How to replace a flat roof?

There can be many reasons why you may need to replace a flat roof – you might find that accidental damage has put it beyond repair, or that you’ve realised you can save more money in the long run through a more energy efficient roofing structure. In most cases, it’s best to work with a roofing specialist like Bauder, who can provide advice and solutions for different types of roofs. However, what are some general things that you should be thinking about when replacing a flat roof? 

Working Out a Problem 

It’s first important to detect problems and the level of damage suffered by a flat roof. If you have a leak, see whether it’s coming through the substrate of a flat roof, or if it’s pooling around joints and corners. You can sometimes get away with patching and repairing membrane breaks and problems with the top surface of a flat roof without having to make a full scale replacement. 

Inspecting Materials 

When replacing a flat roof, you need to think about what materials you want to use, and whether you want a like for like, or a complete replacement. Old asphalt and single ply flat roof systems can become particularly brittle over time, and can be replaced by using polyurethane foam or modified bitumen that’s more hard wearing. You should also look into upgrading the quality of your felt base, and any waterproof materials used with your roof. 

Removing an Old Roof

To remove an old flat roof structure, you need to be careful not to cause any damage to beams or layers that need to be retained. If you’re replacing sections, you can do by using a scraper to carefully remove layers of insulating and foundation materials. You’ll also need to be careful about removing and storing any flashing parts and metal surfaces. 

Inserting Strips and Fixings 

To replace a flat roof, you’ll need to work in sections, beginning with a base sheet or felt lining, which can involve using different materials and waterproof membranes. For asphalt and bitumen layers, you can use hot mopping to seal in different parts using hot tar and other materials. 


Depending on how many layers your flat roof needs to be, you can opt to layer in stages to ensure consistency and a waterproof membrane. Hot asphalt over a waterproof base can provide a traditional solution to a flat roof layer, and can be combined with crushed granite to provide ballast. Single ply membranes can also be combined with modified polymer layers and sheet metals for extra durability. 

Use Self Adhesive Roofing Solutions 

One way to replace your flat roof without having to use a naked flame (illegal on some construction sites), involves using a self adhesive bitumen membrane like Airtech – this roofing system relies on using a polyurethane adhesive, which can be dried using hot air welding equipment. 

Consider Green Roof Modifications 

If you do want to make a more significant alteration to your flat roof, you can consider investing in green roof modifications; this can involve adding several layers of vegetation to your roof, as well as a waterproof membrane base – a green roof can be used to naturally cool and hydrate your roof, while releasing oxygen into the atmosphere to improve a roof’s surrounding environment. 

Della blogs about roofing solutions and DIY. She recommends working with Bauder on your next roofing project. She also blogs about health and safety in the workplace.

Della Moris

I am a freelance content writer and loves to write articles in various topics. Follow me @ G+

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