Advanced options
The base is not optional and not a corner to cut: a shed on damp ground rots from the floor up in 5 years however good the timber: the GBP 120 grid-and-gravel base is the best value insurance in the garden. Grade tells: overlap cladding = budget + shorter life: shiplap/tongue-and-groove sheds shrug off a decade+: pressure-treated timber doubles the interval between treatments. Metal and plastic sheds trade looks for zero-rot at similar prices.
What The Shed Cost Calculator Works Out
- Total cost: the shed price plus the base plus any assembly fee. A 6x4 budget overlap shed runs about GBP 350, an 8x6 mid-grade shiplap GBP 650, and heavy-duty or workshop grades four figures.
- Cost per year of life: the total divided by a realistic life for the grade: 6 years for overlap, 8 for mid shiplap, 15 for heavy-duty and 20 for premium, all assuming a proper base and treatment. The cheap shed re-bought twice out-costs the better one bought once.
- The longevity levers: a shed on damp ground rots from the floor up in 5 years whatever the timber, so the GBP 120 grid-and-gravel base is rot insurance. A GBP 30 pre-emptive re-felt beats a GBP 200 roof rebuild, and a 2-inch airflow gap to any fence stops the blind-side rot.
- Delivery charge (advanced): many retailers deliver free; others charge GBP 20-60, more for remote postcodes or kerbside-only drops to upper floors.
- Treatment per year (advanced): a 5-litre tin of shed preservative costs GBP 15-30 and an 8x6 wants one coat a year, or every 3-5 years if the timber is pressure-treated. Enter an annual average and it is multiplied over the shed's life.
- Expected life override (advanced): replace the grade-based assumption with your own figure, for example 25 years for a metal shed or 12 for a well-kept mid-grade one. Leave it blank to keep the automatic value.
- Security, guttering and electrics (advanced): a proper hasp, closed-shackle padlock and hidden hinge screws run GBP 30-60; a gutter kit and water butt GBP 40-80; a Part P armoured supply with a light and socket GBP 300-600. The contents of most sheds exceed the shed's value, so the security spend is rational.
- Lifetime cost of ownership and true annual cost (advanced): purchase, base, assembly, extras and every year's treatment over the expected life, then that figure divided by the years. This is the number to compare between grades and against metal or plastic alternatives.
- Budget 6x4 route over the same years (advanced): what repeatedly buying a GBP 350 overlap shed every 6 years would cost over your shed's life, on the same base and with the same extras and treatment. It usually proves the buy-once arithmetic.