Whilst this is one of the most important considerations when thinking of adding a conservatory to your home, it is also the most difficult subject to cover precisely.
To help you consider this in more detail, we have summarized the main cost variables below under design factors, building factors and other factors. All of these will have an impact on the overall cost of your project.
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 they have been agreed.
Size
Clearly, the size of the conservatory 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. However, be aware that two conservatories of exactly the same size can be vastly different in cost due the effect of the other factors listed below.
Design Style
The final design style of your conservatory will have a significant affect on the overall cost - generally, the more complex the design, the more expensive it will be.
For example, a ‘lean-to’ style with a single plane roof will be less expensive than a multi-faceted design including roof valleys and projecting ridges.
two conservatories with the same floor area can be vastly different in cost.We would be keen to encourage you to create a beautiful building, but be aware of the potential cost impact of any design decisions that you make. For more details on design styles, see our section on The Design Process.
Specification and Materials
Your choice of materials and specification will have a major impact on the overall cost of the works.
Some items, you will have little or no choice on such as external wall finishes which will generally match the existing property.
However, be aware that different companies will often use very different building standards for items such as foundations, floor and wall construction. Because conservatories are generally exempt from building regulations approval (see our factsheet on Building Regulations for Conservatories), there is little or no independent control and it is easy to cut costs by reducing the amount of concrete or insulation in the design.
At myhome mygarden, our view is that the foundations, wall and floor construction should be the same standard that you would use for a traditionally built extension as this will give a much better performance when using the building.
Your choice of material for the framework will affect the cost – generally, PVCu is the least expensive followed by aluminium and timber being the most expensive.
Glass to the roof will cost more than polycarbonate and it is a good idea to ask for a cost option on both.
Also remember that your choice of fixtures, fittings and finishes will have a significant influence on the final cost of your extension. Floor tiles, radiators, blinds all vary hugely in cost.
When budgeting for your project, make sure that you allow sums for all the items.
Fixtures and fittings such as your choice of heating can vary enormously in costArchitect/Designer
Your choice of architect or designer will influence 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.
Many conservatory companies will carry out the design work in house and offer a design and build service but check if this includes dealing with any council submissions.
At myhome mygarden, we offer a design service that is independent from the conservatory supplier 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 site can affect the building cost as land locked gardens (i.e. where there is no access except through the house itself) will lead to the work being more labour intensive.
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.
Many Victorian properties were supplied with water from a well which may still be in the area of your proposed extension.
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. You may discover all sorts of things including wells, poor ground conditions, air-raid shelters, damaged drains, water pipes or electric cables in the area where works are being carried out.
Other areas of work such as 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 effect 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. Get advice at an early stage.
How can we help?
myhome mygarden can provide a comprehensive Feasibility Study for any conservatory that you are considering 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 conservatory 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.