First Paver Project - Questions

Sam1220

LawnSite Member
Location
Philadelphia, PA
A little background... a large tree root broke up my original builder concrete walkway. After living with the broken and missing sections I decided to wait until the hottest, most humid time of the year to dig it up and replace it with pavers.

I removed the 36" concrete and the (varying) 0-4" of stone they put under it, then dug down another 5" (9" total) to get to good soil. I compacted that with a 4000lb plate compactor about 20-30 passes. It's well compacted. I have a hard time driving a bright spike in with a dead blow.

At the front entrance/pad/door there was no slope. It was dead level from the front step to about 6' out before the walkway turned and went toward the drive. On the long part parallel to the house follows the grade and only slopes down 3" over about 45'

Overall I believe my plan is sound. I'm going to put the geotextile fabric in next, I have 10 tons of Class 2A modified stone in the drive ready to go do in 2" lifts up to 6" base, and as you can see I have the sand ready to go down as well. But, I'm second guessing myself and am looking for a little guidance before I make a 10 ton mistake.

1. In the first picture below, where I'm standing, there was a tree with an enormous root ball. It was removed and the surrounding bed dirt was raked into it which really lowered the side of the bed. In the other picture you see that it isn't even 6" high, so when I put the sand down it's going to be higher than the bed. I excavated 6" wider on both sides, but do I need to backfill that now or put a form board in, or will I be OK and can just fill the bed back in when all the pavers are down? I built the area up a lot with clean fill from other areas to give me a 3" slope over the 12' run from the front porch to the parallel part. That just raised me up more than the bed but seemed like the right thing to do for water run-off.

2. The whole path is well compacted and essentially flat, but there are some minor dips and variations, maybe 1/2" - 1" in some isolated places for a foot or so, meaning that when I measure from my string line it might be 9" at one spot, then 10" a few feet away. My question - does the sub-base need to be dead flat? I have enough stone to fill in and get up to my 6", but do I need to fill all these little spots and get it perfectly flat and level the whole way?

3. I'm really worried about leveling the pavers to the grass. Over the parallel run the slope is only 3". I've checked in a lot of spots using a level from the grass to the center of the walkway to check depth and it's never less that 9". My thought is 6-1/2" stone, 1" sand, 2-3/8" paver that will compact to 2" so 9" overall. Since I'm down 9" overall the pavers would be about 1/2" higher than the soil line. Is that OK, or should I be making it close to level with the soil line? When I'm done and do final grading I'll backfill the edge restraint with soil and plant seed.

Any help would be appreciated. I don't want my first project to end up being on the Wall of Shame somewhere.

Thanks all.


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nickg13

LawnSite Member
Location
NY
Sounds like you've got all the right direction and not skimping on the sub base which crucial for a long term success. (I put 12" which is overkill but I never have to worry.)

What is the soil type & condition in the excavated area?

What brand & size pavers?

In the other picture you see that it isn't even 6" high, so when I put the sand down it's going to be higher than the bed.
No problem you can easily raise the bed as long as it does not cause pitch problems for water drainage away from the house. That is very important.

I excavated 6" wider on both sides, but do I need to backfill that now or put a form board in, or will I be OK and can just fill the bed back in when all the pavers are down?
Assuming you're using a vibrating plate compactor (ie. not a jumping jack) to compact every 2" then the base will firm up within the 6" excess, as long as you're not running the compactor completely off the edge disturbing it, and keeping the layers just moist, and have the proper proportion of RCA components (don't want too much or too little of any component). It'll form a natural 30-45 deg support angle. You can't backfill it now because there's nothing to keep that from falling into your excavated area. BUT see below.

to give me a 3" slope over the 12' run from the front porch to the parallel part. That just raised me up more than the bed but seemed like the right thing to do for water run-off.
That's more than enough (double, actually) . Typically 1/8 is fine, but if you have the height it's good to ensure water gets away. Just be sure your adjacent property is inline with the pitch (see below).

does the sub-base need to be dead flat?
does the sub-base need to be dead flat? I have enough stone to fill in and get up to my 6", but do I need to fill all these little spots and get it perfectly flat and level the whole way?

No, it doesn't. Shoot for as straight as possible, and each layer of RCA gives another opportunity to adjust. So your first layer down should target all the low spots, then the rest are mostly even. Try to keep the variance within 1/2" over 4'+ feet.
Then the sand will take care of the remaining dips. But be sure your sand screed rails are perfectly flat for that to work.

Over the parallel run the slope is only 3".
So assuming the walkway is only 3-4' wide you don't really need a pitch on that segment, and also assuming you don't have any significant low spots. Another option is to use a very small pitch away from the house which is consistent (but less) than each end.

the pavers would be about 1/2" higher than the soil line. Is that OK, or should I be making it close to level with the soil line?
I always make the top of the pavers higher than the adjacent soil by at least 1" for a few reasons. One is that modern pavers are (or can be) attractive and provide beautiful contrast against grass, so why bury them. The grass' stand and/or mulch will hide the side of the pavers. Another is if the pavers are beneath the soil level water has a harder time running off, and then dirt & mulch bleeds onto the walkway when it rains and makes a mess. Lastly it's trivial to raise the adjacent grass/beds (and they always rise over time), but much harder to raise the pavers.

What's your plan to retain the base, sand, and pavers from lateral movement? If it's only to backfill, the pavers will shift with time, especially in regions with freezing. I've even seen it shift when using the plastic retaining border (gets pinned into the subbase) after years.
I suggest mortaring down the border pavers with at least 3" depth, so it encloses the sand and joins the border continously to the sub.

Lastly be sure to use polymeric sand to fill the spaces to avoid weeds, ant hills, etc.
 
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Sam1220

LawnSite Member
Location
Philadelphia, PA
Nick,

Thank you very much for taking the time to provide such helpful feedback on my project. I really appreciate it and it helps alleviate a lot of my concerns. It sounds like the engineer in me may be overthinking a lot of this.

But, overnight its gotten interesting... I'll put that in another post.

What is the soil type & condition in the excavated area?

Well, based on a recent soil test at 4" for my grass, it said it was loam. Based on what I found yesterday when I came home after the tropical storm blew through (see below) I'm not so sure. Seems like I did a great job compacting, or there's a lot of clay in the soil, or both.

IMG_4276.JPG

What brand & size pavers?
EP Henry, Bristol Stone, 7x7, 7x11, 11x11 - laying them random with a Old Towne Cobble soldier course.

Assuming you're using a vibrating plate compactor (ie. not a jumping jack) to compact every 2" then the base will firm up within the 6" excess, as long as you're not running the compactor completely off the edge disturbing it, and keeping the layers just moist, and have the proper proportion of RCA components (don't want too much or too little of any component). It'll form a natural 30-45 deg support angle. You can't backfill it now because there's nothing to keep that from falling into your excavated area.

Ok, that puts my mind at ease quite a bit. I was worried that the sand was going to blow out the side when I did the final compaction over the finished pavers without some support on the side. It sounds like it's possible, though, that you could build a 6" base on a flat surface, put the sand down, then pavers, and backfill when it was all done? The engineer in me has been overthinking this thing every step.

That's more than enough (double, actually) . Typically 1/8 is fine, but if you have the height it's good to ensure water gets away. Just be sure your adjacent property is inline with the pitch (see below).

Well, apparently I did this part right, because the water definitely didn't pool near the house.
IMG_4277.JPG

No, it doesn't. Shoot for as straight as possible, and each layer of RCA gives another opportunity to adjust. So your first layer down should target all the low spots, then the rest are mostly even. Try to keep the variance within 1/2" over 4'+ feet.

VERY reassuring, thank you! I was filling it all these little spots and trying to make it like a bowling alley. Compact, fill, compact, level, measure, string line, compact..

So assuming the walkway is only 3-4' wide

Only?!?! 4 feet wide?!? :) I was going to make it 54" but thought that would be too big for the front of the house. The previous walkway was 3' so another foot seemed reasonable to upgrade to pavers and make it more comfortable.

I always make the top of the pavers higher than the adjacent soil by at least 1" for a few reasons. One is that modern pavers are (or can be) attractive and provide beautiful contrast against grass, so why bury them.

This is an excellent point, thank you. I've really been debating how high to make them, but showing them off a bit is a good plan.

What's your plan to retain the base, sand, and pavers from lateral movement?

I have decent flexible plastic edge restraint and lots of bright spikes. Mortar may be possible at the end, I have several big bags and want it to last a long time.

Lastly be sure to use polymeric sand to fill the spaces to avoid weeds, ant hills, etc.

4 bags of Techniseal NextGel to cover the 280 sq ft. I think that's pretty good stuff.
 
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Sam1220

LawnSite Member
Location
Philadelphia, PA
So, the saga continues. I had such high hopes to finish this over the weekend, and the tropical storm yesterday had other plans. This is what I found this morning. It's about 2-3" deep in spots. It's receding, but not enough that I'll be able to do anything this weekend.

WTH? What I'm wondering now is where all that water would have gone if the hole wasn't there? Or is this all going to be in the base?

And on top of that, how long do I have to wait to dry this all out before I can get the stone in there?

My next plan was to do some final compaction passes then the Mutual WF200 geotextile fabric and then start filling with stone. At this rate, though, it'll be days before this dries out and isn't a muddy mess.

And does this lake of water indicate anything about my soil that's going to lead to disaster later?

Maybe I should give up the walkway and just turn it into a lazy river ride for the kids...

IMG_4276.JPG
 

Mac-s Lawn & Snow

LawnSite Bronze Member
Pump the water out ASAP and get it drying out. If the pavers are above the grass line the water simply goes in the yard where it should. The wider you make that sidewalk the better it will look(usually). Make sure your bedding sand is uniform-not 2" here and a inch there. Even with best compaction pavers settle, I'd get them as far above the grass line as you can.
 
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Sam1220

LawnSite Member
Location
Philadelphia, PA
Pump the water out ASAP and get it drying out. If the pavers are above the grass line the water simply goes in the yard where it should. The wider you make that sidewalk the better it will look(usually). Make sure your bedding sand is uniform-not 2" here and a inch there. Even with best compaction pavers settle, I'd get them as far above the grass line as you can.

It's actually going down a lot faster than I expected. It's down to mud in a lot of spots now, 3-4 hours later. It look like on/off rain and thunderstorms all week though. Yikes. How do you pros do it when it's constantly raining in the summer?!
 

Mac-s Lawn & Snow

LawnSite Bronze Member
It's actually going down a lot faster than I expected. It's down to mud in a lot of spots now, 3-4 hours later. It look like on/off rain and thunderstorms all week though. Yikes. How do you pros do it when it's constantly raining in the summer?!
When you take this to the next step, make sure you can very close to finishing and 'heal' the pavers in with edge restraint and dirt. There is nothing worse than getting it half done and having your bedding sand wash out from under the pavers.
 

nickg13

LawnSite Member
Location
NY
It sounds like the engineer in me may be overthinking a lot of this.
Nothing wrong with that, and better than under-thinking it, I think. I tend to be the same way, sometimes suffering from analysis paralysis. :dizzy:

Seems like I did a great job compacting, or there's a lot of clay in the soil, or both.
Yep that pic is a good sign. Your soil is compacted, and fortunately the adjacent edges didn't cave into the excavated area.

Ok, that puts my mind at ease quite a bit. I was worried that the sand was going to blow out the side when I did the final compaction over the finished pavers without some support on the side.
Personally I'm not a fan of running the compactor over the pavers, especially smaller ones like these. I believe if all other steps are done properly then it's unnecessary and potentially harmful (paver rash, lateral movement, etc); only need a rubber mallet to set them. If the sand or RCA isn't done right compacting the pavers will hide smaller flaws but only for a little while. Eventually they'll resort to the subs layout. (For the engineer in you: neither the sand nor RCA (assuming properly compacted when applied) will compact further. So a plate compactor will flatten adjacent pavers because of the plate's size & weight distribution, but it's not really flattening the underlying support layers.)
And while on the topic, be sure your base sand is consistent in moisture before screeding (I recommend completely bone dry) for consistent density. If it's moist or wet it can be inconsistent and then you'll have unevenness in the end.

Anyway, the sand & pavers should be restrained from lateral movement before a final compaction, else the edges will start to shift under the vibration.
Basically the walkway in it's entirety should be self-standing & supported. The backfill is more like dressing than support.

backfill when it was all done?
Right.

Well, apparently I did this part right, because the water definitely didn't pool near the house.
:clapping:Always a good sign!

Only?!?! 4 feet wide?!? :) I was going to make it 54" but thought that would be too big for the front of the house. The previous walkway was 3' so another foot seemed reasonable to upgrade to pavers and make it more comfortable.
This is definitely an aesthetic thing but I prefer things to be in proportion. If the house or yard are very small then I think a paver walkway should be closer to 3'. As they get bigger so should the walkway, though perhaps not linearly. I find 4' is comfortable.

I have decent flexible plastic edge restraint and lots of bright spikes.
Can you post a pic? I'm curious if it's the same good quality plastic edge restraint I used about 15 yrs ago. It went down quick & easy (using 10-12" spikes) but over the years sand around the edges gradually seeped out and those parts of the edge shifted out of level. Not a big deal to fix, but...
The plastic edge restraint anchors into the RCA, which means you need RCA well beyond the walkway's perimeter (for my app it was about 6"), which made it nearly impossible to maintain good grass up to the walkway (too little soil above the RCA), especially in the summer.
Mortaring the border solves all those issues.

Mortar may be possible at the end, I have several big bags and want it to last a long time.
It'll likely take more than that but you can do it in sections.

What I'm wondering now is where all that water would have gone if the hole wasn't there? Or is this all going to be in the base?
If by "hole" -- you're referring to the excavated area for the walkway base, the question is really more of "Where did it come from?" Most likely most of it came from the adjacent areas: once they saturated with water the rest overflowed into the ditch which presented no resistance. Once your walkway is in place it won't accept much water (the pavers & poly sand resist it, the sand base doesn't hold it, and the compacted RCA resists it), so what you see there would've followed the pitch surrounding the walkway and handled accordingly.

And on top of that, how long do I have to wait to dry this all out before I can get the stone in there?
Wait until you can walk the ditch without mud accumulating under you. Doesn't have to be fully dry.

And does this lake of water indicate anything about my soil that's going to lead to disaster later?
Nope, it's a good sign.

Maybe I should give up the walkway and just turn it into a lazy river ride for the kids...
Something tells me the kids would never forget it!
 
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