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Article on Estimating project cost by adam

Estimating project cost

Adam Weaver

How much will the build cost?

... would have to be the number one question facing any owner builder. 

From our perspective, it's a vital question, too, as that sets the maximum amount of money an insurer can reimburse you following damage.

Build cost

For a starting point, talk to your council or to your private certifier. Chances are they've seen all of this before, and might have some tips for you as to a "standard" sort of per-metre figure to use. But that figure is just a starting point, costs can increase from there.


Hopefully you've worked out a project timeline (whether in a Gantt chart or just with pencil and paper) so you have a rough idea of what needs to happen when. Now factor in some slippage - what happens (for example) if the brick delivery is delayed? Or the concreter falls ill (or busy on another job). What will a two week delay cost?

Sadly, delays cost more than just time. Hired in plant, equipment and temporary buildings need to be extended at additional cost, and the "competitively priced" tradesman may not be available for that new window of time.

Again, talk to your certifier or your builder to find out what a reasonable "slippage" percentage would be.

Materials shortages

Sometimes, some of the more exotic building materials have an unusual supply chain. The fancy wall materials coming from Eastern Europe (this is a real incident) could be delayed massively by shipping, or even a disaster like a fire at the originating factory. Those panels tick all the boxes, but if you can only have one supplier, there's additional time & money risk to account for as well.

Mistakes and accidents

Lastly, any damage on the project will cause delay while your tradesmen have to clear away the old damage and start again. Hopefully you're insured so the extra materials & labour cost will be indemnified ... but the time delay can't be insured.

We've seen disasters happen at the 11th hour, sending the owner builder almost back to the start line to rebuild. The costs were fully insured, but the aggravation and heartbreak isn't.

Simple advice

One simple thing is to find out what a professional builder would charge to do the work. It will probably be a lot more than your own projections, but part of that extra cost will be the builder factoring in slippage, supply chain disasters, and a general "cost overrun" allowance as well. On top of that Allrisk owner builders receive a 15% allowance for "escalation" to cover off some increased costs (typically following regional catastrophes) so you have a bit of additional leeway.

Why not get a range of quotes from us today? Our quote process is very simple to complete - 90 seconds on our online form and you'll have a quote document in your e-mail setting out a range of options to consider.

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