What to look for in a doorway canopy?

[Adsibob]

I’m looking to get a canopy to put up above our side door so that the two steps we have outside the door stay a little bit dryer. Our side door is 90cm wide and opens inwards. The side door is also in the alleyway between two semi detached houses only 190cm apart, so it’s fairly sheltered already.  So I’m thinking the canopy doesn’t need to be huge. Maybe 120cm wide, with a projection of about 80cm. Does that sound about right?

i found some cheap ones here: https://www.manomano.co.uk/p/120cm-black-door-canopy-transparent-awning-shelter-front-back-porch-outdoor-shade-patio-roof-16314208?model_id=16314197

 

but wondering what the catch is. Is the fact that most of these are made of transparent pvc likely to mean that it will get dirty/green with algae, which will then be visible from underneath?

 

[Tennentslager]

Watch it Boris the centimetre police will be along shortly with a fixed penalty notice and the mods will have set up an inquiry.