How to Set Pergola Posts in Concrete
You set pergola posts in concrete by digging proper holes, placing each post level and straight, then pouring mixed concrete around them. Keep the posts braced until the concrete cures, giving you a rock-solid foundation for your pergola.
How Do You Set Pergola Posts in Concrete?
You set pergola posts in concrete by placing each post in a pre-dug hole, checking it is straight, and filling the hole with mixed concrete. Hold the post in position until the concrete firms up. This creates a stable base that supports the full weight of the pergola.
The process is straightforward: dig, position, check level, pour, and brace. With the right preparation, you'll have stable posts ready to support your pergola structure.
It’s worth bearing in mind that we do provide pergola posts in various types in order to help you attach your pergola to the ground. These are quick and easy and come with the tools that you’ll need to get them set up. This guide is for those who want to really go all out and have the pergola set into the concrete.
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What Tools and Materials Do You Need to Set Pergola Posts in Concrete?
You only need a few reliable items to get started. Having everything ready keeps the job smooth and stops unnecessary trips back to the shed.
Essential tools you'll need
Grab these before you begin:
- Tape measure for accurate spacing
- Spade or post-hole digger for excavation
- Spirit level to check alignment
- Drill and screwdriver for assembly
- String line or chalk line for marking
- Rubber mallet for adjustments
- Saw if posts need trimming
- Work gloves and safety goggles for protection
Materials required for the job
Your shopping list should include:
- Pergola posts (appropriate height)
- Concrete mix (general purpose or fast-setting)
- Water supply nearby
- Temporary bracing timber
- Gravel for drainage
- Ground anchors or metal post bases (optional)
Having everything ready keeps the job smooth and stops unnecessary trips back to the shed.
How Do You Mark Out Your Pergola’s Footprint Accurately?
Start by laying out the exact area your pergola will cover. Mark each corner with a peg and run string between them to create a straight visual guide.
Check the spacing twice before you dig. A simple diagonal measurement helps confirm everything is square. This small step saves massive headaches later when you're trying to fit crossbeams.
If your pergola comes from the Gleaming Gardens range, the spacing will be included in the assembly details. Stick to those numbers for a perfect fit every time.
How Deep and Wide Should Pergola Post Holes Be?
Most pergola posts need holes that are 300–400 mm wide and around one-third of the post's total height in depth.
If your post is 2.4 m tall, aim for a hole roughly 800 mm deep. That depth helps the post resist sideways movement and wind pressure without tipping.
Add a small layer of gravel at the bottom. This helps water drain away and keeps the base firm over time.
How do different ground types affect hole depth?
The type of soil in your garden makes a big difference to your approach.
Soft or sandy soil needs deeper holes and extra gravel for stability. The loose texture won't grip as firmly, so compensate with depth.
Clay soil requires more drainage at the base to prevent water pooling. Clay holds moisture, which can weaken your concrete over time.
Rocky ground may need slightly wider holes so the post sits neatly. You might struggle to dig deep, so width becomes your friend.
If you have porcelain, concrete, or paving slabs, consider using metal post bases bolted down through the slab instead of digging holes.
How Do You Keep Pergola Posts Straight Before the Concrete Sets?
This is the part that worries most people, but it's easier than you think.
Place the post in the hole, then brace it using two timber lengths fixed at an angle. These braces hold the post steady while you work on the concrete.
Use a spirit level on two sides of the post to check that everything is perfectly upright. Check both the front-to-back and left-to-right alignment.
Think of the braces as your extra set of hands. They don't complain, and they don't drift off to check their phone whilst you're pouring.
I’ve done this countless times and honestly, even if the first time was a little scary, there is no need to feel that way. Even if you think it’s not straight in the beginning, there is more than enough time to get it completely straight before the concrete sets.
How Do You Mix and Pour Concrete for Pergola Posts?
Follow the instructions on your concrete mix, as each brand has its own ratio. Most mixes need you to pour the dry mix into a bucket or wheelbarrow and add water slowly until the texture becomes smooth and workable.
Here’s a simple flow:
- Pour water into your mixing container.
- Add concrete mix a little at a time.
- Stir until smooth with no dry patches.
- Fill the hole around the post slowly.
Press the concrete gently with a piece of timber to remove air pockets. Slope the top surface slightly away from the post so rainwater runs off instead of pooling.
How Long Does Concrete Take to Cure Before You Can Build the Rest?
Concrete starts to firm up within a few hours, but it needs proper time to reach full strength.
Fast-setting mixes allow light handling after 1–2 hours. You can remove braces and start thinking about the next stage. Even though you can remove the braces, I prefer
Standard mixes need 24–48 hours before any pressure is applied. Don't rush this part, even if you're keen to crack on.
Full cure takes 1–2 weeks to achieve maximum strength. Your pergola will be strongest if you wait this long before heavy use.
You can remove the braces once the concrete feels solid and the post doesn't shift when you nudge it gently.
Be patient here — rushing this stage can cause wobble issues that haunt you for years.
What Mistakes Should You Avoid When Setting Pergola Posts in Concrete?
There are plenty of mistakes that people make when they try things for the first time. However, if you know that these are reall errors, you can ensure that they don’t happen to you when you come to do it.
Here are the common slip-ups that catch people out:
- Digging shallow holes that weaken the entire base
- Forgetting to check posts for level on two sides
- Pouring concrete too quickly without removing air
- Skipping the bracing stage completely
- Leaving air pockets around the base
- Ignoring drainage needs in wet soil
- Not waiting long enough for concrete to cure
Avoid these mistakes, and you'll have a pergola base that feels tough and stable for years to come.
FAQ
How do I fix a pergola to porcelain slabs?
Use a metal post base made for porcelain. Drill carefully with the correct bit and follow the fixing guide to avoid cracking the slab.
How do I fix a pergola to the ground without digging?
Use post bases that bolt to concrete or slabs. Check the base can handle the weight of your pergola.
What concrete should I use for pergola posts?
A general-purpose concrete mix works well for most gardens. Fast-setting mix is handy if you want quicker results.
How deep should pergola post holes be in the UK?
Aim for 300–400 mm deep or around a third of the post height. In colder regions, dig below frost depth to prevent movement.
How long before I can continue the build?
Most pergolas can be built after 24–48 hours, depending on the concrete mix and weather.
