Ground Screw Technical Guide – Engineering Principles, Installation & Design Standards

What Is a Ground Screw Foundation System?

A ground screw foundation system is a deep foundation element consisting of a hot-dip galvanized tubular steel shaft fitted with one or more helical flight plates — the screws — that is advanced into the soil by applying a controlled rotational torque to the pile head. Unlike a driven pile, which displaces soil by brute impact force, a ground screw advances through the soil in a continuous threading motion, with each rotation advancing the pile by one helix pitch and embedding the flight plates progressively deeper into the soil profile. This threading action causes minimal soil disturbance, generates no spoil, and creates immediate, measurable ground-structure contact at the helix bearing surfaces before installation is even complete.

The structural anatomy of a ground screw has three functional components. The shaft — a circular hollow section steel tube of 51–168 mm outer diameter and 3–8 mm wall thickness — provides the structural spine of the assembly, transmitting both axial load (compression and tension) and bending moment between the superstructure above and the soil below. As the CHANCE Technical Design Manual documents, the shaft transmits torque to the helical plate during installation and transfers axial load from the structure to the helical plate bearing stratum during service — and must be sized for both torque and load demands simultaneously. The helical flight plate — a circular steel plate of 150–400 mm diameter, pressed to a true helical geometry with a constant pitch — is the primary bearing element of the foundation. In compression, the helix bears downward against the soil below the plate; in tension (pull-out), it bears upward against the soil above; in both cases, the bearing area of the plate and the shear strength of the bearing soil determine the axial capacity per helix. The termination — the top adapter, cap plate, post socket, or adjustable head system — connects the ground screw to the structure above, transferring the structural load path from the building frame or racking system down through the shaft and helix to the bearing soil stratum.

Load transfer in a ground screw foundation follows the path documented by Downforce Piling’s comprehensive technical analysis: Structure → Pile Cap / Termination → Shaft → Helix → Soil Bearing Stratum. In the soil, resistance is generated by three mechanisms that operate simultaneously: direct bearing pressure on the upper and lower faces of the helix plate; unit skin friction along the cylindrical surface of the shaft in contact with the soil; and in multi-helix pile configurations, cylindrical shear resistance along the soil cylinder between the upper and lower helix plates. The relative contribution of each mechanism depends on the soil type, pile geometry, and helix spacing — and forms the basis of the analytical design models used to calculate ground screw capacity.

Why Technical Design Matters in Foundation Performance

Foundation design is not a generic exercise. A ground screw specification that is correct for a 6 kW residential solar array in compacted sandy loam in Virginia may be inadequate — or wastefully over-engineered — for a commercial greenhouse in soft clay in Ontario, or a security fence on coastal sand in Florida. The governing load type, the soil bearing mechanism, the frost line depth, the corrosion environment, and the required safety factor all vary between applications, locations, and structural configurations in ways that cannot be resolved by a single universal “standard specification.”

The consequences of foundation under-design are not immediately visible. A ground screw that has been installed too shallow, driven into inadequately bearing soil, or specified without accounting for frost heave in a cold climate will perform acceptably — or even perfectly — until the first severe wind event, winter frost cycle, or saturated soil condition that pushes the system toward its actual structural limit. At that point, the deficiency manifests: as a displaced solar racking post, a heaved greenhouse base frame, or a leaning fence post. Avoiding these outcomes requires applying the correct engineering methodology — load calculation, soil assessment, frost depth verification, and installation quality control — before a single screw is ordered or driven.

This technical guide provides the structured engineering knowledge to make those design decisions correctly, regardless of application type or scale. It is organized into six technical clusters — Fundamentals, Installation, Load Calculation, Soil Conditions, Corrosion and Durability, and Selection — each of which addresses one complete dimension of the ground screw foundation design problem. Together, they form an integrated engineering design system that supports technically sound specification from first site assessment through installed quality verification.

How This Technical Guide Is Structured

The technical guide is organized into six sequential engineering clusters, each addressing a distinct design domain. Fundamentals covers the structural principles of helical pile mechanics, load transfer theory, and the torque-to-capacity relationship that underpins field installation verification. Installation Engineering addresses equipment selection, installation methodology, quality assurance procedures, and common errors and their corrections. Load Calculation covers the analytical design of ground screw foundations for axial compression, tension (uplift), lateral, and combined loading — with specific sub-pages for uplift resistance, lateral versus axial load comparisons, safety factor methodology, and weight capacity reference data. Soil Conditions addresses the engineering behavior of the soil types most commonly encountered in ground screw applications — clay, sand, rock, and frost-susceptible soils — with dedicated sub-pages for each. Corrosion and Durability covers the selection of appropriate galvanizing specifications for different soil chemistry environments and the long-term service life performance of ground screw materials. Selection Guide provides the integrated decision framework that connects structural load requirements, soil conditions, application type, and corrosion environment into a specific screw diameter, length, and material specification.

Structural Design Principles

The structural design of a ground screw foundation begins with establishing the load demand at each foundation point — the forces and moments that the structure above will transfer to the screw under all foreseeable loading conditions — and then selecting a screw geometry and embedment depth sufficient to resist those demands with an appropriate factor of safety against failure. This process follows the same limit state design framework used for all foundation engineering: ultimate limit state (ULS) design, which ensures the foundation does not fail structurally, and serviceability limit state (SLS) design, which ensures the foundation does not deflect or settle by amounts that impair the function of the structure above.

For most ground screw applications in the residential and light commercial sector — solar, deck, fence, greenhouse — the ULS axial capacity calculation is the governing design step, and the SLS settlement check confirms that deflection under service loads is within the tolerance of the superstructure. For tall fence posts, elevated deck platforms, and greenhouse end wall foundations, the lateral ULS check — ensuring the embedded shaft has sufficient passive soil resistance to resist bending without excessive rotation — becomes equally important. The full structural design principles for each load case are covered in detail in the Ground Screw Fundamentals → section of this guide.

Load Transfer Mechanisms

Three distinct mechanical mechanisms transfer structural loads from a ground screw shaft into the surrounding soil. Helix plate bearing is the primary mechanism: the helical flight plate(s) bear directly against the soil above or below the plate face, mobilizing the soil’s bearing resistance across the full helix area. In compression, the lower face of the lowest helix bears downward; in tension, the upper face of the helix (or all helices in a multi-helix pile) bears upward against the soil cone above. The bearing capacity per unit of helix area is determined by the soil’s shear strength parameters — undrained shear strength (Su) for saturated clay soils, or the friction angle (φ’) and effective overburden stress for granular soils.

Shaft skin friction contributes additional capacity along the length of the embedded shaft in contact with the soil, through adhesion in cohesive soils and interface friction in granular soils. For single-helix piles in soft soils, shaft friction can contribute 15–30% of the total axial capacity, rising to 40–50% for deeply embedded multi-helix piles in dense soils. Cylindrical shear is the mechanism operating between the uppermost and lowermost helix plates in a multi-helix pile configuration: under axial loading, the soil cylinder bounded by the helix plates and the pile shaft shears along its perimeter rather than allowing individual helix plates to punch through the soil. Research published in the Canadian Geotechnical Journal confirms that the cylindrical shear model provides more accurate capacity predictions for closely spaced multi-helix piles in dense soils, while the individual plate bearing model governs for widely spaced helices in weaker soils.

Torque-to-Capacity Relationship

The most practically important engineering principle in ground screw foundation design is the empirical relationship between installation torque and axial pile capacity. The CHANCE Technical Design Manual and the Mountain Scholar research compilation of 799 full-scale load tests both document that the ultimate axial capacity (Q) of a helical pile is proportional to the final installation torque (T) through a dimensionless empirical factor (Kt): Q = Kt × T. For typical residential and commercial ground screws with round shaft diameters of 51–114 mm, Kt values in the range of 7–14 m⁻¹ are established in the literature, with specific Kt values depending on shaft diameter, helix geometry, and soil type. The ICC-ES evaluation service reports used by most North American ground screw manufacturers establish project-specific Kt values through load testing programs, allowing the simple field torque measurement to serve as a real-time, continuous, cost-effective load test at every installation point.

This torque-capacity relationship transforms installation quality control from a secondary post-installation check into the primary structural acceptance criterion. An installer who measures and records the final installation torque at every screw position — using a calibrated inline torque sensor, a hydraulic pressure gauge on a machine drive head, or a calibrated handheld torque indicator — has directly confirmed the structural capacity of every foundation point as it was installed, without any additional load testing program. Pile Buck’s February 2026 guidance on torque monitoring confirms that this real-time feedback enables immediate adjustments if subsurface conditions vary from expectations — a capability that is simply unavailable with concrete post footings, where foundation quality can only be inferred after the fact from concrete mix documentation and visual inspection.

Installation Equipment and Methods

The equipment used to install a ground screw determines the maximum shaft diameter and soil density that can be practically achieved on a given project, the positional and angular accuracy of each installed screw, and the ability to record and verify installation torque throughout the drive sequence. Equipment options range from compact handheld battery-powered drivers for 51–76 mm residential screws in light soils, through compact machine-mounted hydraulic drives on mini-excavators for 76–114 mm commercial screws in standard soils, to high-torque dedicated foundation installation rigs for 114–168 mm heavy-duty screws in dense or rocky conditions. Each equipment tier matches a specific combination of screw size, site access constraint, and installation productivity requirement — and selecting the appropriate equipment for a given project is as important as selecting the correct screw specification.

Detailed guidance on equipment selection, site access planning, machine configuration, and drive parameter setting for each equipment tier is provided in the Installation Guide →

Torque Monitoring & Quality Assurance

Effective torque monitoring during ground screw installation requires both calibrated measurement hardware and a systematic recording protocol. Pile Buck’s authoritative analysis of helical foundation quality control confirms that installation torque is influenced by soil type, density, moisture content, and helix geometry — meaning that raw torque readings require interpretation against the site’s soil profile to confirm adequate bearing engagement. A screw that achieves the required minimum torque specification at 700 mm depth in stiff clay has confirmed adequate capacity; the same torque reading at 400 mm in dense gravel may indicate premature refusal on a cobble rather than adequate bearing in the founding stratum. The installer must understand what the torque reading represents at each depth — which requires a pre-installation understanding of the soil profile that the screw is being driven through.

For commercial and utility-scale projects, digital torque logging systems that capture continuous torque and depth records during installation — and export these as a timestamped per-pile quality record — are increasingly required by structural engineers, building inspectors, and project lenders. These records provide the audit trail that demonstrates compliance with the foundation design specification, supports structural warranty claims, and satisfies the quality assurance requirements of building consents, planning approvals, and agricultural grant programs that mandate evidence of engineered foundation design for permanent structures.

Common Installation Mistakes and How to Avoid Them

Ideal Foundations’ analysis of screw pile installation errors in practice identifies seven categories of avoidable installation failure, the three most common of which are: inadequate soil investigation before specifying screw length and diameter (leading to under-depth installation in soils where the competent bearing stratum is deeper than assumed); incorrect load calculations that underestimate wind uplift or concentrated point loads (leading to under-capacity screws that meet torque criteria but provide insufficient reserve against peak load events); and failure to monitor installation torque continuously during driving (leading to installations that appear correct by depth alone but have not engaged adequate bearing material).

The American Ground Screw Installation Manual documents two critical field errors that are immediately identifiable during installation: soil cuttings rising to the surface around the screw shaft during driving (indicating that the screw is being pushed rather than screwed into the ground, or that the drive pitch exceeds the helix pitch — both of which cause soil disturbance rather than clean helical penetration); and screw inclination from vertical that develops progressively during driving without correction (which introduces pre-stress into the racking or structural connection and reduces the effective axial capacity through eccentricity in the load path). Both errors are correctable in real time when the installer understands what to look for — and both are prevented entirely by appropriate pre-installation training and site supervision.

Axial Load Capacity

Axial load capacity is the foundational engineering calculation in ground screw design — the determination of how much compressive force a given screw geometry in a given soil can reliably resist without failure, with an appropriate factor of safety. The analytical approach uses the individual plate bearing model (governing for widely spaced helix plates or single-helix piles) or the cylindrical shear model (governing for closely spaced multi-helix piles in dense soils), with the capacity per helix plate calculated from the soil’s shear strength parameters and the helix projected area. Research published in the Canadian Geotechnical Society proceedings confirms that accurate capacity prediction requires correct soil classification — distinguishing between cohesive (clay-dominated) and cohesionless (sand-dominated) soils is the first step in selecting the appropriate bearing capacity model and factors. For a complete explanation of axial capacity calculation methodology, reference tables, and worked examples for common residential and commercial applications, see load calculation overview →

Uplift Resistance Explained

Uplift resistance — the ground screw’s ability to resist tensile forces pulling it upward out of the ground — is the governing structural design parameter in solar, greenhouse, and wind-exposed deck applications, where aerodynamic uplift forces on the structure above exceed its dead weight by factors of 2–5 under design wind conditions. The uplift capacity of a helical pile is determined by the same bearing area and soil shear strength parameters as compressive capacity, but mobilized in the opposite direction — with the helix plate bearing upward against the soil cone above, rather than downward into the bearing stratum below. The New Zealand Screw Pile Design Practice Note confirms that a lower strength reduction factor should be applied for tension and uplift loads compared to compression, reflecting the greater uncertainty in the uplift failure mechanism, particularly for shallow piles where the failure surface intersects the ground surface. For detailed uplift design calculations and application-specific guidance, see uplift resistance explained →

Lateral vs Axial Load Differences

Lateral load resistance — the ground screw’s ability to resist horizontal forces acting perpendicular to the shaft axis — is a structurally distinct design problem from axial capacity, requiring a different analytical approach and governed by different soil and pile parameters. While axial capacity is governed by helix plate bearing and shaft friction, lateral capacity is governed by the passive soil resistance mobilized along the embedded shaft as the pile deflects under horizontal load — a bending mechanism rather than a bearing mechanism. The New Zealand Practice Note documents that lateral capacity depends on soil strength, pile shaft stiffness, embedded length, and the depth of soil disturbance created during installation (typically to a depth of 4× the shaft diameter above the uppermost helix). Understanding the difference between these two load resistance mechanisms is essential for correctly designing fence post foundations (lateral governs), deck foundations (axial governs), and solar ground mount foundations (uplift governs) — three applications that share the same product family but have fundamentally different structural performance requirements. See lateral load vs axial load →

Safety Factor in Foundation Design

The factor of safety (FOS) in ground screw foundation design is the ratio of the calculated ultimate capacity to the design working load — a multiplier that accounts for uncertainty in soil properties, variability in installation quality, statistical variation in structural loads, and the consequences of foundation failure. For helical piles verified by torque monitoring, the CHANCE Technical Design Manual establishes a typical working FOS of 2.0 for axial compression and 2.0–2.5 for tension/uplift in standard residential and commercial applications. For critical applications — foundations supporting occupied structures, high-consequence wind uplift scenarios, or installations in highly variable or poorly characterized soil conditions — FOS values of 2.5–3.0 provide additional robustness against the tail risks of soil variability and extreme loading. For the full methodology governing safety factor selection across different application types and consequence classes, see safety factor in foundation design →

Weight Capacity of Ground Screws

The working load capacity of a ground screw — expressed as the maximum safe compressive or tensile force per screw under service conditions — ranges from approximately 5 kN (500 kg) for a 51 mm diameter screw in soft residential garden soil, to over 150 kN (15,000 kg) for a 168 mm diameter heavy-duty pile in dense granular soil or fractured rock. Within the residential and light commercial range most relevant to solar, deck, fence, and greenhouse applications, 76 mm diameter screws in typical compacted garden subsoil typically develop working capacities of 15–30 kN (1,500–3,000 kg), and 114 mm diameter screws in the same soil develop 40–80 kN (4,000–8,000 kg) per pile — capacities that comfortably exceed the demands of any residential-scale structural application at reasonable post spacings. For capacity reference tables organized by screw diameter, shaft length, and soil type, see how much weight can a ground screw hold →

Ground Screws in Clay Soil

Clay soils are the most common residential and agricultural subsoil type in temperate climates and present a specific set of engineering characteristics that ground screw design must address. Clay soils develop high bearing resistance through undrained shear strength (Su), which allows good axial capacity at moderate embedment depths — but they are also susceptible to seasonal volume changes (swelling when wet, shrinking when dry) that can apply significant uplift or compression forces to a foundation shaft passing through the active zone. Clay soils also exhibit higher adfreeze bond strength than granular soils in cold climates, increasing the frost heave force transmitted upward through the shaft in winter. The critical design response for clay soil installations is ensuring that the helical bearing anchor is embedded well below the depth of seasonal moisture and temperature variation — typically 800–1,200 mm in temperate climates — so that the anchor is seated in stable, undisturbed clay that does not participate in surface volume changes. For full clay soil design guidance and installation parameters, see ground screws in clay soil →

Ground Screws in Sandy Soil

Sandy and gravelly soils — the dominant subsoil type in coastal areas, river plains, light arable land, and many residential areas on former agricultural or glacial outwash deposits — behave very differently from clay under ground screw loading. Without cohesion between particles, sandy soils develop bearing resistance entirely through intergranular friction and effective stress, making bearing capacity highly dependent on the effective overburden stress at the helix depth. This means that shallow screws in loose sand develop less capacity than equivalent screws in clay at the same depth — and that increasing embedment depth has a proportionally greater benefit in sandy soils than in cohesive materials. For full sandy soil design guidance including depth-to-capacity tables and installation parameters for coastal and light agricultural sites, see ground screws in sandy soil →

Ground Screws in Rocky Soil

Rocky, gravelly, and stony soil conditions — encountered in upland farming areas, alpine and sub-alpine terrain, glacially deposited soils with cobble content, and sites with shallow weathered bedrock — present the most challenging installation conditions for any ground foundation system. Ground screws fitted with hardened carbide pilot tips can penetrate through stony loam and weathered fractured rock formations that would refuse a post auger, with the higher torque resistance encountered in rocky material confirming enhanced bearing capacity rather than indicating installation failure. This adaptive capacity — advancing to torque rather than depth — allows ground screws to self-calibrate to the variable bearing conditions within a rocky soil profile in a way that pre-designed concrete footings simply cannot. For installation guidance in rocky and stony conditions, including pilot tip selection and torque interpretation criteria, see ground screws in rocky soil →

Frost Heave Resistance

Frost heave is the dominant seasonal foundation hazard in cold-climate applications — the upward displacement of foundation elements caused by the expansion of freezing pore water in frost-susceptible fine-grained soils, which can generate vertical pressures exceeding 100 kPa and lift a shallow foundation 20–50 mm or more in a single winter. The frost heave resistance of a correctly specified ground screw derives from two complementary design features: the small-diameter tubular shaft minimizes the adfreeze surface area through which frost heave forces can be coupled upward from the freezing soil to the pile head, and the helical anchor seated below the frost line provides positive mechanical resistance against any residual upward force with a pull-out capacity that is typically many times greater than the frost heave force acting on the shaft above. The Terrasmart documentation on frost heave in solar foundations confirms ground screws successfully resisting frost depths of 59 inches (1.5 m) in northeastern U.S. utility solar applications — the same mechanism that protects residential, greenhouse, and deck installations in cold climates when screws are specified to the correct length. For full frost heave design methodology including frost line depth maps and minimum embedment requirements by climate zone, see frost heave resistance →

Galvanizing Standards & Coating Thickness

Hot-dip galvanizing to ISO 1461 is the baseline corrosion protection specification for buried ground screw foundations across all application types. The galvanizing process immerses the cleaned steel component in a bath of molten zinc at approximately 450°C, producing a metallurgically bonded zinc-iron alloy coating with a pure zinc outer layer. The American Galvanizers Association documents that the corrosion protection mechanism is twofold: the zinc coating acts as a physical barrier between the steel substrate and the corrosive soil environment, and it acts as a sacrificial anode — being consumed preferentially to the steel if the coating is breached, cathodically protecting the exposed steel surface from further corrosion until the zinc reserve is depleted. ISO 1461 specifies minimum average coating thicknesses by steel section thickness: 45 µm for sections under 1.5 mm, 55 µm for 1.5–3 mm sections, 70 µm for 3–6 mm sections, and 85 µm for sections above 6 mm — with the thicker coatings required for structural ground screw shafts providing service lives of 35–75 years in most agricultural and residential soil environments. For full galvanizing specification guidance organized by soil corrosivity class, see corrosion & durability guide →

Soil Chemistry & Corrosion Classes

The corrosion rate of buried galvanized steel varies over a 100× range depending on soil chemistry — from less than 0.2 µm/year in well-drained brown sandy soils with neutral pH to over 20 µm/year in waterlogged organic soils with acidic pH and high sulfate or chloride content. The key soil chemistry parameters that drive corrosion rate are: pH (acidic soils below pH 5.5 attack zinc at accelerating rates); soil resistivity (low resistivity soils — below 1,000 ohm-cm — are highly corrosive because they support electrochemical corrosion currents more readily); chloride content (from seawater spray, road de-icing salts, or agricultural inputs); sulfate content (from fertilizers, industrial contamination, or naturally occurring gypsum horizons); and redox potential (waterlogged anaerobic soils create reducing conditions that accelerate both zinc and steel corrosion through sulfate-reducing bacterial activity). Soil corrosion class selection — ranging from Class C1 (very low corrosivity, neutral sandy soil) to Class C5 (very high corrosivity, waterlogged organic acid soil) — determines the appropriate zinc coating thickness, supplementary coating requirements, and expected service life for any specific buried ground screw installation environment.

Choosing Diameter & Length

Ground screw diameter selection is driven by the required axial and lateral load capacity per foundation point: larger diameters provide greater helix bearing area, shaft section modulus for lateral bending resistance, and higher torsional capacity for installation in dense soils. Shaft length selection is driven by the depth required to reach competent bearing soil below the topsoil cultivation horizon, the frost line depth in cold climates, and in uplift-dominated applications, the embedment needed to develop adequate pull-out resistance. For a given application and soil condition, there is typically a range of diameter-length combinations that satisfy structural requirements — and the optimal selection balances structural adequacy against installation feasibility, screw material cost, and the torque capacity of the available drive equipment. For the full diameter and length selection matrix organized by application type, soil class, and load level, see ground screw selection guide →

Matching Screw Type to Application

Different application types have distinct structural profiles that drive specific screw selection criteria. Solar ground mount foundations are dominated by wind uplift and require screws with high tensile pull-out capacity — typically 88–114 mm diameter screws with long shaft lengths to place the helix well below the frost line and the wind uplift load reversal depth. Fence post foundations are dominated by lateral bending load and require adequate embedded shaft length for passive soil resistance — typically 76–88 mm diameter screws at 750–1,200 mm embedment depth, with screw selection governed by the fence height and wind exposure class. Deck foundations are dominated by axial compression from occupancy loads and require consistent bearing in the natural subsoil — typically 76–114 mm diameter screws depending on deck size and point load concentrations such as hot tubs or outdoor kitchens. Greenhouse foundations combine uplift resistance requirements from wind loading with precision leveling requirements for glazed frame systems — typically 76–88 mm diameter screws at perimeter spacings of 1.5–2.0 m, specified for the local frost depth and the greenhouse manufacturer’s anchor load requirements.

Engineering Consultation Process

For projects that require formal structural engineering documentation — commercial solar developments, large-scale agricultural greenhouse complexes, security fencing on critical infrastructure sites, or any application where building consent requires an engineer’s sign-off on the foundation design — Solar Earth Screw’s engineering team provides a structured technical consultation process. The process begins with a site information submission: project location, structure type and dimensions, soil profile information (either from a prior geotechnical investigation or a preliminary field assessment), local design wind speed, and frost line depth. From this information, the engineering team develops a project-specific screw specification including pile diameter and length, minimum installation torque per pile, corrosion class designation, and installation parameters. For projects requiring formal load testing or statistical capacity verification, a test pile program can be designed, executed, and reported as part of the engineering service package — providing the independent verification data needed to satisfy the most demanding structural engineering and building consent review processes.

Solar Applications

Ground screw foundations for solar energy systems — from 6 kW residential backyard arrays to multi-megawatt utility solar farms — are the highest-volume application in the Solar Earth Screw portfolio. The governing engineering challenge in solar foundation design is wind uplift: aerodynamic forces on tilted panel arrays that pull the foundation upward under storm conditions, demanding high tensile pull-out capacity from the helical anchor in the soil below. The load calculation, soil conditions, and frost heave resistance sections of this technical guide are all directly relevant to solar foundation design across residential, commercial, and utility scales.

Solar ground mount foundation →

Structural & Outdoor Applications

Deck, fence, and greenhouse foundations share the same ground screw product family as solar applications but are governed by different load cases and design priorities. Deck foundations are primarily compressive load applications requiring consistent bearing capacity in domestic subsoils and frost-resistant embedment depth. Fence foundations are primarily lateral load applications requiring adequate passive soil resistance along the embedded shaft. Greenhouse foundations combine uplift resistance from wind loading with the precision leveling requirements of glazed frame systems. The fundamentals, installation, soil conditions, and corrosion sections of this technical guide apply equally to all structural outdoor applications — the selection guide provides the decision framework for choosing the correct screw type and specification for each.

Deck foundation screw →