HOW LONG DOES IT TAKE TO BUILD A HOUSE / EXTENSION?

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When planning a building project a major part of the project that many people fail to fully appreciate is the time it takes from the day you decide you want to go ahead to the day it is all fully complete and you can enjoy your new home.

There are several aspects to a project that can impact on its overall timeline, below is an insight to the key stages and their impact on the completion date.

Finding a plot of land
Obviously if your project involves extending an existing building this will not impact on you. However if you are looking for that perfect building plot this can take years to find. Here’s a post I wrote previously about helping to find a plot of land.

Choosing your design team
Finding the right people for you project is key to getting the best end result. As you will probably work closely with your architect it is key to find someone you can get on with, who you trust to understand your needs and deliver the appropriate designs for what you are trying to achieve.

There are also several other people who may be called upon as part of the design process depending on the specifics to each project, such as: Structural engineer, site investigator, ecologist and many more. These specialists can often have a waiting time before they are able to undertake the required work and so this can sometimes lengthen the design process.

Project Design
Once the design team has started work on the project you should get initial proposals pretty quickly, maybe in a week or 2. These will then be developed further over the following weeks and months following client feedback. A simple extension should be designed within a couple of weeks, a more complex, bespoke home could take several months.

Developing a design should always be a collaborative effort with the client and Architect. They will require feedback from the client on their proposals to develop them further. Therefore, if you are going away on holiday or have a busy lifestyle this can prolong the design process.

Planning
Once you have a design for your build, there is a good chance you will need to submit this to the local authority planning department for approval. The standard time for them to give their decision is 8 weeks, sometimes this time can be lengthened in more complex applications.

If it is a small extension it may fall into Permitted Development. Although this means it will not require planning approval it will still take some time to design and will probably still require building regulations approval too.

Building regulations
The planning drawings only deal with a certain aspect of the design and further, more detailed, drawings are required to be provided for building regulations approval. These generally deal with the detailed specifications and materials for how the building will be built. It is common at this stage to have other consultants, such as a structural engineer, to provide aspects of the information.

As this part of the design process can often be quite complex and require coordination of specialist consultants in can take several weeks to complete. As always the more complex the project the longer it will take.

Tender & Choosing your builder
Once you have all your design and construction information for your project you need to get quotes from builders, this is called “going out to tender”. The builders will look through the detailed information, consult with their sub-contractors and suppliers and then return with a price for what they can build the project for.

For a simple extension this would take a few weeks, but as the project becomes bigger and more complex this could take a couple of months or even longer as the builder will need to get prices for individual elements from many different people.

Construction
Good builders are often booked up weeks, if not months, in advance. Once you have your chosen builder from the tender process it may a while before they are available to start on site.

Depending on the size and complexity of your project, the length of time can vary considerably. A small extension may take only 3 months, a larger extension maybe 6 months. A full new build large house on a complex site could easily take 12-18 months.

2 of biggest things that can regularly add time onto the length of construction are; bad weather and changes to the design. The weather is a difficult one to predict, as building in the UK you can have lots of rain any time of year! It is advisable to avoid starting a build during the winter as cold frosty conditions are not good for building in.

Many clients make changes to the design once the construction has started. This is fine but you must be prepared for additional costs and a delayed completion if work has to be redone.

Snagging
The project may have reached what is called practical completion and you can move into your new home, however little jobs may still need to be finished. These often focus on the finishes, such as the last bit of tiling or touching up scuffed painted work. If you are not careful this can drag on for several weeks if not months. Withhold part of your final payment to the main contractor until these minor issues are fully finished and they will be done much quicker!

The unexpected!
Like adding a 10% contingency into your financial budget it is always advisable to add similar into your timeline. This can cover anything from unseasonal bad weather or the planning department delaying their decision, to waiting for a preferred builder to be able to start and people being ill or going away on holiday.

You can often be faced with unexpected extra work once construction has started. This can sometimes occur when the ground conditions are not as expected, or finding old hidden cellars and wells. When working with an existing building there can be many unknowns that do not become apparent until the building is uncovered, from poor electrics and plumbing to major structural defects.

These unforeseeable issues cannot only add cost to your build but also time.

Example
Below is an example of how long it could take for an “average” extension:
Finding a plot of land – 0 months
Choosing design team – 1 month
Project design – 2 month
Planning – 2 months
Building Regulations – 2 month
Tender & choosing builder – 1 month
Construction – 4 month
Snagging – 2 months
Contingency – 1 month

Total – 15 months



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