A hip dormer — known in Dutch as a steekkap — is a small roof extension that cuts perpendicularly into the main roof slope, bringing light and headroom into the roof space. The dormer effectively “cuts into” the main roof, giving it its characteristic appearance.
Hip Dormer vs. Other Roof Additions
| Type | Description | Position |
|---|---|---|
| **Hip dormer / Steekkap** | Roof that cuts perpendicular into the main slope | Rising from the gable end |
| **Dormer window** | Rectangular extension with flat or shed roof | On the roof slope |
| **Hipped end** | Sloped triangular end of a roof | At the short end of the building |
| **Gable** | Triangular wall above the eaves | At the short side |
How Does a Hip Dormer Work Structurally?
A hip dormer is formed at the intersection of two roof pitches. This intersection creates a valley (valley rafter). The construction requires:
- Hip rafters — diagonal roof timbers at the intersection
- Jack rafters — rafters connecting to the hip rafter
- Waterproof junction — lead or EPDM in the valley gutter
When Would You Choose a Hip Dormer?
- To give a gable wall a window that would otherwise be blank
- To bring more natural light to the attic without a full dormer
- When a traditional architectural style better suits the character of the building
Maintenance of a Hip Dormer
The most vulnerable point is the valley gutter — where water collects at the inner corner. Check annually for:
- Leaf debris and blockages
- Damaged seals or flashings
- Rust in metal valley gutters
What Does a Hip Dormer Cost?
| Option | Cost (approx.) |
|---|---|
| Hip dormer built by contractor (incl. carpentry + roofing) | £/€ 4,000–9,000 |
| Valley gutter repair | £/€ 500–1,500 |
| DIY (materials only) | £/€ 1,500–3,500 |
> More guides and building plans: fredsdiyplans.com
Related Terms
- Hip rafter — diagonal timber at outer roof corner
- Valley rafter — diagonal timber in the roof valley
- Dormer window — rectangular roof extension