It is pretty much all purchased separately, they are definitely all very important for a proper installation. The only thing i would stay clear of is the Low expanding foam, i don't believe any window mfr recommends its use anyway. The foam back they are referring to is "foam backer rod" which is foam in a roll or long pieces depending on its thickness which is used in the opening between the window frame and the rough framing to fill in the gap before you caulk.

Thanks afsa, I just checked Andersen's cutsheet and they say ecpanding foam is optional and they illustrate using it in the do. I would prefer using field tested methods recommended by trade pros on this website so I appreciate any of your further thoughts, as well as those of others.

Thanks again,
Joe

A low-expansion foam is better to use, in lieu of "expanding foam", with respect to window and door installations. Regardless of which is used, it is important to apply the foam in 1" intervals -most important with expanding foams. Simply apply a 1" deep amount of foam into the rough-opening cavity and walk away from it until it has fully cured. Remember, the outer crust of the 1" bead will cure quickly, but the heat from the middle of the foam bead remains "active". If applied in excess, the outer crust cures quickly, while the inner heat pushes the foam horizontally (sideways within the rough opening) and will deflect either the structural framing or the window/door frame -whichever is the least structurally sound (i.e. windows and doors). This cause the window and door frames to buckle, compress or "hourglass", and otherwise create a window or door frame that is no longer square in the rough opening.

By the way, there still remains the option of the tried-and-true method of installing fiberglass insulation into the rough opening space. The advantage of the foam sprays are due to the small spaces that today's window manufacturers are suggesting for a rough openings, thus not providing must space to properly apply shims, let alone fiberglass insulation. Therefore, your best initial effort should be to ensure your rough openings are absolutely square, plumb and level, or as close as humanly possible (insert smilie -for common human errors).

I wish you good luck, and it's a simple process if one remembers to simply "feel" the window or door operation and visually check the sash/panel-to-frame reveal from the exterior and ensure it is equal on four sides.

Lastly, it is helpful to envision how water runs down the exterior face of a building, and consider how it could penetrate the hole you are attempting to conceal. One of the more modern advancements in technology that has made window installations tighter, is bitumeous(sp?) membranes (i.e. Ice and Water Shield). This is a black waterproof and self healing membrane that is commonly used for roofing underlayment. Its benefits also apply to window & door installations, and we use to cut rolls of I&WS on a chop saw into 6" mini-rolls. Today, manufacturers are producing rolls of this product specifically for windows and doors (often referred to as "window wrap"). Depending on your exterior facade, use this material to overlap your W&D nailing flanges prior to your siding/stone/stucco installation -this membrane should also overlap onto the protruding four sides of the window or door frame to allow for a proper seal. Remember to cut and lift your head section of house wrap, and apply the window wrap under the head piece of "Tyvek". During the entire process, don't forget to envision how water runs down the face of the building and hits all these overlaps and sheds away from the seals/joints -all your sealing work should start at the bottom of the building and work its way upward, so that all overlaps point downward and away from water migration.

Excellent mcs but i am still not a fan of any spray foam in window and door installation, one reason being as you said the chance of it bowing the jamb and the fact that once you do that is it very tough to repair with expanding foam present. Plus as you stated you the foam inserted in the opening you cannot see is just impossible to control and a proper installation is all about controlling your work environment

I agree. We currently disregard manufacturer's rough opening specs, and simply request frame sizes for our required R.O. dimensioning. Using the actual frame size, we allow an absolute minimum 1/2" on four sides of the window to allow for proper installation of fiberglass insulation.

Window and door foam is still far and away the best option is in the hands of someone who is careful with its installation.

Layering is key as mcbldr mentioned to allow for proper curing and controlled expansion.

Filterglass does nothing to stop air infiltration and has a lower R-Value per inch. The R-Value of fiberglass is also only a theoretic value. If there is any air movement, even convective looping, the R-Value drops like a stone.

Window and door foam also provides some structural support as it dries semi-rigid.

It is better in every application if used properly.

Thank you mcs, afsa and windows,

All these points are valuable and appreciated. If I choose to use the foam (low expanding) I'll be sure to use a careful application - with respect to the 1" intervals - are you suggesting multiple beads (say, 2 of 1" size) around all four sides of the r.o. I do see how it will be imperative not to overuse, and also pay particular attentiion to plumb, square opening before proceeding. The fg insulation idea sure seems like it would be more forgiving and less likely to lead to difficult to repair error.

Again, thanks for all the guidance.
Joe