Replacement windows, also known as inserts, do not have nailing fins because they are typically installed with existing cladding still on the wall. Nailing fins are thin strips of metal that extend out from the frame of the window, making it easy to attach the window to the rough opening in a wall. They help keep the window in place while shims and screws are installed.
The main purpose of nailing fins is to secure the window to the wall sheathing and keep it together while the shims and screws are installed. Fins also help keep wind and water out by working in conjunction with the water-resistive barrier (WRB). To get flashing details right for the common nail-fin-style window, make leakproof transitions between the water-resistive barrier (WRB) and the flanges that fasten the window to the wall. Improperly lapping the window flashing segments with the window’s nail fin, other window flashing segments, or with the WRB can ultimately lead to water intrusion.
In this Fine Homebuilding Shop Class video series, professional builder Jake Bruton demonstrates the crucial steps for getting the flashing details right when installing a flanged window in a wall covered in a layer of rigid-foam insulation. Nailing fins, also known as mounting flanges, are thin strips installed on the exterior sides of a window, usually set back from the outer edge of the window frame and having fastener holes punched into it.
Installing nailing fins is a quick, easy process, making it easier to level and plumb the window and acting as a stop to prevent the unit from going to the wrong side. Measure the entire placement on the flange and carefully drive a 6 inch timber screw through each hole.
📹 Replacement vs Nail Fin Window Installation
Learn about the differences between nail fin and replacement window installations. Learn about some potential drawbacks and …
📹 Part 4: Air-Seal and Insulate a Nail Fin Window in a Wall with Exterior Rigid-Foam Insulation
Spray foam and high-quality sealant bridge all of the gaps between the framing, shims, and window for a durable and …
Jeramy, Thanks for the article! I’m old school and knew nothing about this new nail fin design. My home if lap siding (not vinal) and typical wood windows with wood brick mold on the outside. Isnt there ANY way to replace my old window (sill rotted and part of window frame at one corner) without taking down or and/or replacing the siding? I’m retired military and just cant afford all that. Thank you for your proffesional experienced advise.
Excellent article! I bought a 23 year old house that needs new windows and siding. It is sheathed in OSB that was not wrapped in a WRB because the code at the time did require it. My plan is to use new construction windows so the rough openings can be inspected and repaired as necessary. Then the sills will be reflashed with modern day materials and the windows with nail fins will be installed with caulk and correctly flashed for proper water management. My question is, can all this be accomplished without removing all the interior window casings which are beautiful and in perfect condition? I have seen new construction windows with foldable nail fins and was wondering if the window could be shimmed, foamed, fins nailed/screwed, and perimeter flashed all from the outside?
The worst and disastrous window installation. You did not put membrane all around. The water will infiltrate and will ruin all unprotected wood. A no flange window requires 10 more protection and skill to install. You should delete it. On the bottom you do not put the membrane behind the siding; the water will get behind the siding! It is to be over the siding. This will not pass code!
If you wanted to put a new construction window in an already existing house (replacing current windows with new construction windows), do you just have to remove the siding pieces in the way around the window frame for the new nail fin to be nailed into the stud or do you have to remove the portion of wall itself (the OSB or what ever they use)? – (Which is what i assume im looking at at 9:40 in article)
People make articles assuming every opening is the same. I been installing windows for 30 years. This guy would not want to sit down with me and show how little he actually knows. The only time a aluminum frame. Is ever left in place is on newer stucco homes because that is a seal you don’t want to break. If you want to pay extra thousands of dollars to have your stucco cut back and replaced repainted feel free. Or thousands more if you have stucco banding around those windows. If your stucco is cracking and you pull the frames it will leak. Ever other opening the aluminum frame should be removed. Its ridiculous to assume people are leaving frames in. Any person that tells you you should install flanged windows in sold brick openings is a idiot. Professional installers can remove the old window frame and all. Use their trim break to build a perfect flash pan that will last for ever and install a retrofit window without doing any damage to your brick but if you want to pay thousands of dollars to have brick removed so you can use a new construction window feel free. Hardy or wood siding you always pull the full aluminum frame. Don’t assume you can pull off a 1×4 and expose a nailing fin for the old window. Its behinb the siding. You extract the old window without damaging good trim. Anything not under a patio will have a Z flashing that keeps water from getting behind the trim. You measure and cut back the sheetrock so the new window sits back past the face of the hardy. If your tearing everything off then by all means use finned windows.
Pay attention to what your actually getting, because I just realized Anderson windows can come labeled as “new construction” and “replacement”. Excuse me, yeah I was looking at a window display and noticed the nailing fin corners weren’t looking sealed after asking the employee he gave me an answer I wasn’t comfortable with and showed me the same style, same company, same series window, and I noticed the nail fin was all sealed together as a solid piece. Came home and realized the window I was looking at was labeled as both “new construction” and “replacement” so that nail fin can literally be removed, not the answer I got from the employee. But Anderson does sell windows strictly labeled “new construction” that the nail fin is fully sealed and won’t come off. Lesson learned, thankfully before I pulled the trigger on any purchase.
I’ve taken on a semi major project, myself and on a fixed income budget…& thought I ‘d found a REALLY good buy from Habitat for Humanity, really nice thick windows….only to get home & realize..there are no casing nor window fins…the windows are in 2 parts..the top (lock) & bottom (part the locks fit in.)….(I know nothing, as you can tell; about windows..just that these are thick & nice…my question..how can I install them???Can I purchase the fin(s) so I will have something to nail the window into my 2×4 frame?? Can I make these windows work?? I welcome all the advice I can get Thanks for all the info!
Regarding window replacement with nail fin windows: The depth of windows between the nail fin and the inside face of the window is different for different window brands and lines. If that depth (which is not the nail fin setback) for the existing window is 1-3/8″, and it is 1-7/8″ for the replacement window, you will be cutting back interior drywall returns and window sills so that the nail fin can sit on the exterior wall sheathing. If you are going to attempt this, have your drywall finisher, trim carpenter and painter ready to repair the interior issues that will result.
Phoenix Arizona. Home built 1999. Replaced construction grade aluminum window with vinyl replacement windows in 2010. The company is no longer in business. The south facing windows (and most all the rest) have extensive stucco cracking. Stucco guy said these windows are Masonry Windows because they do not have a flange or nail fins. What do I replace them with and How? Some say I don’t have to replace the window. I am at lost. Please Help!
We purchased replacement windows for a home renovation we are doing. We didn’t realize at the time there was no nailing fin or flange. So Im thinking they are block windows. We spent too much to not use them. Any advice on how to install them so we don’t have to worry about leakage? Im seeing a lot if different install methods. We will be putting them in a newly framed window opening if that makes a difference
You guys get it!!! I am a siding replacement contractor in San Diego, CA. It is extremely frustrating to have window replacement companies in our area sell the homeowner on the quick and easy retrofit style window option. I can’t tell you how many times I get a call from a homeowner asking for a quote to replace the siding on their home right after they have had their windows replaced with retro style. 😩
Jeremy, I’m afraid I had my six front vinyl windows replaced with those vinyl replacement flush fin windows. My exterior wall is stucco, two stories. I didn’t ask what install method was to be used. Can I remove those new windows and start from scratch using the correct method you suggested or will that damage the wall?
how do you replace old vinyl windows? 1994 vinyl-therm, out of business in 1996. recently bought house, had receipts of install date. They are still in working condition, just a bit drafty, way better after I recaulked inside frames, double hung the whole 9 yards of efficiency, elow, tinted, double pain, all that jazz. Just have one moisture inside and picture window doing same. MN weather. Outside has all the drip edging and all that done. recaulk the outside around framing, and 1/4 inch gap all around with a bead already? Steel siding. The windows I have no idea how to take out, no levers to use. Has full screen built in it seems. Thank you for the information!
“Block Frame Window”. Thank you. The trouble with a Flange Mounted Window is the fact that it made the Window Shutter decorative-only, no longer functional. All these people hanging plywood over their windowns and creating new moisture penetration holes for incoming huricanes “get to” repeat the process for every new threat. Block Frame Windows would permit the homeowner to CLOSE THE SHUTTERS then open them again when the threat passes. I honestly believe that the flange design was the cheaper method, both cost and result. It permits a retrofit for existing homes and is the quickest way to build a home but not the best.
Thank you! This was actually very helpful. We had our aluminium siding removed & replaced with vinyl around 2006 or 2007. It’s still in great shape, but we unfortunately did not have the budget for new windows at the time. So we are stuck with hideous metal windows (some of which are cracked or even broken and patched with duct tape). The house was built in the 30s or 40s so it is very old. The door sills are rotted but I can’t tell if there is any problem with the windows as they have J-trim all around. I would like to remove my metal windows, remove J-trim & pull back vinyl siding carefully, install flashing all around (I will check to see if there is z-flashing above the windows), and install new double pane vinyl windows. Could I use a new installation window with a nailing flange if I pull the siding back far enough? Would I put flashing over the nailing flange as well? Would I be able to just pop the J-channel trim back in place afterward? (I live out in the middle of the woods and I have a hard time finding reliable installers & while I do intend to hire someone for it, I want to make sure it’s done right & that I order the correct windows).