Having a window frame replaced by a tradesperson costs on average €400 to €1,200 per window, including materials and installation. Doing it yourself saves €200 to €600 in labour per window – but you need to know what you’re doing.
What Does It Cost to Replace a Window? DIY vs. Tradesperson
Cost Comparison per Window
| DIY (materials) | Tradesperson (including labour) | |
|---|---|---|
| uPVC window (standard size) | €150 – €350 | €400 – €700 |
| Timber window (standard size) | €200 – €500 | €500 – €900 |
| Aluminium window (standard size) | €300 – €600 | €700 – €1,200 |
| Front door surround (including door) | €600 – €1,500 | €1,200 – €2,500 |
Window Frame Materials: Wood, uPVC or Aluminium?
Material Comparison
| Timber | uPVC | Aluminium | |
|---|---|---|---|
| Purchase price | Medium | Low – medium | High |
| Maintenance | High (paint every 5–8 years) | Low (wipe down) | Low (wipe down) |
| Lifespan | 30–60 years | 30–40 years | 40–60 years |
| Uf value | 1.1 – 2.0 W/(m²K) | 0.8 – 1.6 W/(m²K) | 1.3 – 2.8 W/(m²K) |
| Appearance | Warm, classic | Clean, modern | Slim profile |
Glazing U-values
| Glazing type | Ug value | Saving vs. single glazing |
|---|---|---|
| Single glazing (old) | 5.8 W/(m²K) | — |
| Double glazing | 1.1 – 1.4 W/(m²K) | ~50% |
| High-performance double (low-e) | 0.7 – 1.1 W/(m²K) | ~60% |
| Triple glazing | 0.5 – 0.7 W/(m²K) | ~65% |
Materials List: Replace a Window Frame
| Material | Approx. Cost |
|---|---|
| New window frame (made to measure) | €150 – €600 |
| Low-expansion foam (2 cans) | €15 – €30 |
| Silicone sealant (2–4 tubes) | €10 – €40 |
| Pre-compressed foam seal (compriband) | €15 – €30 per roll |
| Vapour control membrane (inside) | €20 – €40 |
| Frame fixings (stainless steel, 6×100 mm) | €10 – €15 |
| Frame packing blocks | €5 – €10 |
Step-by-Step: Replace a Window Frame in 9 Steps
Step 1: Measure and Order the Window
Measure the rough opening (width and height at 3 points each). Use the smallest measurement. The new frame should be 10–20 mm smaller than the rough opening. Allow 3–6 weeks for made-to-measure windows.
Step 2: Protect the Room
Remove curtains and window dressings. Lay dust sheets on the floor.
Step 3: Remove the Old Frame
Remove the glazing beads. Carefully remove the glass. Saw through the frame corners. Remove frame pieces with a crowbar.
Step 4: Clean and Inspect the Opening
Remove all old sealant, foam, render and paint. Check for moisture and mould.
Step 5: Apply Pre-Compressed Foam Seal to the New Frame
Stick pre-compressed foam seal all around the outer face of the new frame (10–15 mm from the outer edge).
Step 6: Insert the Frame
Place the frame in the opening. Use packing blocks. Level and plumb the frame. Check with a spirit level on all 4 sides.
Step 7: Fix the Frame
Drill fixing holes through the frame into the masonry (minimum 4 fixings per side). Use stainless steel screws. Re-check level after each screw.
Step 8: Fill with Low-Expansion Foam (Inside)
Fill the gap between frame and opening on the inside with low-expansion foam. Allow to cure (30–60 min). Then apply vapour control tape over the foam.
Step 9: Seal and Finish
- Outside: Use neutral-cure silicone (acetate-cure silicone corrodes metal and smells of vinegar). V-shaped bead minimum 6 mm wide and deep.
- Inside: Acrylic sealant (paintable).
- Always mask up for a clean finish.
- Allow 24–48 hours before exposing to rain.
Common Mistakes
1. Not Measuring at Multiple Points
Wall openings are rarely perfectly rectangular.
2. Setting the Frame Directly on the Sill
Leads to capillary moisture. Always use packing blocks.
3. Using Standard Expanding Foam
This pushes the frame out of shape. Use low-expansion or window-specific foam.
4. Not Sealing the Outside
Always seal all round including the underside of the sill.
FAQs
What does it cost to replace a window frame?
DIY: €150–€600 for the window plus €50–€150 in materials. Tradesperson: €400–€1,200 per window.
Which window has the best insulation value?
uPVC windows with triple glazing achieve the lowest Uw values (around 0.7 W/m²K for the whole unit).
Do I need planning permission?
Usually not, if the window is the same size and in the same position.
Building Plans and Guides
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