Caerphilly sticking French doors: what it means and what it costs
Sticking French doors behaves slightly differently here than it does on newer estates. Stone-fronted terraces, post-war semis around the castle and newer estates out toward Bedwas means deeper reveals and older fixings, so what looks like a serious fault often turns out to be adjustment. We cover CF83 on a regular run via A468, so a diagnostic visit rarely sits in the diary long.
What actually causes it
- 1the master leaf dropping on its hinges and closing the middle gap
- 2the slave leaf shoot bolt sockets clogged or out of alignment
- 3the frame flexing because the head has no packing above it
- 4seasonal expansion on a sun-facing pair with dark foiled frames
Why this comes up in Caerphilly
- Council
- Caerphilly
- Postcodes
- CF83
- Main route
- A468
- Nearest town
- Cardiff (7 mi)
Around Bedwas, Trethomas, Machen the recurring local factors are wind-driven rain off the mountain ridge; noise from the A469 corridor; tired 1990s-era double glazing failing at the seals. Commercial neighbours such as Pontygwindy Industrial Estate and Bedwas House Industrial Estate change the exposure again on the elevations that face them, and the Caerphilly County Borough Council area sets the standards any replacement work is signed off against.
- Bedwas
- Trethomas
- Machen
- Energlyn
- Llanbradach
- Abertridwr
- Rudry
- Nelson
- Ystrad Mynach
- Senghenydd
- Aber Valley
What you'll notice first
- the two leaves catch on each other in the middle as they close
- the slave leaf shoot bolts no longer drop into their sockets
- a visible taper in the gap down the meeting stile
- one leaf closing fine while the other needs a firm pull
Your realistic options
Both leaves reset at the hinges, shoot bolt sockets cleaned and repositioned, then the pair set so the meeting stiles close parallel.
New keeps and a fresh gasket run restore compression, which stops the draught that usually arrives alongside the sticking.
Where the frame has bowed in a wide opening or the leaves have distorted, a new set — with the head properly packed this time — is the durable answer.
French doors are very often adjustable back to perfect. The exception is a wide opening where the frame head has deflected, because that pushes the leaves out of parallel every time you correct them and it will keep coming back until the structure above is dealt with.
What we check on survey
- we check the gap down the meeting stile top to bottom before touching anything
- we test each shoot bolt individually with the other leaf open
- we look for deflection in the frame head, which is the fault that keeps returning
- we confirm the threshold is still level across the opening
How it's priced
Realignment is a single short visit. Keeps and gaskets add a small parts cost. A replacement pair is priced by overall width, glazing spec and whether a threshold change is needed.
How urgent is it? Fairly prompt. If the shoot bolts aren't engaging, only the master leaf lock is holding the pair shut, and that's not adequate security on a rear elevation.
What we typically find on survey
- A homemade timber threshold has been screwed to the concrete cill in front of the patio door.
- One sash locks by lifting a nail out of the frame — a bodge from a decade ago that everyone forgot about.
- The bay-window front elevation has a visible smile — the middle mullion has sagged and taken the head with it.
- Original door furniture is 90s brass, tarnished, and no longer matches anything else on the elevation.
- The escutcheon on the front door is loose and rotates as the key turns.
- The stay arm on the top vent has bent and no longer sits into its rest bracket cleanly.
How we actually carry out the work
- The frame reinforcement steel is confirmed by knock-test before selecting the fixing pattern.
- The internal architrave is coped rather than mitred where the reveal wall is out of true.
- The frame drainage slots are checked and blown clear before the beads go in — a plugged slot fills the chamber.
- The composite slab is not trimmed on site — if it doesn't fit, a new slab is ordered rather than reduced.
- The threshold is bedded on butyl mastic under the outer skin, giving the fitter a second waterproof line behind the perimeter silicone.
- The frame perimeter sealant is a low-modulus polymer where the substrate is going to move — plain silicone otherwise.
Stopping it coming back
- always drop the slave leaf bolts before locking — leaving them up loads the meeting stile
- oil the shoot bolts and hinges twice a year
- don't let the doors swing in the wind; a gust into an open leaf is what bends a hinge
French Doors That Stick Or Won't Shut — questions we get asked
Why do my French doors only stick in summer?
Dark frames on a sunny elevation expand. If the pair was set with minimal clearance, they'll bind at the hottest point of the year and free up again in autumn.
The slave door bolts won't drop — what's wrong?
Usually the socket has filled with debris or the leaf has moved a few millimetres. Both are adjustment jobs, not replacement jobs.
Can French doors be adjusted or do I need new ones?
Adjusted, in most cases. Replacement is honest advice only where the frame or the leaves have physically distorted.
Is sticking French doors more common on Caerphilly properties?
It's shaped by the local stock. With stone-fronted terraces, post-war semis around the castle and newer estates out toward Bedwas, plus wind-driven rain off the mountain ridge and noise from the A469 corridor and tired 1990s-era double glazing failing at the seals, the components involved in this fault tend to age faster here than on sheltered inland new-builds.
Do you cover sticking French doors across the whole of Caerphilly?
Yes — CF83 and the surrounding villages, including Bedwas, Trethomas, Machen, Energlyn. Easy in via the A469, and we're 10 minutes from the A470 for vans loaded with full-house glass.
If replacement is the answer
Other faults we see in Caerphilly
A composite slab that catches on the frame has almost always moved at the hinges, and hinges are adjustable in three planes.
ReadYellowing is cosmetic and treatable; splits at the welded corners are structural and aren't.
ReadFriction stays are consumable — when they corrode or bend, the sash drops out of square and everything else starts to fail with it.
ReadFull background on sticking French doors
The main guide covers the mechanics of this fault in more depth, without the Caerphilly context.
Read the French Doors That Stick Or Won't Shut guide →Let's make your house feel more like home.
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