The Brew Cabin

Tony,
I live in upstate NY where freeze/thaw of ground is of concern. I am interested in building a patio/walkway of a certain type, and have found the recommended methods on your web site. I've found a few archived posts that address freeze/thaw, but really would appreciate your help specifically for my project.

I'd like to attempt "crazy paving" including "laying flags to free edges." As such, I believe you recommend a semi dry grit sand and cement bedding, a mortared edge (for the free edges), and wet grouting to joints. Correct?

My question is this--are any or all of these methods too risky for my climate?

I'm not 100% sure, Pamela, as I'm not familiar with your part of the world.

However, going off what other people have said, in those parts of the US where frost heave is a problem, the usual construction involves a significant thickness of reinforced concrete as a base for the flags. The use of a semi-dry laying course material, and mortar pointed joints is of less significance - it's the base that matters most, apparently.

While we in these temperate maritime islands of Britain and Ireland can get away with laying patios on a scratching of sand, it seems that the preparatiuon to cope with frost heave involves digging down to half a metre (18") or more and building a base or sub-base that is designed to move with the frost without upsetting the paving.

Maybe our US correspondent, Mr Landscape Mann, can help?

Hmmmm...before Mr. Mann gets a chance to reply, I'll add that I already have about 8" (200mm?) of sub-base filled and tamped. The sub-base is "crushed rock" (small rock down to dust size).

I am a bit confused on the concrete bed idea for frosty climes. Everyone in these parts says concrete will crack over winter--don't do it.

Mr. Mann?

Quote: from pamela on 2:01 pm on Aug. 6, 2004
Hmmmm...before Mr. Mann gets a chance to reply, I'll add that I already have about 8" (200mm?) of sub-base filled and tamped. The sub-base is "crushed rock" (small rock down to dust size).

I am a bit confused on the concrete bed idea for frosty climes. Everyone in these parts says concrete will crack over winter--don't do it.

Mr. Mann?

Pamela,
You are quite correct as far as a subase. 8" CR6 is great.
No concrete subase.


Pam wrote:
" I'd like to attempt "crazy paving" including "laying flags to free edges." As such, I believe you recommend a semi dry grit sand and cement bedding, a mortared edge (for the free edges), and wet grouting to joints. Correct?"

Pam,
What type/size of flagstone are you installing?

I have not used the method you describe
above. I tend to shy away from anything set in cement. It seems in our Climes they will all crack at some point in the future.

What part of NY are you in? I am going to be up at my Brothers place in Mahopac NY later this year for some extensive Hardscape projects.

I live in MD.

LandscapeMann

(Edited by LandscapeMann at 12:33 am on Aug. 7, 2004)

Landscape,

Glad to hear you like the CR6 subbase, cause it ain't coming out!

I plan to install PA bluestone. I have several pieces of the bluestone around the outside of the house, which I am consolidating for use as this new patio/walkway. Originals were about 12" x 24", and so the pieces are a bit smaller, perhaps 2-3 irregularly shaped pieces per original stone.

The best local advice is the CR6 subbase, 1-2" bedding of stone dust and then jointing using something called "stabilizing sand." Tony plus another source say bedding could be 10 parts stone dust to 1 part concrete, for some stabilization. Stabilizing sand sounds very much like sand or stone dust also mixed w/a touch of concrete.

As the thickness of the bluestone varies per stone (even across a single stone), I like Tony's recommendation that the stones should be individually bedded. I don't know whether that'd be wet or dry.

What methods could you recommend for my "little" project?

Pamela

P.S. I'm outside Rochester, NY, just a hop, skip and a jump and a two-hr ferry ride from Canada. Spent many years in MD, however, near rockin' Rockville. Where in MD are you?

Pamela,
I have installed many Pa Blustone patios and walks.

I am not sure of the purpose of the stabilizing sand. If you have a properly tamped subase and your stone dust laying bed is formed to bed each thickness stone securly the patio/walk will be stable.

As far as the project you are attempting. IMO it is one of the more/most difficult methods to get a level/even surface.

Reason: when each piece of Pa Bluestone is a different thickness and a different shape. It is quite difficult to get a professional looking job. Of course when one is doing a project for a client. A higher standard may be required.

All the Pa Bluestone patios that I have installed where first drawn up as a plan using many different size stones. But no irregular broken pieces etc. When properly layed out and installed. They make for a beautiful life long project.

I have always found that with the amount of work and planning nessasary to excavate/ grade/install subbase etc. etc. required to do a first rate job. Is worth using the very best grade material to pave it.

In other words the investment of labor involved in properly getting a project to the final stage of laying your paving is a much greater investment ( in labor)
Than the laying of the surface.

My point is you might want to consider if using a irregular shaped varied thickness flagstone that may be very labor intensive to install correctly. Is worth the effort as opposed to using a paving type of a more uniform size and thickness. There are Pa Bluestone available that would meet that standard. But I do realize that they are very expensive.

Of course the choice in pavers is almost endless.

I am located in (Yuppy) Columbia. Bout 20 miles from (Rockin) Rockville.

LandscapeMann

On Edit,
Please realize that I am just trying to illustrate a possible alternative course of action here. Your setting/situation may make your choice of material the best one.

I am just relaying my experience which or may not have any relevence at all to your project.

(Edited by LandscapeMann at 8:21 pm on Aug. 7, 2004)

Isn't the Stabilising Sand a polymeric sand? Over here, the most widely-distributed product is the GeoFix stuff (you'll wet yourself laughing when I tell you we pay the equivalent of over &#3630 for a 20lb pack!) but in the States there's TechniSeal, Sandlock, EcoGuard, and several others whose names escape me at the moment.

I guess I should have figured that out on my own.
I just used Techiseal for the first time on the walk that I just did. &#3615 per 66 lb. bag. Was a bit time consuming to install as per directions. But seems like a neat concept. When I stop down to my site to take some pics. I will see how the Techiseal cured.

LM