Paver Patio Construction
We have been building high end paver patios in Central Ohio for the last 14 years. There was a time when we all did them the same way with the same gravel and the same materials. The hardscape world has changed a lot since then. Unilock was the first paver manufacturer in our area to think outside of the box. Other manufacturers have had to play catch up to maintain market share and this has led to an incredible line up of new materials in the last 5 years, and it increase every year. In that same time those of us that install these products have had to come up with new construction methods to meet the needs of evolving designs and materials.
Comparing two companies even if they are bidding on the same design is nearly impossible. The methods and vary so much between companies that you can not make an informed decison without knowing what goes into your new patio, aside from the pretty plants or the flashy new pavers.
Hands down, no matter how a patio is designed, this is where your true investment lies and it's also the number one place hardscapers fail. Typical old school style base preperation entailed the use of 411 gravel (or 46D or 304) with 1-2" of concrete sand, then your pavers. There were some legitimate reason why sand was important, but these are becoming nil with todays pavers and materials.
Our base consists of:
4-5" of crushed 57 limestone- This is the primary make up of the patio base. This is standard on raised patios and we have made the decision long ago to use this on all of or patios. The main benifit is compaction. Since 411 has stone dust and 57's do not a higher rate of compaction is achieved vs 411. This in turn helps prevent possible settlement. The other added benifit is the drainage behavior of 57's allow for water movement under the patio without affecting the base material itself.
1" of 411- I know I just talked bad of 411, but it does make a smoother surface than the 57's. To create a smoother finished base, and to lock in the uper layer of 57's we use 1" of 411's.
1/2" of 9 limestone- We use NO sand under our pavers. Sand does not compact, it washes out, critters don't mind digging through it, power washer blow it out, ants like it....etc. You have none of these issues with 9's (an crushed angular gravel smaller than pea gravel). The other key is 1/2". Long ago as a foreman I had issues with guys not making the base level and making up the difference with more sand. To prevent this I took away their 1" poles and gave them 1/2" poles. Your base has to be perfect (within 1/8") to use them. Since all gravel and sand compact at the same rate if there is a low spot in the base it will show up in the finished patio surface. With 1/2" you can't cheat so you have a perfect base and a perfect patio.
For segmental retaining walls and staircases they blocks are bound together with a specialized retaining wall adhesive. With the right adhesive the glue will be stronger than the blocks themselves and require a chisel and sledgehammer to break them apart. The other long term factor is deterioration of the adhesive by trapped moisture. After a decade of practical use and 5 years of actual in house testing of 6 major suppliers we have settled upon Titebond as our primary adhesive. At around $10 for a large tube the only downside is the cost, but if the safety of your stairs or the integrity of you wall is dependent on adehsive it's worth a few extra bucks. You won't find any $2.58 a tube Liquid Nails anywhere in any of our trucks!
Note: We are currently wrapping up a two year test of a new glue. This first test is to break apart two blocks that were glued in April of 2012. As a more epxoy based adhesive I am anxious to see the results. I will post a new blog pentry with the findings.