After replacing most of our regular windows ourselves we figured that we could splurge and replace our 5'x5' living room window with a garden window, and have it be maybe slightly more complicated, but nothing too out of the ordinary. So we ordered a garden window from Milgard and it seems a nice enough unit structurally and appearance-wise. However, the installation instructions consist of the back of the window sticker, which shows a cut away view of the window, and refers to a generic window installation document that does not explain how to install this. The manufacturer's web site could be kindly described as "unhelpful".

Here are the differences from (what I consider) a normal window.
- The nailing fin is a solid 1 1/2" piece of metal all the way around the window instead of being slotted vinyl. There are no holes in the fin anywhere.
- There are two heavy duty ~7 pound metal bars, about 1" square by 5' long, with a deep groove running down the length (it could fit onto part of the fin, but doesn't seem designed for it). There are no holes in these bars, although there is a small U shaped cut out on each end. The cut out goes to the edge, so you would not be able to use that to bolt it to the house.
- There are two angle iron brackets, surprisingly with holes in them. The holes are relatively small (I was expecting lag screw size, but these can just fit an average sized nail). Also there are no corresponding holes in the bottom of the unit to attach these to.
- The fin is on the edge, depthwise, of the window, not in the middle. This means that no part of the window can sit in the rough opening. The window also is not designed to fit from the inside of the house.

I will call the manufacturer tomorrow, but I would be surprised if they were significantly more helpful than their instructions . Please let me know if you have any suggestions about how this is intended to attach to the house.

Thanks! (edit, corrected nailing fin size)

 

Could you provide a few more details about the window, such as the name and model number?

Is it the Milgard Classic Garden Window, Model 5920?

I have not installed that particular window, but other garden windows that I have installed are similar in construction. They mount on the outside of the home (onto the sheathing) with a nailing flange, almost like a storm window. The square tubes and angle irons sound like something that would be for horizontal reinforcement. If there are no holes in the nailing flange, you will simply drill your own. Since you mentioned the flange is metal, there is no need to have slotted holes.

The garden windows I have installed usually have a seat that extends into the rough opening, but I'm not suprised that yours is fully on the exterior. Once the window is installed onto the exterior of the home plumb and level, you will need to line the rough opening with a jamb that will meet up with the garden window. Then the perimeter of that jamb will be trimmed with casing.

If the rough opening is not the correct size to install a jamb and have it meet up with the garden window nicely (in a symetrical fashion), then you would wisely resize the rough opening before installing the window.

 

Checking the Milgard website and their technical data pdf files, there are two installation types. One is like Xsleeper said, that is applied over the sheathing, and the other is installed on the framing prior to sheathing with a holey nailing fin. Not sure which one you got.

 

Chandler, which technical data files are you referring to? The installation instructions pdf files are for standard windows, and mostly talk about how to flash the window using methods A or B. I had put in Jeldwen's for the rest of my house which came with fairly detailed instructions for a relatively straightforward product. I am always amused at the instructions that presume you are replacing windows in a new house with building wrap and the like, instead of an older home with aluminum window frames held in with a few nails...flashing, caulk, building wrap, what's that?

Anyway, the window "paperwork" (yeah it cracks me up that the window sticker is the extent of the paperwork) doesn't say what exact model it is, but it looks exactly like the one on the site, so I would guess that model 5920 is correct. It does say the window fin is supposed to be predrilled on the web site, but well, it ain't.

I called Milgard HQ up and after bouncing to several people, they predictably referred me to professional installers, who quoted me $500+, and a month lead time to install the window. They don't have any information on how to install their own products lol and alternately suggested I call Home Depot up for more info. Home Depot didn't expect it to come with these mysterious long metal bars, and asked me to bring them in.

A correction to my earlier post, the nailing fin is only 1 1/2" when I measured it instead of eyeballed it. I'm sure the angle iron brackets are for reinforcement below, but I have the feeling I should be using lag screws into studs. The predrilled holes in them are way too small though (1/4" dia), so what did they really intend? A relative suggested the metal bars are for an alternate method of installation, and not needed if you install with the brackets supporting the weight below.

I never like having parts left over after installation and trying to guess how their engineer designed it to be installed in the first place.

Thanks again for the suggestions.

 

Unless I get more feedback, I think I'm going to lag screw a pressure treated 2x4 to the outside bottom of the window frame and have it sit on that (can't snug it to the ext wall until the window is installed due to the bottom fin though). I'll also use the angle brackets, with the largest nail that will fit the 1/4" holes. Unfortunately, most of the other manufacturer's that at least have instructions for their garden windows seem to have only fairly small ones that don't need extra support, not like the 200+ pound monster this one is. I haven't been able to figure out a way to use the long metal bars, so I guess they'll be left out.

Hopefully this is somewhat useful to future people left scratching their head at this particular window.

 

Post installation -
If anyone else buys this window (which was model 5920), the long steel bars are supports for the glass shelf, which my wife figured out a day after we finished the install. They seem excessively heavy duty for that, but hey. Too bad Milgard couldn't tell me what they were for. We put a PT 2x4 and a 2x12 on top of the angle brackets to support the entire depth of the window. Also I enlarged the holes on the angle brackets so I could use 3/8" lag screws into the studs. Hope this helps someone in the future.