Building Question

[SCDAWG]

I am putting in a house for my folks. 2200 sq. ft. slab home. General contractor says the fiber is fine and doesn't need the welded wire mesh. The mesh is no good if it is not put in correctly. I am of the opinion it needs mesh and rebar. The rebar would tie in the blocks to the slab. What do you guys think

[SwampDecoy]

Tell him to give you a written warranty that the Slab will not crack at all, not within some tolerance limit, using his Process with Fiber Only. Otherwise, tell him you want Rebar.

[Saltydog235]

Tell him to give you a written warranty that the Slab will not crack at all, not within some tolerance limit, using his Process with Fiber Only. Otherwise, tell him you want Rebar.

Well, nobody would ever guarantee that since one of the properties of concrete is that it is going to crack. You put in control joints in order to try and make it crack where you want it to. However, that doesn't always work.

If the house is a stem wall construction, they should pour the blocks at the same time as the slab so that it is monolithic. If they fill the block prior, then they should be resteeling at about every 32" out of the block core. Fiber is OK, I do prefer wire but most of these residential idiots won't pull it up where it is supposed to be so 90% of the time it's on the bottom of the slab unless you sit there watching them. Your grade beams and isolated footings should have rebar in them.

[turbo]

A slab is gonna crack.

You just want it to crack where you tell it to.

Fiber is fine. The messicans that finish the concrete are going to top the wire chairs over anyhow. So, mesh doesn't do you much good.

As far as the block, I'd tell him that the CMU wall must be tied into the slab with steel. I'd also tell him the size and spacing of the bolts for your sill plate attachment. If he doesn't like it, find another builder.

[turbo]

Salty already said all that needed to be said.

Listen to him.

[kquinn]

Tell them to use a macro fiber.

Bust there balls on proper compaction more than anything.

[lowbudget]

Well, nobody would ever guarantee that since one of the properties of concrete is that it is going to crack. You put in control joints in order to try and make it crack where you want it to. However, that doesn't always work.

If the house is a stem wall construction, they should pour the blocks at the same time as the slab so that it is monolithic. If they fill the block prior, then they should be resteeling at about every 32" out of the block core. Fiber is OK, I do prefer wire but most of these residential idiots won't pull it up where it is supposed to be so 90% of the time it's on the bottom of the slab unless you sit there watching them. Your grade beams and isolated footings should have rebar in them.

Question 1: What is specified on the plans? If you are going to deviate from that then you own it, and if it should crack/tilt/crumble/separate later on you have no one else to fall back on.

I second the wire mesh comment, its a better reinforcing method, but only if done correctly. I've cored countless slabs, and have never seen wire mesh anywhere but the bottom in residential and commercial construction. If they have already poured the block, you want the reinforcing steel epoxied into the grouted cells of the block. Not hardware store liquid nails, a commercial grade 2-part epoxy made by Hilti or another reputable company. Also, personal opinion, I'm pretty sure fiber is snake oil. I've never noticed a higher compression strength or flex strength on a fiber/non fiber mix. If its free I would take it, but I sure wouldn't spend good money on it. If you are really concerned get him to deduct fiber and wire mesh from the bid, then ask how much for 5" of concrete instead of 4". 25% more concrete is a much better and idiot proof way to spend your money.

[Bigtimber2]

3" precast brick or chairs will keep the mesh where it needs to be. 6x6 W2.1/W2.1 mesh is over kill but does not bend like W1.4 when they are finishing. Like Salty said you want a rebar dowel from the stem wall into the slab. I would want the dowel from the foundation into the stem wall then bent down into the slab after the block are laid. Fiber mesh is fine for 300k sf warehouse where slab prep is done worth heavy equipment.

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[PBiz]

What do your Structural Drawings say?

I'd make him do it like that..

Concrete was made to crack...

[Bigtimber2]

Bust there balls on proper compaction more than anything.

This also, there are millions SF of large commercial builders with slabs not cracked and level. The slab prep is done properly and tested. Commercial concrete subs do not like warranty work.

[turbo]

This also, there are millions SF of large commercial builders with slabs not cracked and level. The slab prep is done properly and tested. Commercial concrete subs do not like warranty work.

Show me where it is and I'll find you a crack.

[FishSticker]

I am putting in a house for my folks. 2200 sq. ft. slab home. General contractor says the fiber is fine and doesn't need the welded wire mesh. The mesh is no good if it is not put in correctly. I am of the opinion it needs mesh and rebar. The rebar would tie in the blocks to the slab. What do you guys think

All of these replies are useless. You have to go with whatever your engineered drawings call for...As your minimum standard. If he gives you options, you can go with either 3000psi or 6*6 wire mesh. At that point it doesn't matter, because he bumped his ink on it...Any structural issues related to the foundation are on him. He will spec rebar and anchor bolt spacing.

If it means anything, I put WWF in my personal house...But be prepared to pay additional funds to have it done properly over the finer mesh cost.

[Bigtimber2]

Find a tilt wall construction building anywhere in Charlotte. Excluding sidewalks. The Kings Mountain area has several data centers with nearly perfect floors.

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[2thDoc]

and I thought offshore fishing lingo was rad....

[SCDAWG]

Not called out in the specs. At a minimum I think rebar should be used. The price of rebar couldn't be that bad. That just isn't a place to skimp. Thank you for the replies.

[PBiz]

Not called out in the specs. At a minimum I think rebar should be used. The price of rebar couldn't be that bad. That just isn't a place to skimp. Thank you for the replies.

It has to be on the structural drawings..

[Bigtimber2]

The engineer will amend.

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[PBiz]

If not, some little peckerwood inspector won't know which box to check..

[lowbudget]

Find a tilt wall construction building anywhere in Charlotte. Excluding sidewalks. The Kings Mountain area has several data centers with nearly perfect floors.

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If you pour more than 15 linear feet of concrete, it will crack. It may crack along a control joint, or be a very small hair line crack, or be flush on both sides so you dont notice while walking around but it cracked I promise. The only exception I have seen is Post Tension Slabs. I've seen a few smaller post tension slabs that didn't crack because of the confining compression. But I highly doubt a large scale building like you referenced is post tension.

Long story short, the slabs you have seen cracked you just didn't notice.

[Saltydog235]

It has to be on the structural drawings..

A lot of these residential engineers have gone to calling for either/or and putting the language in some obscure detail. They've gotten as bad as the architects on half assed information.