Soffits & fascias
White uPVC does not stay white outdoors. It collects a grey-green film that a hose will not shift, and the fix is a cleaning agent plus contact time rather than more pressure.
Method
The risk here is not to the plastic. It is to what sits behind it.
The grey-green film on white uPVC is biological growth bonded to a slightly textured surface, and a hose will not shift it. What works is a suitable cleaner left to dwell and then agitated by hand. Pressure at a roofline is actively bad: it forces water behind the fascia and into the soffit, which is the one place on a house you least want it.
Soffits, fascias, bargeboards and the outside faces of the gutter are cleaned with brushes on poles rather than blasted from below. It is slower than spraying and it is the only way to get the underside of a soffit clean without pushing water up into the eaves.
Deionised water leaves nothing behind as it evaporates, which is what stops the roofline drying with spots and streaks. Rinsing white plastic with hard tap water is how a job that looked finished when wet ends up looking worse than when it started.
The equipment is already up there, the surfaces are adjacent, and the outside of the gutter is filthy in exactly the same way. Doing both at once costs meaningfully less than booking them separately, which is why this page exists as a companion to gutter cleaning rather than as a standalone sell.
Being straight about it
There are two different problems here and only one of them is dirt.
Rub a finger along the fascia. If it comes away green or grey and the surface underneath is still glossy, that is growth and it cleans off completely. If it comes away chalky white and the plastic underneath is dull, that is oxidation — years of UV have degraded the surface of the material itself.
Cleaning an oxidised surface gets it clean. It does not get it white, because there is nothing left to clean off. Restoring colour at that point means a uPVC restorer or a coating, which is a different trade with a different lifespan and a different price. We would rather tell you that in advance than take payment for a clean that was never going to do what you were hoping for.
Most people book this alongside gutter cleaning, which is the sensible way round — same access, same visit, and the outside of the gutter needs it anyway.
Useful to send: a photo of the roofline from the ground, and a close-up if you can get one. The close-up is what tells us whether it is growth or oxidation, which decides whether cleaning is the right job at all.
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It is biological growth rather than dirt. uPVC has a slightly textured surface that holds moisture, and in a damp climate algae establishes on it — heaviest on the shaded side of the house and under the gutter line where water runs. It is not a sign the plastic is failing, and it comes off with the right cleaner and some contact time.
Not by cleaning, and this is worth understanding before paying anyone. Chalkiness that comes off on your hand is oxidation: UV has degraded the surface of the plastic itself, and there is no growth left to remove. Cleaning removes dirt from an oxidised surface and leaves it oxidised. What restores the colour is a uPVC restorer or a coating, which is a different job with a different lifespan, and anyone quoting a clean to fix chalking is quoting the wrong work.
It can, and the damage is not to the plastic. A lance aimed up at a fascia forces water behind it, into the soffit, and onto the roof timbers and insulation — a slow problem that shows up as damp in the eaves rather than as anything visible outside. Rooflines are cleaned by hand for that reason, not because the uPVC is fragile.
That is gutter cleaning, and it is a separate piece of work — this service covers the outside faces, the fascia behind them, the soffit underneath and the bargeboards. In practice the two are almost always booked together, because the access is identical and doing one without the other means paying for the set-up twice.
Send a photo from the ground and a close-up, and we will tell you whether it is a clean or something else.
