Any advice on whether to paint or stain a deck (diy job)

What is the deck surface made of?
If wood, factory treated or untreated?
Has it ever been painted or what finish is on it now?

I think it is pine, I don't know if is it factory treated (I expect not) and it has stain on it now.

The reasons to coat a deck are; preservation from decay and aesthetic coloring.

It has stain now and probably some wear with color warn off. If true, your are going to need a heavy enough coat to blend/conceal the previous. Power washing (carefully) may remove what is left of the existing.

Consider this; paint covers good and it will peel and flake over time. Stain can vary, some soak in very good and will not peel, some are closer to thin paint and will peel but not as bad.

Personally I'd my first choice would be an oil based true stain. Tinted (or not) linseed oil and turpentine mixed 50/50%.

There are stains which are nothing more than thinner formulated paint (labeled as stain).

My last choice, paint. You'll need to prime the wood to improve adhesion, and then still expect it to flake over time. Looks great initially... but I believe up keep is more. If treated wood, it can be painted but needs time to weather some before paint will stick.

Good luck!

Thanks for the advice

If paint, prime it with an oil based primer & paint with oil based exterior paint. If it isn't oil based, it won't stick to the stain that's already there.

I'd go with stain, personally. I think it's better for the wood. And, if you have an untreated pine deck, you will want to stain it sooner rather than later 'cause the sun and whatever moisture happens to hit it can warp it pretty well unless it's at least oiled (linseed is good stuff).

I agree with big_hawg.
Âio, you and I are in the same area/altitude and environment. When I first moved in, my deck looked pretty bad and I couldn't tell if it was pine or not (that's how crappy it looked). The first year (been here 10 yrs now), I power washed and found the beautiful redwood deck! I stained it with oil based Behr...it didn't last a summer I would not recommend paint either, as the deck surface will get slick. Likewise, stay far away from Thompson Water Seal.

Over the next couple of years, I tried a number of different stains without success. Then about 5 or 6 years ago, I power washed and did some light sanding and then used (on a recommendation) Super Deck (oil base and tinted--not solid--stain). I've never looked back. I do a good thorough power wash every-other-year and apply the Super Deck. Keep in mind, the UV protection you'll need at this altitude. I've found that SD really protects the wood from the harsh sun.

The results? Although these are not great shots, Tüko digs it and so do I.
The last shot was after a rain and 2 years after I did the deck last. It really holds up well...

Thanks so much for the advice - where could I get the Super Deck product?

and those decks look like an inside floor. The best looking deck up here.

Aspen Park Hardward (Ace) has it. Good stuff...tried several of the others and it's as good if not better than all of them.

Yep, I support Aspen Park Hardware. Bergen Paint also carries Super Deck.