Many houses in the UK tend to have solid wood floorboards. Although these usually last for years when installed correctly, many older properties suffer from poor building practices, such as poor ventilation and excessive moisture, causing the wood to rot. Therefore, before flooring issues get out of hand and the wood falls apart from rot, it’s usual to replace floorboards.
The average cost of replacing rotten floorboards depends on the extent of the rot and other factors. But generally, a professional charges £200-£350 to replace up to five rotten floorboards. Furthermore, replacing a joist costs an additional £100.
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This guide discusses how floorboards become rotten, how to replace them and how much the job costs. We also discuss the factors that affect the prices and how to find a suitable professional who can do a good job.
Main Topics
How Much Does Rotten Floorboard Replacement Cost?
There are many operations included in replacing rotten floorboards. Here are a few tasks with estimates of average costs and how long each procedure takes:
| Operation | Estimated Duration | Estimated Cost |
|---|---|---|
| Fix loose floorboards | 4 hours maximum | £150-£200 |
| Repair broken floorboards | 1-2 days | £200-£350 |
| Repair floorboards & joists | 1-3 days | £300-£450 |
| Remove rotten floorboards in a single room & replace with chipboard | 1-3 days | £300-£550 |
| Remove rotten floorboards in a single room & replace with plywood | 1-3 days | £450-£800 |
| Remove rotten floorboards in entire house & replace with chipboard | 10 days maximum | £1,500-£2,500 |
| Remove rotten floorboards in entire house & replace with plywood | 10 days maximum | £2,00-£3,200 |
Note: The estimates in this guide were correct at the time of writing (September 2022). However, they may change depending on various factors discussed later.
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Floorboard Replacement Price Factors
The previous table shows that the price can vary when dealing with rotten floorboards. This is because of the many factors affecting the costs. Therefore, bear this in mind when researching a quotation.
Replacement Floorboard Material
Several types of material can replace rotten floorboards, each with its typical price range. Note that most flooring grade boards use tongue and groove joints to provide a strong connection and to help prevent floor shrinkage issues while the wood naturally dries out over time.
| Flooring Material | Flooring Type | Average Estimated Cost/m2 |
|---|---|---|
| Softwood | Planed Tongue & Grooved 18mmX119mm | £33/m2 |
| Planed Tongue & Grooved 18mmX144mm | £35/m2 | |
| Planed Tongue & Grooved 21mmX137mm | £45/m2 | |
| Chipboard | Tongue & Grooved P5 Grade 18mmX600mmX2400mm | £13/m2 |
| Tongue & Grooved P5 Grade 22mmX600mmX2400mm | £16/m2 | |
| Plywood | Square Edge CE2+ Grade 12mmX1220mmX2400mm | £13/m2 |
| Square Edge CE2+ Grade 18mmX1220mmX2400mm | £15/m2 |
You can see that engineered wood, such as plywood and chipboard, has a lower cost per square metre (£13-£16/m2) than natural wood (£33-£45/m2).
Size
With average estimated prices of floorboards ranging from £13/m2 to £45/m2, the size of the area you have to cover affects the overall price. For example, replacement boards will cost £130 to £450 plus labour to cover a floor of area 10m2. However, if you are reflooring many rooms or one large room, it’s worth asking the supplier if there is a discount for buying in bulk, as many suppliers offer this facility.
Damage
Rotten floorboards don’t always need replacing. If the damage is minor, it’s possible to repair a board or two. But, only consider this when hiring a professional as they know the correct repair method. And, of course, repairs will usually cost less than replacement unless the damage is expansive.
Cause Of The Rot
Depending on the cause of the damaged floorboards, you might have to treat the new flooring and the supporting joists with fungicide or pesticides. Fungi, such as dry rot, can cause damage, attracting other problems such as woodworm and other wood-boring insects. So, a sensible approach is to treat new and existing undamaged wood with a suitable pesticide and fungicide to prevent repeating the existing problem. Treatment such as this will cost more. But, if there’s only a small amount of damage, you can buy fungicidal wash for £11-£25 for a 5L container for a DIY job. Alternatively, with significant damage, use a professional with the training and equipment to apply industrial-strength chemicals to large areas.
Location
The cost of living varies around the UK. Therefore, labour rates differ too. Typically, day rates for a qualified carpenter range from £150-£250/day. Often, you’ll find that labour in London and the Southeast is higher by £4-£8/hr than in other regions. So, expect to pay more if you live in the Southeast of England.
Other Rotten Floor Components
The main problem with dry or wet rot is spreading to adjoining surfaces. Therefore, if you have a rotten floorboard, look at other adjacent surfaces, such as joists, skirting boards, and plastered walls.
- Damp plaster usually requires removing, allowing the surfaces to dry, treating for dry rot and replacing with new plaster.
- Remove skirting boards, and allow the wall to dry completely before treating the masonry wall with a fungicide
- Remove rotten joists and remedy the underlying cause. Usually, this is an issue with the damp-proof course allowing rising-damp to damage untreated wood, which causes wet rot and provides a breeding ground for dry rot fungus. Replacing a joist can cost up to £500.
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Additional Work
To replace floorboards, a carpenter needs a clear floor area with enough space to manoeuvre and cut long lengths of floorboard. Therefore, removing the furniture and carpets from the room will help speed up the job, and the work will cost less.
Causes Of Floorboard Rot
Floorboard rot can be either wet or dry rot, which are different from each other. But, both can result in severe problems if left untreated. So, although replacing or repairing a rotten floorboard is pretty straightforward, a professional often needs to notice and understand the underlying cause and how to remedy the issue to prevent it from happening again.
Here is an overview of each kind of rot, so you can see the difference and perhaps understand the underlying cause of the floorboard rot.
Dry Rot
Dry rot is a fungus that infects wood and masonry in your home. Its Latin name is Serpula Lacrymans, and its spores are everywhere, especially if you live in an area with trees. In the outside environment, it does an excellent job as it assists with the breakdown of dead wood into nutrient-rich soil. However, if moisture levels in the wood used in your home reach about 20%, spores will grow and spread into the wood and masonry found in the average home unless you kill the fungi and remove the moisture.
Once the fungi take hold and spread using white tendrils, it can look fluffy like cotton wool. When the fungus matures, it produces fruiting bodies looking like mushrooms or toadstools, which release airborne spores, further infecting the area.
As increased moisture levels usually cause dry rot, it often takes hold in buildings with poor ventilation, rising damp, and condensation. The telltale signs of dry rot are that the wood looks brittle, warped and dried out, often with crack lines on the surface. You might also notice a musty odour reminiscent of mushrooms.
The Problem’s Solution
Dry rot spores can affect your health, especially if the occupants have respiratory complaints. But, the main issue is compromising the structural integrity of your property. Therefore, you should always use pressure-treated seasoned timber in new structural work. However, the best way to tackle dry rot in an existing property is to remove all affected wood, plaster and other masonry surfaces. Then, treat what’s left with an approved dry rot fungicide.
Although a DIYer can buy fungicides and treat the areas, it’s much better to hire a professional with the equipment and training to deal with dry rot effectively and provide you with a guarantee. Only then should you think about replacing rotten floorboards.
If you think you have dry rot, the first step is to have a dry rot survey costing £200-£400, followed by eradicating the fungus costing up to £5,000 if done professionally (and correctly).
On the bright side, dry rot is much less common than wet rot and is usually found only in old damp buildings with little ventilation.
Wet Rot
Wet rot is the much more common cause of rotten floorboards. Although not as severe as dry rot, it can cause problems if left untreated. It’s commonly seen in windows, doors, fascias, soffits, and other external wooden surfaces without rain protection. So, it should be evident that its principal cause is excess moisture soaking into the structure of the wood rather than a fungal infestation. Rising-damp, rainwater flowing through an external wall, flooding, or leaking plumbing all cause wet rot. And because it’s caused by spreading water, the rot can spread into floor joists, plaster, carpets etc., which will need thorough drying and possibly replacing.
Wet rot doesn’t have a particular odour but will feel damp and spongy because of the moisture held within the structure. You might also see black mould forming on and around the wet rot patch.
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How To Spot Floorboard Deterioration
Although different processes cause wet and dry rot, they often damage floorboards similarly. However, it can be difficult to spot issues with your floorboards as usually, they have a carpet hiding them from view. So, we’ll also look at various signs other than visual.
Floor Covered By Carpet
- Does the floor feel springy when walked on? If so, the rotten floor is no longer held in place by nails or screws as the wood structure has crumbled around the fixing.
- Are there areas of the floor that feel hollow or missing? Floorboards might have collapsed or broken, leaving gaps in the wood.
- Are some areas raised? If so, the floor has absorbed water and swelled up.
- Is the carpet permanently damp?
- Are there problems with rotten skirting boards?
Uncovered Floor
- Do the floorboards look bleached or fibrous? This can be one type of wet rot.
- Are there cracks along the grain, and does the wood appear darker than usual? This can be another type of wet rot or, perhaps, dry rot.
- Do the floorboards spring when walked on even if the metal fixings remain motionless? If so, the boards might have become thinner by crumbling from the underside.
- If the floorboard fixings move as well, you might also have a rotten floor joist.
- You probably have dry rot when the floorboard shows cuboid-like cracks along the board’s grain.
- The board might have lost all structural strength and cannot support your weight when walked on.
- The board might appear worn down through constant use.
Whichever issue you find with your floor, you should call in a professional who knows how to diagnose the problem correctly and has the skills to put things right.
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Replacing Rotten Floorboard Timescales
When replacing rotten floorboards, you must do a competent and professional job. Your safety depends on it. So, depending on the extent of the damage and the circumstances under which the damage has occurred, you might have many jobs to do. But, because of the varied situations, not every task is necessary. Therefore, to be sure, hire a professional who knows what they’re doing.
How To Replace A Rotten Floorboard
The following shows typical tasks while replacing a rotten floorboard:
- Remove furniture and carpet to expose the rotten floorboards and replace carpet and furniture when finished.
- Inspect the floor to determine the extent of the damage and the best way to remove the boards.
- If there’s significant damage, removing the entire board is probably better. Otherwise, only remove the damaged part.
- If removing an entire board, use a wood chisel to split the wood and remove pieces along its length.
- When repairing a part board, use a wood chisel or nail bar to lift a free end of the rotten board. Prise the board from the joists until you reach sound timber. Lever it above the top surface of the floor. Cut across the board at a floor joist using a saw to remove all the damaged wood.
- In both cases, remove old nails, screws, and glue to provide clean support for the new board at each joist.
- Inspect the joists for rot.
- If a small amount of rot is present, cut away until you reach sound wood. Then, bolt a replacement piece of joist to it, supporting its end in a galvanised metal joist hanger.
- If there is severe rot in the joist, lift the boards to gain access to the joist’s entire length. Then, remove the old timber and replace it with a newly treated beam.
- Remove all debris from beneath the floorboards and joists.
- Take the floorboard, remove the underside of the machined groove, and drop the board into place by inserting the tongue into the adjoining groove.
- Screw each board into place, ensuring the screw heads finish below the surface
Duration
The durations for these operations are as follows:
| Operation | Duration |
|---|---|
| Remove and replace furniture and carpet | 1-4 hours |
| To remove up to 4 rotten floorboards and prepare for fitting new | 2-5 hours |
| To replace up to 4 rotten floorboards | 3-6 hours |
| Remove and replace rotten floor joists and boards | 1-3 days |
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Relevant Building Regulations
- If you are renewing or renovating more than 50% of the floor, you must insert insulation to ensure the energy efficiency reaches the required level. You must comply with Approved Document L.
- If renewing floor joists, they and their supports must comply with Approved Document A – Structure.
- Flooring and its insulation must be fireproof to prevent a fire from spreading. This comes under Approved Document B – Fire safety.
- New joists and floorboards must be protected from moisture rising from below or soaking through the wall from outside. This comes under Approved Document C – Site Preparation and resistance to contaminants and moisture.
- All walls, ceilings, floors and windows must resist the passage of sound. Find soundproofing guidance within Approved Document E – Resistance to the passage of sound.
- There must be adequate ventilation under the flooring to prevent condensation. Therefore add ventilation according to Approved Document F – Volume 1.
As you can see, there are many Building regulations to comply with. So, it’s a good idea to ask for advice from the Building Control office at your local council before beginning the job.
What To Ask Your Joiner Or Carpenter
Repairing or replacing a floor is a skilled operation. You should hire a professional carpenter or joiner who knows all the safety aspects rather than attempt it yourself, especially if your joists need replacing, as these are structural parts of your home. Therefore, ensure you hire someone with experience in this kind of work.
Ask Around
Ask friends and family to recommend someone to do this work. It might cost more to hire a professional, but it’s worth it.
Ask About Experience
Not every professional carpenter or joiner has experience with structural woodwork and flooring. Therefore, ask for references and follow them up before deciding on the contractor.
Associations & Accreditation
The British Wood Flooring Association (BWFA) encourages education and training courses for carpentry contractors working with wood flooring. Members must prove competence in wood floor installation, and the organisation has a database on its website so you can find qualified members near you.
Although qualified carpenters don’t need accreditation, it helps them look more professional and shows they understand the latest safety regulations.
Get A Written Quote
Choose a shortlist of three or four qualified carpenters and ask for a quote from each. But, don’t automatically choose the cheapest. Instead, choose one that is midway between the two extremes.
Ensure the quotations are like-for-like. That is, ensure they’re quoting for the same thing and will use the same quality materials. If in doubt, ask the contractor for more information.
A written quote will specify:
- The contractor’s name and contact details
- What are the job’s details, with a list of tasks and how to do them?
- How much does the job cost?
- What materials will they use and their specifications?
- Who will remove waste materials?
- When must the customer make payment?
This information is essential as it prevents misunderstandings around pricing, and everyone knows what must be done.
Check If They Have Insurance
Insurance is essential for everyone. It doesn’t matter how skilled or experienced your carpenter is; accidents happen, and you need the peace of mind to know that if damage occurs, there is enough money to cover it.
You’ll also find that someone who doesn’t carry insurance probably doesn’t think much about safety in their day-to-day work. So, avoid them!
Don’t believe contractors when they say that your home insurance will pay in the event of an accident. Insurance companies probably won’t pay out as the person causing the damage isn’t you or your family. So, remember, it’s up to the contractor to have their own insurance for damage to your property and to cover injury and death for you, your family and any other third party.
Qualification Checklist
These days all professional carpenters have formal qualifications issued by recognised bodies such as City and Guilds. They will also have served a government-recognised apprenticeship as part of the qualification. However, having the qualifications doesn’t necessarily mean they can work on structural woodwork. Instead, look at the government-approved Competent Persons Register. The UK government provides a booklet to explain to customers the advantages of using a person registered on the Competent Person Scheme. The main advantage is that a contractor registered on the scheme can sign off their work without having a building control inspection. You will also receive financial protection if the work was later found non-compliant with the Building Regulations.
Find Local Pros
Rotten floorboards are something that you should fix immediately. Rot won’t get better by itself and can only worsen if you don’t improve the root cause. Therefore, select a qualified carpenter with experience in dealing with structural woodwork.
Complete the form on this page, and you’ll receive up to four floorboard replacement quotes so you can inspect them in the privacy of your home.
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