I am replacing windows in a house on the bluff over looking the Pacific Ocean. We will use Ice and Water Paper for the vapor barrier..... I will tape over the window flanges with bitumen. Also use caulking redundantly. I am shingling with hardi shingle panels... I am at a cross road weather to blind stop, then but shingles to the stops, and then trim....or just shingle to the window. Also I may put head flashing over the top of the lower windows.....since the upper ones are really tucked under the roof. It is a dilemma, I have done many, many windows, and always struggle with the weatherproofing as if I have never done it. I wonder why that is? Also, is there any diagram out there that shows decent flashing techniques....I have looked online at a barrage of flashing details. Have not found any specifically for shingles......
Fine Home building magazine has many great articles on door and window flashing techniques and technology. Google "fine homebuilding window flashing" and you'll see at least a dozen great articles plus a lot of videos.
Many of them could be subscription only but it would be well worth the cost to you for what you have at stake. It's 40 bucks and year or 6 a month for the online subscription. You could get (download) all you need in one month. Heck, you could probably purge the site of everything on flashing in the 14 day FREE trial period.
What kind of windows are you installing? Do they have integral mounting flanges?
If you're using a housewrap (Tyvek or tar paper), run it over the window opening. Then cut a big 'X' in the opening and wrap each piece into the window opening.
Then install a self-stick membrane along the bottom of the window opening, from the inside edge of the wall, wrapping around the outside edge of the wall. The membrane should also wrap up the lower corners of the opening, or you should install separate pieces for the lower corners. Since you are in a coastal area with lots of wind blown rain, you may want to install a sill pan or have custom flashing made to fit the window opening. Basically, you're trying to ensure any water that gets around the window is directed back outside and not into the wall.
Caulk around the window opening, then install the window by nailing around the flanges.
Now install strips of self-stick membrane over the flange on each side of the window. Then run another strip of membrane over the top flange of the window.
The housewrap above the window should overlap the self-stick membrane flashing above the window.
If you install trim above the window, caulk it well and add another metal flashing at the top to keep water from getting behind the trim.
You have to think like a rain-drop. Each layer should shed water to the outside, just like roofing shingles. If water does get behind a layer, there needs to be a way for that water to get out. That's why I don't caulk along the bottom of a window for instance.
Yes, I do agree with your methods. I am using Ice and Water Shield for the walls. It is a rubber product, with stickum on the back. Yes, we are putting bitumen tape over the flanges.... I am planning a metal flashing over the window since I am using hardi shingles and no trim. I do not like the trim detail that was there, and I am trying to minimize trim, and use panel shingle siding We will use copious amounts of Big Stretch on anything that smacks as an intrusion. You do have a good understanding of the problem. Thank You, 'John
Hi John,
What kind of windows are you installing? Do they have integral mounting flanges?
If you're using a housewrap (Tyvek or tar paper), run it over the window opening. Then cut a big 'X' in the opening and wrap each piece into the window opening.
Then install a self-stick membrane along the bottom of the window opening, from the inside edge of the wall, wrapping around the outside edge of the wall. The membrane should also wrap up the lower corners of the opening, or you should install separate pieces for the lower corners. Since you are in a coastal area with lots of wind blown rain, you may want to install a sill pan or have custom flashing made to fit the window opening. Basically, you're trying to ensure any water that gets around the window is directed back outside and not into the wall.
Caulk around the window opening, then install the window by nailing around the flanges.
Now install strips of self-stick membrane over the flange on each side of the window. Then run another strip of membrane over the top flange of the window.
The housewrap above the window should overlap the self-stick membrane flashing above the window.
If you install trim above the window, caulk it well and add another metal flashing at the top to keep water from getting behind the trim.
You have to think like a rain-drop. Each layer should shed water to the outside, just like roofing shingles. If water does get behind a layer, there needs to be a way for that water to get out. That's why I don't caulk along the bottom of a window for instance.
For the entire wall? I used that on parts of our roof, but it wouldn't have occurred to me to use it on a wall. I suppose it would be a good idea in a coastal environment for the same reasons it's used on roofs. Seal around perforations and stop wind blown moisture.
Without separate trim, wouldn't the flange of the window serve the same function as the metal flashing?
I guess it wouldn't hurt anything to have a secondary flashing, but then I would worry about the detail at each end of the flashing. What happens with the water that runs sideways off the ends of your flashing? That's the one detail with top flashing I've never really thought out.
It sounds like you've got it under control and have probably thought it out more than I have.
Nothing that can't be solved with duct tape and LOTS of caulk! :)
Yes, the either side of "Head Flashing" or over the window, trim, or window itself is always an interesting problem. What to do with the ends? I just figure, you can only go so far, do so much, and then move on. I just let the either side of the window flashing drip out and over the lower siding...no end detail..... john
John,
For the entire wall? I used that on parts of our roof, but it wouldn't have occurred to me to use it on a wall. I suppose it would be a good idea in a coastal environment for the same reasons it's used on roofs. Seal around perforations and stop wind blown moisture.
Without separate trim, wouldn't the flange of the window serve the same function as the metal flashing?
I guess it wouldn't hurt anything to have a secondary flashing, but then I would worry about the detail at each end of the flashing. What happens with the water that runs sideways off the ends of your flashing? That's the one detail with top flashing I've never really thought out.
It sounds like you've got it under control and have probably thought it out more than I have.
Nothing that can't be solved with duct tape and LOTS of caulk! :)
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