Whilst this is one of the most important considerations when thinking of converting your cellar, there are a lot of variables that will affect the final cost of the work.
To help you consider these in more detail, we have summarized them under design factors, building factors and other factors.
Remember to add the cost of any design/architects fees, council charges or other professionals such as structural engineers and party wall surveyors.
A. Design Factors
The various aspects of the design of your proposal will play a major part in determining the cost of the project. Be sure that before you agree to a final design, you have a good idea of the likely cost as it can be expensive and time consuming to change your plans once work has commenced.
Size
Clearly, the size of the cellar will have an effect on the overall cost. Generally the bigger it is, the more expensive it will be as more materials, labour and plant are required to build it.
If you are planning to increase the size of an existing cellar, then make sure you have a good idea of the cost of this before proceeding.
Design Style
Remember that ultra modern can also mean ultra expensive!
The final design style of your conversion will have a significant affect on the overall cost - generally, the more complex the design, the more expensive it will be. For example, a curved wall with large amounts of glass will cost more than a straight wall with a single window or door. If you are creating large open spaces, remember that extensive structural steel work is expensive.
We would be keen to encourage you to create a beautiful space, but be aware of the potential cost impact of any design decisions that you make.
Specification and Materials
Your choice of materials and specification will have an impact on the overall cost of the works so make sure you are aware of the cost of other items such as floor finishes, heating, etc before agreeing to them.
Make sure that you have allowed for upgrading the insulation to the correct building regulations standard and decide on how the floor and walls will be waterproofed.
Your choice of fixtures, fittings and finishes will have a significant influence on the final cost of your conversion. Supply and fitting kitchen units and appliances can vary from £1,500 to £50,000. Sanitaryware such as showers, basins and baths vary hugely in cost.
Fixtures and fittings can vary enormously in cost
Your designer should provide you with a detailed specification for the work so that that there are no misunderstandings as to what has been included.
Architect/Designer
Your choice of architect or designer will have an affect on the overall project cost. Some designers will cost more than others although be aware that a well thought out and specified design could save you money in the long run by avoiding misunderstandings at the building stage.
At myhome mygarden, we offer a design service that is independent from the builder and will arrange for a number of quotations from our approved contractors (for more information, refer to our Project Services section.)
B. Building Factors
If you were to give the same set of plans to twenty separate builders, it is unlikely that any two would provide you with exactly the same figure. It is not uncommon to find a vast difference between the lowest and the highest quotations, leaving you as the homeowner with no idea of what the true value is and who to choose to carry out your work.
Below we look at the various factors at the building stage that will affect the overall cost of your project.
Access
Access to the cellar can affect the building cost as there is likely to be some amount of excavation work involved. If the only route is through the house then there is likely to be more labour involved to move new materials and dispose of soil, etc.
In the last decade, the building process has become more and more mechanized and if the builder can not complete the work using equipment such as mini-diggers, he is likely to charge a premium for this.
Choice of Builder
Your choice of supplier or builder will undoubtedly affect any quotation you receive. Builders work in different ways with some carrying out one job at a time and others carrying out many projects simultaneously. Some will have higher overhead costs (i.e. office, yard, vehicles, etc) and will need to allow for these in their quotation.
Builders will take differing views on the level of profit they will expect. Some are happy to earn a daily wage and will treat any additional profit they make as a bonus whilst others will want a good return in addition to a daily rate. Generally successful and busy builders with good reputations know that they do not have to charge rock bottom prices to get work in and will probably be more expensive.
At myhome mygarden, we carry out a thorough vetting process for the builders and tradesmen we use and, as we are confident in their workmanship, put our own warranty on the work they complete.
The Unexpected
Even the best builders in the land are not fortune tellers and finding unexpected additional costs once works have commenced is a regular occurrence on building projects.
Groundworks such as foundations and drainage works, in particular, are the most common areas for this due to the difficulty in assessing conditions on the site. If you are lowering the floor level, you may need to allow for underpinning the existing house foundations so it is a good idea to dig trial holes first.
Other areas of work such as rotten or woodworm infected timbers, poor quality plumbing or electrics may also be discovered once works have commenced. The older the property, generally the more chance there is of finding the unexpected.
We would advise you to allow a contingency sum in your budget of 10-20% to cover the unknown.
Human Error/Misunderstanding
Whilst this may sound minor, many arguments between the customer and builder relate to the original cost of work and what was included in the quotation. The builder may have genuinely missed an item of work out when preparing his quote which other companies have allowed for and you assumed was included.
Make sure that all the work is clearly defined in order to avoid this as you will encounter problems if you choose a builder that is half the price of all the others because he has not included some of the work. This normally results in continual requests for additional payments or the builder walking off site or even going bust.
C. Other Factors
There are some influences on the cost of the work that do not fall into either of the above categories and these are summarized below:
Location
Building in city centres will often cost more due to traffic and parking problems.
The location of the property in the country will affect the overall cost as labour costs vary between the north and the south. As property is cheaper to buy or rent in the north, tradesmen can charge lower rates for their services. The Royal Institute of Chartered Surveyors (RICS) provide a Property Makeover Price Guide which, using a specific example of a 3m x 3m single storey extension shows that it would cost approximately £23,940 in Greater London compared with £19,320 in the North West.
You may also find that properties in city centres are more expensive to extend due to the additional time and cost of deliveries, getting to work and parking.
Demographic
In recent years there has been a glut of quality EU tradesmen but many of these are now returning to their native countries and this has reduced the level of competition. The RICS Property Makeover Cost Guide states that the cost of improvement work has increased by 20% in the last two years as a result of this and rising costs of transport and raw materials.
Be aware that quotations will only be valid for a certain period of time and the cost of the project may rise if you decide to go ahead after the validity date.
Interest Rates/Inflation
Many people fund their project by extending their mortgage so any change in the interest rate may have an effect on the amount you repay.
VAT
Some design services and builders are not VAT registered as their turnover is lower than the required limit. Businesses with annual sales below £67,000 (2008-2009) do not have to register for (and therefore charge) VAT, but they may choose to do so voluntarily. If they don't, the price you pay for their goods or services may be cheaper than if you bought the same goods or services from a VAT-registered supplier.
However, be aware that £67,000 in building turnover is not a high level and builders working below this are likely to be small jobbing builders.
Some works such as works for disabled persons are zero rated for VAT so you will be able to claim any VAT incurred back.
Summary
Some or all of the above items will have an affect on how much your project will cost you and they demonstrate the importance of getting expert advice and employing experienced people to carry out your project for you.
How can we help?
myhome mygarden can provide a comprehensive Feasibility Study for any cellar conversion which is an excellent way of finding out how much a proposal will cost.
See the Feasibility Study section of our site for more information and a sample report and plans.
If you decide to use myhome mygarden for your conversion project, our system is set up to minimize misunderstandings and building costs are tightly controlled under our Project Management system.
Call us Free on 0800 3800 141 to find out more