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  • Flat Roof Replacement Cost

    Want to know how much a flat roof replacement or repair will cost? In this article we look at the prices of different roof replacements and repairs per square metre, including the cost of materials and labour. This makes it easy for anyone to calculate how much replacing a roof will cost them.

    Average Cost to Replace a Flat Roof:

    Depending on the complexity of the job, it usually takes: 2 to 3 days

    £2000

    How Much Does Replacing a Flat Roof Cost?

    The average cost of a flat roof is anywhere from £1000 to £5000. This seems like a rather wide range, but this is due to all the factors that affect the price. For example, depending on the type of flat roof you opt for, the price could either reduce or increase.

    There are other factors to consider, including the size of the house, the labourer’s expertise, and the ease of access to the roof. This is all in addition to other considerations like scaffolding and so on.

    The material used on the roof is one other factor to consider. There are four most commonly used materials in flat roof construction: felt, rubber, fibreglass, and lead. For instance, if you opt for a felt roof, you can expect to spend between £40 to £70 per m2.

    It’s worth noting that replacing a flat roof can fluctuate in cost as it is affected by several factors, which we will discuss in more detail. The most crucial factor is the size of the house and what section you want the flat roof placed. For example, a flat roof for a one-bedroom apartment is between £1500 to £3000.

    Also, note that this is assuming the flat roof will act as the main roof. However, if you are on a budget, you could use the flat roof for a section of the house like the garage, in which case, the price could come down to somewhere between £700 to £1000.

    You also need to consider the price of labour which is vital when considering flat roof cost. Different companies will have their own quotes, so be sure to compare them to get a great deal.

    One other factor that affects the price is the materials used for construction. For instance, a metal roof generally costs more than one made out of rubber.

    Replacing a Flat Roof Prices

    For further understanding of flat roof replacement costs, you can check out our table below for a brief rundown on the prices.

    Description Duration Cost
    Flat roof (main) 2-3 days £1500-£4500
    Extension roof 2-3 days £500-£3000
    Porch 1-2 days £300-£600
    Double garage 2-3 days £1200-£2000
    Dormer 1-2 days £700-£1500

    The below table sets out the costs for drain maintenance and other repairs.

    Job Description Price
    Cleaning up drains £60-£200
    Unclogging drains £150-£200
    Roof patchwork £200-£500

    Supply Costs Only

    Labour takes up a significant chunk of any amount budgeted for flat roof costs, so it is also an excellent idea to get a sense for how much the project will cost without additional labour fees. This gives you an idea of how much the labourers charge when they present a quote.

    So, how much does a flat roof cost per m2 UK? Typically, this depends on the material. The table below details the different materials and the prices they go for.

    Material Price (m2)
    Felt flat roof £40-£70
    Rubber flat roofs £80-£100
    Fibreglass flat roofs £80-£110
    Lead bay roof £90-£110

    Additional Costs

    There are a few other costs to consider when dealing with a new flat roof. In this section, we’ll consider some of the other jobs that might need to be carried out before you lay a flat roof.

    Scaffolding Costs

    By law, scaffolding is necessary for any job that requires height. And since replacing a flat roof needs the labourer to climb to the roof, some scaffolding might be necessary. There are situations where a ladder could do the job, but this isn’t the case with flat roofs as they take a considerable amount of time.

    So, what is the average cost of hiring scaffolding when repairing a flat roof? Well, the average price should be about £900 to £1000.

    Just like with other aspects of work done on a roof, there are factors that affect the price of scaffolding. For instance, high-level scaffolds, like the ones used for chimney work, will set you back between £800 to £900.

    Also of note are some of the scaffolding kits available for DIY enthusiasts who might want to embark on the project themselves. Scaffolding kits are affordable and useful, which is why they are quite popular with a lot of people. In addition, they are very easy to put together and are easy to manipulate by a single person.

    On the flip side, they aren’t as versatile as scaffolds that are created by professionals and considering that a flat roof project will require a sturdy scaffold that can work in different ways, a professionally constructed one might be your best bet.

    Gutter Cleaning Costs

    The term ‘flat roof’ is slightly disingenuous as the roof isn’t really flat, but slanted somewhat to ensure that water and debris doesn’t pool together and cause damage over time.

    That said, even with the water sliding off the roof, debris, leaves, and so on can still cause a problem if they are left unattended. Not only do they damage the roof, but they can also clog up the gutters and drainage system. In this case, you’ll need to have your gutters regularly cleaned.

    On the bright side, having your gutters cleaned is relatively cheap since no additional materials are required, and labour is the only real consideration. The average tradesperson will charge around £100 to 250 for the job.

    Cleaning up the gutters regularly is very important as neglect could easily lead to an overflow that will only cause problems. Furthermore, if the debris is left unattended, it could block rainwater pipes and underground drains. No doubt, having underground drains unclogged is a whole lot more expensive than regular maintenance.

    Furthermore, if you are worried about the cost of gutter cleaning, then you can rest easy as this is a straightforward DIY job.

    In fact, it can be done manually with the help of a ladder and a pair of gloves. The benefits of regular maintenance are apparent as they save you a lot of money since they prevent the need for extensive repairs or work to fix the drainage problem.

    Roof Repair Costs

    Before work can commence on your flat roof, most contractors will inspect it to ensure that there are no persisting problems that could undermine the work to be done.

    One of the most common problems that an existing roof could have is sagging. This is when the roof starts to cave in and bend. This could be due to the timber suffering from rot or if the roof is under undue pressure.

    When this happens, you’ll first need to deal with this problem. The cost of doing this varies depending on what the job requires. For example, if the problem is excess weight, then it’s best to install additional joists or rafters that can pitch in and help handle the weight better.

    This operation could cost between £1000 to £2000 depending on the number of materials or joists required.

    Apart from weight, waterlogging is another common cause of a sagging roof. This could be due to lack of maintenance which could lead to irreparable damage to the structure. In this case, it is recommended that the roof be changed.

    Labour Costs and Timescales

    As alluded to earlier, the cost to fit a new flat roof is shared between the necessary materials and labour. Therefore, if you are hiring professionals to handle the job, you’ll need to get hold of a good roofer with adequate experience. They will usually charge between £25 to £50 per hour.

    It is also essential to consider that the job of fitting a new flat roof could take up to two days. In addition, most roofers require an extra hand to carry out their jobs effectively. Therefore, you will likely be paying two people for the job.

    Most contractors will include their prices with the overall cost to replace the flat roof. So pay attention to the quote to ensure you aren’t charged arbitrarily. Generally, a flat roof replacement should cost somewhere between £200 to £500 in labour fees.

    However, the price and timescale for the job could change in some circumstances. For instance, the material used could impact on the time necessary to carry out the job as some materials are easier to work with than others.

    Also, ease of access is vital. The job will take a longer time if the labourers don’t have an easy way to get to the roof. For this reason, a scaffold might be necessary. This not only ensures the safety of the worker, but also saves time.

    Cost Factors of Replacing a Flat Roof

    Presenting accurate prices for flat roofs is tricky as so many factors affect the price; from the size of the house to the expertise of the labourer. In this section, we’ll examine some vital factors that affect the cost of replacing a flat roof.

    Type of Flat Roof

    There are four commonly used materials in the construction of flat roofs. They include felt, rubber, fibreglass, and lead. These four materials all have different properties and drawbacks. In terms of price, felt is perhaps the most affordable while lead could cost a pretty penny.

    Not only the price, but materials can also affect the amount of time needed for the job as some materials are easier to work with than others. On top of that, some contractors might increase their price depending on the complexity of the job.

    Location of the Property

    The cost of living in large cosmopolitan cities is pretty expensive. This usually has a knock-on effect on other things, including food, and, in this case, labour costs. Therefore, if you live in a big city, a new flat roof cost could be higher than initially expected.

    This is also true in rural areas as the availability of competent tradespeople might be hampered due to the location which could lead to an increase in the price.

    Also, if your home is distant from the company or tradesperson coming over to embark on the project, this could increase. This is due to the common practice of contractors billing clients from the moment they leave their offices or workshops. Therefore, a long commute could end up costing you a lot of money.

    Ease of Access

    There are a lot of things that could affect the time and effort required to install a flat roof. One of the most important is the ease of access to the roof. Each project comes with its set of challenges. This will include existing problems on the roof or the need for additional materials.

    For instance, if the roof is for a three-storey building, scaffolding will be required. This will obviously come with additional costs. Also, if the roof is in poor condition and there are clogged gutters, and so on, this will reduce accessibility and hike up costs.

    Size of the Flat Roof

    Size matters. This is not only because of the material, but also the amount of labour required and the time needed to finish the project. As mentioned earlier, a felt roof could cost somewhere £40 to £70 per m2, and this means the total cost of the roof will depend on how large it is.

    For instance, the price of installing a flat roof on the entire house would be significantly more than just doing the porch roof. Apart from materials, since larger roofs take more time, the labourers are likely to cost more money.

    Scaffolding Hire

    Scaffolding is a necessity for most height-related jobs in the UK which means you might want to add scaffolding costs to the budget. Obviously, a flat roof requires some height and more often than not, a scaffold will need to be erected.

    Earlier, we already determined the costs of hiring scaffolding. Be sure to check your quote so as not to end up paying more than necessary.

    Waste Removal

    Flat roof repairs could get pretty messy, depending on the situation. This is because dealing with waste could be a real problem. Thankfully, most companies deal with waste and add it into their quotes, meaning you don’t have to think about it. However, if you do the job yourself, it might be necessary to pay for the disposal of waste.

    What's Involved in Replacing a Flat Roof

    Since different materials are used to construct flat roofs, they have slightly different methods for replacing or repairing.

    Therefore, in this section, we’ll examine how repairing and replacing might be carried out by professionals and point out how things might differ. This way, you’ll be able to follow up with your contractor to ensure that the right steps are being implemented.

    1. Inspecting the Roof

    2. The first step to replacing a flat roof is to inspect the existing one to see if there are any deficiencies and if anything will need changing or repairs. During this stage, the contractor might notice several things from a sagging roof to blocked gutters.

      If the contractor recommends for repairs to be carried out first, this could cost some extra money, but it is worth it. For instance, if the timbers underneath the roof are weak or rotting, they’ll need to be replaced before work can commence. This is because installing a new flat roof on a defective foundation will only cost more money in the long run.

    3. Removing the Old Roof

    4. Once the inspection is done, work can commence. The first thing any contractor would do is remove the old roof before a new one is installed. This varies from material to material as the tools needed might differ.

      For instance, removing a felt roof will require a small spade while a rubber one will need a utility knife. The contractor will use the knife to cut the rubber roof to pieces and dispose of them.

      The complexity of each material also means that this could increase the cost of the project as a lead roof usually requires a diamond-tipped grinder. In the case of a quick repair job, the only bit that needs to be removed is the damaged section. This is significantly cheaper and easier and requires a lot less energy.

    5. Measuring the Space

    6. Once the old roofing material is gone, the next step is to measure the space. This is important as it informs the contractor how much material is needed for the job. It is usually advised to order more material than necessary; as it’s always better to have a surplus than a deficit.

    7. Installing the New Roof

    8. The final stage is the installation proper. Depending on the material, this can go in different ways. For instance, with felt, the material is laid in place and secured with nails or drills. Meanwhile, with rubber, the best means of securing the material is with a strong adhesive.

      A similar technique is required when repairs are necessary, but simply on a smaller scale. So, once the damaged section is inspected and removed, the last steps are to measure it and replace the old material with the new one.

      However, replacing one section of the roof without touching the other areas could lead to its own problems. So, if there is a problem with the roof, or some damage occurs, unless the effect is minuscule, the standard recommendation is to replace the entire roof.

    Can I Replace a Flat Roof Myself?

    DIY roof repairs or replacements are tricky. Although they look easy enough on the surface, there are usually several unseen complexities lurking underneath. The easy answer to the question of replacing a flat roof by yourself is yes.

    That said, there is a real case to be made for getting a professional to have a look at the roof; especially as they are trained to notice the little issues in the roof that you might typically identify.

    Typically, the first indication of a damaged roof is if there are leaks, but it is possible that this isn’t caused by damage, but rather blocked drainage or guttering.

    If you insist on going the DIY route, ensure you have the right tools. This includes a shovel, crowbar, nail gun, hammer, heat gun, and so on. Also, we advise only to go down the DIY route if the repairs are small as this saves more money than engaging a professional.

    As noted earlier, small repairs are usually problematic as they can cause further damage, and it is best to replace the roof if there are any problems.

    While repairing the roof yourself is possible and much cheaper, a poor job could lead to structural issues which will only come back to haunt you in the future. More so, it could even become a safety hazard if left unchecked.

    Building Regulations for a Flat Roof

    The British building regulations are the prevailing legislation when it comes to dealing with a flat roof. Since the work usually carried out is less complicated, there aren’t any particular rules to live by.

    As with most other roofs, the regulations stipulate that the roof must be at a slope of 1:80. In addition, it is also necessary to have a competent drainage system. Also, ensure that the roof is strong enough to walk on and is insulated if cold.

    Apart from that, any other necessary regulations will be pointed out by a contractor. If you need more information, you can visit here.

    Planning Permission for a Flat Roof

    There’s generally no need for any permission to carry out work on an existing roof. However, there are some exceptions, including if the new roof will work differently from the previously installed one.

    Also, if there are to be any structural alterations, then permission might be necessary. Again, just like with building regulations, your contractor should bring this information to your notice. If you’d like more information, click here.

    Choosing a Flat Roof

    Flat roofs are commonly defined by the materials used in their construction. In this section, we’ll examine the materials used in the creation of a flat roof, their advantages and disadvantages.

    Felt Roof Cost

    Felt roofs are made with a felt material. They are also made to be light and easy to install. They are also one of the more affordable flat roof variants.


    Pros

    ✔ They are affordable and save money.

    ✔ Maintenance is a lot easier and cheaper than other types.

    ✔ They are a lot easier to work with.

    Cons

    ✖ Due to the quality of the material, they typically do not last long.

    ✖ Depending on the weather conditions, they can get damaged quite easily.

    ✖ Once repairs are carried out, they don’t look very aesthetically pleasing.

    Rubber Roof Cost

    Rubber roofing, as the name implies, makes use of rubber in its creation. It is generally easy to work with, and replacing will require the contractor to cut up the existing rubber with a knife to dispose of.


    Pros

    ✔ It is much more eco-friendly.

    ✔ The installation process isn’t difficult.

    ✔ The material is resistant to thermal shock.

    Cons

    ✖ The colour fades over time, and it doesn’t look nice.

    ✖ Rubber isn’t a great material for DIY enthusiasts to work with.

    ✖ It can be scarce and difficult to find.

    Fibreglass Roof Cost

    This is usually made with layers of fibreglass, which is reinforced to protect the roof further. It is a very popular method since it tends to last longer than a lot of the other variants available.


    Pros

    ✔ Since it is such a versatile material, fibreglass is the go-to material for many homeowners, and it’s beautiful aesthetic doesn’t hurt.

    ✔ It is pretty lightweight.

    ✔ The material is easy to access and exists in abundance in the market.

    Cons

    ✖ It comes pre-cut which means additional work might be necessary to get the required shape and size.

    ✖ Maintenance isn’t easy and requires the attention of a professional.

    ✖ Fibreglass needs to be handled with care, which makes it less suitable for DIYers.

    Lead Roof Cost

    Lead roofs are typically the most durable due to the materials involved in the creation. This means they last really long since they are water and corrosion-resistant. Also, they require a slightly different method for maintenance which is called ‘flashing’.


    Pros

    ✔ Lead is highly flexible which makes it really convenient to work with.

    ✔ It is incredibly durable and stays in good condition for a while.

    ✔ Lead roofs are recyclable which also makes them eco-friendly.

    Cons

    ✖ Lead is in low supply and is difficult to come by.

    ✖ It is a toxic substance, so if it affects the water in a home, it could be potentially harmful.

    ✖ It is a pretty heavy material which means that if the underlying timber isn’t strong enough, it could cause sagging.

    Alternatives to Flat Roof Costs

    While flat roofs are great, there are other alternatives available to homeowners which they might find more attractive. In this section, we’ll consider some of the more common ones.

    Roll-on Roofs Cost

    These are very decent alternatives to traditional roofs and are incredibly easy to install. They simply need to be rolled in place and nailed.

    Pros

    ✔ They are easy to install.

    ✔ They are cheap and affordable.

    Cons

    ✖ They don’t last very long.

    Sheet Metal Roofing Cost

    Sheet metal is incredibly durable and is used for a lot of structures. Not only does it last long, but it doesn’t rust or corrode, which means it tends to look really nice. Therefore, this is an excellent option for sheds, barns and other outbuildings.

    Pros

    ✔ It is a durable material to work with.

    ✔ It doesn’t rust or corrode.

    Cons

    ✖ It is heavy which could lead to sagging.

    Asphalt Roofs Cost

    Asphalt roofs used to be really popular, but this is changing. That said, it is quite affordable as it is similar to felt material. It is usually the best option if you are renovating on a budget.

    Pros

    ✔ It is very affordable.

    ✔ It is easy to work with.

    Cons

    ✖ It has a short lifespan meaning you might need to change it only a few years after initially installing it.

    Do I Need to Replace My Flat Roof?

    That depends. While flat roof repair is usually frowned upon, there are situations where they might become necessary. In this section, we’ll discuss some of the reasons to replace your roof and the signs you might notice.

    Leaking

    This is one of the most common signs of a roof in need of repairs or replacement. Roofs are made to keep water out and protect the home from the weather.

    Therefore, if there is water seeping into the house, this is a sure sign that there might be a problem with the roof.

    Algae stains

    Airborne algae might settle on your roof and over time could start to discolour it. While it might not necessarily affect the shingles, it doesn’t make for pretty viewing. If you’ve had your roof for a while, this could be a good opportunity to replace it.

    Moss

    Moss tends to grow between little spaces in the roof, especially in colder climates. Also, while they might not be a great danger, they generally don’t look right. Removing moss isn’t difficult, but you need to be careful to ensure that you don’t damage other parts of the roof in the process.

    Removing a Flat Roof Cost

    Removing a flat roof is usually done when it is about to be repaired, or a new one installed and is therefore usually added to the flat roof repair cost. That said, there are situations where removing the roof might be part of another project like converting the roof.

    In this case, a professional will likely charge between £80 to £100 per m2. Once the removal is complete, disposal is the next problem, and while most companies will add it to the initial bill, some contractors will bill between £100 to £150 to get rid of the waste for you.

    Hiring Someone to Replace a Flat Roof Checklist

    Before you hire a professional to work on your flat roof, consider the following:

    • What qualifications are needed: A good example is a Level 3 (NVQ) Diploma in Roofing Occupations.
    • What experience do they have? Two years plus experience might be a good start, depending on your budget.
    • What’s their previous work like? A good portfolio will give you an idea of what to expect.
    • Have their previous customers rated them highly: Check for online reviews/feedback of their work.
    • re they part of any accreditation? The more proof they offer of their skillset, the more confidence you will have in their ability.

    FAQs

    What is the best material for a flat roof?
    This depends on what the roof is for. There are different materials used to build a flat roof, each with its advantages and drawbacks. While a material like felt is affordable and easy to work with, it doesn’t last as long as lead.
    How long does a flat roof last?
    Typically, a flat roof should last between 10-20 years
    What is a flat roof?
    A flat roof usually isn’t flat but is tilted slightly to ensure that water doesn’t pool which could cause damage to the roof’s structure. They are made with different materials and are great for all sorts of building.
    Do I need to insulate my flat roof?
    This depends on the purpose the roof serves. For instance, a flat roof over an outbuilding doesn’t usually need to be insulated, and they are known as cold roofs. On the other hand, if the roof is over habitable areas, then insulation might be necessary.
    Is there ever a time where repairing the roof is better than replacing it?
    Under normal circumstances, replacing the roof is always a better option compared to repairing it. However, if the damage is minimal, then repairs might be more economical than a complete overhaul.

    Sources

    https://www.fixmyroof.co.uk/videos-and-guides/flat-roof-replacement/flat-roof-costs/
    https://www.aabcoroofinginc.com/pros-and-cons-of-rubber-roofing/
    https://www.topseal.co.uk/news/news-article/flat-roof-alternatives/
    https://www.owenscorning.com/en-us/roofing/tools/do-i-need-a-new-roof

    Last updated by MyJobQuote on 29th October 2020.

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