I built my two storey extension for 20% of builder's quotes

This site shows how - step by step from design to completion

Designing your own House Extension


Not being an architect by trade, designing my own extension seems pretty daunting. However, my objective is not to become a qualified architect. I don't care about the stuff you need to know when designing skyscrapers, box girder bridges or a new, straighter tower for the good people of Pisa. All I want to learn is the 'stuff' needed for my, pretty mainstream, project.

Building an extension where to start! I logged on to my Local Council website and downloaded the plans for recent applications in my area to give me house extension plans examples. I pored over them to see what home extension ideas architects were using when designing extensions for my neighbours.

I scribbled down some design ideas and talked them through with my wife. I think it is important not to rush the design stage. Even when we thought we had come up with everything possible, given mulling time another idea would pop into our heads. Some designs raised some technical questions. Again, with a bit of trawling, I found architects plans that had addressed any issue in my mind. Also, a trip to a Self Build show in Swindon (there are many throughout the country - just Google self build show) proved very useful as there are manufacturers and experts all to happy to chat.

existing-rearTwo before and after models I would later create in Sketchup, but for now, show you what I was thinking.



Eventually, considering our goals, namely our desire not to gut the period property and make it totally unrecognisable, our budget (how to extend house cheaply) and the Conservation Area sensibilities, we settled on a design which involved raising our present single storey to two storeys and infilling with a single storey. The design didn't tick every single one of our boxes but it is rare that any design doesn't have some element of compromise. 

I started Googling like mad about every aspect of design. For example, obvious, but easy to overlook if you don't do this every day, different roof tiles are designed to suit different roof pitches. I wanted my extension to have roof tiles to match my existing tiles, so knowing the acceptable roof pitch for such tiles was essential prior to design.

I found that manufacturers and suppliers offered a considerable amount of technical information on their websites. Whenever a question raised in my mind, I contacted suppliers of roof tiles, underfloor heating, blocks, bricks, insulation, roof felt, windows etc. I found that they were only too pleased to chat, help me with my query and send me literature.

I was ready to press ahead with my design and draw up the plans. It would cost me nothing other than time to make accurate drawings of my scribbles, so, with nothing to lose, I fired up Autocad knowing that if my drawings ended up looking like a bad Jackson Pollock I could always back down and employ an architect. There is now a good deal of software available to design an extension online free. There are also house extension cost calculator online.