The idea of getting several prices for your project is designed to encourage building contractors to keep their margins down, so you can find the best price, but how do you make sure the quotes you get for your building project are realistic, and how do you select which quote to go with?
Comparing quotes from several builders is not straight forward, as price is far from the only variable but you should never base your judgement on price alone.
Everyone’s dream is to get their building project completed in the shortest possible time frame and on budget. This ambition is achievable, but usually at a price, and usually only if you hire a main contractor with a large well-organised workforce, good experienced project managers, and if you have a set of accurate drawings and specification documents with every detail finalised.
Whilst this level of organisation will allow your project to progress as near as possible like clockwork – and you will have the security of a watertight formal contract with penalty clauses for late completion – this is a very expensive way to build. At £2,000 – £3,000/m² for new build work, plus 7-12% in supervising architect’s fees, this route is well beyond what most self-builders would be willing, or are able, to pay.
At the other extreme of the builder market is the small contractor who may have at most two or three employees on his books, with the bulk of the building trades undertaken by a network of subcontractors that they can pull in, as and when they need to.
They, too, will be able to provide you with a quote for your new home, and will agree to work to some form of contract. With smaller overheads to maintain, and a less expensive workforce, the smaller contractor’s price is likely to be considerably lower than a large contractor’s — perhaps £1,200 – £1,800/m² for new build work.
The quote you receive, however, is unlikely to be anywhere near as detailed as the one provided by the main contractor. The larger firm will almost certainly have used a quantity surveyor to work out the price to the last minutiae. The smaller contractor is more likely to have relied on their experience to come up with estimates for each aspect of the project, making the two quotes difficult to compare.
Whichever route you choose, you should end up with the same house. Go with the cheaper price and you will usually save money, but the downside is that the job is likely to take longer, depending on how much other work the contractor has on at the same time, and how busy – and reliable – the subcontractors that they depend upon are.
These two examples illustrate some of the reasons why prices for the same work can vary so enormously, but there are many others that you should take into account when comparing quotes.
Getting a QuoteTo get an accurate price, you’ll need to supply builders with lots of information
The starting point is inviting builders to quote for your project — as opposed to giving you an estimate of the cost. A quote is a more binding price calculated using the information you, or your architect, provides. A builder will not be able to produce a quote until you have full plans and a detailed specification. The documents required by a builder in order to prepare a quote, known as the ‘tender documents’, need to include the following information:
Apples for apples? Even when you've ensured your builders are pricing the same thing, quotes often bear very little resemblance to each other — here’s some reasons why
Quotes vs EstimatesA quotation (quote) is a fixed price that can’t be changed once accepted by the customer. An estimate is an educated guess of what a job might cost, but it isn’t binding. You’re looking for quotes based on full specification documents and plans, as opposed to estimates.
Knocking through internal walls can be a great way of making the most of your existing space, but there’s a lot to consider first...
Changing the internal ‘flow’ of a property can be one of the best ways to transform its appeal without spending a fortune. Knocking through interior walls is potentially a great way to create a feeling of light and space — sweeping away cramped, dark and dingy rooms. For example, in properties with tiny kitchens, taking out the wall separating this room and an adjoining dining room can dramatically improve the layout at minimal cost compared to building a new extension.
But inevitably, any job involving indoor demolition is going to come with a number of health warnings. For a start, internal walls can play an important role in holding buildings together, so in some cases, ripping them out can be structurally unwise. In period properties there can be a real danger of creating a sterile environment devoid of historic features and original layouts that many buyers demand.
However, as long as they’re carefully planned, layout alterations can be highly successful at overcoming drawbacks with the original design.
Taking down or altering internal walls isn’t an activity that normally concerns the planners, unless, of course, you’re working on a listed building. However, before making any sort of structural alteration a Building Regulationsapplication must be made. Building Control will then inspect the work on site and ultimately issue a completion certificate.
In most cases you will also need to consult a structural engineer to design a suitable beam or some other supporting structure so the remaining loads are safely transmitted to the ground.
Before demolishing an internal wall it’s also worth considering whether it protects you from fire. For example, where the loft has been converted, the walls around the staircases offer protection, allowing you to escape in the event of a house fire. Altering these walls will again require Building Regulations consent, even if they’re not load-bearing.
On a similar basis, should you want to convert the loft in the future, partition walls that separate entrance halls from reception rooms are best left intact, since they form a ready-made fire escape corridor to comply with Building Regulations.
In terraced or semi-detached houses, where new beams need to rest in the party walls that separate you from the neighbours, it’s also advisable to first talk to a specialist Party Wall surveyor to ensure compliance with the relevant legislation.
It’s not unusual when buying a property for the conveyancer to glumly announce that there is no evidence of Building Regulations consent having been obtained for structural alterations. Even though there may be no apparent defects, if there is no completion certificate to prove that the work was properly carried out, this could be an accident waiting to happen.
In this situation the best course of action is to contact Building Control and arrange an inspection. At worst you may need to obtain a Regularisation Certificate, which is the equivalent to making a retrospective Building Regulations application. This normally requires a certain amount of physical opening up of the work to establish that it is structurally sound and verify compliance; the cost of making good afterwards will be down to you.
Be prepared for the dust:
Identifying Load-bearing WallsSome internal walls are fundamental to the structure of the house, whereas others simply divide up the interior space and are relatively straightforward to alter or remove. Depending on the age of the property, the internal walls will be built of either solid masonry (brick, block or stone), or of lightweight timber stud or metal frame construction; sometimes a mix of both of the latter. As a rule, older, pre-1970s homes tend to fall in the solid masonry camp (which homeowners tend to prefer because it’s easier to fix things to them and they have better soundproofingqualities).
Conventional wisdom has it that if you tap a wall and it sounds hollow it’s just a studwork dividing wall. In fact, somestud walls are load-bearing. Conversely, solid masonry internal walls aren’t always ‘structural’ — some were built as simple partition walls. If in doubt, the best advice is to consult a structural engineer or building surveyor, but in most cases it’s best to assume a Building Regulations application will need to be made.
As a general guide, to see if an internal wall is load-bearing, you need to check if it’s supporting any of the following:
Roof loadings:In older houses the roof structure often relies on support from an internal wall. More modern roofs with W-shaped roof trusses (introduced in the late 1960s) are designed to span right across the house from the main wall to another without internal support.
Floor loadings:Floor joists rarely span more than about four metres without support from an internal wall or beam. Look for nail runs in floorboards to identify the direction the joists are running in (usually at right angles to the direction of the floorboards).
Loadings from walls above:Ground floor walls often continue above as bedroom walls. However, sometimes upstairs walls are offset or supported on a beam. Most modern houses have lightweight stud walls to the upper floors.
Lateral support:In older houses, internal walls often provide ‘lateral support’ helping to tie together the adjoining walls either side.
Builders tend to refer to internal wall demolition jobs as ‘knock-throughs’. This might involve anything from just cutting a new door opening, through to the complete removal of an entire wall.
Building Control normally require a structural engineer to specify an appropriate beam or lintel, and this should be done before getting quotes from builders so they know how much to charge.
As with most jobs, there are a number things that can sour relationships unless properly factored in from the outset:
For new door openings, the upper part of the old wall will be left in situ above the new opening (known as the downstand). But where an entire load-bearing wall is removed, a ‘clean sweep’ at ceiling level may not be possible as the new beam will normally be visible. Bear in mind that steel beams need to be boxed in with plasterboard to comply with fire regulations. If a continuous ceiling is aesthetically important, one solution is to build a new suspended ceiling to conceal the beam.
Once a wall is removed it often becomes horribly apparent that the floor levels in the newly conjoined rooms either side aren’t perfectly aligned, because they were never designed to meet. Even a small difference of a few millimetres will stand out, requiring additional floor levelling work. Similarly, newly exposed wall surfaces may require the attention of a skilled plasterer.
A steel lintel resting on padstone engineering bricks supports the new opening:
Creating a New OpeningOnce the structural engineer has calculated the loadings and come up with a suitable solution to satisfy Building Control, work on site can proceed. But before any demolition work is carried out, the masonry above must be temporarily supported while a slot is cut for the new beam or lintel. This slot normally needs to extend either side of the opening with a bearing of at least 150mm. To spread the load, additional support will be needed under the ends of the lintel, such as padstone engineering bricks. The new opening can then be cut out underneath.
Bear in mind that party walls in older properties aren’t always ideal for supporting new loadings. For example, some were built one-brick thick (about 100mm), and may not be sufficiently strong for this new role. In which case, it may be necessary to build new brick piers or install steel columns to support the new beam — which could mean having to excavate small foundations internally, adding significant expense and disruption.
Adding living space is more popular than ever, but many people start their extension project without knowing enough about design, the law, construction and planning
20 things you must know about extending — and probably don’t.
1. The ‘Right to Light’ Exists in LawYour neighbour may attempt to block your plans by claiming they have a legal right to light to one or more of their windows. There is such a thing as a legally established ‘right to light’, usually established automatically ‘by prescription’ after 20 years, however, it is only relevant in limited circumstances.
A right to light is a type of easement and overrides anyplanning permission you might have and your permitted development rights. It can in theory, therefore, prevent you from blocking out a neighbour’s window. However, it only provides for whatever light is reasonably required for the use of the building. It does not mean that your extension cannot obstruct a neighbour’s window or view, or reduce the amount of sunlight entering – these are planning considerations.
Rights of light are only likely to be relevant in city centres where buildings are very close together. In such circumstances contact a specialist lawyer.
2. You Can Have WCs and Shower Rooms AnywhereIt used to be a requirement of the Building Regulations for there to be a lobby between a WC and any other room. This was commonly conceived to be for reasons of hygiene and to relate to the kitchen where food is prepared.
Although it is desirable for reasons of privacy to locate WC facilities off hallways, circulation space, lobbies or theutility room, this is no longer necessary under the Building Regulations. It is, however, necessary for there to be a wash basin and suitable ventilation to all WCs.
You can also put a shower room anywhere that has enough space. A basic shower room need measure only 900mm wide by 1.8m (or 2.6m if it is to include a WC and basin). The cost of creating a shower room within a bedroom will be £2,500-3,000 providing the plumbing is within reasonable proximity.
3. Minimum Ceiling HeightsAlthough the legal minimum ceiling height has now been removed from the Building Regulations, there is still a practical minimum height and this is especially worth thinking about in attic and cellar conversions. All rooms should normally have a floor to ceiling height of at least 2.1m throughout (standard ceiling height is 2.4m). In rooms with sloping ceilings, at least 50% of the floor area should normally have a floor to ceiling height of at least 2.1m.
4. You Need Site InsuranceMany people don’t know that most home insurance providers will not cover the building if you are changing the structure of the build — for example extending, doing a conversion or renovation. When carrying out the works you need to have site insurance with an A rated insurer to cover the existing structure and the new works until you complete the works.
Builders will often say they have insurance but it is important to check their documents as the majority have liability cover which will require you to prove fault in the event of a claim, which can mean a lengthy legal battles. This may also not cover any natural events claims, such as fire, flood and storm damage.
If you are vacating the property during the build, you will require site insurance or unoccupied buildings insurance which will usually be a minimum six month policy. Always contact your existing insurance provider to notify them of works before you start.
5. Avoid Through RoomsWorking out the most efficient and practical way to access an extension is often the greatest design challenge. Do not sacrifice more than you are gaining, for instance by slicing up a good sized bedroom in order to gain access to an extension that adds only one more bedroom of a similar size.
Using an existing room to access an extension rarely works unless it is sufficiently large and the furniture carefully arranged. Such rooms usually end up as nothing more than a corridor and a dumping ground for homeless storage.
Circulation space is very important to the healthy function of a house, ensuring that it is liveable and that the best use is made out of all of the space. When extending, this may mean rethinking the function of every room in order that the principle rooms, most importantly the kitchen, dining and living space, can all be accessed directly from the main hallway.
In smaller houses where there is no space for a separate hallway, it is a good idea to have at least a small lobby or enclosed porch to create privacy from the front door.
6. Make Your Conservatory Part of Your HomeYou can integrate a conservatory into the existing house to make it an extension to an existing room, rather than a bolt on, but you have to be careful with the design.
The Building Regulations require most conservatories to be separated from the existing house by exterior quality doors. Such a doorway with a threshold can leave the new space feeling isolated from the rest of the house and unless the conservatory is large enough to work as a room in its own right (the minimum is around 3m x 4m) it can end up being an expensive, underused space.
Double doors can be left open to help make a conservatory feel like part of the house, but even double glazed conservatories lose heat quickly and so most people end up closing their conservatory off for the winter months to help keep their home warm and their fuel bills down.
With a bit of redesign to reduce the glazed area, the section of exterior wall separating it from the existing house can be completely removed. This turns the conservatory into a true extension, and by incorporating sections of plastered wall and insulated solid roof, a conservatory can be used to extend an existing room such as a dining room or kitchen.
To turn a conservatory into an extension you must provide your local building control department with calculations that show that the amount of glazing in the windows, doors and roof of the conservatory/extension, together with the amount of glazing in the windows, doors and any rooflights in the original house, do not exceed 25% of the floor area of the conservatory and all floors of the house added together.
New windows and doors in the conservatory/extension will need to meet the current U-values required by the Building Regulations.
7. Consider Adding Basement SpaceIf you have an existing cellar, you can convert it into living space without using up the volume allocated to you underpermitted development rights. Creating basement windows and external access will not usually require planning permission either, although it is always worth checking your local authority’s policy on basements. All work must, however, comply with the Building Regulations laid out in the Approved Document – Basements for Dwellings 2000 (www.basements.org.uk).
Converting existing cellar space to bring it up to habitable standards costs from £1,000-1,500/m² providing there is already enough headroom. Creating a new basement beneath an existing building to add extra space is also possible. The cost is £3,000-4,000/m². Due to the cost, it is usually only financially viable to retrospectively add a basement in high value areas such as Central London.
8. Balance Your AccommodationAlthough there are no legal requirements to provide more than one bathroom, it is practical to have a least one full bathroom on the same floor as the main bedrooms. For larger households it helps to have at least one en suite bathroom — ideally to the master bedroom.
If you are extending to add extra bedrooms, clearly creating the number of bedrooms needed for the household is the main priority, but this should, if at all possible, be balanced by an increase in the number of bathrooms. Future buyers will expect at least one bathroom and a shower room on a four or five bedroom house and without this the value will be constrained.
An additional bathroom on the ground floor of a house should be a last resort. It is functional but will add little if anything to the property’s value as bathrooms away from bedrooms are impractical (aside from for those who work outdoors).
9. Know the Building Regulations for ExtensionsEven if you do not need planning permission for your extension, because you are using permitted development rights, you must get building regulation approval.
The Building Regulations set out minimum requirements for structural integrity, fire safety, energy efficiency, damp proofing, ventilation and other key aspects that ensure a building is safe.
Most repair work is excluded from the Building Regulations, with the exceptions of replacement windows, underpinning and rewiring. However, apart from certain new buildings such as sheds, outbuildings and some conservatories, all new building work, including alterations, must comply with the Building Regulations.
Typical Examples of Work Needing Approval:
10. You Can Start Within 48 Hours of Notifying Building ControlOnce you have dealt with planning, if you are in a hurry to start extending, you can commence work immediately after giving the local authority building control department 48 hours’ notice. You are required to submit a ‘Building Notice’ and the required fee.
Generally the Building Notice method is more suitable for simple works where detailed drawings are not required, but it can be used for any project, with the exception of work to listed buildings.
For most extensions it is best to make a Full Plans application. This involves submitting detailed drawings, specifications, calculations and a location plan for inspection by the local authority, together with the application forms and appropriate fee.
Building control has to respond within five weeks unless you agree to give them an extension to two months. A Full Plans submission allows any irregularities to be resolved before work commences.
With a Building Notice, the building control officers can ask for proof of compliance at any stage, so it is essential to make sure they make all necessary inspections and provide any structural calculations when requested. When the project is completed and inspected by the local authority, a completion certificate will be issued which will prove useful if the property is ever to be sold on. Application fees are set individually by each local authority.
11. What About Removing Your Walls?You don’t need walls to define rooms. Creating larger, more open spaces by knocking down walls will help to make a properly feel larger. The fewer walls you use, the more spacious and light a property will feel. This applies whether you are extending your home or just choose to remodel instead.
You can define separate rooms and functions by using all sorts of other features such as furniture, lighting, floor coverings, decoration, floor or ceiling levels, and informal room dividers such as kitchen island or peninsula units, fireplaces, open shelving, island walls or even the staircase.
If you are unsure whether it will work, visit show houses built by developers. Most now feature at least an open plan kitchen breakfast space instead of a separate kitchen and dining room.
12. There are Different Rules For Extending in Conservation AreasIf you live in a Conservation Area your Permitted Development rights – extensions and alterations that do not require planning permission – are restricted. Each local authority has its own policy for Conservation Areas but generally the basis of the policy is to prevent the loss of character of the Conservation Area. So, if you are thinking about extending your home, always contact your local conservation officer first.
Consequently planning permission is required for the addition of dormer windows or any other change to the shape or height of the existing roof, including the addition of Velux rooflights if they face the highway. This means that attic conversions will almost always require planning permission in a Conservation Area.
13. Have You Really Thought Through Your Loft Conversion?Before embarking on an expensive attic conversion think carefully about the cost relative to the amount of useful space that can be gained, and the impact on the existing accommodation. In order to comply with the Building Regulations to form an additional bedroom in the roof space, the floor may need strengthening and the roof will need to have at least 150mm of insulation, plus a 50mm clear air gap (unless you are able to replace the existing roofing felt with a breathable membrane).
The result of bringing the loft space up to habitable requirements is that the ceiling height will typically be lowered by 60-100mm and the floor level raised by at least 15-20mm. Both of these changes will reduce the amount of usable space with good headroom. If steel purlins or joists need to be added, too, this can further reduce the space.
If the usable space is limited, consider raising the roof height by rebuilding it, or even lowering the existing ceiling height below. Accessing a habitable loft conversion requires a permanent staircase and this will need landing space.
If you decide the cost of a full loft conversion cannot be justified because of space constraints, consider improving the loft space to create storage accessed by a fold-away loft ladder or space-saver staircase? This can be achieved at a significantly lower cost than a full conversion. Attic conversions cost from £600/m² for a simple conversion, up to £1,500/m² for more complicated work.
14. Extending a Listed Building Can Be ProblematicPermitted development rights do not apply to listed buildings, so any extensions will need both planning and listed building consent. The design of any extensions to a listed building need to be of a very high quality and it will be necessary to use the services of a specialist architect or surveyor.
It will be essential to work closely with the local authority conservation officer if you are extending your home. Each officer will have their own perspective on what will alter the character of a listed building. It is a criminal offence to alter a listed building, inside or out, without listed building consent.
15. Permitted Development is Not Always StraightforwardUnder the new rules, the ‘original’ (as it stood in or prior to 1948) rear wall of a detached home can be extended by up to 8m in depth with a single storey extension; this is reduced to 6m if you are extending a semi-detached home or terrace. If your proposed new extension will be within 3m of a boundary, then the eaves height is limited to 2m under Permitted Development.
If you hope to build a two storey extension (no higher than the house), this can project up to 3m from the original rear wall, so long as it is at least 7m from the rear boundary. It’s also important to note that no extension can project beyond or be added to what is deemed to be the front of the house or an elevation which affronts the highway. A side extension cannot make up more than half your house’s width.
Furthermore, with the exception of conservatories, new extensions must be built of materials ‘similar in appearance’ and with the same roof pitch as the main house. So while Permitted Development rights are beneficial, there’s a lot to consider before extending.
Is there anything else I can do under my Permitted Development rights?Prior to the new legislation, volume limitations were applied to the entire house — so if you were extending, you were unlikely to be able to convert your loft under Permitted Development rights as well. The good news is that the latter has now been separated out, allowing you to undertake both without one restricting the other. So when you are extending your home, you can also convert your loft into a bedroom or extra living space by up to 50m³ in a detached house, or by 40m³ within any other home.
16. Minimum Room SizesIt can be tempting to try and subdivide existing and new space into as many bedrooms as required, particularly if budget or the size of the extension permitted is restricted. However, there are minimum sizes beyond which rooms will not function.
When considering applications for conversions, most local authorities have recommended minimum room sizes which planning applications must conform to. However, the rules about sizes are more applicable to social housing and are usually relaxed for private accommodation, but you should still bear them in mind if you are extending.
Function of roomMinimum Size
Bathroom and WC3.6m²
Bathroom only2.8m² (or 1m² of circ.)
Hallways and landings900mm widthIn addition, rooms must always have external windows, with the exception of non-habitable rooms such as kitchens, bathrooms, dining rooms and studies.
17. Know the Party Wall ActYour neighbours cannot stop you from building up to, or even on, the boundary between your properties, even if it requires access onto their land (providing you have planning permission to do so, and there are no restrictive covenants).
The Party Wall Act etc. 1996 allows you to carry out work on, or up to, your neighbours’ land and buildings, formalising the arrangements while also protecting everyone’s interests. This is not a matter covered by planning or building control.
If your extension involves building or digging foundations within 3m of the boundary, party wall or party wall structure, or digging foundations within 6m of a boundary, the work will require you to comply with the Party Wall Act. In these cases you may need a surveyor to act on your behalf. The act does not apply in Scotland.
(MORE: The Party Wall Act)
18. There is a Difference Between an Estimate and a QuotationAn estimate is normally a contractor’s guess as to what your extension will cost. Whether given verbally, or in writing, is not legally binding and the final bill may exceed it.
A quotation is a definite price. When deciding which builder to choose, always get written quotations from at least two firms, ideally ones that have been recommended to you.
The written quotes should itemise the work to be done, provide a breakdown of costs and a total, and state whether VAT is included. When you receive the bids, check whether there are any caveats which might involve extra expense. Also, compare provisional sums for work such as foundations to make sure you are comparing like with like.
19. Beware of Removing TreesSome trees are protected by Tree Preservation Orders (TPOs). Even if an extension does not require planning permission you cannot alter or even prune a tree that has a TPO on it without planning permission.
All trees within a Conservation Area are protected by legislation and effectively have a TPO on them providing they have a trunk of diameter greater than 75mm. Altering a tree that is protected by a TPO is a criminal offence and can result in substantial fines so take care if you are extending your home near to a protected tree.
20. You Probably Can’t Claim VAT Relief if You Are ExtendingMost extensions will be subject to VAT on labour and materials at the standard rate of 20%, especially if you use a contractor to undertake the work. If you use local tradesmen who are not VAT registered you can save the 20% VAT on their labour, but you will still have to pay VAT on materials at the standard rate.
Some extension projects are eligible for VAT relief, such as work to listed buildings (zero rated), the conversion of an existing dwelling that changes the number of units (reduced rate of 5%) and work to a building that has been unoccupied for at least two years (reduced rate of 5%).
To benefit from VAT relief if you are extending a listed building or renovating an unoccupied home, you must use a VAT registered builder — you cannot reclaim the VAT yourself.
The big reveal has finally happened at the DIY SOS project in Welwyn and the family were delighted.. well done to our carpenters Rich and Will for all their hard work over the last 2 weeks.