What is a mansard loft conversion?
A mansard loft conversion rebuilds the roof with a nearly vertical slope (about 72 degrees) and a flat top, effectively adding a new storey. Small dormer windows sit within the steep slope. Mansards are common on period terraces in towns and cities.
How much does a mansard loft conversion cost in Merthyr Tydfil?
In Merthyr Tydfil, a mansard loft conversion typically costs £60,000–£87,500 for a typical rear mansard, including VAT at 20% (standard rate). Building costs in Wales run about 8% below the UK average, and the figures for Merthyr Tydfil are adjusted to reflect that. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| A typical rear mansard | £60,000–£87,500 |
| Higher specification | £87,500–£109,500 |
The biggest cost drivers are:
- Front, rear or both
- Bathrooms and finishes
- Number of dormers and lead work
- Scaffolding on busy streets
Your exact price depends on the survey and drawings. The guide price tool gives a quick range in the meantime.
Do you need planning permission for a mansard loft conversion in Merthyr Tydfil?
The approval route for Merthyr Tydfil is set by planning law in Wales. In Wales a mansard roof needs planning permission and is judged against local design guidance.
Building regulations in Wales are set by the Welsh Government. Approval comes from the council’s building control service or a registered building control approver, with inspections during the work and a completion certificate at the end.
Our first visit includes a check of your planning history, so you know the route before paying for drawings.
What we handle
What we take care of:
- Dormer windows
- Planning drawings and application
- Structural design and calculations
- Staircase and fire-safe escape route
- Building control sign-off
- Party wall notices to both neighbours
How long does it take?
The build itself usually takes 9 to 12 weeks on site, after planning approval. Allow time beforehand for drawings and approvals, usually 3 to 4 months.
Building in Merthyr Tydfil
Terraced houses in Welsh towns often have narrow plots, which suits rear and side return extensions and rear dormers.
If your home is in Merthyr Tydfil or close by in Aberdare, Rhondda and Ebbw Vale, a free home visit is the first step.
How it works
- 01
Free visit
We look at the property, talk through what you want and measure up. There is no charge and no obligation.
- 02
Design and fixed quote
Drawings, structural calculations and an itemised, fixed price for the agreed specification.
- 03
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 04
Build and sign-off
We run the build to a written programme and hand over the completion certificate.
Questions about mansard loft conversions in Merthyr Tydfil
Do you build mansard loft conversions in Merthyr Tydfil?
Yes. We build mansard loft conversions across Merthyr Tydfil, including postcodes CF47. Every project starts with a free home visit.
How much does a mansard loft conversion cost in Merthyr Tydfil?
In Merthyr Tydfil, a mansard loft conversion typically costs £60,000–£87,500 for a typical rear mansard, including VAT at 20% (standard rate). Your fixed price depends on the survey and drawings.
Can I stay at home?
Usually. The new roof is built under a temporary cover so the house stays dry.
How long does it take?
Around 9 to 12 weeks on site, plus 2 to 3 months for planning and party wall matters beforehand.
Do I need party wall agreements?
Yes, mansards on terraced houses almost always involve both party walls.
Do I need planning permission for a mansard loft conversion in Merthyr Tydfil?
In Wales a mansard roof needs planning permission and is judged against local design guidance.