Flashing windows in New Home Construction

[Joe Bartolucci]

Thanks
Joe

[wedgie]

Dupont Tyvek's site has some good guidelines on flashing windows and integrating the flashing with the housewrap. They use Tyvek tape to flash, but you could use other stuff, like Grace Vycor... Here are the links. Hope this helps!

http://construction.tyvek.com/pdf/K02107HRBeforeInstall.pdf

http://construction.tyvek.com/pdf/K02108HomeWrapAfter.pdf

[giddonah]

Removing the original question just leaves an answer out of context. Why would you do that? It doesn't help anyone else that may follow...

[Joe Bartolucci]

I tried to retract the whole post but did not know how so I deleted the question.

[stuccoman]

If tyvek is truely a moisture barrier shouldn't it be over all the flashings and not just taped!

[Sweep]

Tyvek is an air barrier and therefore the tape is adequate to seal joints for that purpose. Somehow contractors started thinking of Tyvek as a substitute for a moisture barrier but it is rarely installed in a manner that creates an effective moisture barrier. Of course, it is rarely installed in a manner that creates an effective air barrier (no sill-seal or head-seal).

[Joe Bartolucci]

Hi All:

Thanks again for the help. I finally figured out the best way to flash a window for new construction. the windows I purchased are Bonneville Windows that are sized for a 6" wall and are aluminum clad with nail fins. The house is wraped with Typar. This is how I do it.

I cut the inverted Y within the window frame and secure the Typar onto the jam, and sill of the window frame.

I then cut another piece of Typar and install it on the sill and stuff the sides under the outer Typer and staple.

I apply the sill flashing material on top of the Typar just under the sill and extend it past the framed width to the required length.

I then apply the caulking along the edge of the framed window on top of the Typar. I leave 2 spaces between caulking at the sill for water or moisture to escape. I am using the Fortiflash system with there Moistop caulking. This is approved to be used with the Typar, I checked with the manufacture.

I then place the window into the frame, level and shim then nail down the outer nail fins.

I then measure and place the flashing on the jams and then the head. I extend the head flasing a few inches just past the jam flashing edge.

I then take the Typar and tape it over the head of the window flashing making a nice tight seal.

The only thing no one has mentioned are the corners. I have to cut pieces of flashing to place over the corners once I fill them in with caulking just to be sure i get a good seal.

Now with all this said, I would like you opinion, what did I miss? There will be vinyl siding going around these windows. Oh I just thought of it, do I need a drip cap? Okay thanks again for your help!

Joe

[Sweep]

Your description appears to be that of a typical Fortifiber FortiFlash system used over a plastic housewrap instead of Fortifiber's Jumbo Tex or Fortify asphalt saturated kraft paper moisture barrier. You seem to have added some Typar at the sill which, of course, is compromised as soon as you put a staple or nail into it. Don't fall into the trap of thinking of housewrap as a flashing material.

It appears to be Fortifiber's assumption that modern clad trimless nail-fin windows do not need flashing completely under their sills (called pan flashing) such as the kind used for the last hundred or so years for all-wood windows with casing trim. The basis of this assumption is apparently that water cannot penetrate the FortiFlash self-adhered flashing placed over the nail-fin and the sealant placed under the fin. The success of this idea relies on the water proof integrity of the window itself and the ability of the FortiFlash peel-and-stick membrane and Moistop polyurethane sealant to adhere to Jumbo Tex (or Fortify) and an aluminum or PVC fin. In other words, the system relies entirely on adhesives, sealants and the tightness of the window itself.

In your case, you have substituted Typar for Fortifiber's asphalt impregnated material. There is no way to know how well and how long Fortifiber's adhesives and sealants will provide a seal to Typar. You say this combination is approved by the manufacturer but you don't say which one. You need to check with BOTH manufacturers. I doubt either one will offer a warranty any of it. I have experimented with Tyvek and Ice & Water Shield which are similar products and they still show a tight bond after a couple of months. However, I don't really know if the materials are chemically compatible or if they will remain adhered under field conditions for the long term.

Fortifiber must also assume that water cannot get behind the moisture barrier membrane since the window is sealed only to the membrane which allows the possibility of water passing behind it.

In summary, the success of this system depends on:

• the integrity of the clad windows
• the adherence of FortiFlash to Typar
• the adherence of polyurethane sealant to Typar
• the adherence of polyurethane sealant to the fin material
• the integrity of the moisture barrier

Perhaps it will work but it is not a system I would use.

[Joe Bartolucci]

WOW!
Thank you for the detailed insight. I checked with Fortifiber's tech dept as well as Typar's tech departments and they both agreed that the Fortifiber and Typar would work good together.

As for the sill cover, it makes sence that a staple will ruin it's integrity. I have not seen metal sills installed in any windows on the new construction jobs I have been on and I thought that practice was not necessary.

As for what I am doing, I have the Fortiflash tight up against the edge of the window cladding on top of the nail fins which sits on top of the moistop which is on top of Typar.

Okay, now I thought this would be the cream of the crop for window installations. From you last sentence, you would do it differently. Can you please tell me what you would do differently. I only want to do this once. I thank you again in advance for your comments.

Joe

[Sweep]

Joe
I'm sorry if I have caused you to worry about your approach. I am afraid that the way I would install a window would not be acceptable to many people including you since after specifying and detailing aluminum windows for 35 years, I have little confidence in the nail-fin, mitered-corner construction system used for most clad windows. And I have never seen plastic housewrap installed so that it was an effective air or moisture barrier although I guess it is not impossible to do.

Now that I have messed you up, I would like to help you get back on track. First, tell me what systems and components you are already committed to use: clad nail-fin windows?, no casing trim?, plastic housewrap?, Typar (instead of Tyvek)? What is the sheathing material? Where are you located? is there an advantage to you to use Fortifiber self-adhesive flashing products rather than those of W.R. Grace or DuPont? Who is going to do the work?

[Joe Bartolucci]

Hi, thats okay. I am committed to this installation with the exception on adding metal sill flashing on the windows not yet installed.

The house is framed with 2x6 and is mostly wrapped with Typar. Thats what the framer used as he was doing the work so I figure I would stick with it. There are some areas I still need to wrap.

I will be doing the work. I am an Electrical contractor and have been around for a while. We purchased the land in Eastern PA and I had an architect design the layout to meet my wifes requests. Its a center hall colonial with an open floor design. I am going to install stone veneer on the bottom front of the house and vinyl the rest.

The windows are from Bonneville and are maple wood framed with aluminum cladding on the outside with retracting nail fins that pop out.

I am using the Fortifiber because I was able to talk with a sales man who helped me in detail with my questions. I was also surprised to learn how inexpensive the product is. I am using the 9" wide x 75' rolls for around 40.00 a roll, I am sure there are better prices out there.

I contacted the manufactures engineers / techs and asked them detailed questions on compatability between all the products that I have listed here and all agreed that there would be no problem now nor in the furure with the installation I am currently doing.

I am concerned now that you mention about the sill flashing. I have permently installed 8 windows out of 38 and now would be the time to make any changes.

What do you think? I can slide metal flashing under the installed windows and add it to the rest or with the amount of flashing I am installing on the outside will I even need to worry about the sill flashing?

I hope I answered your questions and again I do appreciate your help and advice.

Thanks again!
Joe

ps. I have included a picture of the garage windows I have installed.

[Sweep]

The most important thing to do is to cover the fin-to-window connection with the self-adhering flashing. That is where a snap-in fin type of window will leak. Be sure to press it in place with a small steel or wood roller.
The rough opening sill should ALWAYS have pan flashing. The easiest way to do it is with DuPont's Tyvek FlexWrap
http://construction.tyvek.com/en/productServices/Flashing/flexWrap.shtml
or WR Grace's Corners.
http://news.thomasnet.com/fullstory/464808/3283
Fortifiber sells a pre-formed corner flashing as well.
http://www.fortifiber.com/FBSG/warranty.htm#moistop_corner_shield

You can also use an adjustable PVC sill flashing
http://www.enduraproducts.com/suresill/why.asp

In my opinion, the best source of flashing information is from Marvin windows. Open their PDF file titled "Clad Window Installation" at
http://architect.marvin.com/products/product.cfm?view=installation&oid=F215AF94-0DD4-4090-AD6B6D05F87645B3

[stuccoman]

Tyvek is an air barrier and therefore the tape is adequate to seal joints for that purpose. Somehow contractors started thinking of Tyvek as a substitute for a moisture barrier but it is rarely installed in a manner that creates an effective moisture barrier. Of course, it is rarely installed in a manner that creates an effective air barrier (no sill-seal or head-seal).

The sales reps in kansas city will tell you it is a MOISTURE barrier!

[Sweep]

Whatever the rep calls Tyvek, DuPont (in addition to calling it an "air barrier") will only call Tyvek a "weather resistive membrane" or a "multi-functional membrane" or a "secondary weather barrier". DuPont refers to Tyvek's "water holdout capabilities" and says Tyvek "helps hold out bulk water and wind driven rain". DuPont will never call Tyvek a water or moisture barrier in print.

The reason for this careful wording is the fact that Tyvek is very difficult to attach to a building without compromising its water resistance and contact with certain exterior finishes (unfinished cedar and cementitious stucco) can degrade its water resistance (as they warn in their brochures). To call Tyvek a water or moisture barrier would imply a standard of performance that is rarely achieved in actual construction.

All Tyvek Weatherization Systems (Home, Stucco, Commercial and Header Wrap) are specified under Section 07270 Air Barriers.

[Joe Bartolucci]

Hi Sweep;

Thanks again for your input as well as everyone else. I have another question. It has to do with pump jacks. As you can see in the picture above I used the older style pump jacks to get me up high enough to install these windows.

I have had nothing but problems with them. I could go up but was not able to come down. I am now ready to return them so I can get the type that rides on the aluminum pole.

I followed the directions I kept the platform as level as possible but still had trouble. To get down, I raised the foot peddal up, step on the lower release and turned the handle. The handle would just spin. I would notice that the bottom catch would not release which would not me me go down.

I have HAD IT! I need your help in deciding if the aluminum system is better than the steel / wood system. This is whats hoding me up from doing the siding of the house. I have also thought of just getting scaffolding but I like the variations of elevation the pump jacks can give me. What do you think?

Thanks
Joe

[tinner666]

You missed the flashing at the bottom corners. Look at any window with J channel. Notice how there is a 1/2" hole at each bottom corner. All the water hitting the top and sides of the window goes behind the siding.
After the opening is wrapped/flashed, I install the window WITHOUT nailing the bottom corners. After all is plumbed and squared, I take a piece of 14" x 14" piece of aluminum, cut out a rectangle 8" tall by at least 5" wide. I fit the notched area behind the nail-fin, then nail it at top corner only and nail the fin the rest of the way.
Let it flat in the wind. When the siding is installed, GO BEHIND the piece of aluminum until the last UNCUT piece of siding is installed. The cut the piece of aluminum FLUSH with the LOCKING edge of the last piece of siding. It does not need any nailing. Cut and install the rest of the siding normally. ALL the water getting into the J-channel will flow onto the piece of aluminum and out of the siding at the lock joint of last uncut piece of siding, instead of staying behind the siding.

Frank

[Joe Bartolucci]

Hi All:

Here we go again. I just typed a nice responce and went to attach a photo then lost it all. Damit!

(Thanks Frank for the input. That is exactly what I had planned to do before I learned of the sticky flashing.)

So, the windows are done and the house is ready for vinyl. I installed the windows just as describes in previous posts. I also purchased a video from the Installation Masters Institute which shows the installation of nail fin windows on top of the house paper and with the staple paper flashing from Fortifiber. The intresting thing about this is that there is no use of any sill protection for any of the fin window installations. They show the installation of sill pans for brick mould windows and doors.

As I looked at the windows during the last rain I found some moisture at the bottom corners which I had caulked tight. In my search I had found that in the outdoor cladding, there is a small hole on the bottom of the mullion where it meets the sill. I tried to attached a picture but no good. This windows instruction has no mention on this being a weep hole it is also directly above the wood sill. I will call the manufacture (Bonneville) tomorrow. I would still like your opinion. What am I missing?

I again thank you in advance.
Joe