Calculation

Know your options

There is a wide range of GroundPlug® TwisterTM Foundations with different lengths and diameters. Each GroundPlug® product has different advantages regarding specific applications. It is therefore essential to choose the correct GroundPlug® TwisterTM Foundations for your project.
To determine how many and which kinds of GroundPlug® Foundations you need for a project, there are three options:

The easiest way to know how many and which kinds of GroundPlug® TwisterTM Foundations you will need for your project, is to fill out the form below and get an engineer calculation for free. Our in-house engineers calculate every project, no matter the size. We will typically get back to you within 48 hours.

What are you going to build?

Select one or more options

If you do not know your soil conditions, remove the top 12 inches of the soil layer and take a sod of the soil you find below.

(If nothing is indicated, we calculate for stiff clay by default)

Attach file
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Select one or more options

If you do not know your soil conditions, remove the top 12 inches of the soil layer and take a sod of the soil you find below.

(If nothing is indicated, we calculate for stiff clay by default)

Attach file
Attach file
Attach file

Select one or more options

If you do not know your soil conditions, remove the top 12 inches of the soil layer and take a sod of the soil you find below.

(If nothing is indicated, we calculate for stiff clay by default)

Attach file
Attach file
Attach file
Which kinds of GroundPlug® TwisterTM Foundations

Which kind of GroundPlug® TwisterTM Foundation you will need for your deck depends mainly on two parameters: The terrain distance* of your deck and the quality of your soil.

Terrain distance = Distance from terrain to the lower edge of the beams.

The following tables and graphics are suitable for a wide variety of soil conditions, such as loose sand, dense sand, soft clay and stiff clay. If you are unsure about your soil condition or if you know your soil has a low bearing capacity, please contact us.

See which kind of GroundPlug® series you should use, depending on your terrain distance:

  • Decks up to 8′ terrain distance: GroundPlug® M12 series.
  • Decks from 8′ to 20′ terrain distance (wall mounting required): GroundPlug® M16 series.
  • Decks from 8′ terrain distance (without wall mounting): See section about elevated decks.

See which specific GroundPlug® foundation to use for a particular terrain distance:

[Img of terrain distance for decks with and without wall mounting]

Example: For a deck with 15cm distance between terrain and lower edge of the beam, GroundPlug® TwisterTM 12/750mm foundations are needed.

How many GroundPlug® TwisterTM Foundations?

After you have chosen the right kind of GroundPlug® TwisterTM Foundation, you need to determine the amount of GroundPlug® TwisterTM Screw Pile Foundations you will need for your project. You can use the table below for orientation:

[Table for amount of foundations per ft2 for a deck]

Double or single layer construction?

You can either choose to build a deck with double or single layer. Single layer means that there is only one level of beams in which case you will install the GroundPlug® Screw Piles directly on your joists. For double layer beam, two levels of beams are mounted on top of each other in which case you will install your GroundPlug® Screw piles on the lower beam layer. Decks with a surface of minimum 30cm from the ground can advantageously be built with double beam construction, as the screw pile foundations can be distributed to their maximum capacity in this way.

For elevated decks, it is a good option to build a post construction with GroundPlug® TwisterTM Foundations and GroundPlug® TwisterTM Post brackets.

As these kinds of projects are a little more complex than standard decks, we recommend using our free engineer service in order to determine how many GroundPlug® TwisterTM Foundations you need for your elevated deck project.

For small outbuildings, like sheds, annexes, cabins and the like, you will typically use our GroundPlug® M16 series. The table below gives you an overview over the kinds of GroundPlug® Foundations you should use for a small outbuilding project.

[Table for M16 to sheds smaller than 538 ft2 (EU mes = 50m2)]

Soil condition

The above table is suitable for a wide variety of soil conditions, such as loose sand, dense sand, soft clay and stiff clay. If you are unsure about your soil condition or if you know your soil has a low bearing capacity, please contact us.

Free engineer service

Buildings are bit more complex to calculate than fx decks, as there are more parameters influencing the amount of foundations needed. If you are unsure which and how many foundations you need for an outbuilding, we recommend using our free engineer service in order to calculate your specific project.

If you are building a carport, pergola, deck roofing or another project that requires a post construction, you can combine a GroundPlug® TwisterTM Screw Pile Foundation with a GroundPlug® TwisterTM Post bracket to support a post.

Depending on the size of your project, you will typically use our GroundPlug® TwisterTM M16 or M20 series. In the chart below, you can see how many GroundPlug® TwisterTM M16/40″ Foundations you should use for your project.

[Table for M16/40″ + Post brackets]

If you are in doubt about which kind and how many GroundPlug® TwisterTM Screw Pile Foundations you need for your project, we recommend using our free engineering service.

[Online deck calculator – insert shortcode or likewise here]

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