Structural insulated panels

Short answer

A foam core bonded between structural facings, often wood. Fast to crane into place. Wind, wetting, and insects are the questions a finished note has to answer with sources, not adjectives. This page is a reference note in an open library, not a recommendation for a specific lot. Scores stay blank until a source is attached.

Quotable summary. Cite the note title, BuiltStrong.ai, and the date once a reviewer signs the slot above.

What it is

A foam core bonded between structural facings, often wood. Fast to crane into place. Wind, wetting, and insects are the questions a finished note has to answer with sources, not adjectives.

The sections below are the template every technology page uses. On an outline, the slots are still empty on purpose. A finished note replaces each slot with a sourced paragraph, and it is willing to say when the system is the wrong one.

Structural insulated panels is one entry among many. BuiltStrong is not captured by it, and the library is meant to keep growing past the six systems on the comparison sheet.

How it is built

[Step slot] Conditions
The site condition that has to be true before this assembly is even a candidate. Flood zone, wind, fire exposure, or soils — name the one that governs.
[Step slot] Sequence
The order a crew actually builds it, including the inspection that happens in the middle, not only the finished photograph.
[Step slot] Closeout
The submittal, listing, or inspection that lets you say the assembly is the one the note describes.

Trade-offs

[Trade-off slot] What this system does plainly well, with the comparison named. “Better than what, on which hazard.”
[Trade-off slot] What it gives up: cost, crew, thickness, openings, drying, or a hazard it was not built for.
[Trade-off slot] The regional limit. A system that is ordinary in one market is a specialty order in another.

When we do not recommend it

We do not recommend it when a higher-ranked priority of yours is a hazard this assembly does not address.
We do not recommend it when the only crews who build it are a day’s travel past what the schedule can bear.
We do not recommend it when the sourced cost band, once we have one, sits outside the budget you gave us. [3]

Performance notes

A blank cell is the honest state. Filling it is a citation, not a design decision.

Hazard notes for SIP. “Not scored” is not a zero.
Hazard	Note	Source
Hurricane	Not scored. This note is filed under the hazard, which is not a rating.	[Source slot]
Flood	Not the subject of this note.	[Source slot]
Fire	Not scored. This note is filed under the hazard, which is not a rating.	[Source slot]
Mold	Not scored. This note is filed under the hazard, which is not a rating.	[Source slot]
Termite	Not scored. This note is filed under the hazard, which is not a rating.	[Source slot]

Sources

[1] Citation slot — standard, evaluation report, or book. Publisher, year, section. Supports: [the claim this number is attached to].
[2] Citation slot — local code or flood map. Authority, edition, panel or map id. Supports: [the site constraint].
[3] Citation slot — cost or labor note. Region, date, what was included and excluded. Supports: [the cost band].

Questions

Is SIP the right choice for my lot?

This page cannot say. It files the system with the hazards it is about. Your plan uses the lot, the local maps, and the order you put on those hazards. Until then, treat every number you hear from a seller as unsourced.

Why is there no score?

Because a score without a source is a brochure. The cell stays at “Not scored” until an evaluation report, a standard, or a named data set is attached. The same rule is on every page in the library.

Who pays BuiltStrong?

You pay for advisory work: a written briefing, a concept package, or a site visit. If we introduce a builder and you sign a contract, that builder pays a referral fee. The method note is written before a builder is named. The fee is not a reason to pick a system.

Is this SIP note a design for my house?

No. It is a reference note. A recommendation comes from your lot, your priorities, and your budget, and it is still an educational advisory. Your builder’s architect and engineer size and stamp the work.

Facings: MgO vs OSB

Direct answer. A SIP is a foam core glued between two structural skins. Almost every SIP sold in North America has OSB skins; a smaller group uses magnesium oxide board. The core and the panel joints are the same either way, so wind and seismic performance come from the engineering, not the skin. The skin decides how the panel behaves in fire, in a wet wall, and with termites. If you are building in a wildfire zone or a humid climate where you don't trust the cladding to stay dry, MgO facings are worth the premium; if the wall will stay dry and fire exposure is ordinary, OSB is the cheaper, better-understood choice.

	OSB-faced SIP	MgO-faced SIP
Structural track record	Decades; the facing the SIP industry's test data and span tables are built on `[judgment]`	`[tested]` Lab work — Smakosz, Kreja & Pozorski (2021) tested MgO-faced composite SIPs in edgewise compression and reported high strength and stiffness. U.S. field data and the number of manufacturers holding SIPA or ICC-ES reports that specifically cover MgO skins are smaller than for OSB. Confirm the exact report for the panel being specified.
Fire	Combustible skin; interior needs a thermal barrier (typically ½-in gypsum) over the foam `[code]`	Skin can be noncombustible under ASTM E136 depending on the specific product and its report (see /library/mgo-board); the foam core is still combustible, so the code-required thermal barrier is still required `[code]`. May simplify WUI exterior assemblies `[judgment]`.
Moisture and mold	`[judgment]` OSB swells and supports mold if the wall stays wet; the industry's known failure mode is roof-panel rot at unsealed joints	Inorganic skin resists mold; but MgO is hygroscopic and not waterproof, and chloride-based skins can weep in humid air — ask for sulfate chemistry and a chloride-ion figure
Termites	Skin is edible; core is not food but is a tunneling path `[judgment]`	Skin is not edible; core is still a tunneling path
Weight and handling	Lighter; standard crews	Heavier; more care at edges `[judgment]`
Cost	Baseline	Higher

Questions to ask any SIP maker, whichever skin: Which evaluation report covers this exact panel? What is the facing chemistry (for MgO: sulfate or chloride, chloride-ion content)? What is the joint sealing detail, and who is responsible for it on site? What roof-to-wall and panel-to-foundation connections were engineered for your wind zone?

[judgment] One rule of thumb: the SIP industry's worst outcomes have been moisture at joints, not facing material. A perfectly sealed OSB SIP beats a leaky MgO SIP. Choose the installer first and the skin second.