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Flat Roof to Pitched Roof Conversion Costs

Material Costs, Labour Fees and Time Frame Estimates for Flat Roof to Pitched Roof Conversion

If you plan a flat roof into a pitched roof conversion, average costs would be around 3000-£4500. However the final costs will be affected by the specific materials you’ll be using, the dimension of your roof, and whether there’s a need for scaffolding or not. If you intend to use concrete tiles, costs would be around £0.75-£3 apiece. Clay tiles can range between £1 and £5 and slate will usually be priced at £1-£12 apiece. Larger tiles will cost more although the final figure may be less since you’ll require fewer pieces to get the entire roof covered. 

Cost Breakdown

If you intend flat roof into a pitched roof conversion, expect the costs to add up to £4000. Of that, £2600 covers the materials, £1200 for the tradesmen fees, ad £200 for waste removal. 

Time Frames and Labour Costs

Consider this roof conversion project as a major job and will require the presence of a number of roofers at a £150-£250 daily rate. Generally, it would take up to three days to complete the job, depending on your roof’s dimensions. 

Considering that this roof conversion can cause considerable change to your home structurally, it is safe to get the assistance of a professional architect to get the plans drawn up. Expect them to charge around £50-£90 hourly. 

What Does the Job Entail?

Before proceeding with the roof conversion, make sure that you have considered and exhausted all your available options. You will want to refer to structural engineers who can give you sound advice on the options available for you. 

When doing a flat roof conversion, these steps will be carried out:

  1.       The project starts with getting the old flat roof removed. This means the tiles, covering and even the battens need to be removed. A roof specialist will need to evaluate the structure and its condition and make sure that there isn’t any rotting to proceed.
  2.       The specialist will also check the spacing of the joists to assess that it can indeed accommodate the installation that is about to take place. Once confirmed, every second joist will have tissues placed over it so it can then get connected to your wall structure.
  3.       After the trusses have been placed, the measurement of the gable ends will follow. This is to determine the amount of plywood that will be required to cover the area. The plywood covers the whole roof and is attached to the trusses. This helps form the roof’s new shape.
  4.       To ensure that the proof is waterproofed, tar paper is used along the roof’s length and towards its peak. It will be nailed into the surface followed by the installation of the bridgeboard and the tiles.
  5.       The gable ends will need to be covered. Siding material and roof covering are used for this purpose. Plywood will be used to secure the fixtures. Waterproofing substance is then used to get the entire area primed. 

Cost-Affecting Factors

Once the work commences, the costs you’ll need to cover next will have to do with the installation and removal of old roofing materials. Remember that this is one serious task and expertise and time are needed if you are to do it right, you’ll even have to spend more time and effort in the event that there is damage as this means repairs have to be carried out first before any additional work can be carried out. 

Expenses will depend on the specific roof you choose. Less expensive choices include mono-pitch which costs about £40 a square metre and ideal for those would rather keep their budget low. If you’re going for the king post truss roof, the trusses could cost around £1100-£2250. They are considered the most expensive and are usually utilized for roofs of larger dimensions. 

Also, how complex the construction of your roof is will also need to be taken into consideration as ultimately this can have a bearing on how much the final cost is going to be. A pitched roof that is shallowed can be an option to consider. It is less complicated to install which could mean savings on labour costs. 

Take note of the gutter condition too and see if there is cleaning required or if there are repairs needed. Cleaning the gutters can cost around £2-£5 a metre. If you intend to have an old guttering system replaced, the costs could run up to £30 a square metre. New support brackets can range between £15-£75 a square metre, with cast-iron materials being the most expensive. 

Additional Costs

On top of the work that needs to be performed on the main structure, you may also want to consider additional tasks like creating new roof angles, adding gables, adding a new window, or even choosing more intricate trusses. Remember that customisations will come at an extra cost. So, if you’re hoping to keep the costs down, keeping things as straightforward and simple as possible is very important. 

There may also be a need for you to get some supplementary work done. For instance, your ceiling might require some supplementary work due to the structural changes brought about by the installation some parts may have also been damaged due to wear and tear. Also, you might want to look into the possibility of removing your chimney stack. You can also get your siding redone too, along with your structure’s cladding. 

You might need to hire a crane too, which could cost about £380 daily for a mobile crane with 35 tonnes capacity. Remember that since the crane needs a qualified tradesman to operate, a specialist will usually charge about £700 daily. 

Scaffolding may also be needed for this project so make sure to include the costs in your budget. Generally, this would cost you around £40-£150 daily. 

Can My Flat Roof Be Converted?

Most rooms may be able to accommodate a replacement but there are instances when the process may be significantly complicated than the rest. For instance, constructing a pitched roof even when there isn’t a new floor built first can affect the number of joists that can be installed.  A flat roof with excessive damage can usually make it impossible to convert to a pitched roof. Repairs may be necessary before any conversion can be done. 

DIY Conversions

Roof conversion is a structural change to your home which affects its architecture. It is also considered a risky job so it is best not done DIY. It must be carried out only by approved, certified, licensed, and highly experienced professionals and tradesmen. More importantly, it requires planning permission and building regulations to be followed and only seasoned builders and professionals can be sure that. 

What you can do DIY, however, is the removal process. Just see to it that you’re wearing the right protective attire. Make sure you have safety glasses on too which could cost about £1-£45 depending on the brand and quality. You’ll also need a spade to aid you in the removal process and it can cost around 8-£40.

Pitched Roof vs Flat Roof


The design for this type of roof is almost level, with the pitch not going over 10 degrees. Among its pros include:

  • Inexpensive
  • DIY installation possibilities
  • Straightforward installation
  • More contemporary

Among the cons of flat roof include:

  • Can be prone to leaks
  • Shorter lifespan
  • Costly repairs
  • Requires maintenance regularly


This roof has a sloping downward design with the pitch not going beyond 12.5 degrees. Among the pros of this roof type include:

  • Easy maintenance
  • More traditional style
  • Better drainage capacity
  • Lasts longer

 Among the cons of a pitched roof are:

  • Costs more than flat roof
  • More complex to construct
  • Will require more time to install
  • Will likely cause disruption upon construction 

Benefits of a Pitched Roof

Pitched roofs are beneficial since they are considered to be the most sustainable among roof types. When installed right, they can have a lifespan of up to a century and usually require little to no maintenance. It is also designed to withstand even the harshest weather conditions. Thanks to its triangular shape, it is effective at avoiding waterlogging, rotting and leaks. 

It is highly energy-efficient too. Its top-quality ventilation ensures that wastage of energy is prevented. Their overall efficiency can even be maximised through the installation of solar panels, which should be easy considering the roof’s design. There will also be more space in the roof area so if you plan on a loft conversion, later on, this would be more than ideal. 

Will This Add Value to My Home?

Installing a new pitched roof can bring about 63% of returns in terms of property value. After all, it doesn’t just improve your home aesthetics, but it is always expected to include the durability and the lifespan of your roof. These are generally considered attractive to buyers. 

Is Planning Permission Needed?

Since this will result in an architectural change to your home, you’ll be expected to secure planning permission. Generally, it would cost about £210 for residents in the UK whilst homeowners from Wales will have to pay £190. 

Building Regulations

You’re going to need to process an application for building regulations if you plan to do the following:

  • Changes to the insulation need to meet specific requirements for thermal insulation where the insulation will be placed over the rafters for warm deck and between the joists for a cold deck.
  • The covering material needs to be durable in order to withstand harsh weather conditions.
  • Pitched roofs located in boundaries must have the necessary fire prevention features.
  • Appropriate ventilation is necessary to ensure that air is able to successfully enter and exit.
  • 12-metre long straps with cranked ends should secure the roof and it needs to be effectively fixed onto the plate. 

Costs for the approval of building regulation requests will be dependent on the local authority as gees in different locations can vary. 

Reducing the Costs

If you’re hoping to keep your expenses low, consider lowering the costs of the pitched roof and to stick to your plan of following your set budget as strictly as possible. This is also effective at helping you avoid added costs later.  

You have the choice to recycle old tiles too. However, this is only possible if they are still in very good condition. Try top-quality tiles including clay, concrete and slate as they are known to last a century. Never skimp on materials as well. Sure, it would cost you less from the start but it might result in massive costs later down the road. 

It’s possible to get the roof converted DIY. Note that this is only possible if you have any roofing experienced. It’s never a good idea to try and construct the roofing on your own without prior experience as this will only likely end up in costly repairs down the road. 

Pitched Roof Removal Costs

If your pitched roof has been around for some time and you have noticed significant damage on the fixture along with leaks, getting it replaced is something you might want to consider. For expert removal and replacement, the cost could be around £80-£115 a square metre. 

Take note of waste removal costs as well, especially if you intend to get rid of the old coverings and tiles too. You can hire a skip for this purpose which should cost about £215. You can choose to get the removal done by yourself to pay on cost, but this is rather tricky and you will likely not be able to do this on your own, help from a few friends may be necessary. Also, scaffolding will have to be erected which should cost around £40- £150 daily.