Why a single shed price is unreliable
Two sheds with the same 8×6 ft label can have very different costs. One may sit on reused slabs with basic overlap boards and mineral felt; another may use a concrete slab, graded treated framing, structural sheathing, breathable membrane, durable cladding, insulated lining and quality doors. Location, access and labour widen the gap further.
A better estimate is a work breakdown. Price the base, floor, wall frame, roof frame, sheet materials, weather layers, openings, finishes, fixings, delivery, plant, waste and labour separately. The Make My Shed timber schedule gives one reliable starting quantity, but it intentionally does not pretend to be the complete bill of materials.
Base and groundworks
Groundworks can be almost free in cash for someone reusing sound materials on easy ground, or one of the largest packages where spoil removal, access and concrete pumping are involved. Include excavation, membrane or geotextile where specified, compacted sub-base, slabs or concrete, reinforcement, formwork, supports and drainage adjustments.
Also price the unglamorous logistics: skip or grab collection, wheelbarrow routes, temporary protection and reinstating lawn or paving. A low online slab price is not the installed base cost. If the site slopes, separate retaining or stepped-foundation work may exceed the shed framing budget.
Structural timber and sheet goods
Use the generated cuts to request merchant quotes by finished section, grade and treatment. Compare the cost of exact-length stock with standard lengths and sensible optimisation. A small saving from short stock may disappear when extra joints, connectors and labour are added. Allow for rejecting badly twisted pieces rather than forcing them into accurate frames.
Then add floor sheets, wall sheathing or bracing panels and the roof deck. Sheet thickness, exposure class and edge support affect price. Count complete sheets from a cutting layout rather than dividing total area by sheet area, because offcuts may not fit the remaining shapes and expansion gaps consume space.
Cladding, roof and openings
Cladding prices vary dramatically between basic softwood boards, treated profiles, thermally modified timber, composite products and metal. Add battens, membranes, insect mesh, corner trims, starter details, coatings and stainless or coated fixings. Surface area is larger than floor area and openings do not always reduce purchased quantities by much.
Roof costs include deck, underlay or membrane, the final covering, adhesives or nails, edge trims, fascia, gutter and outlet. Doors and windows combine frames, leaves, glazing, hinges, locks, stays, seals and flashings. Homemade openings can save money only if the materials, tooling and time are genuinely available.
Labour, tools and services
For a self-build, value your time and list tools that must be bought or hired: compactor, mixer, saw, nailer, access equipment and lifting help. Professional labour may shorten exposure to weather and improve accuracy, but quotes need a clear scope. Confirm who supplies materials, removes waste, prepares the base and applies finishes.
Electrical, plumbing, heating, insulation and internal lining can turn a shed into a small-building project. Obtain specialist prices rather than applying a percentage to the shell. Cable trenching and consumer-unit work are easy to overlook, as are ventilation, fire precautions and condensation control.
Build a budget that survives contact with the site
Create three columns: quantity, unit rate and extended cost. Mark each rate as quote, retail check or allowance. Add delivery by supplier rather than once overall, because timber, concrete and roofing may arrive separately. Include VAT consistently and note quote expiry dates. A contingency is for uncertainty, not for known omitted work.
Compare design choices by changing one package at a time. A pent roof may alter wall timber, roof area and drainage together; a wider door changes framing and ironmongery; a slab may remove the suspended floor but add concrete work. Re-run the designer schedule after each structural change, then update the rest of the budget manually.
Compare quotes on the same basis
Normalise merchant and contractor quotes before choosing. One price may include VAT, delivery and treated stock while another shows net rates for untreated timber collected from the yard. Convert them into the same units and highlight exclusions. For cladding and sheet goods, compare usable cover rather than face width or gross sheet area; laps and tongues reduce what reaches the wall.
Track committed, forecast and paid costs separately during the build. Update the forecast as soon as a design choice changes, not when the invoice arrives. Keep a small list of optional upgrades—better lock, extra gutter, internal paint—so they can be removed cleanly if essential groundworks exceed the allowance. This is more effective than cutting hidden structural or weatherproofing details to recover an arbitrary headline budget.
Price durability as a whole-life decision
The lowest initial price can be reasonable for a short-lived tool store, but it is not automatically economical for a workshop expected to last decades. Better drainage, accessible edges and replaceable roof details may save more than premium decorative finishes. Compare maintenance intervals and the practical cost of recoating, clearing gutters or replacing a membrane where access is tight.
Spend first on the parts that are difficult to revisit: formation, base levels, structural frame, concealed membranes and roof weathering. Doors, internal shelves and surface finishes are easier to upgrade later. Write the intended service life and maintenance plan beside the budget so cost reductions can be judged against an explicit goal rather than appearance alone.