Top 7 Lean To Pergola Roof Installation Points

With the increase of outdoor living in the UK, and globally, lean to pergolas have become an essential consideration and dream for every garden and homeowner!

Pergolas are great affordable projects as they can be built to suit a wide range of budgets and can be used in so many ways. Popular pergola uses include hot tub pergola roofs, patio pergola roofs and decking pergola roofs.

However, there a lot of factors to consider when installing a pergola so here are the top 7 things to consider when building a lean to pergola with a roof.

Top 7 things to consider when building a Lean To Pergola

1. Are you creating a flat roof pergola or a pitched roof pergola?

 When thinking of the pitch, or slope, of a pergola most people tend to envision either flat or a medium pitch, however, every pergola most have a slight pitch to allow for water drainage. Pergolas can actually be created to any angle; however, the pergola style tends to be low pitch roof and a minimum 5 degree pitch is considered to be normal best practise 

Did you know that the steeper the slope of your pergola the more self cleaning it will naturally be? The steeper the pitch the better the rain and water run off will be which in turn cleans your roof better and reduces the chance of direct/leaves settling on top

Slope roof pergolas or slanted roof pergolas are 10 degrees plus which creates a distinctive silhouette and can be great in complementing the angle on your house. This means pitched roof pergolas tend to be popular for lean to pergolas that are against a house wall or on a back door patio.

In comparison, flat roof pergolas are between 5 to 10 degrees so are the typical choice when you are creating a freestanding pergola in your garden. This is because the flatter slope can look more natural on top of a decking or patio area and be a more subtle natural shape in your garden!

2. Is it a timber pergola or self supporting Pergola? 

The next key question to address is what your structure is going to be made of and there are two options here; wooden or aluminium.

Timber Pergola 

The most common pergola build is a wooden pergola roof structure because it is cost economical to create and requires basic DIY skills to install. One of the benefits of constructing a timber pergola roof is that you have a lot of flexibility in the shapes and styles you can create.
Different types of softwood and hardwoods can suit different garden pergolas and complement or contrast to your house style. For example, an oak pergola lean to will look stunning alongside a rustic cottage or in a rural location. On the other hand, a Red Western Cedar pergola would nicely complement a red brick house.
The downside of a wooden pergola roof is that the expected lifespan can be less, depending on the grade of timber used, than a fully aluminium system like Alukap-SS Self supporting.
Our Timber Pergola glazing bars are our Snapa® Snap Fix system or our Alukap-XR Aluminium Glazing bar system, see the next point for more info!


Self Supporting aluminium Pergola 

A self supporting aluminium pergola removes the for any timber so using a fully aluminium system, like Alukap-SS, can significantly the expected lifespan of your Pergola to 20 years plus!
The aluminium pergola option is popular for modern houses for its clean and quality look which suits a more minimal style. Additionally, an aluminium pergola has a huge range of colours options to add a wow factor to your property!
The downside of a self supporting pergola is that you have less flexibility on the shape and style that you can create.
If you are looking to build a free standing pergola with a polycarbonate roof like this you will need to use self supporting glazing bars, like our Alukap-SS Glazing Bar range.

3. What colour of glazing bars will be used? 

When building a pergola with roof and sides there are three colour options, which are White, Brown and any Bespoke RAL colour.

Alukap-XR Glazing Bar in White
White Glazing Bars - White is the most popular colour option as being a neutral colour can be used to compliment a lot of different colour schemes. With a lot of windows in the UK being white a matching white pergola works well.
Alukap-XR Glazing Bar in Brown
Brown Glazing Bars - Dark brown pergola glazing bars as often used when building a timber pergola roof as the dark tone complements the characteristics of the wooden frame.
Alukap-XR Glazing Bars in Bespoke RAL Colour
Bespoke Powder Coated Glazing Bars - For a small premium, our bespoke colour bars are worth every penny, giving you the choice of any RAL colour so you can match existing themes or add a standout colour to your property!
Which colour is available for you will depend on which pergola glazing bar system you are using. Snapa Snap fix Glazing Bars are only manufactured in white and the Alukap Glazing bars are available in all three colour options.

4. What roof glazing type will be used?

There are three main glazing options for Pergolas which are Axiome® Multiwall Polycarbonate Sheets, Axgard® Solid Glazing Sheets or Glass. With each there are pros and cons, for example, a pergola glass roof can be quite expensive so we have created a handy guide below to help!

Lean To Pergola Roof Glazing Guide 

Roof Sheet / Glazing Type Glazing Colour Options  Compatible Glazing Bar Options  Pros & Cons
Axiome Multiwall Polycarbonate Sheets 




⭐- Snapa Snap Fix Glazing Bar

⭐⭐⭐⭐ - Alukap-XR Rafter Glazing Bar 

⭐⭐⭐⭐⭐ - Alukap-SS Self Supporting Glazing Bar

Pro: Most Cost Effective

Con: Not as visually Clear as Axgard

Axgard Solid Glazing Sheets





⭐⭐⭐⭐ - Alukap-XR Rafter Glazing Bar 

⭐⭐⭐⭐⭐ - Alukap-SS Self Supporting Glazing Bar

Pro: Virtually unbreakable, shatterproof

High clarity and light transmission

Wide range of colours

Glass Clear

⭐⭐⭐⭐ - Alukap-XR Rafter Glazing Bar 

⭐⭐⭐⭐⭐ - Alukap-SS Self Supporting Glazing Bar

Pro: Unrivalled Clarity

Con: Quite Costly

Limited colour options

Shatter Risk

What glazing bars are used for glass?

The best glass glazing bars are our Alukap-XR and Alukap-SS glazing bar ranges. These glazing bars for glass have designed specifically for use with glass with strong seals and a full top caps to maximise your roof lifespan.

5. What Roof Glazing Colour?

In essence the colour of the sheets that your use on your lean to pergola roof are determined on the type of glazing you go for. However, with Axiome Multiwall Polycarbonate Sheets and Axgard Solid Glazing Sheets there are three main colour options that you can have on your pergola

  1. Clear Pergola Roof (most popular) - High light transmission and maximum sunshine!
  2. Opal Pergola Roof - Reduces heat build-up, nice cool glow, and bright overall appearance
  3. Bronze Pergola Roof - Reduces Sun Glare, retains heat and nice aesthetic when creating a wooden pergola

 An alternative glazing option when creating pergola with a polycarbonate roof is our Axgard® Patterned Sheets which have a high light transmission but create privacy and a glass like effect.

6. A pergola with roof and sides or without sides?

With sides or without? It's personal opinion on this but the majority say with! Bamboo or slatted sides are an option top add some style to a pitched or flat roof pergola. However, when you are building a pergola with a roof and sides the best option is to use our Alukap-XR Glazing Bars to simply clamp Axgard sheets vertically to the sides of your pergola. This is easily done and adds an extra level of waterproofing and security.

We found by cladding the side of a pergola with Axgard sheets on two sides it massively reduced gusts and was a great windbreak! What's more the Axgard patterned or tinted options provide privacy for your outdoor living area!

7. What base/flooring to use under my Lean To Pergola?

There are three options for flooring options below your pergola, which are decking, outdoor ceramic tiles and slabs.

Slabs are very durable and functional but carry a more rugged and basic look compared to ceramic Tiles. Outdoor ceramic tiles are growing in popularity due to the range of styles ang colours available now so prove popular for Hot Tub Pergolas and dining areas pergolas.

A favourite for all pergolas, whether a patio pergola roof or flat roof pergola, is using decking. Decking is super easy to install especially our Alupave® Aluminium decking which simply locks together and does all the hard work of protecting the sub frame and drainage for you! 


In summary, pergolas are not only an affordable additional to your garden but are easy to install and stylise. Simply follow the Top 7 Key Pergola point for cover the main project points!

Have any other questions about how to build a pergola with a polycarbonate or glass roof? Simply Live Chat to our team below!


Other Common Lean to Pergola Questions

Here is a summary of some other Pergola questions DIYers also often have:

How to cover a louvered roof pergola?

A Pergola with a louvre roof, or sometimes called a slatted roof pergola, can look great, however, with a with a bit of British Weather can limit your pergolas roof massively! Best to make sure your pergola is usable in rain, hail or shine with a full waterproof roof to get maximum usability at all times of year!

What do I use on a solid roof pergola?

To best roof a solid roof pergola you would use either our  Awnapol Premium Bitumen Roof Sheets or our Corrapol-BT Bitumen Roof Sheets. Colour options include Black, Green, Brown and Red, with Black and green being the most used!

How to create a Rooflight or Clear panel in a Solid Roof Pergola?

If you are building a solid roof pergola then save it being shady or dark you are best to create a rooflight or clear vision panel in one part of the roof to bring in the light. The easiest way to do this is with our Alukap-XR Glazing bars and either Axgard or Axiome Polycarbonate Sheets.

What glazing bars do i use for a pergola with a glass roof?

When creating a pergola glass roof you can our use Alukap glazing Bar Ranges

If it’s a wooden pergola with glass roof that you are building then Alukap-XR Glazing Bars will suit or self supporting then our Alukap-SS is the range for you!

Remember the Pergola glass roof effect can also be created using Axgard Glazing Panels which are virtually unbreakable, more cost effective and easy to install.

What lean to pergola with pvc corrugated roof?

Creating a lean to pergola with a pvc roof and using Corrapol® corrugated sheets requires a different structure and set up to a standard pergola. Simply visit our Corrapol® Installation Guides here to see how this is done. 




Great questions Tim, thank you!
There are two main options when choosing a wind break for a Lean To Pergola Roof: Multiwall Polycarbonate or Solid Polycarbonate. Solid Glazing sheets, like Axgard, are one of the best options as they are very robust and there are different tint options for different styles. Axgard 5mm or 6mm is our most popular thickness for this kind of application.
Then there is our Axiome Multiwall Polycarbonate which is a more budget option but visually doesn’t look as quality. If using multiwall polycarbonate as a wind break we would suggest a minimum of 16mm thick. How much support you have is also a key factor as with the right amount of support you would also use a clear corrugated plastic sheet like the Corrapol Stormproof.
This all depends on how windy your location is so bear in mind site specifics when deciding!
Please find links below to these products:



What’s the best wind break solution for strong winds

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