I have a large cement patio with rotted 2x4's between the sections. About 450 lineal feet of 2x4's. I plan on ripping them out and replacing them. I live in northern California. No freezing conditins but some rain. Cement sections in good shape. Just 35 years old. Wood rotted.
1. Is there a better product to use other than wood. Anything new out there that I should consider?
2. If I use wood, what is best. Redwood or chemically treated. Other??? My wife does not like the chemicals in treated wood as we have grandkids who play on the patio.
Any general advice before I start?
Any wood that is in contact with concrete outdoors needs to be treated. Your wife's misgivings about treated wood are pretty much unfounded unless your grandkids actually consume the wood. CCA was phased out a while back and replaced with ACQ, which is a friendlier product.
If the dimensions work out, you could certainly consider a composite deck product (Trex, etc). It could be ripped to width and used in the gap, and would last for a very, very long time. If it were too narrow, you could use some flexible elastomeric sealant for concrete to bridge the gaps.