Do You Need A New Layer Of House Wrap When Replacing Siding?

Investing in a whole new set of siding for your home may increase its value and will refresh its exterior look. However, what's installed just below the siding is almost as important for the long-term durability of the house. House wrap, usually made of breathable materials like tar paper or Tyvek, is essential for most types of siding installation. Find out how this wrap is generally used during a siding replacement project and what limits its use.

The Role of House Wrap

Regardless of the precise material, all house wrap products offer similar benefits. They're designed to:

  • Keep cold air drafts from blowing through the cracks in the walls and gaps around doors or windows
  • Control moisture seepage through certain types of siding and protect the underlying wall structure
  • Prevent mold and mildew growth by allowing air to flow through the surface for thorough drying.

There are house wrap products to match every type of exterior wall finish. While Tyvek products are commonly used with plank siding made from vinyl or wood, there are other wraps available that bond with stucco, veneer brick, and other finishes. Siding replacement contractors must match the right wrap to the exterior finish for good results.

The Options for Adding New Layers

In general, it is fine to leave any old or existing house wrap in place when the old siding is removed. New house wrap is easily applied right over these old layers, even if they're not made of the same materials. Badly damaged or mildewed wrap may need removal for the long-term health of the structure. Peel-and-stick membranes used for sealing around windows and doors in particular may not adhere to all types of older house wraps. If the material was recently applied but the siding is getting replaced regardless, you may not need a new layer of wrap at all.

The Choice of Installing Siding Over Siding

Wood or plywood siding that is in good condition is the only siding safe to leave in place when a new layer is installed. Vinyl siding in particular is often installed directly over wood siding to help stabilize and insulate it. Cement board is also installed this way. It's generally a good idea to apply house wrap over the wood siding and under the new siding layer. This prevents moisture exchange between the two different materials so there are no issues with mold or rot.

Investing in a little house wrap during the siding replacement process protects the structure and siding alike. Make sure to check the length of time the wrap can stay exposed to sunlight and plan for siding installation so the material isn't damaged by a delay.