.

Thanks again,

Rob


viz 5 years ago

Thank you so much for this helpful article. I have a double hung wooden window with rotted outer sill. Outer window trim is covered with brick mould and vinyl siding around it and foam board behind. I am planning to install new vinyl double hung window with flange. How do I install window flange inside vinyl siding?


Rob Jundt profile image

Rob Jundt 5 years ago from Midwest USA Author

Viz:

This is a bit tricky. In essence, you'll have to pull out the entire existing window. While doing that, you will of have to remove the J-channel and vinyl siding surrounding the window unit. If the wood window is original, it should be nailed to the home's original framing which is to your advantage; because then all that is left is to nail the new flanged window into the opening. The flange should install where the old brick mould was. From there, I would tape the seams, install flashing over the entire top of the new window, replace whatever foam board you had to remove, and then put back the vinyl siding with J-channel. One other part: since the brick mould that was removed was approximately 1-2" in width, you'll have to re-trim the new window with comparable trim boards. I would probably go a little wider than the original brick mould just to ensure your vinyl siding will fit. It's always better the cut it back than to be short. I hope this helps. Please leave any further comments here as I will check every day. Thanks for dropping by.

RJ


Rob Jundt profile image

Rob Jundt 5 years ago from Midwest USA Author

Viz:

This is a bit tricky. In essence, you'll have to pull out the entire existing window. While doing that, you will have to remove the J-channel and loosen the vinyl siding surrounding the window unit. If the wood window is original, it should be nailed to the home's original framing which is to your advantage; because then all that is left is to nail the new flanged window into the opening. The flange should install where the old brick mould was. From there, I would tape the seams, install flashing over the entire top of the new window, replace whatever foam board you had to remove, and then put back the vinyl siding with J-channel. One other part: since the brick mould that was removed was approximately 1-2" in width, you'll have to re-trim the new window with comparable trim boards. I would probably go a little wider than the original brick mould just to ensure your vinyl siding will fit. It's always better to cut it back than to be short. I hope this helps. Please leave any further comments here as I will check every day. Thanks for dropping by.

RJ


Viz 5 years ago

Thank you for your quick and helpful response. Looks like it is a bit complex than what I thought. Yes they are original wood windows. I am thinking of installing American Craftsman(HD)3000 Double-Hung Vinyl Windows. Brickmoulds were also rotten near sill. How to avoid wood exposure outside? Do you have any other suggestions?


Rob Jundt profile image

Rob Jundt 5 years ago from Midwest USA Author

Viz:

The rotten brick mould at the sill is not a problem since it is part of the original window frame you are taking out. As for the windows themselves, since I've been out of the business so long (going on over 4 years now) brand quality is not something that I've kept up with. Thanks again for stopping by!

RJ


AWest 5 years ago

Great hub! We just bought 2 new construction Andersen 400's to install in place of the original single pane double hung in our 1963 home. Rough opening matches with the Andersen specs. My question is how to handle the flashing that I'm going to need to remove once I install the new windows. Of concern is the wide aluminum siding. Will I be able to remove that flashing without damaging the siding? Any ideas? Thanks. AW


Rob Jundt profile image

Rob Jundt 5 years ago from Midwest USA Author

AWest:

Sorry about the delay; I'm getting ready for finals. Anyway, on to your question.

If you can, save as much of the original flashing as possible but since it is more than likely installed under the existing siding you'll have to take extra care not to damage the siding while removing; which is your original concern as noted. Without seeing how the siding is attached, it can be a bit tough to say whether or not the flashing can be easily removed. Typically, after you have the old window removed the J-channel that was used to tuck the siding into it should be with the old window. If so, then you should have a loose end of siding. From there, gently pull on the siding (it should be nailed at the top) and slowly try to loosen a few nails. Do not, however, yank hard on the siding because then it might bend or break. This may be a slow process but I think you can loosen the siding enough to have access to the flashing. If possible, remove a few pieces of siding to gain access to the flashing which should be nailed either to the house framing or insulation board. Once this is done, simply pry the nails loose from the house and remove keeping as much intact as possible. If the flashing is damaged, more than likely it can be easily replaced after a trip to the local box store. I hope this helps. Let me know if you have other questions and thanks for stopping by.


Tim 4 years ago

hi rob is the there a diffrents between new constration windows and pocket one besides the nailing flang and is it standard practice to use the window tape around it or is that an extra thanks


Rob Jundt profile image

Rob Jundt 4 years ago from Midwest USA Author

Tim,

The primary difference between a new construction and pocket, or retrofit, window is the nailing flange. However, most pocket units have deeper jambs with foam insulation to allow for wall thickness. As for window tape, I feel it is a necessary step, but for many builders it is an extra. Hope this helps.


maxie 4 years ago

Go for the professionals they know what to do. I have been calling to the professionals. I am a very satisfied customer.

New Jersey emergency board up- http://waterbasementnj.info/


Lyla Burns 4 years ago

This actually doesn't seem super difficult. Maybe we can get away with doing it ourselves and not having to hire a residential window installations Portland OR company. I am curious on the price of doing it yourself though. Any information would be great! http://joesglassinc.com


Rob Jundt profile image

Rob Jundt 4 years ago from Midwest USA Author

No. The process really is simple with a few basic carpentry skills. As for cost, the cost of the window and supplies and, of course, your time. Thanks for reading. Hope the info helped.


Peg 3 years ago

I have t 11 siding I do not have any house wrap or moisture barrier under the siding I have installed sticky back window tape on the sill have calked across the top and down the sides then set the window how do I complete the flashing with the sticky tape


Rob Jundt 3 years ago

Peg,

You place the Sticky tape over the flanges in this order: bottom, sides, then top and then trim as usual. Hope this helps.

Rob


joshabrams1980 profile image

joshabrams1980 3 years ago from Israel

I really liked the tips here. I think they are useful. Instead of paying so much money to professionals, there are thousands of things you can do on your own and they are quite simple. I come from the field of construction and I am always surprised to learn that there are so many simple things people can do, but they prefer to rely on others.


Hady Chahine profile image

Hady Chahine 2 years ago from Manhattan Beach

Great hub! Installing new windows can be a tricky task to master. Although these tips are helpful I think I'll stick to doing what I do best and hire the pros for any kind of window installation. Regardless, your hub gives property owners a good impression of what this type of home improvement entails. ~ Voted up.


Charles Norton 2 years ago

My windows in my home are slowly starting to need to be replaced. A lot of them won't shut all of the way so cold/warm air will trickle in. I would rather not have to have someone install it for me, so this step by step process has been really helpful.

http://kcglassinc.com/commercial-glass/


jim c 20 months ago

I am installing aluminum thermal barrier new windows in rough openings on a new construction sun room. I have conflicting theories about what goes under and on top of nail flanges. Should the 7/16 inch sheathing go under or over the nail flange? I plan to use foam backed vinyl siding which I presume would have to be on top of nail flanges? Entire outside wall is 7/16 inch sheathing and the foam backed siding which is one inch thick. Sure would like to hear about. Already read about thermal aluminum windows not all that energy efficient


Rob Jundt profile image

Rob Jundt 18 months ago from Midwest USA Author

Nailing flanges are designed to be self flashing and should always be nailed to the framing of the house. All other siding goes on top. If you can't cut away the 7/16 board at least caulk and tape over the flange and make sure the trim boards are also water tight.


gepeTooRs 8 months ago

It’s really a great and useful piece of information. I am satisfied that you simply shared this helpful information with us. Please keep us informed like this. Thanks for sharing.


Tom 5 months ago

I am replacing all the windows in my home in a similar manner. My question is, what do you do about foam insulation between the window frame and the rough opening. I want to get that in there to manage air flow but short of cutting more of the drywall away and having a 3/8" gap or so between the window and drywall return, I don't know how else to get it in there. Any ideas?

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