Window installation

Is it acceptable for a window installation (new home construction) to be installed in the folllowing manner: Vinyl window installed, THEN edges on exterior sealed with 3" foil tape serving as flashing all around? (then vinyl siding placed over)

As far as I was aware, I thought 4 inches of overlapping flashing were required to be installed BEFORE the window was put in place… This was confirmed by every window installation source I could find, but I thought to check here to see if maybe it was technically allowable (although not recommended).

Before I make the builder fix every window in the home (28 of them) I thought I would check first. I could not find tha name of the manufacturer name, or I would just cite their instructions.

Its not uncommon to tape around the window, however, there are additional aspects of the installation that have to be required.


  • First, tie back branches from shrubs, trees, etc., away from the house so you’ll have room to work. Remove anything that will interfere with the siding installation, such as lighting fixtures, downspouts, shutters, etc. Scrape old caulking out of the junctions between the old siding and windows, doors, etc., so vinyl accessories will fit better.
  • If the walls are uneven (for example, you are covering lap siding), nail 1x3 furring strips 16" on center from the foundation to the eaves. Also nail furring strips around all doors and windows. Shim out any low spots so you have a flat surface to work with.

  • Use a mason’s line and line level to find the lowest corner of the house. Measure up from that corner the distance specified by the manufacturer and snap a level chalk line all around the house.
  • Using the chalk line as a guide, nail starter strip all around the bottom of the building. Leave 1/4" between the ends wherever two pieces butt together (see image above).
  • Install the inside and outside corner posts. Leave a 1/4" gap at the eaves and let the post extend below the bottom of the old siding 1/4".
  • Install J-channel on the sides and then across the tops of all doors and windows. Notch the J-channel to provide a drip edge at the corners (see image). Then install J-channel along the sloped eaves at all gable end walls.
  • Nail undersill trim under all windows and along all horizontal eaves.
  • Install the siding panels, working from the starter strip up. Stagger the joints 4’ apart.
    *]Overlap the panels 1" at each joint with the overlap away from entrances or high traffic areas to minimize visibility (see image below). Leave 1/4" clearance wherever the ends of panels butt into J-channel or corner posts.

The sill flashing is done before but the sides and top/head flashing is done after the window is installed.

Click on “flashing window using house wrap” or “flashing window using building paper”.

Thanks, Larry. Unfortunately, there is no home wrap or building paper anywhere near this house. Just foil tape around the window installation which, it appears, would guide water under the siding to the unprotected sheathing.

OK - just checking. I think what I was looking for is the building paper installation. Usually where is see this, the window area has the building paper installed, then the window, then other flashing.


I have found this many times where the perimeter is taped without flashing. (a Toll House?)

It does not meet the design of any of the window manufacturer’s recommendations that I have reviewed.


See page 4

Thanks, Joe.

I know it isn’t to spec with manufacturers ( I checked a lot) and the lack of any underlayment violates the vinyl siding specs as well (also the recommended procedures of the vinyl institute).

It isn’t a Toll…it’s a small Berks Co. builder called “Hearthstone”. It is in a new development where several buiders are building…only Hearthstones have no home wrap, step flashing installed after the roofing is in place, and items like this kind of window flashing.

Then it will look like this!

And in new construction this is being used in the kc metro!

Hey Joe, and Joe…Toll Brothers are one of the better builders in Arizona, just to give you an idea of the pathetic, unskilled, no-speaki-engi people assembling these buildings.

Doing construction phase inspections I use the spanish dictionary far more than any other tool…:smiley:


We have plenty of those subs here too (several rumors and over-generizations about their citizenry, etc abound, but I can’t subtantiate so I will not repeat them).

A builder’s quality is only as good as the work of the subconactors and the attention to detail of his project manager.

For what it’s worth, I think Toll Bros. is one of the better builders in this region as well, in most cases. Like I said, bad subs abound…


Read the window manufacturer’s installation instructions for proper installation techniques. They vary by manufacturer, but most require a minimum 4" tape or flashing.


Thanks, Russell. I have researched many window manufacturers to find exactly what you have mentioned - they all require 4" overlap, and all speak of underlayment or wrap of one type or another…

In this case, and as I am finding is increasingly popular among builders, the manufacturer info stickers are missing (torn off at installation) and the info is not present anywhere on some of the lower-end windows.

So, without a specific manufacturer, it is hard to say, but calling it out and recommending installation as per factory specs may get it done…

:slight_smile: :slight_smile:
*The preferred method around here is to use Vicor which is the same prodout as ice and watersheild, and comes in widths that you desire. *
*A strip of Vicor is installed under the sill, before the window installation, and then a Vicor strip is installed on the sides and the top. *
*Consequentlly, the building paper is installed over that. *
*This is a common practice and approved by most Window Manufacturers. *
*Hope this helps. *
*Marcel *
:slight_smile: :slight_smile:

Thanks Marcel. That’s pretty much what I come up with everywhere. What happens when there is no wrap or building paper is another issue I get to contend with now…

Incidentally, here is the picture…

window flashing.JPG

I’d say that they are going to have a leaker, Joe were you able to pull or tilt a window out, some times there is some information on the sash that might lead you to a manufactuer.


:slight_smile: :slight_smile:
Cann’t quit make out the mess in this photo.
Is it tin foil? No wind retarder? or what is it?
*Marcel *

Glorified tin foil, a.k.a., foil tape. No anything else.

I did call the owner today to recommended he try the tilt out to get a manufacturer, but he couldn’t find anything. Thanks for the idea, though!