http://www.thompsonswaterseal.com/homeTried and true for many, MANY years!! Easy to apply. Works on concrete and brick (both vertical and horizontal applications. Thompson's is available "clear" or colored and will not ruin the pretty graining of wood products such as redwood if applied correctly.
Real redwood left "raw" is a very lasting wood product too. Resists most problems associated with other decks. I didn't even know you could buy redwood products for extensive use any more. Interesting.
Cedar and old growth cypress are becoming more and more difficult to find as well, but are also good to resist rot and insects.
Untreated pine or fir which so many contractors and people have used for decks are an abomination and soon rot or decay or are insect ridden and split and fall apart. It's a real shame so many decks have been built with thee products and left untreated. And, the material used should have been pressure treated to begin with anyway. I have repeatedly said in many of these threads that a ground level deck should be stone, flag, concrete, pavers, etc., instead of wood to avoid problems in just a few years.
The old tried and true pest and rot resistance was creosote - but a mess unless applied at mill.
Wolmonize has been around for a long time, and is another well known and specified treatment.
Weatherguard (Lowe's and Home Depot) helps but is not as good as Wolmonize or adding Thompson's to pressure treated lumber and boards. Thompson's in addition to Weatherguard treated lumber really extends the life of decks, etc., significantly.
Pressure treated landscape timbers do not use creosote any more that I am aware, and so Thompson's, Creosote, etc., will prolong a landscape timber's life if it is going to be in direct contract with the ground as well.
Railroad ties are all creosote soaked and protected and why they last so much longer.
