Home>Discussions>EXTERIORS>Flashing old windows in new construction wall- no nailing flange
5 posts / 0 new
Last post
slade72
Flashing old windows in new construction wall- no nailing flange

I have a question that I'm hoping some of you have experience with. The back wall of my 100 year old house was in bad shape....sagging with a rotted corner post etc. It had novelty style drop siding(shiplap joint) on it with no sheathing whatsoever. It was just siding nailed directly to the balloon frame with heavy rosin paper in between. Since many changes were being made to the wall ( a window where there used to be a door for a 2nd floor egress, a door where there used to be a window on the 1st floor , a larger kitchen window etc.) I decided to add sheathing to the wall.... 1/2 OSB ( for strength and also so I could re-wrap it more easily).
I pretty much ended up reframing the entire thing by the time I had repaired the existing framing and made the changes I needed to make for the openings. I will be wrapping it in Tyvek later this afternoon.
So....my question is this. The windows and doors that I'm putting in are all wood frame. The 2nd floor windows (3 of them) are all old style double hung 6 over 6. The patio doors are Marvin but have no nailing flange and the kitchen window is this weird awning window (it tilts out from the bottom) also with a wooden jamb and no fins/flanges.
What is the best way to flash these? Adding fins/flanges is out of the question as I am already too far behind schedule with winter approaching and 3 other sides of the house that need my attention. There is a lot of info on the web regarding new windows in old houses but this is the opposite.....and perhaps it's a unique situation. Who on earth would want to use those old windows when everything else is shiny and new? Well, I guess I would.
Anyway......the best two methods that I've seen in my web searches are either-

1) stapling tar paper strips over the edge of the rough opening, with the head flashing lapping the side flashings, applying caulk to the tar paper, then installing the casings embedded in the caulk. I believe this is sort of the old school approach and it sounds easy....which would be great
2) another approach which I've seen with a few variations ( including a Dupont PDF on flashing fin-less windows) is......using a peel and stick membrane doubled back on itself in some complicated way, then applying the casing. I don't really understand this method and am not sure it's the way to go. At the same time I am already going to be using peel and stick flashing on the rough sill so I will have that material on hand (protecto wrap)

So does anyone have any experience with this? It seems like wooden windows were being installed in wood frame houses for a lot of years before modern technology changed the game. I can't imagine that they always leaked. There's got to be a simple way of doing it, right? And if so, such as with the tar paper strips described above, what happens with the house wrap? Does it wrap in to the R.O. on the sides? Or does it get trimmed flush? I figure whatever I do is going to be worth the 1/2 hour or so per window that it will be. I just want it not to leak and I also don't want to alter the window jambs.
Sorry for the long post....just trying to describe the situation in as much detail as I can. Any advice is most appreciated. Thanks

Mastercarpentry
Re: Flashing old windows in new construction wall- no nailing flange

You'll want the do the house-wrap first, then use self-sticking "soft flashing" (Vycor is one brand) on the sill. Caulk the window moldings all round so they seal against the house-wrap, then add a hard "head flashing" above the window. That one can be copper, aluminum, or lead; avoid galvanized as it will eventually rust. Once the window is nailed in place I like to run an additional tiny bead of caulking around all 4 sides, then install the head flashing. The reason the older methods used the 'tarpaper' strips was because there was nothing waterproof under them, but the house-wrap will serve that purpose now so they are not necessary. Also some local building codes now require soft flashing to be used on all 4 sides of the opening though I don't think it is an appreciably better method myself. Do check with the local codes department before proceeding so you don't have to redo these!

There are special techniques to using these materials properly such as how you make the cuts, and how to let the soft flashing go up each side 4", and how to bend the head flashing. You can get that info from the material manufacturers or see what you-tube has on it. Tom Silva did one of these on a TOH show with lead head flashing but I can't remember which house this was on or I'd send you there for the video.

Phil

slade72
Re: Flashing old windows in new construction wall- no nailing flange

Thanks for the reply. I actually got the idea for the tar paper strips from Tom Silva doing it on the Bedford house. As of this afternoon the house is wrapped in Tyvek but I just went over the window openings and will begin detailing those later this week. Not too cold yet so I can live with it for a day or two.
I've seen some great info about the rough sill detailing using flexible membranes and am definitely planning on using a metal flashing over the drip cap on the head casing.
As far as using the soft flashing membranes on the sides.....are they just flat taped on the exterior plane up to the edge of the rough opening or would they wrap inside like the sill pan? That's got me confused.

Mastercarpentry
Re: Flashing old windows in new construction wall- no nailing flange

Where the inspector wanted this I just flat-taped the sides without turning it in. All he could tell me was that codes said windows were to be soft-flashed on all 4 sides which would make sense with a flanged window, but doesn't make sense here. That particular county has a couple inspectors that seem to enjoy their power a little too much :(

Sounds like you've got it right but do check with the local inspector in case you've got inspectors like this one!

Phil

slade72
Re: Flashing old windows in new construction wall- no nailing flange

Yeah. Better safe than sorry. I already bought a roll of protecto wrap so I might as well use it regardless. I'm thinking I might just run it around the perimeter lapping the pieces in the logical manner, then run a thick bead of caulk on top of the membrane for the casings to bed into. Thanks again for your response.

Sponsored Stories

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.