A shell loft conversion quotation needs an itemised description of the condition in which the space will be handed over. The word “shell” alone does not tell you whether stairs, insulation, electrical work, plasterboard or final decoration are included.
Ask each supplier to price the same drawings and explain what the next contractor would receive. You are then comparing a defined scope, and differently finished spaces are not treated as equivalent offers.
Describe the handover before comparing the price
Start with the approved design information and the current proposed package. Ask what will be physically complete, what remains exposed and what temporary arrangements will remain when that package ends.
England's Planning Portal loft guidance identifies matters including structure, fire escape and stairs for a habitable conversion. Splitting the project into packages does not remove the need to address the whole design and applicable approvals.
List planning permission, building regulations and any other relevant property requirements as project matters. A supplier's package name is not evidence that those matters have been resolved.
Use a shell-to-finished-room comparison
Copy this matrix into your quotation comparison. Record included, excluded, allowance or unresolved for every row, with a drawing or specification reference.
| Element | Boundary to confirm |
|---|---|
| Structure | Design responsibility, structural work, openings and relevant inspection information. |
| Roof and exterior | Weatherproofing, rooflights or dormer details, external finishes and temporary protection. |
| Stairs and existing rooms | Supply, installation, guarding, landing changes and making good below. |
| Insulation and lining | The complete specified build-up, service interfaces, board finish and decoration readiness. |
| Services | Heating, plumbing, electrical work, ventilation, final connections and specialist checks. |
| Finishes and handover | Doors, skirting, flooring, decoration, snagging and the documents supplied. |
Add access, scaffolding, waste removal and protection of the occupied home. Identify who removes temporary works and who repairs areas affected by subsequent trades.
Compare two unpriced example packages
Say Offer A includes the structural and external work plus the staircase, while Offer B leaves the staircase and landing alterations to another contractor. Both use the word shell. This is an illustrative comparison, not a Vayton project or a standard industry package.
Before comparing totals, ask Offer B's supplier to define the stair opening, temporary protection, design interfaces and condition left for the stair installer. Obtain the missing scope and associated price on the same basis. Do not simply add an assumed staircase allowance.
Make the interfaces visible
Separate contractors can depend on the same information. The lining installer needs the agreed service positions and build-up. The stair supplier needs the relevant dimensions and levels. Later finishes depend on the condition handed over.
Record the decision owner and what must happen before each follow-on package starts. Discuss who coordinates changes and how a design revision reaches every affected trade. Agree the inspection and handover information at each boundary.
Check the cost of reaching the intended finish
List the quoted package and every separately procured item needed for your intended outcome. Include design and approval costs where applicable, client purchases and making good. Keep the tax basis consistent and count each item once.
For a London loft conversion enquiry, send the existing and proposed drawings, specification and preferred package boundary. Say whether you want a shell or a finished room, then define what that means in the documents so a comparable scope can be discussed.