Building a pergola with ground screws

Are you keen to give your garden an added dimension?

A pergola in the garden gives you an additional space where you can sit down for a cup of tea, have something to eat or socialise with family and friends and enjoy summer.
A pergola gives your garden a boost and creates a lush extra space. But what is a pergola actually, and what should you consider if you are about to build one?

What is a pergola?

The word pergola is Italian and means colonnade or garden alcove. A pergola can have many different designs and fulfil several different purposes. Many people see it as an outdoor space where family and friends can gather to talk, eat and enjoy time together. Climbers are perfectly suitable plants in a pergola and create a lush and opulent impression, while providing shelter and shade. It is also possible to attach a sail on top to protect against the weather.

Choosing the right timber

Once you’ve planned and measured where you want your pergola, it’s time to choose timber. As it is a permanent structure, you should choose impregnated timber. This will make the maintenance of your pergola easier – you just don’t want to cut back your climbers every year to clean the timber. If you think you might add a roof to your pergola in the future, this must be taken into consideration when choosing the timber. It must withstand both the weight of the roof and any possible snow cover. However, many people prefer to let the climbers grow and form a natural and lush ceiling. Keep in mind that your climbing plants will not only wrap around the rafters but will also hang down. Therefore, you have to allow for extra ceiling height.

Positioning the pergola

There are many suitable places for the pergola in the garden. If a wind screen is added, this can create a lush and cosy garden alcove. Most common however, is to place the pergola as an extension to the house. This creates an atmosphere of an outdoor room. As many of the plants in the pergola thrive in the sun, a south facing position is excellent.



There are several factors that determine the type and number of ground screws you require. These include the weight of the finished structure, the size and type of joists or supports it uses, and the type of terrain and soil you are building on. Here you can assess your project’s needs, and get an estimate for installing a ground screw foundation. Contact your local installer for a complete quote.


Finding an authorized installer near you

Stop Digging's experienced and certified installers are found throughout NZ. Contact us if you have any questions, want a competitive quote or book an installation.


01 Why use the ground screw?

Stop Digging’s ground screws provide a secure and stable foundation that saves both time and money. They make construction easier and smoother; no more lugging heavy concrete blocks or laboriously digging holes and shifting piles of soil to make way for the foundations. Ground screws are easy to place and move if a site needs to be adjusted due to an unforeseen discovery or for better support. Ground screws are ready to use after they are installed – no waiting for wet concrete to harden, and they can be installed in all soil types and weather conditions.

A ground screw from Stop Digging should not be confused with a lightweight, DIY ground anchor.  Our groundscrews are specified and installed only by our nationwide network of experienced and certified installs.

02 When can you use ground screws?

Ground screws can be used to support most types of construction. This includes lightweight timber or steel frame houses, Tiny Homes,  transportable units and cabins, shipping containers, decks, pergolas, sheds, playground equipment, carports, conservatories, greenhouses, fence posts, sign posts, street furniture and much more. We offer several different models and sizes such as the adapter, pipe, post and beam screw, all designed to tackle tricky terrain and soils. In addition, ground screws are ideal for flagpoles, signage or solar panels and for inaccessible locations where alternatives are not an option. By selecting from a range of models, you can tackle even the most challenging of terrain with our versatile screws – the question isn’t when you can use a ground screw, but when you can you not?

03 How deep can a ground screw go?

How deep a screw needs to be depends on the terrain and the required load. We offer screws between 580 mm to 2500 mm long, much deeper than conventional concrete foundations. Our experienced fitters will choose the right screw for each project and site, providing stable and long lasting foundations for your project.

04 How many ground screws do I need?

For example: when using a typical timber bearer size of 140x90mm, according to the NZ3604 span tables, this has a max span of 1.65m.  You would therefore need to have sufficient groundscrews installed to keep within this dimension.  A smaller bearer size of say 90x90mm would require more groundscrews as the maximum span of this is only 1.3m.

Larger timber sizes would therefore require less groundscrews, however there is sometimes a balance between the sizes of timber you can fit to certain height requirements – especially with low decking next to concrete slab foundations.

Please contact us for design advice, and you can try our price calculation module to estimate the number of screws you will need!

05 How long does the ground screw need to be?

This depends on the soil type, load bearing required and the nature of the project. We offer four basic models – adapter, pipe, post and beam screw – in a variety of lengths to meet your specific needs. In addition, we can install ground screws with our special attachments that are designed to support installations such as flagpoles or solar panel systems and other unusual projects. All of our screws are robustly designed to withstand harsh environmental conditions, and to exceed all requirements of the building code.

06 How do you use ground screws in difficult terrain?

Just as we would pre-drill hard stone for fixing a normal screw, we always drill a pilot hole before installing our ground screw in tricky terrain. This forces smaller stones or gravel aside and our equipment is powerful enough to split medium-sized rocks. If you are building on solid or large enough rocks, our installers can anchor with a drilled steel stud and use ground screws where the ground is more suitable. We offer a complete service with no need to wait for another specialist.

In newly excavated, soft or disturbed soil, our installers are trained to assess the ground and select longer screws if necessary to provide a secure and stable foundation. Our installers are specially trained to select the right screw for your project, install it correctly in whatever terrain they face and finish with the minimum of disruption.

07 When do we install the screw?

We can mount ground screws all year round, even during a cold, hard winter. Our screws were originally developed to cope with the harsher conditions found in Scandinavia, and are therefore perfectly suited to conditions in New Zealand, Australia and the South Pacific. Do you want to know more? Feel free to ask your local installer, who has a specialist knowledge of your area and useful reference materials.

08 How do ground screws handle slopes?

Easily! Our ground screws are ideally suited to work on slopes to anchor, for example, decks or stairs or other structures. Our equipment can install the screws in difficult to reach locations at the required depths. Furthermore, by combining the various ground screw sizes and models produced by Stop Digging, together with our attachments such as plates and L-supports, we can create a tailored solution whatever the terrain or slope your project faces.

09 Do ground screws settle after installation?

Just like concrete supports, a ground screw can be affected by the ground settling over time, but they are not generally affected by other forces such as frost heave. Settlement of soil is especially an issue with freshly excavated or disturbed soil and our installers are trained to identify this and select longer screws to provide a deeper, more secure, fixing as needed.

10 How do you calculate the screw load bearing?

When designing pile foundations for timber or steel subfloors, the spans of the specified timber or steel size will dictate the quantity of piles needed.  In New Zealand a typical design using the span tables from NZ3604 will result in design loads that are well within the load bearing capacities of our groundscrews.   We offer a professional in-ground pile test on our groundscrews, in accordance with AS2159, to confirm that we are specifying the correct length of groundscrew to achieve the required design load in the site specific ground conditions.  We have a variety of lengths of groundscrews available which allow us to achieve good results even in poor ground conditions.

11 How much load can a ground screw bear?

All of our screw models have been rigorously tested to cope with load, pressure and tension bearing and you can read more about our screws here. Our tests were made in normal arable land which we use to calculate the performance of our screws in different soils and terrain. We can test your ground to provide precise feedback for your project planning.

Our steel ground screws (ISO 630 FE 3604) are specially developed and adapted to northern climates in terms of thickness (4 mm) and surface coating. All of our CE marked ground screws are hot-dip galvanized according to ISO 1461 – HDG600 and manufactured by ISO 9001 certified production facilities. They are designed specifically to exceed the requirements of the building code for durability.

12 How much do ground screws cost?

We offer a fixed price per installed ground screw. However, our prices vary depending on which screw you need to use and where in the country you are located. Try out our price calculator to estimate the cost of the ground screws for your project.

Our vision is not only to provide a high quality product, but to deliver and install it to the highest professional standard. A ground screw from Stop Digging should not be confused with a lightweight DIY ground anchor.    They are a standard, permanent pile foundation that is specifically designed for the application. We offer professional installation only, through our nationwide network of experienced and certified installer partners. Contact your local installer for a quote.