I'm an architect myself and (after working with a lot of builders myself!) would urge anyone to re-consider skipping the design process in a home renovation project... whatever the size. There are many, but here are a couple of good reasons...
1. A designer can produce a comprehensive set of drawings and specifications. These are important to communicate the design to the builder and this will ensure that the builders’ quotations are competitive
and easy to compare. The drawings then form part of the building contract, resulting in less chance of surprise costs (and disputes with the builder)
2. If you would like, your designer can help manage the construction phase of the project. They will ensure you have a good contract with the builder, and will oversee the work to make sure it is carried out in line with the design and specification.
3. The right designer will find the best solution for your brief – whether this is to create more space, stamp your own style on your home or add value. A home renovation project can be a big investment and a good designer will help you spend your money in the best way possible.
AND architects/ architectural designers aren't necessarily as expensive or unobtainable as you'd think...
I recently started a website called Design for Me http://designfor-me.com/
which matches your project and requirements to the best architects and designers for you. It works a bit like a dating site. You shortlist your favourites and then invite up to 3 for a consultation. This is when you'd get their quotes for the work. You can choose to take one on... or not, that's up to you!
If you are trying to keep costs down, on the site there are students/graduates, freelancers and 'architectural designers' (who are not registered, and so cant officially be called an 'architect')... and their fees would probably reflect this.
We will also handpick and recommend some suitable designers for you. Let me know if I can help further.. my email address is firstname.lastname@example.org
p.s Oooops, sorry for writing an essay (i'm v. passionate that people get a designer as well as a builder!)