A DIY Guide to Waterproofing a Garage Roof

If you’re researching waterproofing a garage roof yourself, you’ll already know that there are a wide range of options. We’re here to highlight some of the fastest, easiest and most effective ways of doing it well in our handy DIY guide. 

Different types of garage roof

In the UK, there are an estimated ten million or more garages of varying shapes and sizes - standard garages, double and single garages and bespoke constructions. Many homeowners (more than half, according to industry surveys) don’t use them for parking cars, but rather for storage, workshops or conversion into useable living spaces.

Some of the most common types of UK garage roof:

• Flat garage roof
• Apex roof
• Mono-pitch roof
• Pent roof
• Lean-to garage

Traditional UK garage roof coverings include felt and hot bitumen-based coatings, metal and roof sheets, which have historically proven to be effective in the short-term but require maintenance and regular repairs over time. 

Regardless of the shape, size or scope of the project, more homeowners are taking an increasingly sustainable view. This means turning away from the traditional and investing in a longer-term approach that can hit the mark if they require more from the garage than just storage or a vehicle. EPDM and liquid roof systems are good choices for DIY.

Choosing the right approach for a garage

When it comes to waterproofing, the intended use is important. Traditional UK garage roof materials won’t necessarily provide enough reliable protection for a garden office conversion, for example, which will contain sensitive equipment and papers that shouldn’t be subject to condensation or damp. 

If you’re replacing a leaking covering but only use the garage for storage of garden tools, then you may not be looking for a high-performance system. 

Determine the intended use and decide whether you’re going to install additional elements, such as insulation or skylights, for instance. This can help to guide you towards the best type of system and materials.

Waterproofing materials have changed over the years and have become more accessible for the DIY sector. If you’re planning to tackle the garage roof yourself, select a system that is within the capabilities of a small team, such as a single-piece membrane or a liquid coating. 

Covering different substrates and handling details

In the UK, there are a small handful of typical garage roof substrates, most commonly wood or concrete, but sometimes metal or sheets. Which type of substrate you are working with might be the best way to choose your approach. 

For example:

Rubber roofing is perfect for a timber substrate, and it can be installed quickly in a single sheet up to 15m x 60m using water-based roofing adhesive. 

Concrete garage roof decks require mechanical fixing and bonding of membranes, which can be slightly more complex for DIY. We’d recommend using a liquid coating for this type of garage roof.

The roof design and the condition of the deck should also be a part of your plan. Some can be complex with various angles or drops and others are straightforward – standard, off-the-shelf and rectangular with even angles. If you have multiple extrusions, a reliable seal will be crucial, and these will be areas to focus on when you choose your preferred system. 

• Are system accessories provided to deal with extrusions? (pipes, flues, etc)
• Is the system itself straightforward to install or apply?
• How much support is offered by the supplier for DIY?
• Are certificates and technical declarations provided?

What types of garage waterproofing systems are available?

Garage roofing felt

• Roofing felt was a popular choice for many years in the UK, historically unreliable over long term projects and giving flat roofs a poor reputation. Today, felt has come a long way and is still widely available. It is diminishing in popularity due to comparative performance to some of the latest systems and often complex, hot-based installation methods.

Bitumen sheets

• Bitumen and concrete-based garage roof sheets have been a traditional go-to waterproofing method, performing better than felt systems by more than a decade, typically. Installation must be precise, and seals handled carefully in these types of systems, which is why they are most commonly professionally installed and not popular for DIY.

Corrugated sheets

• Corrugated roof sheets are common in the UK, especially for freestanding garages. Although effective in certain situations, it can prove difficult to fully seal this type of roofing and it would not reduce a build up of condensation, rendering it unsuitable for a conversion project. 

EPDM membrane

• EPDM is ideal for timber garage roof decks, as long as they are in good condition. The single ply membrane is compatible with modern insulation and can be installed in a single sheet to eliminate seaming. This fast and easy approach is perfect for DIY and good membranes, such as RubberCover, can last for more than 50 years. 

Liquid PU coating

• Liquid PU coatings can cover almost any substrate, making them ideal for effectively sealing concrete garage roofs with no seams. Liquid PU is quickly and easily applied with a roller, and cures fast, delivering a showerproof coating in about half an hour. 

DIY tips for waterproofing a garage roof

• To make waterproofing a garage roof yourself as straightforward as possible, we’ve got a few tips:
• Save time by ascertaining the type of substrate and its condition 
• Make any necessary repairs and ensure you have a good base – replace the roof deck for new if needed
• Gather a small, skilled DIY team together and discuss your options and capabilities - review potential system installation processes to help you decide
• Buy a complete garage waterproofing kit to minimise the risk of incorrectly quantifying the materials – these are available in both EPDM and Liquid PU right here in our store
• Ensure you have any necessary system accessories to deal with extrusions

Browse the PermaRoof range of EPDM garage roof kits here.

Can we help you?

PermaRoof UK can help to simplify waterproofing a garage roof right from the start, during the planning stages and throughout your project. 

We offer expert advice via phone, email or chat and have a wide range of free, read or download roofing installation guides here and in our corporate resource library here. Certificates and technical information is also fully accessible. 

We developed our range of EPDM garage and other flat roof kits especially for DIY and include RubberCover EPDM and everything else you need, even down to the trim. If you need to add accessories, give us a call or use our free Kit Builder App. We also offer our own P100 liquid roof kits in off-the-shelf 5m2 and 10m2 project sizes.

Finally, if you get to the crunch and change your mind about DIY, we can connect you with a dependable local trade roofer to manage it for you. Try the PermaRoof way and get full support, performance products and a professional approach. 

Talk to the award-winning sales and customer support teams if you need help with your order on 01773 441 947 or contact us via the live chat for an answer to your quick query.