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The long side of a modular house resting on the lawn: under the wall, flush with the grass, a row of galvanized steel T-Block ground screws.

Ground screws: what they are, how they are installed, where they are used

Ground screws are steel elements screwed into the ground instead of concrete footings. No digging, no pouring, no waiting: the structure goes up as soon as the screw is at level and, when it is no longer needed, the screw comes out. This guide by T-Block®, an Italian manufacturer since 2004, explains how they work, where they are used and when concrete is still the right choice.

No digging
and no concrete pour
Load at once
as soon as they are in
Unscrewed
they leave no trace

What ground screws are

A ground screw is a steel body with helices welded to its lower part. It is screwed into the ground to the design depth and becomes the bearing base of the structure: the same job as a concrete footing, without the excavation, the pour and the days of waiting.

The same screws hold a structure that pushes down, restrain it when the wind pulls it up and keep it still sideways. That is why they are used both as foundations, under a house, a shed or a canopy, and as anchors, for a gazebo, a tensile structure or a sign.

People call them many things: ground screws, screw foundations, screw anchors, helical piles. The principle is the same. We call them T-Block® screw foundations and screw anchors.

How T-Block ground screws are made

  • Materials: galvanized steel, hot-dip galvanized to ISO 1461 or electro-galvanized, and AISI 304 stainless steel.
  • Heads: flanged, hexagonal, or headless, to slot in the post of a fence or a sign directly.
  • Sizes: eight length classes, from T1 to T15, in four load ranges.
  • Custom: besides the standard catalogue, T-Block makes custom models with geometries and materials to the customer's specification.
The ground screw catalogue

How a ground screw works

What a screw holds depends on three things: the type of soil, the geometry of the helices and the depth reached. The principle comes down to three moments.

  1. Gloved hands guiding the shaft of the screw into the ground while the driver turns it.

    1 of 3

    Screwing in

    The screw goes into the ground by turning. The helices pass through the soil without removing it: the soil stays where it is and the screw reaches the design depth.

  2. A row of T-Block ground screws already installed along the edge of the site, all heads at the same level.

    2 of 3

    Bearing

    The helices act as bearing points spread at depth, and the shaft adds friction with the surrounding soil: together they hold the structure in every direction.

  3. Timber platform mounted on the feet bolted to the screw heads, while the crew installs T-Block ground screws to extend the platform.

    3 of 3

    Mounting

    The structure is fixed to the screw head with a flange, bracket or fork. There is no concrete to cure: you build as soon as the screw is at level.

How ground screws are installed

The sequence is the same for a garden fence, a pergola or a solar farm; the tools change with the model and the number of points. A 4×4 m deck on 9 screws is done in under two hours, a solar installation with 100 screws in one or two days.

  1. 1. Setting out

    The points where the screws will go are marked on the ground at the spacing set by the design: tape, string and pegs for a few dozen points, a laser level or GPS for large sites.

  2. 2. Pilot hole

    In most soils a small-diameter pre-drilled hole is made, not an excavation: it clears surface stones, reduces the effort and helps the screw start vertically.

  3. 3. Screwing in

    The screw is turned clockwise to the design depth, by hand, with a power driver or with a rotary drive: the method depends on the model and the number of points.

  4. 4. Check and mount

    Head level and verticality are checked and, when the design requires it, the final installation torque. Then the structure is mounted straight away.

Four ways to screw them in

By hand

With the T-wrench or a socket, up to the T6 series: 1–2 people, no machinery, 5–15 minutes per screw.

Installing by hand with the wrench

Power driver

High-torque driver with socket and reaction bar, up to the T7 series: quiet, no excavator.

Power driver and reaction bar

Excavator

Hydraulic rotary drive on the mini-excavator arm, for large sites and the series above T7: 2–5 minutes per screw.

Excavator and rotary drive

Tracked machine

The mast holds the T-Block vertical; pilot hole and screwing on the same machine. For fields with many points in a row.

Tracked mast machine
The video is hosted on YouTube and only loads when you press play.

Watch it being done

A hand installation from start to finish: the screw, the wrench, the ground. Other videos show installation with the mast machine on the beach, a wind turbine and a tennis court.

All the steps are on the page how ground screws work; the videos on the page ground screw videos.

Which soils ground screws work in

Almost all: clay, sand, gravel, silt, mixed, peaty, frost-prone and sloping ground. For each soil there are models that perform best. Rock is a separate case.

  • Compact or hard soils: a pilot hole is drilled, which helps verticality and reduces the effort.
  • Loose sand: the screw usually starts on its own; longer screws or one extra screw are used.
  • Rock: there are several types of rock and ground screws are generally not used. The exceptions are cases where special rock models are produced, not in the catalogue, which require a specific pre-drilled hole.
  • High water table: no open excavation to flood; capacity is calculated taking water pressure into account.
  • Slopes and trees: each screw goes to the depth needed, without levelling and without digging that damages roots.

Recommended models for each soil

How much ground screws hold

Capacity depends on the model, the soil and the depth. That is why there is no single figure: the T-Block® range is split into four load ranges, and the value for your project is estimated in the configurator and checked according to NTC 2018.

Light range

T1 · T3

Single light points: fences, small fittings, bracing.

See the models

Medium loads

T4 · T5 · T6

Sheds, gazebos, pergolas, decks, solar, light construction.

See the models

High loads

T7 · T10

PRO range, also in AISI 304 stainless steel: heavier structures.

See the models

Very high loads

T10 · T15

PRO range for infrastructure: uplift of tens of tonnes in compact soils.

See the models

When the design needs a value measured in that soil, a few screws are tested on site: the compression test and the pull-out test.

Where ground screws are used

Wherever a point foundation is needed without a building site: from the back garden to the solar farm, from the beach to the roadside.

Bidding for a beach concession in Italy: Italian beach concessions and removable structures.

Looking by type of structure? Decks, pergolas, carports, signs, greenhouses and the other applications are on the page ground screws by application.

Ground screws or concrete footings

In most applications the screw is the better choice: fences, decks, garden sheds, carports, solar, signs, temporary structures.

Comparison between a ground screw and a concrete footing
Criterion Ground screw Concrete footing
Installation time A few hours (for example a 4×4 m deck) 3–5 days plus curing, up to 28 days
Total cost Usually 30% to 50% less Excavation, reinforcement, concrete and labour
CO₂ 50% to 85% less About 0.9 kg of CO₂ per kg of cement produced
Weather Installed all year round, even in rain or frost Not poured below 5 °C
End of life Unscrewed, leaves no trace and can be reused Demolished and becomes waste

When concrete is still the right choice

On compact rock, for extreme loads above 100 kN per point, when a waterproofed basement is needed or when a local regulation requires it.

The full comparison, criterion by criterion, is on the page ground screws vs concrete.

Projects completed on T-Block ground screws

Thousands of screws installed. Sites told in full, with the photos and the constraints that made the screw the choice.

Service life, permits and NTC 2018

How long they last

With ISO 1461 hot-dip galvanizing the service life depends on the zinc thickness and on how aggressive the soil is. For aggressive soils, with high salinity or extreme pH, AISI 304 stainless steel is considered.

Are permits needed?

It depends on the structure built on top, not on the foundation. The screw is a removable work and for light structures the procedure is often simpler, but the planning status of the work must always be checked with the local authority or the engineer in charge.

Technical standards

Ground screws fall within the scope of the Italian Technical Standards for Construction (NTC 2018). We provide the designer with the data and twenty years of experience in production and real applications.

At the end of their life

They are unscrewed anticlockwise with the same equipment used to install them. No block is left in the ground to demolish and nothing goes to landfill, and screws recovered intact can be reused.

For designers: data sheets, catalogue and capacity calculator are in the technical area; the calculation method and the tests are on the page research and testing.

How to choose the right ground screw

Start from three questions: what you need to support, how heavy it is and what ground it goes on. You can look for the model from any of the three, or make a first estimate in the configurator.

By application

Decks, fences, solar, signs: start from what you need to support.

By load

Four ranges, from light to the T10 and T15 series for the highest loads.

By soil

Sandy, silty, compact, peaty, with rubble: the models that perform best.
Indicative estimate: one of our engineers will confirm it.Ask for a quote

Frequently asked questions

What are ground screws?
They are steel elements with helices that are screwed into the ground instead of concrete footings. No digging or pouring is needed, they take load as soon as they are screwed in and at the end of their life they are unscrewed, leaving no trace. They are also called screw foundations, screw anchors or helical piles.
How is a ground screw installed?
The points are set out, in most soils a small pilot hole is drilled, then the screw is turned to the design depth and level and verticality are checked. The small series are installed by hand with the T-wrench (up to T6), the medium ones with a power driver and reaction bar (up to T7), the largest with an excavator and rotary drive.
How much weight can ground screws hold?
It depends on the model, the type of soil and the installation depth. The T-Block range goes from the light range (T1-T3) to very high loads (T10-T15), which in compact soils reach uplift resistance of tens of tonnes. Sizing is done on the project according to NTC 2018; the configurator gives a first estimate.
How long do ground screws last?
With ISO 1461 hot-dip galvanizing the service life depends on the zinc thickness and on how aggressive the soil is. For aggressive soils, for example with high salinity or extreme pH, AISI 304 stainless steel is considered.
Which soils can they be used in?
Almost all: clay, sand, gravel, silt, mixed, peaty, frost-prone and sloping ground, even with a high water table. In compact soils a pilot hole is drilled; on rock, which comes in several types, they are generally not used, except for special models outside the catalogue with a specific pre-drilled hole.
How much do ground screws cost compared with concrete?
On average 30-50% less than concrete foundations, counting the total cost: materials, labour and time. Prices are given on quotation, based on the model and the quantities.
Are permits needed, and do they comply with the rules?
Permits depend on the structure built on top, not on the foundation: the screw is a removable work, but the planning status of the work must be checked with the local authority or the engineer in charge. Ground screws fall within the Italian Technical Standards for Construction (NTC 2018) and the calculation is done on the project.
Can they be removed and reused?
Yes. They are unscrewed anticlockwise with the same equipment used to install them, leave no trace in the ground, and those recovered intact can be reused.

More answers on service life, soils and permits in the FAQ.

Who makes T-Block ground screws

T-Block designs and manufactures screw foundations and screw anchors in Italy, in Monterchi (AR), since 2004. The story is on the page about us; more technical questions are answered in the ground screw FAQ.

Planning a project on ground screws?

Tell us what you need to support, how big it is and what ground it goes on: we will tell you which T-Block screws you need and how many.

Use the configurator Request a quote