Creating A Cost Estimate For Your Self Build

In a recent episode of our Self Build Hour series, we were joined by quantity surveyor and self-build expert Tim Phillips. Tim provided his invaluable expertise on costing a self-build project to our viewers. If you missed the event or simply wish to revisit the valuable insights shared, don't worry – the video recording is now available on our website.

In this article, we’ll go through Tim’s top tips discussed during this webinar.

CREATING YOUR COST ESTIMATE

Getting a decent estimate of what your project is going to cost is essential, sounds obvious – but many don’t! You may know how much you have sitting in the bank, but how do you know this is enough to cover the costs? You need to obtain an estimate right at the beginning of the project.

In terms of forming your budget, you need to ask yourself these questions:

Can I fund this project? Whether it be an extension, renovation or new build.
How am I going to fund this project? Through equity, a mortgage or a loan?
Can I recover the costs on a future sale if this isn’t my ‘forever home’?

Once you've decided what you want to build, creating planning drawings with as much detail as possible will help you estimate costs clearly. These conceptual stages are best for discussing the scope of work and the specifications. You should also engage in early discussions about the build route.

A good place to start is using online tools like Microsoft excel or Google sheets. This will help you create an elemental cost plan where you can add the prices of your big-ticket items such as your windows and your superstructure. The estimated cost will become firmer and reliable when you decide on the exact specifications and the greater level of detail, but this is the best way to start.

Clearly define what features are ‘must-haves’ and ‘nice-to-haves’ so your team can determine what your priorities are. If you get your budget on time and on track, you may be able to squeeze in everything. The more detailed and complete your design and specifications are, the more accurate your cost quotations will be.

Certain suppliers will give you that information before purchasing, just make sure to check if VAT is included in these. New build houses are zero VAT rated, and extensions and renovations may have situations where the VAT will be 0% on any renewables. Read our article with Andrew Jones the VATman for more information.

Case studies from projects similar to yours are a valuable starting point for getting idea of your costs. Project in similar size may provide a cost per square metre. Online forums, such as BuildHub, or speaking to others at self-build seminars are both effective ways of gaining more information on costs.

ENGAGING A QUANTITY SURVEYOR

The best way to get on top of your costs is to speak to a professional quantity surveyor (QS). This is a highly trained construction professional responsible for managing and controlling costs and ensuring that the financial aspects of construction projects are managed effectively. Quantity surveyors can be brought in in the conceptual stages, even when you are your architect are working on the initial design.

Your quantity surveyor can use online tools such as the Building Cost Information Service (BCIS) to better interpret your material and labour costs. Whether your project is in Carlisle, Cornwall, or Cardiff, all costs are regionalised. Your QS can give you a very early idea of costs, which can help you make key decisions on your build early.

A QS is a vital cog in the commercial world, but their importance in the residential sector cannot be overstated.

The Royal Institute of Chartered Surveyors (RICS) is a reliable source for finding the right QS for your project. You can find out more about the role of a quantity surveyor here.

HOW TO ENSURE COST CERTAINTY IN YOUR SELF BUILD

The first step to effectively monitoring your costs is to agree a ‘design freeze’ to stay on track with your cost plan. This means your design will undergo no major alterations. This is essential to keeping your final cost as close to your original estimates as possible.

Once this has been agreed, your quantity surveyor can prepare a bill of quantities. This bill is what you would use to send out your tender documents.

Eradicating as many variables and unknowns as possible before starting on site. For example, a site investigation conducted before construction begins could identify any unsuitable ground conditions. This would cost around £2000 – 4000 for a self-build home, but it’s very worthwhile if the condition of your ground is unknown.

When hiring self-build professionals, try to avoid fees that are a percentage of the build cost. If your build costs go up, so do your professional fees. A fixed fee proposal is the best course of action, as there is now a motivation to keep the costs as low as possible.

Deciding on how you’re going to build your project will have a significant impact on your cost estimate. Your cheapest option will be managing the project yourself, and the more expensive is hiring a professional project manager or going turnkey. From a cost perspective, managing the project yourself has its attractions, but beware of the time required and the rising costs of your labour and materials. A professional PM comes at a price but can provide certainty and reassurance of fixed costs.

The biggest way to ensure cost certainty is to set your specifications and design early on, as this is where the project can spiral out of control. Your superstructure can fluctuate in price depending on your choice of finish, such as opting for a more expensive brick and block finish over render or timber.

Your interior is another example, as flooring, tiles and paints can bring creeping costs towards the end of the project. Choosing laminate flooring over travertine or mixing your own paint at a paint centre are two ways to keep your costs down and gain a more accurate representation of what those costs will be.

This advice is courtesy of our Self Build Hour webinar with Quantity Surveyor Tim Phillips. Tim has a vast experience as a quantity surveyor and has been featured been featured in Homebuilding and Renovating magazine on multiple occasions. Visit his website or contact him to learn what he can do for your project.