Using Welded Wire Mesh in Concrete Slab
toycept
| Posted in Construction Techniques on
For new construction we are planning….. in our basement, which we will finish and use very often, we will have a concrete slab floor, 4 inches thick. Does anyone have any thoughts, comments, suggestions as to whether or not it is useful, wise, beneficial to incorporate 6 inch welded wire mesh imbedded in the concrete slab. The floor is 26 x26 feet in one section, 18x 13 in another section and 18 x 18 in the 3rd section. I really am trying to avoid having cracks… (we’ll have expansion cuts put in) and am wondering what people’s experience is with using the wire. Is it worth the extra time, trouble and expense. The house is located in NorthEast Massachusetts….
thanks very much for your help.
Replies
Absolutly. And keep it up off the bottom of the pour.
I'd use it even with fiber re-inforced crete, and in some places I think it may be a required issue. I does nothing to stop the cracks, but controls the breakage plane so there is little if any "toe stubbers" , But a properly laid slab should not have them anyway.
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You have any footings for poles or piers in that slab? Isolate them from the slab and run your cuts to them. Mike Smith showed this on a garage pour in ............X............located in the photo gallery.
Don't pour it wet and keep it covered and damp for a couple weeks to attain maximum hardness.
A Great Place for Information, Comraderie, and a Sucker Punch.
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
Because concrete has enormous compressive strength but very poor tensile strength, it almost always requires steel reinforcement. I would recommend both 6" welded wire and fiber (short fiber polyester), since they perform two different functions.
The fiber reduces the likelihood of tiny shrinkage cracks due to overhydrating the mix and/or surface drying during the cure. Mesh reduces the likelihood of large settling or expansion cracks. But, since you have a three-section slab, it's wise to cut or form expansion joints as you're planning. This won't guarantee crack control, but make it more likely.
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Thank you for the replies and suggestions...Calvin, the photos of Mike Smith demonstrating the pour using the Welded Wire Mesh... can you let me know how to access that or find it...thanks
Sorry, tried a few attempts at the Advanced Search for you. Finally got the copper pipe thread (this thing pops up when the machine starts to smoke).
Seek out mike smith or try the seach yourself. There was a long thread-Adverse Conditions (in the photo gallery) I think it was called. You'll see there where mike formed up the post pads. I believe they did the forms on the diagonal to facilitate the cuts they would make in the slab. They will cut to the corners of that footing. This allows the slab to move (if it wants) independently of the footings which will help keep the cracks coming out of that area.
Then they isolated that pour from the garage floor with expansion joint. When the slab was done, they made their cuts to the corners of the post footings.
I think.A Great Place for Information, Comraderie, and a Sucker Punch.
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
View ImageA Great Place for Information, Comraderie, and a Sucker Punch.
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/
Thanks a lot for the good follow ups, Calvin. I do plan on having the contractor put in the cuts. I'm, however, getting resistance when I mention using the wire mesh. I know it's probably a pain to use the stuff, but I'm pretty adamant about having the mesh... trying to minimize any serious cracking.... or at least doing due diligence in keeping it to a minimum.Thanks again. by the way, I did a search, google, and couldn't find the mike smith thing.
Tell us about how the subbase has been prepared.... gravel? sand? compaction?
Nothing has been prepared yet...still in the planning stages. The print calls for 8 inches of compact gravel, poly vapor barrier, wwf and 4 inches of concrete..... the ground is mostly sandy soil.
8" gravel, compacted is very good, make sure you have no organic soil in your excavation.
Isolate the concrete slab from walls and footings, including teleposts or support posts. We use a 1/2" "Buffalo board" or HD EPS.
4" concrete, 3500 psi, fibre re-inforced; you can park your truck in the basement
We have found it unnecessary to put wiremesh down with those specs. As it was mentioned the mesh will not prevent it from cracking. If the slab heaves you have other problems. It is coming back to soilprep.
Hydrostatic pressure?
Edited 1/27/2008 6:32 pm ET by semar
I know people hate me when I post in the concrete thread. but here it is again for the 200 time.welded wire and fiber does the same job, mesh and rebar does not do the same job, you can have cracking by load factors and by stress cracking due to curing. mesh and fiber does not control load factors.I stop using mesh in my placement I went 100% fibers. the rolled wire mesh will hurt you. the mesh that comes in mats is good If you pull the wire. If you walk on the wire it does nothing but throw money out the window. fiber you cant screw up if you had to.once the concrete get hard and cures at it 28 days, the mesh and fiber really does nothing, if it hasnt crack by then, it proberly wont.buty you want a good job. increase your concrete to six inches, add #4 rebar both ways every foot, lay a mesh mat on top of the rebar. place at a three slump, add a super plastizer. that would be the altimate placement.two ways to screw up concrete 1) concrete driver 2) concrete finisher
Is this an underground parking lot?
>>increase your concrete to six inches, add #4 rebar both ways every foot, lay a mesh mat on top of the rebar. place at a three slump, add a super plastizer. that would be the altimate placement
Agreed. Current project has a 4" slab, 6 sack poured at a 3" slump with water reducer and fiber, base = compacted crushed rock in 4" lifts and the excavator's laborer ran the plate over it until his teeth got loose, #3 bars at 12" OCEW, shrinkage joints in the right places, carefully kept wet after the pour for a couple of weeks. No cracks at all 7 months later. I don't know what else I could do to improve on it. I know it's all about the base grading but I can't bring myself to leave out the bars.
HERE is the area in the thread that the picture is from. You might go either way from there to get some more information on the pour.
I amazed myself that it came up this time and I picked the right one to take a chance on.
This stuff here is a crapshoot.
Best of luck.A Great Place for Information, Comraderie, and a Sucker Punch.
Remodeling Contractor just outside the Glass City.
http://www.quittintime.com/