So weirdly enough, one of my favourite hobbies is actually shed building. It is such a common structure around the world however, and is genuinely requested a lot. For personal use or even for work, many do pay for the services to have a shed built, and after a few years I actually have a small amount of advice that I can share for anyone who wants to try to build one themselves!
You should always ensure that the shed is built with a solid foundation. When building a shed you should never expect it to last long if you build with a weak foundation. Really, sheds should be built on strong materials such as blocks of concrete or wood timbers (read my previous post!) that have already been pressure-treated and set directly into the ground with enough spacing. This is to ensure that the sheds supported and levelled correctly. I would also suggest that you build on dry land if you want to really focus on the life expectancy on your shed. When the land you build on is wet, your shed will be more exposed to erosion. On top of that, if the shed will be built in a location which is generally prone to rainy conditions (such as London), then building the foundation on gravel can ensure that the foundation will be protected somewhat from erosion also.
Sheds that are on average larger (such as 200 sq. ft. in size) should really have permanent foundations which have been set down into the land any extended into the frost line. Usually this should be constructed from buried wooden posts or even poured concrete piers. Again, I would always suggest that any wooden materials that you use for shed building have been pressure treated to protect them somewhat from rot and erosion, as they damage more than you realise.
It is just as important to allow air circulation within the shed itself. People do not realise that moisture gets into sheds easily if they are not circulated correctly, and this moisture can rot the flooring, doors and framing. It can even slowly corrode the shed doors hinges over a sustained period of time. But this is easily fixed when ensuring the mudsill (which is the lowest laying wood of the shed) is 6 inches above ground level. This will allow for air to circulate. You can also help circulate air into the shed correctly by allowing enough space around the shed itself, as things such as trees, fences or even hedges allow blockages to sunlight and wind, and ensure that the shed does not give enough clearance space for the shed to keep dry. The space will also allow easy access when making repairs or just for general maintenance and upkeep.
You should also use low maintenance materials if you want to build a long lasting shed. The majority of people who actually build sheds usually do not have the free time spare to ensure that the shed is maintained often enough, which means using materials which are generally low maintenance will save you a lot of time. Although they are more expensive in comparison to regular materials, it is generally worth the time and trouble that is saved. Materials like vinyl, aluminium and plastic lumber and even steel doors, fibre glass and faux-slate roof shingles will all go a long way to ensure your shed is low maintenance. Even fibre-cement siding and composite decking could be considered.
Depending on where you live and the areas general weather, you could also focus building a floor frame that is weather resistant. Allowing enough space and using the right materials can mean that your shed will last longer surviving the weather. Although you would be happier to pay less, your shed won’t be exposed to as much rot or erosion this way.
Granted none of these options I have spoken about are cheap or even easy to install generally, they are actually a lot more time and cost friendly than you think. Considering that you don’t have to spend as much time or money on maintaining your shed, it does pay for itself overall.