View Full Version : Subgrade moist in spots - O.K to install fabric and base?

09-04-2000, 12:26 PM
Hi everyone:

I'm doing a driveway parking area with pavers. My hole is ready except for a few wet spots where a recent rain leaked through my protective plastic covering.

I have typar spunbond fabric on hand and ready to install, and my question is, as the title of this thread implies...can I go ahead and install fabric and base today or should I wait until subgrade dries out completely? The subgrade is not completely wet, just in a few areas.

My customer is getting impatient; I have a compactor rented and sitting idle; it could rain again; etc, etc,

Help!~ What should I do?

09-04-2000, 12:56 PM
Start the job, moisture will help compact the base just make sure your deep enough with your base. Your fabric is not the best for what your are doing, a woven fabric is better unless you are using a heavy fabric(6 oz or up). Make sure your subgrade is compacted and you have at least 8" of base down, compacted in 2" lifts. what type of edge restraint system are you using? Don't want any more problems like the last post:)

09-04-2000, 12:59 PM

Thanks, I was hoping to hear from you or one of the other resident paver experts.

About the fabric....what is the problem with this type? I read the specs on it and it seemed to offer the benefits I am seeking....

I will be using snap edge (sp?)

Also: How can I run a compactor over the subgrade with wet spots? Will it make a muddy mess?


09-04-2000, 01:07 PM
I use a spun fabric but unless it's a heavy fabric you could have problems with rupture. tear strength and puncture strength are most important for a parking area, turning of the tires will cause forces to try to move pavers. check with your supplier on the strenght of the fabric (look for 300 lbs puncture)
as for the wet spot just throw some gravel down (about 1") then run your compactor over it.

09-04-2000, 01:16 PM
O.K., now you've got me wondering about fabric. The specs say that this material will help "squeeze out" excess moixture that may be present. If fabric disallows moisture from reaching base....still O.K. to begin job? Will present moisture still assist in compaction?

Better off skipping fabric all together??


[Edited by turfquip dot com on 09-05-2000 at 12:50 PM]

09-04-2000, 01:55 PM
No fabric will take out moisture, all fabric is for is support for poor subase, or very heavy loads, fabric is not needed for most jobs, go here to find more info on paver installation, http://www.unilock.com/technicalinfo/download.html

or e-mail me for more info @ nelsongroup1@aol.com

also could go to lawnsite chat and find me

09-04-2000, 07:24 PM
Paul, How much water should be added (if any) to each 2" lift to facilitate compaction and/or ****** dust?

Also, how many times should I run the plate over each lift.....and is there a recommended pattern which is more efficient....or does a more thorough job.

I started that job today and opted NOT to use fabric at all since more than one reference source did not recommend it. I first filled the pock marks in the subgrade with 1 to 2 inches, compacted twice over, added 2" - 3" more compacted again twice over in a circular pattern. We used nearly 8 tons of material today and I've got another nine tons of 610 mix on the way tomorrow(first out) for the next lift or two. The plastic is back on for the night.

Thanks for you help and suggestions. Are there any pitfalls to watch for at this point?

Highest Regards,


09-04-2000, 08:04 PM
optimum moisture is 10%-15% for best compaction most stone from the quarry carries this so if it fresh out of the quarry you should be ok, Their is no real way of telling how much compaction you are getting unless you have a nuclear compation tester (ok guys even I don't have one of these) just run the plate compactor over it 3 or four times and if after the last past your not moving any gravel down your looking good, one test i use is a 10" spike that we use for paver restrant, if its hard to pound in you good if it goes in easy then compact some more.

Ok next you need to make sure your grades are right for your final lift use a pipe 3/4" id black iron is best(don't use thin wall bends too easy) and roll over your base checking for low spots or high spots, go both ways. fix these and you should be ready to install sand and pavers.

09-04-2000, 10:52 PM
I don't know if the pattern of compaction makes any difference, but I usually go in a different direction each time - first and second time perpendicular to eachother, next two same, but skewed 45 degrees from first two, then back to original pattern (and I usually make extra passes wherever the pavement ends - grass, other pavements, etc).

Good luck on the project!

09-05-2000, 09:34 AM
Thank you Stonehenge. I took you advice and compacted in three directions. After applying Paul's spike test I would categorize the base resistance as "moderate". Maybe I need to hit it again....I'm using a 3000 psi machine.

A couple more observations: There seems to be an uneven distribution of 'fines' on the top surface of the first lift...any cause for concern? In other words, areas where fines are not noticable on top. Spike resistance seems equal in these areas as well as 'powdered' areas BUT the compactor keeps leaving a rooster tail of loose gravel on each turn.

Paul, I'm beginning to envy you with that vibratory compactor!

09-05-2000, 09:12 PM
As for the uneven distribution of fines - if the delivery was relatively uniform, it may just be that a bit more fines collected in one area - nothing to worry about unless it's an inch or more deep. The rooster tail you describe makes me wonder if the stone isn't wet enough (or too wet - you can get 'rooster-tails' either way).

09-05-2000, 09:39 PM
Stonehenge, others:

I need about 5 yards of base material to finish and I'm wondering if I should request another mix with say - a higher percentage of fines. Reason I ask is that I was just reading Belganhardscapes installation manual and it recommends a near perfect smoothness top of base so that the bedding course can't settle. As I see it, with the material I am getting from the quarry, it's highly likely that the top of base would be porous. Every lift has had probably 40% to 60% surface area with little or no visible fines. In spots where those surface areas "stack up" one over the other with each lift, seemingly would be a weak area??

I'm paniking too, because I've gotten mixed signals on fabric utilization. As I mentioned before, I opted NOT to use it, but the install guide I just read today suggests it.

I will say one thing....a formal education in the science of interlocking pavers may well be in my future. I'm taking too many 'best guesses' i.e. too many chances.
Some of those have been wrong so far.

As far as this job, I'm going to seek divine intervention or something so it'll stay together!

09-05-2000, 10:36 PM
You should get a different "mix" of stone if your base has holes in it. your book is right you should have a smooth surface after your plate has gone over it twice. We use a grade called ca-6 or road base it's is state inspected and when graded out with a rake still has enough fines in it so no holes appear. if they don't have anything that comes close you might want to add fines yourself by ordering a ton or two of fines and mixing them in to your stone.

09-06-2000, 01:08 AM
Another name for CA-6 is Crusher Run. It should compact to a really tight surface. Knowing about the type of sub-base soil you are working with will help you make good decisions in the future.
Regarding the industry training:
Contractor Certification Courses are conducted by the ICPI
(Interlocking Concrete Paving Institute). Your paver supplier or regional manufacturer should be able to tell you when the course is being given in your area. Their web site is: http://www.icpi.org
Good Luck.

09-10-2000, 12:42 AM
Turfquip, how did the job turn out?

09-10-2000, 10:39 AM

The base is finally ready, but that's it. Right now, it's raining so setting the pavers this weekend has been out of the question. All the gravel was shoveled into the hole by hand - between that and waiting on the next load, the days seemed to fly by with little to show.

I do feel good about the base. It's 10 to 12 inches thick everywhere, well compacted, excellent spike resistance, sloped for drainage, smooth (I used the black pipe method you suggested)

I've learned a lot during the experience. Too much to list. My knowledge still only scratches the surface of what I need to know though. I need tools too....lots of them. A RamRod would seem to be the ideal machine for this kind of residentially oriented hardscape work.

Nobody around here has a clue what CA-6 is. I can only imagine and dream what crushed stone with sufficient fines and dust would be like to work with. I ended up using 304's and a thin film of fines on top to smooth things out.

I'll keep you posted....I may have more issues when it's time to lay the pavers.


09-10-2000, 04:42 PM

sorry to hear about the rain..... can really put a damper on a paver job, thats for sure.

As for equipment, I don't know how big of a job this is, but I would strongly suggest some sort of machine for the next time you do one if you have done this all by hand.

You don't have to buy one, just rent if you have too.

As you are learning, pavers can be very dependent on weather. When ever I start a paver job, I try to get the job moving as fast as possible, as a week of rain can take 3 days of work and 'wash it down the drain'. Even a brief shower can really set you back sometimes.

Usually, its nice to at least have a machine for the base excavation and then for putting your base material in. Once the base is in, and compacted, it is pretty much weather proof. If the job is not to big, the stone dust/sand can be wheel barreled with not too much aggravation, but nice to have a maching for that too. Also, its nice to get the machine there to move the pallets to wear you need them.

For the price of a rental for a day, a machine is something that definitely will be worth the money next time. Main thing is to get everything there before hand so that the machine is running all day. A lot can get down in a day if you plan right.

Also, if you are going to start laying pavers and don't think the weather will hold out for you, go buy some tarps now. Not tarping a job that is being done in 'pieces' can lead to A LOT of extra work.

Also, don't forget to tarp you stone dust/sand pile if you will have it sit for while. Wet stone dust/sand is not good to use, is a pain to screed, and will take forever to dry out once it gets wet.

[Edited by steveair on 09-10-2000 at 07:57 PM]

09-10-2000, 08:15 PM
Turfquip, screed out yor sand in small areas so you can start installing your pavers use a piece of edging when you stop at night and compact up to that point,start at the high end so you keep water from puddling under your brick or at your starting point. We still call pavers wet work because if it stops raining we can still work.

09-10-2000, 09:33 PM
Thanks guys. I appreciate the advice and support. Interesting Steveair's comment that once the base is in and compacted, that it's weatherproof. That's encouraging because even though it's tarped, I worry about water percolating through to subgrade. Good advice too on using DRY sand. I was wondering about that. To get the job done, I need to go rent a tub saw and a plate compactor. My gut feeling is that the plate should be a smaller one - say 2000 lb?

Paul, thanks for the suggestion on installing edging and compacting that day's work. I like it. I'm not sure how many days/hours it will take to install this - it's only 500 s.f. with three guys. Right now I'm thinking one guy bringing, one guy laying, one guy cutting.

09-10-2000, 10:03 PM
500 sqft?

If you have three guys, you should be able to have it laid before noon, and cut in by the end of the same day, so long as there aren't any ornate cut patterns you're making. As for cutting, you might want to search some past posts about brick saws - cutoff saws supported with tub saws can really speed up the cutting process. If you're serious about getting into pavers, an investment in a cutoff saw is relatively cheap and can save much in time and $$.

For hollandstone, we average about 300 sqft/hr laid for 3 guys. 2 guys schlep, one guy lays (and schleps when the other 2 can't keep up). The ideal is 3 guys schlepping, 1 laying. We cut in the average patio in about 1-2 hours (but we have 2 tub saws and 3 cutoff saws on site for that part).

So it sounds like you'll have this project done in no time.