- Postcode district
- LL49
- Survey
- Free for new and replacement doors
- Typical lead time
- Typically 6–8 weeks for slimline systems after check survey sign-off
- Guide price
- From £5,095 inc VAT
- Nearby
- Pwllheli, Caernarfon, Dolgellau
- Building rules
- Wales
Sliding doors for extensions and garden rooms in Porthmadog: what to know
Before you settle on a door type, it helps to know what sliding doors for extensions do well and what to check before you order.
Self-building in Porthmadog or elsewhere in Gwynedd? Ask for the sliding doors to be quoted as part of a wider glazing package so the frames, colours and glass match across the house.
For a garden room at the bottom of a Porthmadog garden, think about access: large glass panels need a clear route from the road to the site.
- Setting the finished floor level before the screed goes down allows a low threshold, typically 15–25 mm, or a flush one with a drainage channel outside.
- Slimline aluminium systems with interlocks typically around 20–25 mm maximise the glass in a new rear wall, keeping the view as open as possible.
- Telling the engineer the door type and span early lets them design the beam above it to limit deflection, protecting the smooth running of large sliding panels.
Light and sun in Porthmadog
Because Porthmadog sees long summer days (about 16 h 55 min) and short winter ones (about 7 h 34 min), the elevation your door faces makes a real difference. With the midday sun at about 14° in winter, a south-facing door brings light well into the room; a west-facing door catches hot late-afternoon sun in summer.
What should you budget for sliding doors for extensions in Porthmadog?
The table shows guide prices for common sizes, supplied and fitted, including VAT. Your exact price is fixed in a written quote once the opening in your Porthmadog home has been measured.
| Overall width | Typical panels | Guide price (fitted, inc VAT) |
|---|---|---|
| 1.8 m | 2 panels | £5,095–£6,195 |
| 3.6 m | 2 panels | £7,795–£9,495 |
| 6.0 m | 4 panels | £11,395–£13,895 |
See every size on the sliding doors for extensions page or try the guide price tool.
From survey to fitted door in Porthmadog
Nothing is ordered until you sign off the surveyed specification. The door is made from the finished opening sizes (typically 6–8 weeks for slimline systems after check survey sign-off), and fitting usually takes 1–2 days, scheduled to the build programme. If you are in Pwllheli or Caernarfon, the same process and prices apply.
Rules for sliding doors for extensions in Wales
An extension in Wales needs Building Regulations approval, which covers its doors. The Welsh energy guidance limits the glazed area of an extension unless it is compensated for elsewhere, and glass in doors must be safety glazing.
Specification choices for sliding doors for extensions in Porthmadog
- Two-panel slimline. One sliding and one fixed panel, suiting openings up to around 3.6 m depending on the system.
- Three or four panels. More panels for wider extension openings, with one or more sliding.
- Corner opening. Sliding panels meeting at a corner with no post, for extensions open on two sides.
Questions about sliding doors for extensions in Porthmadog
Can you match other doors and windows in my Porthmadog home?
Usually, yes. Most aluminium and uPVC systems come in standard RAL colours and finishes, and we can quote dual colour where the inside and outside need to differ. Bring photos of existing frames to the survey.
What sliding doors suit a garden room?
A garden room usually suits a two-panel or three-panel sliding door sized to the front of the building, with a header strong enough to carry the roof without pressing on the frame. Aluminium systems are a common choice because they are stable and need little maintenance. Glass with good insulation helps if the room will be used all year.
When should I order sliding doors for an extension?
Order sliding doors for an extension as soon as the opening is built and a check survey can be done, and agree the target fitting date with your builder in advance. Slimline doors typically take 6–8 weeks to make after sign-off. Getting a quote from drawings early means the specification is settled and only the final measurements are needed.
What structural opening size should my builder leave for sliding doors?
Your builder should leave the structural opening size we give in writing for your chosen door, which is the frame size plus a small fitting tolerance on each side and at the head. The exact figure depends on the system and the threshold detail. We confirm it from your drawings early, then check the built opening before the door is made.

