There are three main types of uPVC door hinge: flag hinges, butt hinges and T-hinges. Flag hinges are the most common on modern uPVC doors and offer the most adjustment; butt hinges are found on older doors and offer little; T-hinges sit somewhere in between. You can usually tell them apart in seconds by looking at the shape of the plates, and that tells you how to adjust them and what to buy if one needs replacing.
This guide shows you how to identify each type, how adjustment works, when to replace a hinge and what it means for your door’s security.
Why hinges matter on a uPVC door
uPVC doors are heavy, and the hinges carry all that weight. Over time hinges can loosen and the door can drop, as Homebuilding & Renovating explains. A dropped door causes familiar problems:
- The handle is stiff or won’t lift fully.
- The key is hard to turn, or the door only locks if you push or pull it.
- The door catches on the frame or drags on the threshold.
- Draughts or light around the edges.
Many of these are hinge adjustment jobs, not a broken lock. Getting the alignment right also lets the multi-point lock engage properly, which matters for security.
Quick identification guide
| Hinge type | What it looks like | Typically found on | Adjustment |
|---|---|---|---|
| Flag hinge | A single plate on the frame shaped like a flag, with a knuckle and pin attaching it to the door | Most modern uPVC and composite doors | Usually height, side-to-side and often compression |
| Butt hinge | Two plates (“leaves”) joined by a pin, one on the door and one on the frame; some are cylinder-shaped | Older and lighter doors | Little or none on older types; some newer versions adjust side-to-side |
| T-hinge | A T shape: a longer plate fixed to the door and a shorter plate to the frame | Some older and heavier uPVC doors | Usually height and side-to-side |
You may also come across rebated hinges, where the leaf sits against the door sash so the hinge is largely hidden when the door is closed. Homebuilding notes these typically adjust laterally and vertically.
Tip: before you do anything, take clear photos of the hinge with the door open and closed, and look for any brand name stamped on the plates or caps. That will save time if you need a replacement.
1. Flag hinges
How to spot one
Open the door and look at the frame. A flag hinge has one plate screwed to the frame with a cylindrical knuckle, and that knuckle connects to the door, so the plate sticks out like a flag on a pole. There are usually plastic caps covering the adjustment screws, and a larger cover over the hinge body.
How adjustment works
Flag hinges give you the most control, according to Homebuilding. Remove the caps and you’ll typically find three adjustments:
- Height (vertical): a screw at the top of the hinge raises or lowers the door. Homebuilding says this gives around 4mm of movement.
- Side-to-side (lateral): a horizontal screw moves the door towards or away from the hinge side, typically up to about 5mm.
- Compression: on many models, a screw at the bottom pulls the door tighter into the frame seals or lets it out.
These are usually turned with an Allen (hex) key. The exact key size and which way each screw turns vary between makes, so check the maker’s instructions if you can find them.
Adjusting a dropped door step by step
- Open the door and look at where it’s catching or where the gap is uneven.
- Remove the caps on each hinge to reach the screws.
- Make a small adjustment, such as a quarter or half turn, on each hinge in turn so they share the load.
- Close the door and try the handle and key after every small change.
- When the door closes and locks smoothly, refit the caps.
Screwfix also suggests checking the latch lines up with the strike plate and using the compression adjustment to help with draughts.
2. Butt hinges
How to spot one
A butt hinge has two leaves, one on the door and one on the frame, joined by a pin. On older uPVC doors they are often cylinder or “pencil” style hinges. When the door is closed you’ll typically see the barrel of the hinge between door and frame.
Adjustment
Older butt hinges offer little or no adjustment. Homebuilding explains that on some, you can loosen a grub screw on the top and bottom pins and make a small vertical adjustment with an Allen key, and some newer butt hinges have side screws for side-to-side movement. Make small changes and re-check the gaps each time.
If a butt hinge has no adjustment left and the door still drops, look at whether the screws are loose or stripped before assuming the hinge itself has failed.
3. T-hinges
How to spot one
A T-hinge is shaped like the letter T: a longer plate on the door and a shorter one on the frame. Screwfix notes they’re often used on heavier doors.
Adjustment
T-hinges usually allow height and side-to-side adjustment only. Find the adjustment screw, loosen it slightly, reposition the door, then retighten and check that the gaps are even all round.
When to replace a hinge rather than adjust it
Consider replacement if:
- There’s no adjustment left and the door still drops or catches.
- The hinge is cracked, bent or the knuckle is worn and the door rocks.
- Screws won’t hold because the fixing holes have stripped.
- The hinge is so stiff or corroded it’s straining the door.
Matching a replacement is the hard part. Hinges vary by brand, door system and the depth of the frame, so take your photos and measurements to a door hardware supplier or a uPVC door specialist. Lifting a heavy uPVC door off its hinges is a two-person job. If the door is still under warranty, check with the installer before you change anything. Homebuilding points out that if adjusting doesn’t help, the answer may be new hinges or, for a badly warped door, a new door.
Hinges and security
The hinge side of a door gets less attention than the lock, but it matters, especially where the hinges are on the outside.
- Outward-opening doors: West Yorkshire Police suggest hinge bolts or security hinges to reinforce the hinge side, and hinge protectors or bolts on each hinge of French doors.
- Alignment: a door that has dropped may stop the multi-point lock engaging fully. If you have to force the handle, fix the hinges.
- Screws: make sure all hinge screws are present and tight.
For a wider look at where uPVC doors are vulnerable, see our guide to the top weak points of uPVC doors, or our guide are uPVC doors secure?
Extra protection while you’re home
Once your door is properly aligned and locking smoothly, you can add a layer that doesn’t depend on the lock. The Door Jammer – HOLDOOR hooks under the inside handle of a uPVC door and braces it against the floor, so the door stays shut even if the lock is snapped, bumped or picked. It’s Sold Secure Bronze rated and Secured by Design accredited (Police Preferred Specification), adjusts from 70cm to 120cm, and fits most UK single-handle uPVC doors with the handle on the left or right. It needs no drilling and no tools, so nothing is screwed into your door or frame. It’s used from inside when someone is at home, and isn’t for sliding, French, double or patio doors.
In a fire: find the key, lift the Door Jammer off (or unlock and remove the Door Handle Guard), unlock the door and leave the building.
Frequently asked questions
What type of hinge is on most uPVC doors?
Flag hinges are the most common on modern uPVC doors. Older doors may have butt or T-hinges.
How many hinges should a uPVC door have?
Most uPVC front and back doors have three or four. Whatever yours has, adjust each one a little at a time so they share the load evenly.
Why won’t my uPVC door lock after adjusting the hinges?
If hinge adjustment hasn’t fixed it, check the keeps on the frame. If it still won’t lock, Homebuilding’s advice is that it’s rarely a simple fix and may need a professional.
Can I replace uPVC door hinges myself?
If you can identify an exact match, yes, with a helper to take the door’s weight. If you can’t identify the hinge, get advice from a specialist first.
Next steps
- Open your door and identify the hinge type using the table above.
- Photograph the hinges and note any brand markings.
- Make small adjustments, testing the handle and key each time.
- Once the door locks smoothly, add the Door Jammer – HOLDOOR for extra protection at night.
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