It will be size specific to the home, VERY location specific, as well as specific to the amount of damage that needs to be repaired.

Placing it over the asbestos siding with the water damage that you are currently experiencing shouldn't even be under consideration. It's a HUGE mistake to think that can be done and successfully address the water management issues that you are having. What is there needs to be removed as the sheathing will need to be repaired and the windows reflashed correctly. It's possible that all of the sheathing on the entire home needs to be replaced, and if the insulation has become wet from the leaking windows (likely), it may need that entirely replaced also.

This isn't a "standard" siding replacement job. It's reconstructing the entire exterior of the home, plus the complications of asbestos abatement. A "standard" siding job could be 6-10K around here plus demo, but that will in no way cover what you will need to have done. Quardruple that, and add in a location upcharge if you are pretty much anywhere but the lowest cost area of the country. And then add in a contingency fund on top of that if they find termite issues or foundation rot from the water damage you've been experiencing. All of that will be a big unknown until the siding is pulled off. If the window leaks have been happening for some time, there is no telling how much damage could be underneath. Someone who would improperly flash their replacement windows could have committed all kinds of other sins against the house.

The ONLY way to get an idea of how much this will cost will be to call several contractors. And don't fall in love with the lowball guy who isn't addressing the root of the problems you are having. If you don't fix the sheathing, flashing, and insulation issues, then you are completely wasting your money.

We will be having the windows redone at the same time. I've already received estimates on installing new construction windows.b

I regret the day I ever thought I wanted to own a home. Such a waste of money. I'll never be able to afford any of these repairs, so it seems like I should just let the damn thing waste away...

Unless the windows have rotted out from the moisture infiltration, they do not need to be replaced. They just need to be flashed correctly to undamaged sheathing after the existing siding is removed and everything underneath is inspected.

If the leaking windows weren't disclosed before you purchased, and this is a recent purchase, you potentially could have recourse against the sellers. You would need to contact an attorney though.

We actually contacted a few attorneys who all said it was a waste of time and money to go after the original seller. They said that even if we won, getting the money itself was nearly impossible.

Thy frames do have rot on them so this will need to be replaced or repaired on every window. The problem is that all of these problems came up less than 2 years after buying the home, so we havent been able to get any equity to pay for the repairs, and our savings haven't been replenished yet to afford the repairs. We can't out loans high enough to fix everything that needs to be done, and we are trying to figure out what is absolutely needed in order to maintain the house, and what we can wait on for a few years.

I feel like I'm in a nightmare!

The best way to be able to build equity in any home is to become handy enough to DIY the projects. Basic vinyl siding on a square house is an easy DIY project. Replacing the sheathing is an easy DIY project. Flashing the windows is an easy DIY project. Repairing the windows is less easy, but it's certainly doable. Removing the asbestos siding is also DIYable if you read and understand the precautions that need to be done to do it safety. In some states, classes are offered to be able to become certified to do this. Network with family and friends and barter time working on their DIY projects for time on your DIY projects.

Start making a plan to acquire the skills and tools that any homeowner needs. Once you have the plan in place, you'll feel more empowered.

you say: I've already received estimates on installing new construction windows.

wouldn't you be looking at replacement and not
new construction windows?

at any rate, finding out how to properly flash
windows would be to your benefit.

like this:
http://www.finehomebuilding.com/how-to/articles/flashing-replacement-windows.aspx

best of luck

If the siding is off the house, it makes sense to do new construction windows. Gets rid of the old frames and allows for updated sealing/insulation and flashing.

We found out the windows that were replaced by the last owner were not flashed. They also were installed over rotten frames, so we will need them rebuilt. This is why we were looking to get new construction windows.