If you haven’t yet, we recommend you take a look at our intro post that discusses our original thoughts when first tackling our pool project. The project that consumed our summer and changed us into pool people after all (at least me, Kyle is still on the fence). Here we’ll detail the first few steps of constructing the pool patio which was to install the fence posts to create patio area, and get the stone subbase installed and level. We also replaced all of the pool plumbing. This post represents about a 2 month process overall and although it took the most amount of time, prep work was key to creating the level area we needed before even thinking about laying a paver.
We wanted to get the fence posts in first so we weren’t later digging through stone base. We generally kept the same “L” shape as the previous deck, but modified the footprint. We used pressure treated 4x4x8 posts. The fence would consist of 6 ft wide by 4 ft tall black aluminum panels on the long sides and 2x lumber on the short sides with pressure treated caps. Posts would be spaced 6 ft apart, with the exception of the gates which would be 3.5 feet wide. Also, on the left side, the overall length didn’t allow for perfect 6 foot spacing so we ended up with sections smaller than 6 foot. Since we were constructing the wood fence ourselves on that side, we didn’t need perfect spacing, we’d just cut the boards to fit. On the long sides where the pre-fabricated aluminum panels would be installed, we needed close to exact 6 foot spacing for the panels to install properly.
setting up string lines
We did our best to set the post lines parallel/perpendicular to the pool. We set up string lines off the edges of the pool to get the exact dimensions we wanted; 4 feet from the edge of the pool on all sides except where the larger patio space would be which was about 11.5 feet from the edge of the pool. We first ran string along each of the 4 edges of the pool and tied them out beyond the fence footprint to wooden stakes in the ground. Then, we measured from that string outward to where we wanted the inside of the post. Here we added another string line parallel to the first one and again tied it to stakes outside the footprint of the fence. We did this for each side so we had a string line along the inside of all the posts. During this process, we realized it would have been easier to do a rectangle as opposed to an “L” shape. As we measured for the inside corner of the “L” it got confusing as to where the inside of the posts should be. Also, making this inside corner square to the rest of the fence was challenging.
We spent an entire day just setting up the string lines. We ended up using an “H” shape type stake that allowed slight adjustment and worked quite well. It requires 2 stakes, with a cross member. You tie the stringline to the cross member, allowing you to slide the string left to right. Even though the process was daunting, we would recommend NEVER SKIPPING THIS STEP. You might think you can measure as you go (I did) but spending the time to set the string lines is time well spent to get the posts where they need to be. We spent an entire day setting up the string lines. I only tripped over them a few times…
digging the holes
Next, we (and by we I mean Kyle) used a 10 inch diameter gasoline powered hand auger to dig about 30 to 36 inches below current grade (42-48 inches below final grade). Code in our area is 42″ to get below frost line, but that is based on historical data (frost line rarely ever goes more than 24″ or so below grade). Our soil consists of clay with a lot of cobbles. Not great for digging. Every time he hit a rock, it would kick the auger to the side and change the location of the post hole. We usually got about 2′ down, sometimes less, before Kyle would have to hand did the rest with a post hole digger. We found that some of the holes shifted a bit with the auger, and we ended up digging a lot by hand to shift them in the right direction. It was also important to try and make the bottom of each hole wider than the top to help prevent uplift from frost.
setting the posts
After a lot of extra hand digging we got the posts exactly where we needed them. At the very bottom of each hole, we placed about 6″ of loose gravel that the post would sit on. We leveled them and set temporary bracing by screwing scrap wood to the post and a to stake in the ground to keep them level while we got them set. We added bracing to level the post in both directions, as shown below. This would keep the posts perfectly level as we poured in the concrete and allowed it to set.
We filled the holes with 1 50 lb bag of concrete mix each which filled them about 1.5 feet. We premixed the bags in a wheel barrow with some water from the hose. We then shoveled it in each hole one by one. This will create an anchor for the post to prevent overturning. After allowing the concrete to harden overnight, we filled the holes with crushed stone.
our theory on the post holes
The stone on the bottom allows water between the post and the concrete to drain properly (as the concrete dries, it shrinks and will leave enough room between the post and the concrete for water). The concrete acts an anchor to prevent overturning, and the stone on top creates an permeable cylinder around the post to keep moist soil away from the post and hopefully keep it as dry as possible. Pressure treated wood tends to fail when it is constantly wet. The treatment is forced into the wood fibers using water as its vessel. Since it is a water based formula, if the wood is in direct contact with water or wet soil for long periods of time, the treatment can actually diffuse out of the wood and into the soil around it, losing its rot resistant properties.
Unfortunately, we did not take any pictures of this process (we were kind of in a rush to get the pool filled back up for fear of the side walls collapsing or the pool lifting out of the ground), but I will explain our process.
In simple terms, a pool has a suction and return with a filter in between and a pump to circulate it. Our existing pool had one return, a jet on the shallow end, and a main drain and skimmer on the suction side. The main drain was not a separate line, but rather plumbed to the the skimmer and then the skimmer went to the pump. We read this was a common way that old in-ground pools were plumbed, but was not very efficient.
In the image above, the “From Drain” line was the line from our main drain at the bottom of our deep end. All we did was cut this line as far down as we could, then join it to a new flexible pvc line that we ran back to the pump where we installed a valve. Then we just plugged the hole where it used to go into the skimmer. This allowed us to isolate the main drain or the skimmer if needed, and also gave better overall suction from the main drain since it was not going through the same skimmer line. We replaced all of the plumbing with new flexible pvc and surrounded it with sand to avoid sharp rocks against our new piping.
future electric line
We knew that at some point we would need to run a new electric line to the pool since the existing one was sketchy at best (it had multiple splices with different sized wires). In order to help with this, we buried a 1 1/2″ pvc conduit with loose elbows at each end. That way in the future, we could dig down, take the elbow off and easily fish through an electric line underneath our paver patio.
Now, we were ready to get the subbase set. The top of the pool ranged from about 6 to 18 inches above grade, so we had to build up the surrounding area to create a nice level platform for laying pavers. We’d later add soil to gradually slope the patio to the rest of the lawn. We used about 60 tons of 1 inch minus crusher run which lends to nice compaction due to the fines and angular stones. You wouldn’t want to use something rounded like pea stone because it leaves more void space which allows for movement and does not compact well. Compaction is key when laying a solid base for something like pavers.
moving the stone
We had deliveries of stone over the course of 2 weekends, in 10 ton loads. Because of the narrow space between our house and the tree line on the only side level enough for a truck, we had to use a smaller truck (6 wheeler with a 10 ton max load). We placed the stone via wheel barrows and a small tractor borrowed from my uncle. We learned the tractor bucket was just small enough to fit in between 2 of the fence posts that were slightly over 6 feet apart; however, even though Kyle’s driving skills are on-point, we didn’t want to risk hitting the posts with the tractor. We moved as much stone with the tractor as possible, but couldn’t avoid shuttling it with wheel barrows. This is where bribing family with pizza and beer was absolutely necessary to get the job done. We happened to do this part of the project during the hottest weekends of the summer. It was brutal, but also a great work out. Family members did help out with this, but most of it was done by myself and Kyle, something we still can’t believe we achieved.
setting the slope and compaction
We used a laser level (borrowed from a family member) to achieve an elevation approximately 3 inches below finished grade. We needed to account for 1 inch of sand and 2 inch thick coping stones which would be placed on top of the fiberglass edge, and coordinate this with the 1″ of sand below the pavers which were 2 3/4″ thick. Thus the stone would end 1 inch below the top edge of the pool which would be the bottom of the coping since the coping would sit on top of the pool edge. We sloped the stone at ¼ inch per foot away from the pool for drainage. As a guide, we marked a line along the fence posts where the stone should end so we could keep filling until we met that line. When marking the posts to account for the ¼ inch per foot slope, we had to measure the distance each post was from the pool and subtract ¼ inch in height per foot the post was away from the pool. We really could have done 1/8 inch per foot as the slope seems a little excessive.
The key here is compaction. We compacted the base in 4-6 inch lifts using a plate compactor to prevent future settling as much as possible. Since we didn’t disturb the soil beneath the stone, and we compacted the heck out of the stone, we should be able to avoid any settling issues (fingers crossed). We kept compacting, filling in low spots, and raking out high spots until the base was flat with the proper slope. Any imperfections could later be fixed with the sand which lends to much easier handling and fine tuning than the stone. We added some fill dirt around the perimeter to keep the stone from eroding away for now.
Now we can finally put the shovels away and start laying pavers.