Hardie Plank Questions (and Answers???)

Our 25 year old Florida block home has stucco on the rear of the house, and on both sides below the gables. The top above the gables is grooved wood paneling. The front is natural stone and also grooved wood paneling. We looking at fixing this up and doing the paneling over with Hardie Plank siding.
Weve received several quotes and they are charging material and labor by the square we were told is 100 sq ft (10 X 10). The prices are from $800/square and up (and we mean WAY up). We looked at a local box store and the Hardie Plank (7-1/4 X 12) is under $5/each. This means for 20 of these planks wed cover 10ft tall but 12ft wide or 120sq ft for around $100. This also means these places are charging around $700 per square to install it. And they were all talking of putting it right over top of the existing paneling since its not in too bad shape, to add an extra layer of insulation.
So were looking at doing this ourselves. A couple questions we have. The Hardie Plank requires a water resistive barrier but were wondering that since were going over the existing paneling which has a foil back insulator under it, do we still need to do this? They also speak of putting down a joint flashing layer under the planks but once again since, were going over the existing paneling, do we need to do this?
If anyone has experience with this and can let us know if we need to do this barrier, wed greatly appreciate it. And any advise, warnings, suggestions or any words of wisdom about Hardie Plank siding would be appreciated.
Thanks
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Unless you can figure out how to maintain the existing wood siding after the Hardie board goes up, you should treat the paneling like wood sheathing and install the new siding complete with all weatherproofing details. Caulk doesn't work everywhere and last forever.
Leaving the existing siding under the Hardie board doesn't add any appreciable insulation value.
I can't comment on installation costs as there is no information, just some dollar amounts. You should be aware that some of the costs you're paying a contractor are for risks that you assume when you do the work yourself. Not necessarily a bad thing, but it is often overlooked in the "cost savings of DIY" calculations.
R
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infiniteMPG wrote:

Yeah, I'd put up the "water resistive barrier." How much could tar paper cost? If nothing else, it'll keep the existing wall from rotting due to water intrusion.
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I had a similar experience with Hardy Plank installers a few years back and decided to give it a go myself. The only exception was that I was looking at an $8000 to $12,000 dollar job instead of $800. In my case, I pulled the old siding off, applied the vapor barrier and put up the Hardy Plank. One recommendation is to get someone to help you. I did the job myself on a two story house and it wasn't easy dealing with those 12 foot long planks while climbing a ladder. The application is easy enough using a good power screw driver. Leave about 1/8 inch gap between the ends for expansion and fill with caulking.
If you plan to apply over the existing siding, make sure and secure the existing siding with screws to prevent any warping and poping. Do use a vapor barrier and the flashing since you don't want any water getting in behind the planks and rotting the wood. For two people it would be a few hour job and for one, it still could be finished in a day.
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