How We Build
SIP construction isn't complicated — it's just different from what most people are used to seeing. Panels show up to your jobsite pre-cut, pre-engineered, and ready to assemble. Here's what that looks like from slab to dried-in shell.
Built to Spec in Our Tulsa Shop
Every panel starts right here. Two sheets of structural-rated OSB, a rigid EPS foam core, and vacuum pressure bonding them into a single structural unit. The OSB in SIPs isn't the same commodity sheathing you buy at the lumberyard — it's manufactured specifically for SIP production in large 8×24-foot sheets, which means fewer joints and a stronger panel.
Window and door openings are cut in the shop. Electrical chases are routed based on your plan. By the time panels load onto the truck, most of the precision work is already done.
Where Panels Meet the Foundation
This is where SIP construction starts on site, and the details matter more than most people think. On a concrete slab, we use a double bottom plate assembly — foam sill seal, then treated lumber on the concrete, then untreated lumber on top of that. The panels sit on the untreated plate. OSB should never sit directly on concrete — moisture wicks up through concrete for the life of the building.
On a wood-framed floor system, the panels attach to the rim joist and subfloor with a sill plate. Either way, the connection is engineered for the specific loads of your project.
Walls Go Up in Hours, Not Weeks
This is where people start to see the difference. A SIP wall panel is structure and insulation in one piece. No studs to cut. No headers to build. No fiberglass to stuff in later. The panel goes up, gets fastened, and you move on to the next one.
Panel-to-panel connections use lumber splines or insulated block splines with approved adhesives and sealant at every joint. Corner connections use doubled studs with continuous sealant on both sides. Every joint is air-sealed — that's not an extra step, it's built into the process.
A BASF time-motion study showed 55% less framing labor compared to stick framing. When you're paying a crew by the day, that number hits different.
Every Connection Is Engineered. Every Joint Is Sealed.
SIP construction isn't guesswork. Every Apex project is engineered and stamped by a licensed PE. In areas with no required building inspections — which is most of rural Oklahoma and Texas — our engineering provides the accountability that an inspector would.
Windows, Doors & Rough Openings
Window and door openings are pre-cut in the shop, but the framing still needs to happen on site. King studs, jack studs, and header panels assemble inside the SIP opening using the same nailing patterns you'd use in conventional framing.
The difference is that insulated header panels can be used above openings — maintaining the continuous insulation envelope right through the header instead of losing it to a solid wood beam. That's a thermal bridge conventional framing can't avoid, and SIPs can.
The Roof Is the Best Part
I'll be straight with you — watching roof panels go on is my favorite part of every build. A crane sets panels from eave to ridge. One panel covers what would take a framing crew most of a day with rafters, sheathing, and insulation as separate steps.
SIP roof panels create one continuous insulated plane from the top of the wall to the peak. No rafters. No cathedral ceiling insulation headaches. No venting debates. The panel is the structure, the sheathing, and the insulation — all in one piece.
Beveled ridge connections, eave details, hip connections, valley details — they're all engineered with specific fastener schedules and sealant patterns.
Sealed Tight — By Design, Not by Accident
Here's what sets a SIP building apart from everything else: the air barrier is built into the system. Every panel joint is sealed with adhesive sealant and spray foam. Depending on the climate and the project, SIP tape or a fluid-applied membrane seals the exterior face.
With stick framing, air sealing is an afterthought — you're trying to seal a wall that has hundreds of pieces, dozens of intersections, and gaps everywhere. With SIPs, you're sealing clean, straight joints between large panels. It's not even a comparison.
This is why SIP homes consistently test tighter than stick-built homes on blower door tests. The fewer joints you have, the less there is to leak.
Shell Complete. Trades Can Start.
Once the last roof panel is set and the seams are sealed, you've got a dried-in, insulated, structural shell. Windows and doors go in. Your electrician pulls wire through the pre-routed chases — no drilling through studs. Plumbing runs on interior walls just like any house. Drywall goes up and from that point forward, the interior finish is identical to conventional construction.
The timeline advantage is real. What takes a conventional framing crew three to four weeks — framing, sheathing, insulating, air sealing — a SIP crew handles in days. That's fewer days paying a crew, fewer days on a construction loan, and fewer days your building is exposed to weather.
Engineered. Documented. Proven.
Every Apex SIPs project comes with full PE-stamped engineering. Here's what's behind every panel we build.
PE-Stamped Engineering
Every project is engineered and sealed by a licensed Professional Engineer for the specific loads, wind zone, and conditions of your site. Not prescriptive code — actual engineering.
Span & Load Tables
Roof spans, axial wall loads, and transverse loads are all calculated per your specific design. We size panels based on real numbers, not rules of thumb.
SIPA Connection Details
27 standardized connection details covering every joint in the building — foundation to ridge. Every fastener, every sealant bead, every nailing pattern is documented.
Continuous Insulation
No thermal bridging. Period. The 2021 and 2024 IECC are pushing continuous insulation requirements into more jurisdictions. SIPs meet CI requirements by default.
IRC Section R610
SIP construction is recognized in the International Residential Code. This isn't an alternative building method — it's a code-recognized structural system with 90 years of history.
Wind & Seismic Rated
SIPs are approved for high-wind and seismic zones. Load ratings meet or exceed conventional framing. These panels don't just insulate — they're the structure.
Ready to Build Better?
Send us your plans, give us a call, or come by the shop in Tulsa. We'll walk you through the process and put together a panel package for your project.