Insulation Over Existing Siding

I ve always wondered if this compromised the r value of the wall assembly.

Insulation over existing siding.

One major stipulation with the james hardie siding warranty is that it specifically states that if. Never never never let a contractor remove your old siding and install a tyvek material with insulation over the top. This goes for fiber cement hardwood and masonite siding. If the wood siding is beveled or lapped you.

By installing insulation on the outside of the framing it causes the location of the dew point to move to the outside of the wall assembly. Continuous insulation under new siding has become a popular way to improve energy efficiency on an existing home because it addresses a problem known as thermal bridging. Installing vinyl siding over wood siding wood must be sound. Wrap the house with a moisture barrier usually some type of polystyrene wrap and install desired siding by nailing through the foam board into the house framing.

This reduces the likelihood of condensation within the wall cavity. Foam board is however often added in order to help level out the wall when it has certain problems with it. Removing existing siding and installing osb has several benefits such as having brand new substrate on the home and the ability to inspect the wall cavity and all framing insulation and structural integrity of the home before replacing siding. It also eliminates the problem of mold forming when insulation is attached directly to the substrate.

Probably not significant but if you do insulate over the existing siding you have a separation between the insulation layer and the air barrier layer if there even is one. The exterior insulation also helps keep the siding all vinyl siding leaks further away from the exterior sheathing. In other cases it must come off. Most homes in the united states are built with traditional wood frame construction with studs every 16 on center.

In most cases you can put new siding directly on top of old siding without having to remove the old siding first and in addition it will in fact add an addition layer of insulation thereby helping lower your energy bill. Vinyl siding must be installed against a flat surface. Going over the existing siding adds to the r value by creating an air space between the insulation and old siding. Existing wood siding must be in good shape with no rot or mold and fastened tightly to the wall.