Installing a Nail-Fin Window Over Peel-and-Stick Housewrap

In this studio mock-up we're gonna be installing a Pella flanged window in a wall with a fully adhered membrane. The first step in the assembly is to go ahead and cut open our window value by cutting the sill flush and the head flush on the sides will come in roughly the thickness of the wall so that we're able to turn that in now again. We're gonna make an estimation for what that wall thickness is and we'll cut vertically same on this side, roughly the width of the wall. Now we're able to turn that flap inward and press it to our jamb. The next step in our waterproofing. We're gonna create a positive slope sill in the unit. We're gonna do so with cedar bevel siding. We could also do this by rough framing the sill with a 5 degree pitch but in this case we're just going to be attaching one piece of siding. That'll give us positive drainage to the outside and then we'll continue with our tapes each manufacturers spec might be different here this manufacturer recommends that we're gonna turn our tape six inches up the jamb go all the way across and six inches up the other Jim. This tape is only about three and a half inches wide so we'll do it in two runs. We'll start on the outside after i pre-cut this tape to length. I actually rear old it so that i'd be able to roll it out easily. It's a pressure-sensitive adhesive so I like to set the top edge before I go to make any cuts or turns. On this particular product we're gonna cut vertically at the corner and this piece is going to actually turn down in this direction and I have a little extra here so I'll just trim that back we'll cut the same thing here from that corner will go vertically and then we'll turn this tape down. Now that we've gently pressed it in place by hand we'll use a roller to fully adhere this product. There's a pressure-sensitive adhesive so it's not going to stay long-term unless you apply pressure with the roller. After we've rolled the entire unit we'll go ahead and add a bowtie to cover these little pinholes on both sides. Let me show you how we cut them. I have a block to protect my cell and the tape that we just put down. I've cut a 4-inch piece of their product. I'm going to fold it in half. I'm gonna make two cuts to create our bow tie shape. I like to start by pressing the bowtie into the opening and then I'm able to turn the corner here that'll give us the ability to shed water. I've covered that opening we'll do the same thing again on the other side. I'm going to roll both those bowties and then we're ready to do one more run of tape further into the opening just to push past where the window will be by adding this second piece of tape. Any water that finds its way in will shingle over and then over and wear to the outside. This manufacturer recommends a bead of sealant along the top edge here to just seal that edge off from any water that might find its way down the jamb. We'll do that now with the sausage gun. A quick tip with the sausage tubes a lot of people are worried about making this cut cutting all the way around with their knife it's unnecessary. If you take your knife and just poke it in two or three places that'll be enough so that you'll be able to get it to start coming out. Now we're taking a piece of that cedar bevel siding that we've cut as a shim placing it in the reverse orientation that will give us a level point for our jamb to sit on both ends of the window.

We're using a double stack of two by fours beneath the window so that we can rest the window on it without making the flange fold back down. There are three common ways that a flange window will ship. Sometimes it'll be integrated like this but need to be folded. Sometimes it'll be in the 90 degree orientation. Sometimes it'll be completely separate and you have to install it yourself. If that's the case, you're laying out a bead of sealant and then tapping it in place. Next we're gonna dry fit the window. This will give a interior carpenter the opportunity to help us fit it for Center so that we can maintain our thermal and air break at final install, but here for our purposes we're gonna set it in and trace the flange once we like its location. That gives us a clear spot where we're gonna lay out our bead of sealant. Now that we have that reference line we know where to lay out our bead of sealant. In this case we're using a Henry sealant. You have to check with each manufacturer and make sure whatever you're using to bed the window in is actually something that works with their product. The other good aspect of using their sealant in this application is we have one manufacturer carrying one warranty, so if I ever have an issue or a question I have one rep that I need to call. Now we can bring our window back in for final install. Now that we have the window tacked in place we can check for level plumb and square. If we discover anything is off at this time now would be the right time to make any final adjustments before fastening the window. It appears that our units in the correct position, we don't need to adjust, I'll go ahead and fill every pre-punched hole from the manufacturer, but that's not the case on every window so you need to be sure that you're checking the specs from each manufacturer for each window. You can see here that we're using a modified truss screw this is an approved fastener from the manufacturer. We also could use a galvanized roofing nail. The other thing to note here is while I'm fastening the entire sill we're not actually gonna flash the sill any further than what it is right now because we want to leave it open for drainage. Now that we're fastened we'll move on to the side flashing you.

In this application we're using a bit of the actual blue skin that we've just cut to size for window tape. We're using it so that we're using the same manufacturer and we're bridging from the sheathing on the wall all the way to the edge of the frame and across that flange connection to make sure that flange is waterproof. We're gonna make a cut here at the bottom so that this flange will lay flat. Our head flashing detail with this fully applied membrane is actually going to be two steps. We'll have a piece just like our jams on the sides but then we'll detail the top of this piece with a little bit of their sealant. There are a couple things that were paying close attention to. We're trying to bridge from that frame all the way to the WRB again and we're making sure that this head jamb extends beyond both of our vertical legs. Our final step is a little bit of the sealant across the entire head and then we'll tool it in place. [Music] At this point our particular mock-ups complete on the outside. If we wanted to add a cap flashing we could do this same method. We'd have the sealant and tooling again but for now let's move inside and talk about air and thermal.

Now that our exterior is watertight we're inside and we're gonna deal with air and thermal. We're gonna do that using a spray foam application around the perimeter of the window. This method will actually apply no matter what your WRB is on the outside. Our goal here is not to completely fill the void we're just trying to fill the first inch or so from our side towards the outside. It leaves an open area on the outside of the window that if we ever have any moisture in that assembly it's able to migrate out. We're taking special care to be using the correct foam in this assembly. This is a formulation made for windows and doors which means it's not going to cause our jams to bow or bind in any way. Now that our foams installed we'll let it dry trim back any that needs to be cut away and then we have one more air ceiling detail. Now that we've given the foam a few moments to skin over we can apply a sealant over any shim that we have that will bridge from foam across the shim and back to the foam making one continuous air seal. [Music] But those last beads is sealing in place the interior is detailed the exterior is detailed and we're confident that this is going to be a leak-free installation.