Timber, uPVC or aluminium: the comparison
Three quotations recommending three materials cannot be weighed until you know what separates them. This table sets that out on five points.
| Criterion | TimberRecommended for a pre-war street elevation | uPVC | Aluminium |
|---|---|---|---|
| InsulationU-value of the frame profile itself in W/m2K. Lower is better. The glass counts separately. | 1.4 to 2.0W/m2KHardwood at the low end of that range, softwood at the high end. | uPVC is the best of the three on this point.1.1 to 1.4W/m2KA five or six chamber profile reaches the lowest value; a three chamber profile does not. | 1.8 to 2.4W/m2KOnly with a thermal break. Without one it heads towards 5. |
| MaintenanceWhat you or a decorator have to do periodically to reach the stated lifespan. | Every 6 to 8 yearsrepaintingAllow 60 to 110 euro per frame per repaint on a facade reachable from the ground. | uPVC is the best of the three on this point.Clean, never paintGaskets and ironmongery do wear out; those can be replaced separately. | Aluminium is the best of the three on this point.Clean, never paintA damaged powder coating does have to be made good, certainly near the sea. |
| LifespanRealistic time to replacement under normal use and maintenance. | 50 to 75yearsProvided the repainting interval is kept. If it is not, this drops to 25 or 30. | 35 to 50yearsThe profile outlasts the sealed glass unit and the ironmongery. | Aluminium is the best of the three on this point.50 to 80yearsThe profile barely weathers; the coating and the gaskets decide the moment. |
| Design reviewChance that the municipality approves it on the street side of a pre-war house. Dutch municipalities test appearance against a published policy document; the process is called welstand. | Timber is the best of the three on this point.Approved almost alwaysIncluding in a protected village area (beschermd dorpsgezicht), provided colour and profile width match what was there. | Usually refusedAt the rear it is almost never a problem; the municipality rarely assesses that side. | Case by caseSlim profiles are regularly allowed on post-war houses and on rear elevations. |
| Price per frameTilt and turn window of roughly 1.2 by 1.4 metres, including HR++ glazing, fitting and disposal. | 1,100 to 1,900euroAccoya, or a frame with true glazing bars, sits at the top of the range. | uPVC is the best of the three on this point.750 to 1,300euroWhite profile is cheapest; a coloured foil adds 10 to 15 percent. | 1,300 to 2,200euroExpensive per single window, favourable per square metre of glazed area. |
| Where it is not the best choiceThe case in which you are better off not choosing this material. This line sits inside the table rather than under it, because it weighs as much as the five above it. | Not the best choice if you do not want to repaint and the work is on a rear elevation or a post-war house. There you would be paying for a property you do not need. | Not the best choice on the street side of a pre-war house: the profile is wider and the corner joint is welded rather than mitred. That is the detail the municipal design review committee (welstand) refuses on. | Not the best choice when budget leads, or for individual tilt and turn windows. Aluminium comes into its own on large panes and sliding doors, and on the coast. |
Of the five criteria uPVC wins three, aluminium two and timber one. The recommendation above concerns the front elevation of a pre-war house, where the Design review row outweighs the other four together. If your window is at the back, that weighing reverses.
These figures are ranges taken from current work and from supplier data sheets, not a quotation. What your situation costs depends on the size, on how reachable the facade is, and on whether the brickwork has to be made good.
Which one wins in your case
Three questions, and then this says which material is likely to come out best for your situation. The same weighing as the table above, but for your elevation instead of in general.
Answer the three questions above and this will say which material comes out best in your case.
Have your situation assessed
Calling, sending a photo or filling in the form come to the same thing. With a photo of the current situation it is clear in advance whether this is a repair or a replacement.
How to use the table
Start with the row that weighs heaviest for you, not with the column showing the lowest price. If you live on the street side in a protected village area, the design review row decides and two columns drop out before price even comes into it. For a rear elevation that row does not matter at all.
The maintenance row is the one quotations leave out most often. Repainting every six to eight years over a fifty year lifespan is six to eight rounds of decorating; count those before you set timber against uPVC.
The insulation row is about the profile alone. The glass adds to it separately and is usually the larger item: from single glazing to HR++ is a step from roughly 5.2 to 1.1, while the three profiles differ by less than a whole unit between them.
What the choice measurably delivers
Heat loss through the glass
5.2to1.1W/m2K
Single glazing against HR++, the Dutch designation for a coated and gas filled double unit. In a pre-war house with large openings this is the biggest step a single measure can deliver.
Source: U-values from the data sheets of common glass suppliers.
Noise from outside
30to37dB
Standard 4-15-4 HR++ against an asymmetric unit with a laminated outer pane. The ear reads roughly 10 dB as a halving, so this difference is clearly audible.
Source: Rw values from the data sheets; the unit stays the same thickness.
Payback on glass only
7to10years
Replacing only the glass in a sound frame. Replace the whole frame and payback runs to 12 or 18 years, because you are then paying for the profile as well.
Source: Calculated with the public rules published by Milieu Centraal and a gas price of 1.30 euro per cubic metre.
Guide figures, not a promise. Your heating habits, the insulation of roof and floor, the orientation of the facade and the energy price decide your actual outcome.
Have your situation assessed
A photo, your postcode, the year the house was built and the number of frames produce a range. The quotation follows only after measuring up in the rebate: a wrong dimension is the most expensive mistake in this trade.