Exterior Insulation & Building Wrap
in Apex, NC
Apex Pro Siding & Wrap brings over 15 years of hands-on experience in siding, house wrapping, and exterior insulation systems. Continuous insulation installed over the structural sheathing — beneath the siding and outside the stud cavity — is one of the most effective building envelope improvements available for existing and new residential construction. Standard wood-framed walls lose 20–25% of their thermal resistance through the studs themselves, a phenomenon called thermal bridging. Batt insulation installed between studs does not address this loss — it only insulates the cavity, not the stud. A continuous layer of rigid foam or mineral wool installed over the sheathing covers studs and cavities uniformly, eliminating the thermal bridge and improving the effective R-value of the wall assembly by R-3 to R-15 depending on thickness and product selection.
In Apex, NC — where cooling degree days average approximately 1,900 annually and heating degree days average around 3,400 — wall assembly thermal performance directly affects the energy load on HVAC systems that run year-round. The NC Energy Conservation Code, based on IECC 2021, requires continuous insulation on certain wall assembly configurations in Climate Zone 4A, which covers Wake County. Apex Pro Siding & Wrap installs continuous insulation systems as part of full re-siding projects and new construction packages throughout Wake and Chatham counties, integrated with weather-resistive barrier systems and siding installation for a complete, code-compliant wall assembly.
Why Choose Us
Local Siding Contractors with Actual Experience
We have completed thousands of residential and commercial siding projects across Apex, Cary, Holly Springs, Morrisville, Fuquay-Varina, Raleigh, Wake Forest, Chapel Hill, Durham, and Pittsboro. We understand the housing stock in this area specifically.
Advanced Installation & Repair Methods
Our installation teams are trained on full water-managed wall assembly techniques: continuous house wrap with taped seams, integrated kick-out flashing at all roof-wall intersections, foam backer rod and sealant at all penetrations, and proper clearances between siding and grade or roofing.
Proven Track Record
Thousands of completed projects in the Research Triangle region span single-family residential re-siding, new construction builds, commercial retail and office exteriors, and multi-family properties. More than 94% of our residential customers in the past three years came from referrals or repeat business, which reflects project outcomes more accurately than any other metric.
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Some of the Products We Proudly Use
Exterior Insulation & Building Wrap
Services We Provide
Wall Assembly Assessment and CI System Selection
Continuous insulation system selection depends on the existing wall assembly configuration, the target R-value, the siding product being installed over the CI, and the budget for the project. We assess the existing sheathing condition, stud depth and spacing, window and door jamb extension requirements, and the drainage plane strategy before recommending a CI system. Thicker CI boards require window and door jamb extensions to maintain correct trim depth — a detail that adds cost and must be planned before material is ordered. We provide a written CI system recommendation with product specifications and projected R-value improvement before the project scope is finalized.
EPS Rigid Foam Installation
Expanded polystyrene — EPS — is the most commonly specified continuous insulation product for residential re-siding projects. EPS is vapor-permeable at thicknesses up to 2 inches, which is critical in North Carolina's mixed-humid climate — a vapor-impermeable CI product installed on the exterior can trap moisture in the wall cavity under certain seasonal conditions. EPS is available in R-4 per inch density, is compatible with all siding materials, and can be installed with standard wood screws driven through the foam into the stud framing below. We install EPS in 1-inch, 1.5-inch, and 2-inch thicknesses depending on the target R-value and window jamb extension tolerance.
XPS and Polyiso Rigid Foam Installation
Extruded polystyrene — XPS — and polyisocyanurate — polyiso — provide higher R-values per inch than EPS: XPS delivers R-5 per inch and polyiso delivers R-6 to R-6.5 per inch at installed conditions. Both products have lower vapor permeability than EPS, which requires careful design consideration in mixed-humid climates to avoid moisture accumulation in the wall assembly. Polyiso is the highest R-value-per-inch option for exterior CI and is commonly specified when wall thickness constraints limit the CI board thickness that can be accommodated. We install XPS and polyiso systems with appropriate drainage mat integration and assess vapor permeability compatibility with the existing wall assembly before specifying either product.
Mineral Wool Continuous Insulation
Mineral wool rigid insulation — products like Rockwool ComfortBoard — is vapor-permeable, non-combustible, and provides R-4.2 per inch. Its fire resistance makes it the preferred CI product for applications where fire-resistant wall assemblies are specified, and its vapor permeability eliminates the moisture accumulation concerns associated with closed-cell foam products in mixed-humid climates. Mineral wool CI is heavier than foam products and requires longer fasteners driven into stud framing to carry the load, and the siding installed over it must be attached through the CI to the framing below with appropriate fastener length. We install Rockwool ComfortBoard and equivalent products on residential and commercial projects where fire resistance or vapor permeability is a design requirement.
Drainage Mat and Ventilated Cavity Integration
Continuous insulation installed directly against siding without a drainage layer creates a potential moisture trap at the siding-CI interface — particularly for wood and fiber cement siding that requires back-side drying to perform correctly. We install a drainage mat between the CI surface and the siding on all wood and fiber cement installations over CI, providing a capillary break and a drainage pathway for any moisture that reaches the back of the siding. The drainage mat also provides a small ventilated cavity that promotes back-side drying of the siding panel, extending service life in Apex's humid climate.
Window and Door Jamb Extension
CI boards installed over sheathing increase wall thickness, which moves the siding plane outward relative to the window and door frames. Any CI thickness above approximately 3/4 inch requires window and door jamb extensions to maintain correct reveal depth at interior trim and correct exterior trim integration. We fabricate and install jamb extensions as part of every CI installation where thickness warrants them, using PVC trim material that will not rot, warp, or require painting on the maintenance cycle that wood demands. Jamb extensions are measured, cut, and installed before siding installation begins to ensure correct trim integration at every opening.
Types of Properties We Serve
Existing Residential Re-Siding
Continuous insulation installation is most cost-effective when combined with a full re-siding project — the wall is already open, the siding is already being replaced, and the incremental cost of adding CI to the scope is far lower than a standalone CI project that requires removing and reinstalling siding. We offer CI as a standard scope addition on every re-siding estimate for homeowners who want to improve wall thermal performance while the wall assembly is accessible. The energy savings from eliminating thermal bridging in a 1,990s or 2000s-era Apex home — which were built to less stringent energy codes than current NC requirements — can meaningfully reduce annual heating and cooling costs.
New Residential Construction
The NC Energy Conservation Code requires continuous insulation on certain wood-framed wall assemblies in Climate Zone 4A depending on the cavity insulation R-value and stud depth being used. We work with residential builders throughout Wake and Chatham counties on new construction CI packages, integrating CI installation with ZIP System sheathing and siding schedules for a fully sequenced wall assembly installation.
Commercial Construction
ASHRAE 90.1 and the NC Energy Conservation Code for commercial buildings impose CI requirements on commercial wall assemblies that are more stringent than residential requirements in many assembly configurations. We install commercial CI systems — EPS, polyiso, and mineral wool — on commercial construction projects in Wake County, coordinating with general contractors on sequencing and inspection scheduling. Commercial CI installations are documented for energy code compliance verification as part of the building permit process.
Insulated Vinyl Siding Upgrades
Insulated vinyl siding — vinyl panels with factory-laminated EPS foam backing — is a cost-effective CI option for homeowners who want improved wall thermal performance without the added complexity of a separate CI board installation and jamb extension work. Insulated vinyl siding panels with integrated foam backing improve wall R-value by R-2 to R-2.7 depending on the product, require no jamb extensions at standard window depths, and install on the same schedule as standard vinyl. We offer insulated vinyl siding as the entry-level CI option on re-siding projects where budget or window jamb depth constraints limit the CI board thickness that can be accommodated.
What Our Customers are Saying
"We added 1.5-inch EPS to our re-siding project after Apex Pro explained the thermal bridging issue. Our first full winter after the re-side showed a noticeable reduction in our heating bills compared to the previous year. The jamb extensions were done cleanly and you can't tell they were added."
— Richard and Carol H., Apex, NC
"Our new construction spec called for continuous insulation under the NC energy code. Apex Pro installed the polyiso and ZIP System package in the correct sequence with our window sub and passed the framing inspection with no corrections required."
— James D., Holly Springs, NC
"We went with insulated vinyl siding after Apex Pro walked us through the options. Given our window depths, the integrated foam backing was the right call. The installation was clean and the R-value improvement was worth the small upcharge over standard vinyl."
— Susan M., Morrisville, NC
Exterior Insulation & Building Wrap FAQs
How much does continuous insulation improve wall R-value in a typical Apex home?
A standard 2x4 wood-framed wall with R-13 batt insulation has an effective whole-wall R-value of approximately R-10 to R-11 when thermal bridging through the studs is factored in — studs conduct heat significantly faster than insulation and reduce the assembly's thermal performance below the rated cavity R-value. Adding 1 inch of EPS continuous insulation over the sheathing improves the effective whole-wall R-value to approximately R-14 to R-15, eliminating most of the thermal bridging loss. Adding 2 inches of polyiso pushes the effective whole-wall R-value above R-21 — comparable to a 2x6 framed wall with R-19 batts but without the framing cost or interior space loss.
Does exterior continuous insulation create moisture problems in North Carolina's climate?
It can, if the wrong product is specified. In North Carolina's mixed-humid Climate Zone 4A, the exterior CI product must be vapor-permeable enough to allow the wall assembly to dry outward during the cooling season, when the moisture drive is from the exterior inward. EPS up to 2 inches thick and mineral wool CI are both vapor-permeable and appropriate for Climate Zone 4A without additional moisture analysis. XPS and polyiso have lower vapor permeability and require a wall assembly moisture analysis before specification — in most configurations they perform correctly, but the analysis should be done rather than assumed. We assess vapor permeability compatibility on every CI project before finalizing product selection.
Does adding exterior insulation require a permit in Apex?
CI installation as part of a re-siding project is covered under the siding replacement permit that we pull for the overall project. Standalone CI installation without siding replacement may or may not require a permit depending on the scope — we assess permit requirements for each project individually and file the appropriate permit before work begins. New construction CI installations are covered under the building permit for the overall project and inspected as part of the wall assembly inspection.
How does continuous insulation affect window and door trim?
Any CI board thickness above approximately 3/4 inch moves the siding plane outward enough to require window and door jamb extensions to maintain correct trim reveal depth. We measure existing jamb depths during the pre-installation assessment and specify jamb extension dimensions before material is ordered. Jamb extensions are fabricated from PVC trim material and installed before siding goes on the wall. The finished result — with correctly proportioned trim at every opening — is indistinguishable from a standard installation. Windows and doors do not need to be removed or repositioned for CI board thicknesses up to 3 inches on standard residential framing.
Can continuous insulation be added without replacing the siding?
In most cases, no — adding CI over the sheathing requires removing the existing siding to expose the sheathing surface, installing the CI boards, and re-siding over the CI. There is no practical way to install CI between existing siding and sheathing without removing the siding first. This is why CI installation is most cost-effective when combined with a re-siding project that is already planned — the siding removal and reinstallation costs are already in the project budget, and the incremental cost of the CI boards and jamb extensions is the only addition to the scope.