Planning an extension is usually a major investment for most people and while no-one wants to compromise on quality, they don't want to pay more than necessary. Here are some tips on how to keep costs to a minimum
1. Keep it simple
The more complex your extension design is, the more expensive it will be. Therefore simplifying your plans will make it cheaper and can make a huge difference to the final costing. A rectangle or square footprint with a flat roof will be the most cost effective option, as the biggest cost when carrying out any extension is when bespoke, curved buildings are created. Also look at how much space you are creating with your extension. For example a single storey extension that is rectangle in shape with a perimeter of 40m in length (two walls of 15m, two walls of 5m) will create an area inside of 75m2. Similarly a square extension with the same perimeter, 40m, (four walls of 10m each), would create an inside area of 100m2, an increase of 25%, without any extra cost.
Use standard materials that are readily available such as a felt roof or cast concrete for the floor. Also see if you can avoid building near trees or drains and sewers and other buried services to avoid increased groundwork costs.
2. Love thy neighbour
If you are building on or near the boundary of a neighbour, your extension will need to comply with the Party Wall Act (England & Wales) 1996 and you must notify them in writing about your extension plans eight weeks before you start. If you can get them to write back that they do not object, particularly if you provide the reassurance to make good any damage caused as a result of your building work, you may be able to avoid using a surveyor to arrange a party wall settlement and save on considerable fees. It pays, therefore, to keep neighbours on board with your project, discussing plans in advance and being considerate about any concerns they have, which will help avoid delays once work has started.
3. Avoid cowboy builders
There are plenty of dodgy builders (as in any trade) and they may vastly underestimate costs through lack of experience or possibly, deliberately to secure a job. They may then ask for more money for changes or ‘extras’.
To avoid being ripped off, always ask for references, and check them. Also check if they belong to a trade body such as the Federation of Master Builders, which quality checks all members before they are allowed to join, which provides a guarantee of the quality of their work. Never pay for building work in advance. For a small project, pay when the job is finished. For a larger jobs such as an extension, agree payments at set stages, or interim payments, making sure the last payment is made when work is completed and you have received the final certificate from building control.
4. Negotiate trade discounts
Find out where those in the trade buy their materials and aim to get the same trade prices such as kitchen suppliers. Always negotiate and see if there is any discount for paying in cash, making sure you get a receipt. Buying end-of-line deals can save a fortune, especially on items such as carpets, bathrooms and appliances.
Getting the best deal can mean moving away from big brand names and finding similar equivalents, without compromising quality and still getting the ‘look’ you want. Also consider sticking with a standard specifications such as radiator-based central heating, carpets for floors and standard white sanitaryware. Overspending on finishings and projects taking longer than scheduled are two big areas that will eat into profits
5. Do it yourself
It can be tempting to get the job finished and get back to normal as quickly as possible, including getting your builders or someone else to do the decorating. But you can make considerable savings by doing it yourself. You might even consider doing your own tiling, fitting your kitchen or fixing architrave and skirting etc. However, poor workmanship and wasted materials can be a false economy so make sure you have the necessary skills.
Can you re-use any of the materials you would normally throw away in your extension construction. For example, any floorboards, brickwork and possibly your fittings, can be given some tender loving care and re-used. If they can’t be used again, many salvage yards will sell these items, which will be cheaper than their new counterparts. Re-using will also have the added benefit of reducing the amount of space you need in terms of skip hire by throwing everything away. Also look at recycling radiators and furniture too.
7. Get your measurements right
It has been estimated that 1/6th of the materials purchased end up in landfill. Reducing waste in construction means maximising material usage. With few exceptions lumber, drywall, flooring, sheeting of various types are provided in 2’0” increments. Planning your design with 2’0” increments will dramatically reduce waste.
8. A bit on the side
Extending into the side return to widen the kitchen at the back of a typical Victorian terrace house or semi is a classic design solution. If your neighbour is thinking about doing the same thing, you could make savings by sharing a builder and on the shared party wall at the property’s boundary. Using off-the-shelf rooflights over a single-storey side return is also a cost-effective solution to adding plenty of light, rather than a bespoke single window.
9. Going up
Making use of your existing roofspace is usually the most cost-effective way to add space and value to your home. In contrast, extending under your home is likely to be the most expensive option and, because of the importance of having a guarantee on the waterproof tanking in a basement extension or cellar conversion, it’s not something that you can easily manage yourself with subcontractors.
While basement extensions are the most expensive way to add space, it can be made more affordable by excavating under the garden instead of the house, as you can use a mechanical digger under the garden as opposed to having to dig under the house by hand.
10. Working within your budget
You should have a contingency budget in case anything goes wrong. However you can still bring down the costs of any project simply by planning in advance, getting quotes and knowing where you can safely reduce your outgoings without jeopardising the project.
Most extension work will attract VAT at 20 per cent on labour and materials, and you may decide to use tradespeople that don’t charge it. That is because their turnover is less than the threshold for VAT registration. However, it will only take one or two extensions to take them over the threshold, so make sure you know how experienced they are and question why they are under the threshold. If they are a small trader then make sure they have the manpower to complete your job within reasonable timeframes.
Ginger Dog Homes is a building company based in Kingston upon Thames specialising in extensions, loft conversions and renovations. The team has worked across Surrey and SW London for over 10 years.