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📋 Official Installation Guide

uPVC Residential
& French Door
Fitting Guide

A comprehensive step-by-step guide for a safe, secure and professional installation of your new uPVC door.

⚠️
Read Before You Start — All goods are checked before leaving the factory. Do NOT begin installation if you find any damage or incorrect sizing. Any shortages or damages must be reported within 48 hours of delivery.

Over 90% of remedial work is caused by incorrect installation. Follow this guide carefully. If unsure at any stage, consult a qualified installer.

Section 1

Before You Begin

🚫
Do not remove your old door until you have:
  • Inspected the new unit for any damage
  • Confirmed the new frame is approximately 10mm smaller than your aperture on all sides
  • Verified all components are present: handles, cill, glass, fixings
  • Tested the door operation — lay the frame flat horizontally to test the sash operation

Correct Storage

✅

Correct Storage

Store frames and glass units vertically on soft surfaces such as wooden blocks or carpet. Keep indoors or undercover, away from direct sunlight.

✅

Protective Film

Remove protective film from the inside of the frame before installation. Leave the outside film in place until all external sealing work is complete.

❌

Never Lean Against Sharp Objects

Sharp edges can permanently damage uPVC profiles and glazing seals. Never lean frames against metal, brickwork, or other sharp surfaces.

❌

No Direct Sunlight

Prolonged direct sunlight before installation can cause thermal distortion of uPVC frames. Always store in the shade or indoors. Do not leave any uPVC door panels in direct sunlight, as the protective film will bond to the skin.

Section 2

Safety & Compliance

👥

Manual Handling — Two People Required

uPVC door frames and glazed units are heavy and unwieldy. Always use two people for lifting, positioning, and glazing. Never attempt solo installation.

🪜

Working at Height

Use stable, weight-rated platforms or ladders when working above ground level. Never stand on makeshift surfaces such as upturned buckets or unsecured planks.

🦺

Personal Protective Equipment

Wear cut-resistant gloves when handling glass. Wear safety goggles when drilling into masonry. Steel toe-capped footwear is recommended.

Section 3

Pre-Installation Checklist

Complete every item on this list before beginning the physical installation. Rushing this stage is the single most common cause of remedial work.

Section 4

Tools & Materials

Spirit Level
Long (1.2m+)
Power Drill
+ Masonry bits
Rubber Mallet
For glazing beads
Allen Keys
4mm & 5mm
Tape Measure
5m minimum
Sealant Gun
For silicone
Glazing Paddle
Plastic type
Frame Packers
Assorted 1–6mm
Material Specification Required?
Frame Fixers7.5mm × 120mm minimumRequired
Glazing PackersAssorted 1mm–6mm thicknessRequired
Silicone SealantLow-modulus neutral cure siliconeRequired
Cill Fixing Screws50mm self-tapping screwsRequired
Expanding FoamLow-expansion PU foam (for gaps >10mm)Optional
uPVC Flexi-TrimTo cover foam/silicone edges (sold separately)Optional

Section 5

Measuring & Preparation

📏
The 10mm Rule

Your new uPVC frame should be approximately 10mm smaller than the brick aperture on all four sides. This allows for the mandatory 5mm expansion gap on each side, plus room for packing and adjustment.

5mm 5mm 5mm 5mm DIAGONALS MUST BE EQUAL MEASURE IN 3 PLACES FRAME OPENING
All Sides
5mm
Mandatory expansion gap on every side of the frame
Frame Smaller By
~10mm
Approx. smaller than aperture each side (5mm gap + packing)
Threshold Level
0mm
Floor must be perfectly level. Use mortar or structural packers to correct.
Diagonal Difference
<2mm
Opening is considered square if both diagonals are within 2mm of each other
💡
Out-of-Square Openings

If the brick opening diagonals are unequal, do not attempt to force the frame into a distorted shape. Use packers strategically during installation to keep the new frame perfectly rectangular even if the surrounding brickwork is not.

Section 6

Cill Fitting

  • Size & Cut: Cills are supplied with a 50mm horn on either side. Cut to the width of the brick opening, or leave oversized if preferred for a projected sill finish.
  • Sealing: Apply a generous, continuous bead of low-modulus silicone to the top face of the cill where the frame will sit. This creates a weathertight seal between the cill and frame.
  • Fixing: Screw the cill to the bottom of the frame using 50mm self-tapping screws. Position the first screw 150mm from each end, then space fixings no more than 500mm apart along the length.
  • End Caps: Apply silicone to the inside of the end caps and push firmly onto each horn of the cill. This prevents water from tracking behind the cill and into the brickwork — a common cause of damp.
⚠️
End Cap Sealant Is Critical

Never leave end caps unfitted or unsealed. Water that tracks behind the cill into the wall cavity can cause significant structural damp that is costly to repair.

Section 7

Frame Installation

A
Preparation
Remove Sashes & Pre-Fix Panels

Optionally remove the door sashes from the frame to reduce the overall weight before offering up into the opening. Pre-fix any side panels to the main frame if applicable before positioning.

ℹ️
Side Panel H-Section

If your door includes side panels, place the 20mm aluminium H-section between the door frame and the side panel. It should fit snug but not clip. Screw through the door frame into the side panel using 70mm self-tapping screws, alternating screw positions for maximum rigidity.

B
Positioning
Offer Frame Into the Opening

With at least two people, carefully offer the frame into the brick opening. Support the bottom of the frame with timber wedges at the sill corners to hold it temporarily in position.

  • Position the frame centrally within the reveal, front to back
  • Do not fix the frame yet — this is a positioning step only
  • Ensure the cill silicone is still wet and seats onto the opening sill cleanly
C
Levelling
Plumb, Level & Square the Frame

This is the most critical step of the entire installation. Take as long as necessary to achieve a perfectly plumb, level, and square frame before any fixings are inserted.

  • Check the sill of the frame is level across its full width — adjust packers beneath to correct
  • Check the hinge-side jamb is plumb — pack behind the frame as required
  • Check the lock-side jamb is also plumb
  • Check the frame head is level — adjusting corner packers if needed
  • Measure both frame diagonals to confirm the frame is square (within 2mm)
  • Place packers at all four corners and at the mid-point of each jamb
D
Fixing
Fix the Frame to the Masonry

Drill through the frame into the masonry and secure with frame fixers. Follow the fixing positions precisely for maximum security and structural integrity.

  • Place fixings 150mm from each corner of the frame
  • Maximum 300mm apart vertically along each jamb
  • Security critical: On the locking side, place a fixing as close as possible to the multipoint lock keep (strike plate)
  • Fix the hinge side first, re-checking plumb after each fixing
  • Do NOT over-tighten fixings — excessive torque will bow the frame and prevent the door from closing or locking correctly
  • Always fix through packers — never into an unsupported void

Minimum Fixing Depth by Substrate

Brick / Block
≥50mm
Concrete
≥40mm
Timber Frame
≥60mm

Section 8

Glazing & Toe and Heeling

🚨
Toe and Heeling Is Non-Negotiable

uPVC doors are heavy. Without correct toe and heeling, the door leaf will sag over time, causing it to fail to lock and creating draughts. If a service call is requested and the door is found not to have been toe and heeled, charges will be incurred.

Understanding the Toe & Heel Positions

HINGE SIDE HANDLE SIDE TOE Hinge side bottom corner HEEL Handle side top corner GLASS = DIAGONAL BRACE
Step 1 — Place Toe Packers Insert glazing packers into the bottom corner on the hinge side (the "Toe") first, before the glass unit is inserted.
Step 2 — Insert the Glass Unit Carefully lower the glass unit into the frame rebate, sitting it onto the toe packers.
Step 3 — Lift & Pack the Heel Use a glazing paddle to lift the handle side of the door leaf. Insert packers into the top handle-side corner (the "Heel").
Result — Glass Braces the Door Correctly toe and heeled, the glass unit acts as a diagonal brace, holding the door leaf perfectly square and preventing future sagging.
Step 4 — Fit the Glazing Beads Snap beads back in using a rubber mallet — short pieces first, then long. Apply soapy water spray if beads are stiff to fit.
💡
Stubborn Glazing Beads?

If beads are difficult to snap into place, a light spray of soapy water (washing-up liquid diluted in water) applied to the bead edge will act as a lubricant and help them seat correctly without damage.

Section 9

Hinge Adjustment

Our uPVC doors use Flag Hinges with three independent adjustment points, allowing fine-tuning in all axes without removing the door. Use a 4mm or 5mm Allen key for all adjustments.

↕️
Vertical / Height

Raise or Lower the Door

Use the Allen key on the bottom of the hinge to adjust the door up or down. Turn clockwise to raise; counter-clockwise to lower. Adjust in small increments and check after each turn.

↔️
Lateral / Side-to-Side

Move Door Closer to Frame

Use the screw on the side of the hinge to move the door leaf closer to or further from the frame. This corrects misalignment between the master and slave door, which causes the lock to fail to engage.

🔧
Compression

Tighten Against Seals

Use the screw on the front or top of the hinge to pull the door tighter against the weatherseal. This eliminates draughts and improves thermal performance. Adjust equally on all hinges for an even seal.

🌐
Full Hinge Adjustment Guide Available Online

For a more detailed, illustrated hinge adjustment guide, please visit the Tech & Downloads section at www.justdoorsuk.com.

Section 10

Sealing & Insulation

  • Internal seal: Use a low-modulus silicone or acrylic decorator's caulk to seal the gap between the frame and the internal plasterwork. Smooth with a wetted finger for a clean finish.
  • External seal: Wipe down both the brickwork and the uPVC frame with a clean cloth to remove dust and grease. Apply a bead of high-quality exterior-grade perimeter sealant around the full outside perimeter of the frame.
  • Large gaps (>10mm): Fill with low-expansion polyurethane foam first. Allow to fully cure (minimum 2 hours), trim flush with a sharp knife, then apply silicone sealant over the trimmed foam surface for a weathertight finish.
  • Remove outside film: Only remove the external protective film from the uPVC profiles once all external sealing is complete.
🚨
Use Low-Expansion Foam Only

High-expansion polyurethane foam exerts significant pressure as it cures and will bow and distort uPVC frames, making doors impossible to close or lock correctly. Always use low-expansion foam around uPVC installations.

Section 11

Final Checks

Section 12

Troubleshooting Guide

⚠️ Doors catching or dragging at the bottom
Cause: The door has "dropped" — toe and heeling was not completed correctly, or has shifted over time.
Fix: Redo the toe and heeling process, or adjust door height using the vertical adjustment on the hinges (Allen key, bottom of hinge).
⚠️ Lock won't engage / hooks miss the keeps
Cause: The master and slave doors are misaligned horizontally relative to each other.
Fix: Adjust the lateral hinge screws (side of hinge) to move the affected door leaf closer to or further from the frame until the lock points align.
⚠️ Draughts felt around the door
Cause: Insufficient compression against the weatherseal, or the weatherseal has been flattened or trapped.
Fix: Check compression adjustment on all hinges. Inspect the full perimeter weathergasket for damage, flattening, or trapped sections.
⚠️ Frame bowing inward after foam curing
Cause: High-expansion foam was used instead of low-expansion foam.
Fix: Remove the foam, repack correctly, and replace with low-expansion foam. Add rigid packers at the affected area before re-foaming.

Section 13

Aftercare & Maintenance

Every 6 months
  • Wash uPVC frames with warm soapy water and a soft cloth
  • Spray multipoint lock mechanism with light machine oil or lithium grease
  • Oil all hinges with light machine oil
  • Wipe weatherseal gaskets with a damp cloth to keep supple
  • Check drainage slots in the frame base are clear
Annually
  • Inspect all external sealant beads — re-apply if cracked, shrunk, or debonded
  • Check frame fixings have not loosened — re-tighten gently if required
  • Inspect glazing seals for signs of failure (condensation between panes)
  • Re-check door alignment and adjust hinges as needed
As needed
  • Replace worn or damaged weatherseal gaskets
  • Replace failed glazing units — contact supplier
  • Lubricate door cylinder with graphite-based lubricant (not oil)
  • Replace any damaged glazing packers if door begins to sag
⚠️
Do Not Use WD-40 for Long-Term Lubrication

WD-40 is a water displacer, not a lubricant. It will dry out the lock mechanism over time and cause increased wear. Use light machine oil or white lithium grease for the lock and hinges. For the door cylinder/barrel, use a graphite-based lubricant only — oil-based lubricants attract grit and will damage the cylinder.

🚫
uPVC Cleaning — Never Use Solvents

Never use white spirit, methylated spirits, acetone, bleach, abrasive creams, or scouring pads on uPVC profiles. These will permanently discolour and damage the surface. Use only warm soapy water or a specialist uPVC cleaner.

Just Doors UK uPVC Residential & French Door Installation Guide