From £86,432
WJ Builders is an established and experienced local extension builder in Porthmadog. Please contact us for a free, no obligation quote and competit...
From £86,256
Building & Flat Roofing Contractors is a trusted extension builder serving customers in Porthmadog and the surrounding area. Contact us to today to...
From £86,744
Fiting of door internal/external All joinery work from new joists to fitting off skirting boards Kitchen fitting Staircase or replac...

Building a granny annexe ranges from £86,256 (Building & Flat Roofing Contractors based in LL54) to £86,744 (Balmoral joinery/construction based in LL60), but these are just estimates that can help give you an idea of who will be better value in your area.
The best thing to do is to get quotes to build a granny annexe in Porthmadog by posting a job with HaMuch. We will send it to extension builders in Porthmadog who will be happy to help you.
| Location in UK | Hourly Rate | Daily Rate |
|---|---|---|
| Granny Annexe near Conwy | £28 | £211 |
| Granny Annexe near Conway | £28 | £211 |
| Granny Annexe near Llandudno | £28 | £211 |
| Granny Annexe near Colwyn Bay | £28 | £211 |
| Granny Annexe near Rhyl | £28 | £209 |
Whether you’re looking to extend your kitchen with a side return extension or you want to convert your basement into a liveable space, read our cost guides to get an idea of how much each project costs before getting a more accurate quote from our database of reliable tradespeople.

Underpin a building - £16,977

Two storey extension - £87,216

Build a timber frame extension - £25,477

Build a swimming pool - £80,477

Single storey extension - £44,547

Side return extension - £35,620

Install an RSJ - £1,677

Outbuilding - £9,477

Build a Mansard loft conversion - £51,477

Loft conversion - £28,850

Build a kitchen extension - £41,477

Hip to gable loft conversion - £41,477

Granny annexe - £86,477

Garden office - £9,477

Convert a Garage - £15,477

Garage - £17,977

Build a flat roof extension - £21,477

Build a dormer loft conversion - £41,477

Concrete foundations - £5,727

Convert a bungalow loft - £28,477

Convert a basement - £31,620