Can I Change a Flat Roof Into a Pitched Roof?

Contractors working on top of a roof

Converting a roof is a pretty big task to take on. But will it be worth the time and effort? Flat roofs come with both their pros and cons, but sometimes the latter simply outweighs the former for some people. And that’s why many homeowners end up longing for a high-quality and reliable pitched roofing solution instead. However, if it’s a flat roof that’s already there, you may find yourself asking ‘can I change a flat roof into a pitched roof?’. When it comes to a roof’s construction, it’s not always set in stone. There are just a few things you should know about turning a flat roof into a pitched roof before you begin.

Why Are You Looking to Convert?

One of the first things you need to consider before converting your flat roof into a pitched roof is the reasoning behind the transformation. Flat roofs can be prone to leakages, so if excess moisture is your main concern, you may be better off looking for a more durable, long-lasting EPDM roofing membrane. This is a much simpler, quicker and much more affordable alternative.

However, if it’s more the aesthetics or structure you’re concerned about, it may be best to renew to a pitched roof instead. This shouldn’t be done without knowing the full benefits that simply renewing your flat roof can bring. There are a few ways in which you can go about the replacement, including:

  • Installing a shallow pitched roof over your existing flat roof.
  • Adding a trussed style roof.
  • Building a new floor and installing the pitched roof above that.

The Cost of Converting

If your reasons for converting to a pitched roof are sound, then you should begin to plan for the project. The overall cost of changing a flat roof to a pitched roof ultimately depends on the complexity. While it would be much cheaper to rejuvenate your flat roof with some EPDM, which could also solve moisture-related problems and water buildup too, a pitched roof is seen by many to be visually appealing. 

EPDM has many resistant properties and is considered to be an exceptionally durable material. It also has a low life cycle cost compared to a standard pitched roof, so while you might be getting a fancy appearance with a pitched roof, you’re also getting higher prices. It’s important to keep this in mind when deciding to convert your flat roof. 

The Existing Structure May Affect the Replacement

If you’ve looked at all your options and have decided that a conversion is the best option for you, you need to be aware of the fact that your roof’s existing design may interfere with any planned changes. Depending on how you choose to convert your roof, you may be left with limited options. Look to contact an architect or structural engineer for assistance with what’s the best option for your property or building.

Complicated Roofing Systems

There are many instances where a flat-to-pitched roof conversion is a fairly simple job for someone who knows what they’re doing. Most projects will see a flat roof being turned into a pitched one by using a trussed roof with two angled planes. However, if you’re looking for something a little more abstract, you can have additional valleys, angles and gables built into the system.

Building a Pitched Roof Over an Existing Flat Roof

It depends on a lot of variables, like the condition of the existing flat roof, including the state of the joints and the material its made of. If the structure contains windows, then you’ll need a low pitch, for example. If excessive damage is present you might not be able to do this at all. As we’ve previously mentioned, it’s best to seek direct advice from a professional for this, rather than risking a damaged extension or property. 

Is Planning Permission Required?

In most cases, a like-for-like replacement does not require any planning permission. Simply replacing your existing flat roof with a new one should be a pretty straightforward process. When converting your flat roof into a pitched roof, that’s when planning permission may come into play. A low-pitched roof should be easy enough to gain planning permission for. However, when carrying out larger structural alterations, this may be a little more difficult. Always contact your local planning authority to be sure.

Hidden Flat Roof Conversion Costs 

With the average total cost being £3,000, it’s little wonder that you might forget about certain aspects. Scaffolding may be needed, and tiles generally cost around £1-£3 per tile too. If you hire a professional team of roofers, it will probably add another £1,000 to that figure. Additional work on the ceiling may be needed as well, such as changes to the joists. It would be a lot easier to replace your flat roof, but if you have the finances for it, a pitched roof may suit you better. 

Step-By-Step Guide to a Flat Roof Conversion

While we’d always advocate receiving aid from roofing professionals, we have a brief step-by-step guide to help visualise the amount of work necessary. 

  • The flat roof should be removed first, including the removal of coverings and roof battens. You should then inspect the roof for structural deficiencies. 
  • Joist spacing is incredibly important, as they need to be adequately spaced to support a pitched roof. If sound, trusses should then be placed over every other joist. You can then connect it to the wall too. 
  • You should then figure out how much plywood is required by measuring the gable ends. Plywood should then be placed into the roof to form the pitched shape. 
  • Waterproofing the roof is next, with materials such as tarpaper used for this purpose. The tiles and boards are then fitted too. 
  • Finally, the gable ends can be covered and siding material is placed over the plywood. It’s then recommended that a waterproofing substance is used on these as well. 

We hope this blog provides some insight into converting a flat roof into a pitched roof. If you’re considering revitalising your flat roof instead, please check out our informational EPDM pages or our training opportunities. We’re always happy to help. 

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