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Installing retro-fit replacement window, remove exterior trim?

Installing retro-fit replacement window, remove exterior trim?

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  #1  
Old 08-11-17, 11:11 AM
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Installing retro-fit replacement window, remove exterior trim?

I'm planning on installing a replacement window on an existing aluminum frame. Here are some pictures that show the existing window frame.

3x4 aluminum window - Album on Imgur

My question is what do I do with the existing exterior trim. Can I leave it be and just apply caulking where the new window's fin meets the exterior trim? Or this won't allow the new window to come inside the frame sufficiently because of the thickness of the trim?

Thanks
 
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  #2  
Old 08-11-17, 11:28 AM
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All depends on the replacement window.

Does it have an exterior nailing flange, then the trim has to come off. If it's a "replacement" style window then maybe it can stay.
 
  #3  
Old 08-11-17, 12:02 PM
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Well, your post is a little confusing. A retrofit, or replacement window is generally a pocket replacement that goes inside an existing frame.

Whereas a window with a nailing fin is considered a "new construction" style of replacement where the window goes into a rough opening.

You mentioned both terms which is confusing to say the least.

If your window has a nail fin, your old window should likely be removed completely so that the fin can be installed directly onto the sheathing, where it can be incorporated into the existing WRB, (your existing felt paper or housewrap) along with some window flashing tape as needed.

After your old window is torn out you may need to "pad out" your old rough opening to make it the right size for your new window. New trim is applied over the fin.
 
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Old 08-11-17, 12:13 PM
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I apologize for incorrect use of terminology. I didn't mean a nailing fin but probably flange. It's the "Flush fin" window as described here:
https://www.milgard.com/learn/unders...w-construction

It says it's meant for stucco but I don't know it can work on wood sidings with exterior trim as well.

By the way I haven't bought the new window yet. Just planning things right now.
 
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Old 08-11-17, 12:23 PM
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You will just need to measure carefully and know what you are doing. I never EVER use flush fins as they rely completely on caulk to make them weatherproof.

If I were you I would remove interior trim, find the rough opening size, and order a window with a nailing fin that is 1" smaller than your R.O.

Then go outside and see if that measurement will work / look good / be symetrical outside. Remove exterior trim, install, retrim the inside and outside.
 
  #6  
Old 08-12-17, 12:22 AM
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Yeah, the flush fin is really a Southwestern/Western thing. Since you are leaving the old aluminum frame in place (with it's fin under the stucco acting as flashing) they work fine out here. You don't have to make them super tight like you would with siding or new construction.

Of course vinyl is a real bad choice in AZ. They don't handle the sun well. Santa Clara they'd probably be fine.
 
  #7  
Old 09-18-17, 01:08 PM
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So I decided not to use a flush-fin window and install a new construction window instead. I've tried to get as much information as I can on installing new construction windows as replacement windows with existing wood siding. So far I've pried off the old exterior trim and used a circular saw to cut away 1-1/2" wood siding all around to expose the old window's nailing fin. Next, I will remove the old window and nail in the new one.

I have a question about installing the new exterior trim at the end. Since I've cut away the old wood siding next to the window how do I install the new trim?

1. The new trim is only on the nailing fin and does not overlap existing siding. In this case, I'll have to cut away some more siding to get at least 3" worth of width. I may have to do this anyway when installing the new window and flashing it.
2. use wood (with depth equal to siding) cut to width to cover the space where I cut out the old siding to expose the nailing fin. Then install new trim overlapping existing siding and the new plywood all the way to the window frame.

What's the right way? Thanks as always.
 
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Old 09-18-17, 01:16 PM
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It's pretty normal to cut twice if the fin is underneath the siding. Once to uncover the fin, (in order to get the old window out) then after the new window is in you can cut again if you want your trim to fit exactly between the window and the siding.

No, you don't usually want your trim to lay on top of your siding.

However if you have no sheathing over the studs... or if the siding *is* the sheathing... it might be a different story. If there is no sheathing, there is a limit to how much siding you can cut out. (For instance if you want 4" trim and only have 3" of studs around a window opening.)
 
  #9  
Old 09-18-17, 01:23 PM
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Thanks very much for the quick reply and the clear instructions. So the way the trim was installed originally (on top of the siding) was wrong? Or is that the style used during actual new construction but not when replacing?
 
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Old 09-18-17, 01:39 PM
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Hard for me to say without being there... but it looks to me like your aluminum window is not the original window. It likely replaced a previous one. And yes, that installer probably just did what was quick / convenient.

I guess I would need to see updated pictures, as I am just trying to imagine what you found when you tore it out and replaced it.

I will say that California often has their own unique way of doing things. They tend to overlay trim on top of the siding out there and don't think anything about it. Maybe it's because they can get away with it in the dry parts of the state. But I know it's very common to see that out there.
 
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