Vinyl Window Install Flashing Question
We’re finally at installing windows exactly one year after the demo. (I know, Ineed to post pics, but I spend all my free time building this stupid house!)
These will be Milgard vinyl in casement, awning, fixed and single hung configurations. The Milgard web site suggests the AAMA 2400-02 method for installing http://www.milgard.com/_doc/products/aama-2400-02.pdf
However, they show a method “A”, which puts the window under the jamb flashings and a method “B” with the window over the jamb flashings (this is the one I’m used to seeing).
Is one method preferrd over the other depending on wall finish, i.e. stucco or siding? We are having a combination of both on this house.
Finally, we’re trimming the outside of the windows in 1X4 Hardi-Trim. Can this go directly over the window flashing, or do I have to wait for the stucco paper wrap? Should I bed the trim with caulk against the window fin, or leave a gap for caulking later?
Thanks!
Jim
Replies
Can anyone help? I know it's probably been discussed here before, but you know how "search" goes sometimes.
Thanks!
Can't necessarily give you direct answers to your Qs as I have never built a stucco house, but I do know this. Detailing at envelope penetrations is extremely important with stucco - this was what caused all the hoopla (wall rot/mold/lawsuits) with EFIS back in the 90s. It was not the synthetic stucco products that were defective but rather the installation methods. It's good to heed the window manufacturers's instructions, but If I were you I'd research it form a stucco angle too. Try a Google for "stucco manufacturers installation instructions" or similar.
That said, I have built several houses with siding and the 1x4 window trim type detail. Here are some thoughts:
In your post, and in the window install document you refer to flashing. I like flashing tape far better. I don't know... maybe that is what you meant. There are various types of flashing tape available, but personally I think the peal and stick ones are the best. Some tapes use bituminous based adhesives. These type of tapes are good because they seal around the nails that will be driven through the whole assembly for your 1x4 trim. You have to be careful that the caulk is fully compatible with the whatever flashing tape you use. Some tape manufacturers warn against the use of solvent based caulks with their products.
Do an advanced search here at BT for "window flashing tape". Here is one discussion that I found using that method: http://forums.taunton.com/tp-breaktime/messages?msg=38926.1
The way I do it is install the housewrap first. Then, personally I like to have the sill flashing up underneath the window flange and wrapped back into the opening. Careful detailing is required at the lower window opening corners, and a stretchy type membrane type tape works best. Then the window is installed and then the side and head flashings are applied over the window flanges and housewrap. A slit is cut in the house wrap above the window for the flashing tape to be slipped up underneath. This is kind of tricky as some of the tape is extremely sticky. Then regular house wrap tape can be used to seal up this top slit - basically just hold it in place and prevent air infiltration.
Q: What is the texture of the sheathing wrap you are using below the stucco? The reason I ask is that some stucco paper has quite rough texture and I would doubt the ability of the flashing tape to give a water proof seal at this interface.
Re the 1x4 window trim, I'd install this after I got the window & housewrap install all detailed out (weatherproofed). You are gonna need to somehow shim out the outer edges of the 1x4s as otherwise they will not lay flat because of the thickness of the window flange and roofing nails that are used to hold the window in place. Some use stapled in place folded up roofing paper, I&W shield, and I have used foam sill seal cut in small strips and stapled in place because it's is cheap. Whatever you use it needs to be a material that is un-effected by water - although no water should be getting in there... Bedding the 1x4 in caulk would be some good extra insurance but will add considerably to the installation time - your call. Not sure if you have worked with hardy trim but it is a PIA as it is heavy and breaks so easily. Either way, definitely leave a caulk gap though. Plan on using the best caulk you can get your hands on that is workable - there are some great caulks out there that are extremely hard to work with - get a test tube. Q - what is your bottom window sill trim going to look like - we have discussed this in length here too - or maybe you are just going to use more 1x4?.
You need to give some careful thought to a drip cap above the window head casings (1x4s) too. PVC Plastic drip cap is available and although it looks nice and is a good visual match to the classic drips, I doubt it's ability to really to it's job. Another option is a z flashing - which would likely have to be site bent with a brake. If you go this route be sure you select a metal that is fully compatible with the stucco product you use - I'd suspect that Aluminum would be a bad choice.
Now I'd like to qualify all of the above by saying that different stucco products may require very different flashing and caulking methods. :-)
Anyway, if nothing else this post should get the conversation going...
Edited 2/25/2006 8:53 am ET by Matt
Sorry for not being able to help.
Is there any one knows which fiberglass windows brands are good, I got to learn the benefits from https://hotfrp.com/fiberglass-window-door-knowledge, however it seems they are specialized in the windows profile making only.