If the existing siding is damaged remove it and install tri built fanfold underlayment directly to the substrate.
Fanfold siding installation.
The products are easy to handle score cut and install and no special tools are needed.
A install tri built fanfold underlayments directly over old siding using galvanized or aluminum roofing nails with nails spaced about 2 feet apart.
Foamular extruded polystyrene xps rigid foam insulation offers a comprehensive line of products in a wide choice of sizes thicknesses and edges with a lifetime limited warranty for the life of the home or building.
I have not seen any studies that show how well tape adheres to foam over the long haul.
Exterior fanfold insulation is the foam type of insulation that is applied between your home s exterior and the siding and it offers some protection from moisture in addition to creating a layer of thermal insulation.
Products can be used on wood steel framing or concrete walls.
Fanfold foam residing board is a thin perforated extruded polystyrene foam board faced on one side with a plastic film facer and combines proven xps foam technology with a unique design to enhance the application of new or replacement siding.
Fanfold board is worth the cost and effort to install behind vinyl siding.
Dupont has said on their website and product flyers that if using both fanfold and housewrap and committed to both put the tyvek housewrap over the fanfold but they actually recommend assuming the insulation is totally closed cell with very low absorption rate putting the insulation directly under the siding overlying dupont drainwrap which is designed to provide a better drainage path between the two than regular housewrap.
Like bob said it helps with sound insulation.
It also helps with wind infiltration through the walls.
This creates a horizontal seam every 4 feet.
Verify that substrate dry and free of foreign material that will damage the fanfold underlayment.
R tech ff fanfold is a high performance sheathing consisting of a superior closed cell lightweight and resilient expanded polystyrene eps with advanced polymeric laminate facers.
It also helps to level the walls so you get a better smoother siding job.
R tech ff meets or exceeds the requirements of astm c578 standard specification for rigid cellular polystyrene thermal insulation.
If you have ever seen vinyl siding and the laps looked dirty all the time this is caused by heat buildup between the siding and the wall this heat excapes through the laps and causes stain.
Using proper siding insulation.
Fanfold foam residing board.