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I'm going to build a brick patio. I have been advised to lay down plastic sheeting under the crushed stone foundation. On the other hand, this plastic sheeting would be a perfect place for moisture to collect. Anyone have any advice?
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Slope to drain. Don't use plastic. Cover with awning/arbor. Build it in Arizona.
*Sir,Don't put plastic under your patio. As I recall, doing so sometimes results in small sink holes. I don't know why though. You would probably want to put down a heavy duty landscape fabric. You will always have small weeds in the joints, fabric controls the big ones. Be sure to compact big time.
*If you can dig, use fabric (the real stuff, not Home Depot's), a few inches of gravel, an inch of sand, bed the bricks in the sand and sift more sand into the cracks. All this prevents the weeds from taking root and stabilizes the patio against erosion. Consider using concrete pavers -- we got talked into it and have been very happy with the low-maintenance results. Our neighbors laid brick directly into the clay earth and its look fine but drains poorly.The plastic sounds like a terrible idea. Oh, 1/8" per foot, even 1/16" is fine to drain. 1/4" is pretty obvious, like a sinking ship. The less stable the patio base, the more slope you'll want as insurance. If the water collects, then mold, moss. etc. will follow. Search archives for lots more discussion.
*Dont't bother with any fabric. I did 4-6" gravel mix, 1" sand, and brick with sand in joints. Used plastic edging to hold brick and sodded right up flush to brick. Four years later I have no weeds. Sure there's the occasional weed in cracks or grass that got in when I reseeded the lawn, but Roundup works just fine. These seeds are getting in the cracks (wind blown). Fabric would not help. All done on top of HEAVY clay soil with slope of 1/8" per foot. Fabric (not plastic) might be necessary if you have sand base only.
*Fabric also helps with erosion and stopping dirt infiltration from clogging the gravel field. There was a post a while ago here by an experienced pro who nevers uses edging (which is $$). Heck I used it -- the digging was the only hard part of the project. (dense clay + many tree roots + several hundred potato rocks = pain). The major cost was the pavers -- $2-3 sf for fancy shapes?
*I will agree that the plastic is not a good idea. I should also point out that to make a sand base brick patio weed free and stable you need to spend big bucks and move alot of earth. When I am asked to do a walkway or patio, I usually talk the client into a mortared brick on concrete slab. It is roughly equal in cost to the spendy precast concrete pavers and is bullet proof. Most people end up liking the visual relief a mortared joint provides. Well, that's my two bits,
*A 4" slab? Control joints? Rebar? (Trying to learn some more. On that ... how do you build brick stairs? I can picture a U-shaped footing for the sides and first step ... but how are the upper steps built? Our concrete steps look like they were poured against a diagonal plywood form, the center is hollow.)We moved the earth ourselves, and the pavers weren't too expensive at the trade-oriented masonry yard we use (same or less than HD, better variety). The ulterior motive for the substantial base was to create a dry well sloped away from the house in a perpetually sodden back yard with no drainage possibilities. Spent some money to rent a power tamper. Mongo did a neat job with flagstones, you can search for the picture here.
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Wayne,
The key to a good job is in the base work. Above posts are right - use 4-6" of crushed stone for your base. On a driveway, we use 10-12", but for patios & walks 4-6" is fine. Build it up in layers, and tamp each layer with a power tamper.
Contrary to popular belief, the gravel is not for drainage. Your pitch is for drainage (1/8" per foot is good). The gravel is for establishing a firm base, so you want the crushed stone with the "fines" in it, not screened. Around here they call it crusher-run, and it comes in different sizes. Look for 1" crusher-run for a patio.
Unless you have quicksand-like soft spots after you dig, do not put down plastic sheeting or weed barrier cloth under your gravel. (Sorry to those that have done it.) If I find a soft spot (wet clay around here), I'll use some geo-textile fabric just to stiffen up the base, and to prevent the gravel from disappearing into the goo. Other than that, you don't need it.
Nothing you put under the base will stop weeds, because that's not where they come from. Walter's right, the weeds you may get are wind-blown. I once saw a magazine article suggest using black plastic between the gravel and sand layer! Try keeping that flat while you screed your sand!!
Definitely rent or borrow a saw w/ a diamond blade for the cuts. There is no other way to get professional-looking results.
The guy andrew mentioned is me. He's right, I almost never use the plastic edging material sold for the purpose. Here it is over $1/ lineal foot, and is unnecessary in most applications. Tamped gravel around the edges works well, and can be top-dressed with soil to become lawn or planting bed.
If you use concrete pavers rather than clay brick, you can run the tamper right on them after making your cuts and back-filling(or installing edging if you feel you must). This gives you a really flat surface.
If you have any more questions, just ask.
Mike,
Although I like mortared brick and have seen some beautiful jobs, there is no way that that is comparable in cost to the above method, and they eventially come apart around here. Properly installed pavers on a gravel/sand bed seem to withstand our winters better at less cost.
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Another writer pointed out that some paving systems just tend to work out better in different climates. Where you don't have hard freezes you have more choices. I can appreciate that. There also seems to be a great variance in materials nationwide and that would certainly influence the choice.
You asked about the slab - for a walkway I pour a full 3.5" to 4" slab with a control joint every 15 to 20 feet and #4 or #5 rebar. I generally order a six sack mix because it is only slightly more expensive than standard. I shove the bricks into position with buttered head joints only and then pour a more fluid "grout" mix for the beds using a grout bag. It goes much faster than you think. Don't mortar the joints on top of the control joint; use backer rod and calk. (Anyone else love that Sikaflex polyurethane?)