Method to obtain correct drainage slope?


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Old 07-20-20, 08:22 PM
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Method to obtain correct drainage slope?

I'm redoing the pavers on the front patio and I wanted to know what method is best to obtain the correct drainage slope for the area. The patio area is 8' x 10' and has a concrete border on all 4 sides, and I need any water to drain from NW to SE down the front walkway.What's the best/correct way to prepare the base for this?

 
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Old 07-21-20, 06:07 AM
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One way is to get a very long straight object. I can be a long straight board or half of an extension ladder. Then get a spirit (bubble) level. Depending on the length of your level tape a spacer under one end. If your level is 4' long and you want a 1/4" drop per foot then tape a 1" high spacer to the bottom of one end of the level. Then securely tape your level & spacer onto your long straight edge. Now when you get the bubble level your entire board/ladder has the 1/4" per foot slope.
 
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Old 07-21-20, 01:47 AM
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What's the best/correct way to prepare the base for this?
Like in how to measure or how to actually slope the base?
 
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Old 07-21-20, 05:11 AM
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Is the concrete border top sloped in the direction you want the pavers to drain? What is the relationship you want between top of pavers and top of border?
 
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Old 07-21-20, 07:13 AM
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Like in how to measure or how to actually slope the base?
Yes, both - how to plan it and then actually grade it.

Is the concrete border top sloped in the direction you want the pavers to drain? What is the relationship you want between top of pavers and top of border?
The area is bordered on 3 sides by the house wall, garage wall and a planter wall. The walkway on the 4th side is sloped in the direction I want it to drain. I would like the pavers to be relatively even with the top of the walkway, but I feel that grade might be a bit too high, I dont want it to look/feel like your standing on a slope.

If your level is 4' long and you want a 1/4" drop per foot then tape a 1" high spacer to the bottom of one end of the level.
So to utilize this I would just move the board/level around starting say in the lowest spot (SE corner) and work my way around leveling the base away from there until I reach the highest spot (NW corner), kind of in an arc pattern?

I think the thing that is throwing me off the most is haviing to grade the slope from two directions (away from the house and away from the garage) to achieve drainage from NW corner to SE corner if that makes sense. I know this step is the most important so I want to get it right.
 
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Old 07-21-20, 08:41 AM
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Assuming this is conventional compacted base and slag sand topper I just use a laser level to get the base close, then using conduit running from high to low, check and adjust conduit heights, then fill with sand and screed.

It's not something that has to be accurate within a 1/16" as long as the overall slope is achieved!

Considering I used to use a water level the lasers are even more accurate!
 
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Old 07-22-20, 08:29 AM
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Thanks for all the suggestions, I think I now have the base sloped pretty good and I'm adding the sand today.
 
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Old 07-22-20, 09:08 AM
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If I Were You...

Run a set of string lines to set your slope. Then set wooden stakes or steel pints every 2 feet or so along the strings, to mark the height you want the final surface to be at.

I generally recycle the steel "U" frames from political campaign signs for this.
I usually cut the frame into 3 pieces, 2 legs and 1 top.

Bend the top three times to form a "T" shaped pin. Like this

Then set the pins so that they are JUST at the height of the stringline.

As you form the patio, use the pins to get the correct height, then remove the pins when you DO have the correct height.
 
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Old 07-22-20, 04:49 PM
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That's what I ended up doing actually, I ran a grid of string lines and used pieces of rebar to set the height in between the stakes, not pretty but it seemed to work fairly well for me. I like the idea of the "T" pins, they would be easy to pull out and the hole likely wouldn't require filling. I did add a spacer to my 6' level as @Pilot Dane suggested and it worked really well for checking the slope of the fill.

I was going to add an inch of sand on top of the packed base tomorrow but a thunderstorm is forecast for the afternoon, and I'm worried that some rain will mess up the screed - am I being overly cautious to put it off for a day, or should I not even worry about that?
 
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Old 07-23-20, 06:36 AM
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I put down the sand layer right before setting the pavers. I do not leave screeded sand unprotected overnight. I've had thunderstorms, a dog playing and critters in the night make a mess of the sand requiring me to re-screed it.
 
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Old 07-25-20, 06:07 AM
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Sorry, I didn't realize that the term concrete border meant concrete walls and a sidewalk. Due to the slope, isn't the sand from the paver bed going to transported onto the sidewalk during a rain?
 
 

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