Sorry Joel - the laws of thermodynamics still apply to your home. I assume the other poster was talking about something like a foil coated Polyurethane rigid panel. Straight from the factory, you could get an R9 per inch out of the high end stuff but it degrades over a couple of years to R7 or so. Still, at 1/2 that would get you an additional 3.5. It probably isn't going to be cost effective for you, but if you only have R11 in the walls, it might make the house more comfortable. It sounds like an awful lot of work for minimal benefit though. Did you get the shutters or curtains up yet? That would be a much cheaper and cost effective way to keep the heat in. I assume your double pane windows are still only in the R3 range. That means you are losing 3-4 times more energy though each square foot of window than you are through the walls. Depending on the size of your windows, a good set of curtains might save more energy than marginally increasing the R value of the walls.

I prefer using foam around the perimeter of the window. That said, if the gap between the window and original frame is too narrow, foam will not fit so using just a sealant would suffice. Remember, your okna will have full foam wrap around the window to thwart air leakage. If you actually have weight pockets, only very old homes do, its totally acceptable to use fiberglass insulation due to the cavity being wide. You could use foam but its alot of extra foam and your installer will have to charge extra for that. Usually $20-25 per window extra. Regardless, the weight pocket should be insulated. This post was edited by mmarse1 on Wed, May 14, 14 at 7:53

mnzinnia, I'm a bit baffled at Marvin making a window smaller than what you needed for your opening. Marvin has always been really good at making windows to the specs we require. The only time they can't meet these needs is when we push the over-sized units. Otherwise they've always come within a fraction of an inch of what we need. In your case the person that measured told you the "vertical style", or the proper term being the "Center Mullion or MULL", would be spread to fit. This is a very common practice in the industry used everywhere. We call it a "Spread Mull" when we order a product needing a special sizing. We use it when ordering custom sized doors with side-lights all the time. If your windows didn't come with the spread mull done properly your installer should have sent them back to be done to the right size. We would have never installed these windows if they were to small unless the customer gave us the go ahead to downsize the opening. One thing I've seen lately are the outstate contractors still do things the old school way. Their continuing education on the changes in our installation practices always seems to be light years behind. One thing the installer has to be aware of is the new building codes from 2006 have specifically stated that the manufacturers installation instructions for windows and doors become code. This means every installer must know and understand the application instructions of each product they install or they will void the manufacturers warranty. In your case there's no problem because Marvin's insructions only state that "If You Desire" you can use a low-expansion foam sealant around their window next to the nailing fin. In todays practice we are using a low-expansion foam all the time during our installations. We have also been using the stuff in fiberglass combined with the low expansion foam. We spray the foam in first against the nail fin and then use the stuff in fiberglass behind the foam. The main reason being it stops the expanding foam from oozing out of the opening and making a mess. The use of low-expansion foam properly will eliminate any "Air Infiltration" from around the window. Fiberglass insulation is really made to be most effective at it's expanded 3-1/2" or more. When the fiberglass is compacted around a window in that tiny gap it's air infiltration impedance is nothing. So any air leaking in past the nail fin will find it's way into the home. The low expansion foam forms a barrier that stops air infiltration from entering the home. It will fill the little voids and cracks that the stuff in fiberglass won't. The positive feature of low-expansion foam is it stops water from entering the cavity. If water happens to get past the exterior barriers the foam will act as a watershed and keep the water from penetrating. The stuffed in fiberglass will soak the water up like a sponge and start to break down or sink in the cavity it's suppose to protect. When this happens you get an opening to possible mold & mildew issues that I'm not even going to think about getting into. Just to make you feel a little better about things and I don't send you into a panic attack. The worst case scenario of leaking water and air threatening your lake home is very small. Since it sounds like your completely overhauling the exterior of the lake home you have a couple barriers that will more than likely stop anything before it gets to the window cavity. You've already told me the home was wrapped with Tyvek and flashing was done around the outside of the windows. Hopefully the installers used a nail-fin application that was back caulked before anchoring. If all these items were done properly and drip caps were installed above each window with the Hardiplank siding finishing it off. Your probably going to be just fine. Just make sure all the windows are caulked and sealed to the Hardiplank to form that first coat of armor. In other words I think you'll be just fine and dandy down the road. Sounds to me like your only problem will be that sheetrock dust and touch-up painting. I wish you well in the final moments of your project. Then you can sit back and enjoy the great Summer Minnesota has for us every year!! Good Luck!!!

The storm windows don't even have to be "super tough". A good custom cabinet shop can build them too. The hardware to hang them can be found through restoration hardware types of businesses. In my opinion, the storm window frame would consist of a rabetted edge on three sides, so that it wrapped the exterior top sash stop. Within the rabbet, there would be a kerf cut into the wood where a modern bulb weatherstrip would be mounted. The storm sash would contain a standard glass pocket/plow, or a wider plow to accept modern low-e insulating glass unit. The hard part is to build the sashes to fit the existing window frames. Most older homes have settled and the window frames are no longer square, so templates are often required. Another tip would include building the storm windows with a good, durable and stable wood species. Depending on your quantity, it could be as expensive as buying a complete new window, and the template process is hard enough to deem it a "one-time" job. So spend the money right the first time, just like folks should do when buying their new wood windows. :)