Explain how the loft is used and any future plans. Assess existing insulation and the full build-up before adding layers. External insulation can affect roof height and connections to gutters or neighbouring roofs, as discussed by Milieu Centraal. Include these details and interior finishing in the quotation. Check current subsidy requirements separately before making financial assumptions.
Describe how the space is used
Say whether the attic is storage, a bedroom or a future living space. Mention heating, ventilation and visible damp. The existing use and renovation plans provide context for choosing an insulation approach.
Identify the existing layers
Collect drawings and information about previous insulation or roofing work. Ask which layers are verified and which need investigation. Adding insulation changes the complete build-up, so the decision should not be based on material thickness alone.
Discuss connections before choosing
Include roof edges, wall junctions, rooflights and penetrations in the plan. Ask how moisture and ventilation are considered for the chosen build-up. Those details must suit the existing building and proposed work together.
Compare complete proposals
Compare the same roof sections, removal, access and finishing in each quotation. Identify which insulation and roofing items are included and which are separate. An insulation-only price cannot be compared directly with a full roof renewal.
Make junctions part of the comparison
Ask each contractor to show the transition at retained elements and changes in height. Discuss a rooflight replacement at the same time if planned. This avoids discovering an omitted connection after the main system has been chosen.
Ask what the stated values mean
Check whether a quoted insulation value describes a product or the whole roof component, and which thickness it relates to. Keep the product specification. General guidance is available from Milieu Centraal; your own roof still needs assessment.