Checklist for dormer and loft conversion

Orientation

• What purpose will the room serve (bedroom, bathroom, study)?
• How much headroom is needed?
• How much daylight do you want?
• Which location on the roof is most suitable?
• Is a skylight sufficient, or is a dormer necessary?

Planning permission

• Completed the permit check at the Omgevingsloket (online permit portal)?
• Does it fall under permit-free building?
• Does a different regime apply (protected cityscape, monument)?
• Are the municipality's aesthetic requirements (welstand) known?
• Have you submitted an outline planning application (principeverzoek) when in doubt?

Construction

• What roof structure does the house have (rafters or purlins)?
• Has a structural engineer been consulted for the trimmer (raveel)?
• Are wind and snow loads taken into account?
• Is the construction drawing complete (floor plan, cross-section, details)?

Insulation

• What Rc-waarde (thermal resistance value) is achieved?
• Which insulation material is used?
• Does the insulation run continuously around the dormer?
• Is there a vapor barrier membrane on the inside and a breathable membrane on the outside?

Ventilation

• Is a ventilation grille or a tilt-and-turn window with a ventilation setting included?
• For wet rooms: is mechanical extraction provided?
• Is the extraction humidity-controlled?
• How is overheating in the summer addressed?

Choice of materials

• Which exterior cladding (uPVC, wood, zinc, polyester, Keralit, Trespa)?
• Which window frame material (uPVC, wood, aluminum)?
• Which glass (HR++, triple, possibly fall-proof or safety glass)?
• Which roofing material for the flat roof (EPDM, bitumen, zinc)?

Electricity and heating

• Enough power outlets in the right places?
• Separate circuit in the switchboard?
• Lighting central and/or indirect?
• What form of heating (radiator, underfloor heating, split AC)?

Fire safety

• Smoke detector installed in the loft?
• Is the escape route safe and not through a kitchen?
• For a bedroom: accessible openable window?
• Fire-safe penetrations for electricity and ventilation?

Waterproofing

• Lead flashing or lead substitute correctly applied?
• Is the slope (fall) of the flat roof sufficient?
• Rainwater drainage without blockages?
• Side cheeks neatly connected to the roof tiles?

Interior finishing

• Plasterboards mounted while preserving the vapor barrier membrane?
• What finishing level (wallpaper-ready, paint-ready, turnkey)?
• Window sill and trimming chosen?
• Knee walls placed and storage space made accessible?

Delivery

• Go through the delivery check with the contractor.
• Take photos of all connections.
• Put points that still need fixing in writing.
• Ask for the warranty certificate and maintenance instructions.

Maintenance

• Annual inspection of lead flashing, EPDM, and drainage.
• Keep rainwater drainage clear.
• Check seals and sealant every few years.
• Periodically paint wooden window frames.
• A thorough inspection by a professional once every five years.

Communication with contractor and neighbors

Many projects run well technically but poorly in communication. A few agreements prevent 80% of irritation:

• Single point of contact at the contractor, with a phone number.
• Weekly brief contact (five minutes is enough) about progress and bottlenecks.
• Written documentation of deviations from the quote, prior to execution.
• Construction log in which the contractor notes daily what was done and what follows tomorrow.

For the neighbors:

• Inform in writing two weeks in advance about the work period, hoisting day, and working hours.
• Provide a phone number for complaints — if they can reach you, they won't call the municipality.
• Offer insight into drawings of the shared wall side; goodwill is worth its weight in gold.
• Take photos of the existing condition of the dividing wall, in case of any later discussion about damage.

Planning and living during construction

A dormer or loft conversion takes longer than the working days on site suggest. Count from the first appointment with a contractor:

• 2–6 weeks quotes, choices, and contract.
• 4–12 weeks delivery time of material (especially window frames and prefab elements).
• 6–12 weeks planning permission procedure (if applicable).
• 3–15 working days on the construction site.
• 2–4 weeks finishing, inspection, and outstanding points.

During the construction period itself, the top floor is often uninhabitable due to dust, noise, and open roof phases. Plan for this: sleep elsewhere, remove valuable electronics from the immediate vicinity, keep bedding outside the dust zone. For families with young children, staying with family for a few days or a temporary relocation is sometimes wise.

After delivery: first year

The first year after delivery is the time when hidden defects present themselves — and when warranty conditions for many parts expire. Maintain the following rhythm:

• Month 1: visual check of all sealant, lead flashing, and window frame connections.
• Month 3: after the first heavy downpour, check ceilings, seams, and rainwater drainage.
• Month 6: check for condensation at the coldest moments; consciously manage the ventilation settings.
• Month 11: complete inspection before the end of the one-year construction warranty; report any defects in writing.

Keep a folder with the quote, planning permission, drawings, photos of the delivery, warranty certificates, and invoices. When selling the house, this documentation is valuable; in the event of a complaint, it is indispensable.

Frequently asked questions

Brief answers to frequently asked questions on this topic.

When is a checklist useful?

From the very first moment. The earlier you introduce structure, the less you forget.

Does price belong in this checklist?

Not as a rate; see the guide on cost factors for the price-determining elements.

Do I have to check all the points myself?

Not all, but make sure you know who does what and when.

What is the most important part of the delivery?

A joint walk-through with photos and written agreements about what still needs to be fixed.

What is an outline planning application (principeverzoek)?

A preliminary consultation with the municipality to test whether a plan is likely to receive planning permission.

How often do I inspect my dormer?

Visually annually and thoroughly by a professional once every five years.

Is a smoke detector mandatory?

In a new living space in a loft almost always, and recommended in any case.

What do I do with points the contractor forgets?

Document them in writing immediately — a paper agreement on repairs prevents discussion later.

Do I need to think about storage space in advance?

Yes. Knee walls and small hatches are difficult to add afterwards.

How do I store my documentation?

Keep a single folder (digital or paper) with the quote, planning permission, drawings, delivery documents, and warranties.

Summary

A good checklist guides you through all phases of a dormer or loft project: orientation, planning permission, construction, insulation, ventilation, materials, electricity, fire safety, waterproofing, interior finishing, delivery, and maintenance. Forgetting one point could mean an expensive correction years later.

Conclusion

A dormer or loft conversion is not a project where you can change course halfway through. Go through a checklist like this again in every phase: before construction, during execution, and upon delivery. By working this way, you get a space that functions without surprises and provides enjoyment for years to come.