If this porch is exposed to direct sunshine, I'd be careful of the colour of paint you paint it with.
Paint gets both it's gloss (or, rather, lack of gloss) and colour from tiny particles added to it either at the factory or at the point of sale. The coloured particles added to paint to give it colour fall into two catagories; organic pigments and inorganic pigments.
The organic pigments are particles produced from chemicals in laboratories. These tend to be all the colourwheel colours, like red, blue and yellow, and all the intermediates you can make from red, blue and yellow like purple, orange and green.
The inorganic pigments are really the modern synthetic equivalent of the coloured rocks that artists like Da Vinci and Michaelangelo have been pulverizing into find powders to colour their paints for centuries. The pigment, Sienna, for example, is a mustard yellow colour and is made by pulverizing the mustard yellow rocks found in and around the Italian town of Siena. The synthetic equivalent of Sienna is called "Yellow Oxide" and you can find yellow oxide in one of the canisters of every paint tinting machine in North America.
Rocks are good at being opaque, but they're far better at being old. But, let's face it, anything that is 300 million years old HAS TO BE EXTREMELY CHEMICALLY STABLE. Otherwise it would have decomposed by now. That extreme chemical stability manifests itself in the fact that rocks don't fade from exposure to the Sun. For example, the red planet Mars is red because or all the iron oxide in the rocks on it's surface. Mars is the same colour as the rust on my car and has been exactly that same colour for the past 5 billion years despite it being exposed to direct intense sunlight 24/7.
So, if this porch is going to be exposed to direct sunlight, then buy whatever paint you intend to use from any paint store that also deals with industrial coatings, and deal with their industrial coatings sales person. That person will be able to tell you which of the colourants in their paint tinting machine are basically the modern day synthetic equivalent of pulverized rocks. Tinting your paint with those pigments will ensure that your paint won't fade so that in the future, you can paint over any chipping or flaking of the porch without having to paint the whole thing to get a uniform colour.
Besides Yellow Oxide mentioned above, other inorganic pigments used to tint paint are:
- Red Oxide, which is really just ground up rust. It's reddish brown in colour.
- Brown Oxide, which is milk chocolate brown in colour,
- Raw Umber, which is such a dark brown that it can be mistaken for black.
- White, which in interior paints will be titanium dioxide. In exterior paints zinc oxide is used instead of titanium dioxide cuz titanium dioxide tends to promote chaulking in exterior paints. Zinc oxide doesn't provide as good hide as titanium oxide, but it doesn't promote chaulking and acts as a natural biocide to help prevent mildew growth on exterior paints.
- Black which is actually soot. It's made by burning natural gas in special furnaces with insufficient oxygen to produce copious amounts of soot.
If you use a paint that calls for only inorganic pigments in it's tint formula, the paint you get will not fade from exposure to the Sun. However, it may still discolour with age due to chaulking or any other deterioration of the binder in the paint. The colour of the pigments in the paint won't fade any more than rocks of similar colour would fade due to exposure to the Sun.