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-   -   Plywood vs Concrete for Workshop Floor (http://www.diychatroom.com/f2/plywood-vs-concrete-workshop-floor-188339/)

akimbo 10-09-2013 07:47 PM

Plywood vs Concrete for Workshop Floor
 
1 Attachment(s)
I've been thinking of leveling my very unlevel concrete workshop floor using thin set then a mixture of sand and portland cement on top (as recommended by the concrete company). There is a 3" change in grade from the center of the room to the edge so it's pretty bad and it would be too expensive to use floor leveling compound. A contractor is suggesting the use of shims and plywood because it would offer more insulation. I'm wondering about wear, dampness (which shouldn't be a problem but what if you spill water?), and labour intensive costs or ?? We use the space for some woodworking, bike repairs, potting plants, and storage. Any thoughts?

Fix'n it 10-09-2013 08:00 PM

how about an overall pic. and how big is it ?

wkearney99 10-09-2013 08:14 PM

And how did it get that far out of level? Is that problem still present? As in, it'd be kind of a bad idea to add anything new if the floor's going to continue to shift like that.

akimbo 10-09-2013 08:41 PM

The space is 11 x 15". Will add a photo later.

joed 10-09-2013 09:12 PM

Any concrete you pour over top of that will crack in the same pattern.
Is this an outside garage or inside? What is your location? Do you get frost?

akimbo 10-09-2013 11:34 PM

Quote:

Originally Posted by wkearney99 (Post 1251657)
And how did it get that far out of level? Is that problem still present? As in, it'd be kind of a bad idea to add anything new if the floor's going to continue to shift like that.

Yes. There used to be a carport there and it was removed to add a 12' 2-story extension to this house. It was done with permits and inspection in 1990. We bought this house 5 years ago and various contractors have wondered about the quality of the footings. The interior of the house has some long linear cracks in the ceiling which we repaired 5 years ago, and which have returned. There is not much that we can do about it, and so I just can't worry about it too much.

akimbo 10-09-2013 11:36 PM

Quote:

Originally Posted by joed (Post 1251679)
Any concrete you pour over top of that will crack in the same pattern.
Is this an outside garage or inside? What is your location? Do you get frost?

This is a workshop inside the house. It used to be a carport. See my other post. We don't get much frost. I'm on Vancouver Island.

joecaption 10-10-2013 12:22 AM

Any Unpressure treated wood should not be used in direct contact with the concrete floor.

ddawg16 10-10-2013 12:47 AM

Quote:

Originally Posted by akimbo (Post 1251727)
Yes. There used to be a carport there and it was removed to add a 12' 2-story extension to this house. It was done with permits and inspection in 1990. We bought this house 5 years ago and various contractors have wondered about the quality of the footings. The interior of the house has some long linear cracks in the ceiling which we repaired 5 years ago, and which have returned. There is not much that we can do about it, and so I just can't worry about it too much.

Dude.....Your house is breaking and your worried about how level your garage is?

Cracks in the house? And your worried about the garage?

How big do the cracks have to be before you decide that it needs to be fixed?

wkearney99 10-10-2013 05:15 AM

Quote:

Originally Posted by akimbo (Post 1251727)
Yes. There used to be a carport there and it was removed to add a 12' 2-story extension to this house. It was done with permits and inspection in 1990. We bought this house 5 years ago and various contractors have wondered about the quality of the footings. The interior of the house has some long linear cracks in the ceiling which we repaired 5 years ago, and which have returned. There is not much that we can do about it, and so I just can't worry about it too much.

Wow. Yes, the possibility of having to repair a serious structural defect could be something people would want to avoid worrying about. But that doesn't change the fact that it's there. And apparently continuing to be a problem. One significant enough that 'various contractors' are wondering about it.

If you remember the old TV show "Lost is Space" this is where the robot would flail his arms and shout "Danger, Will Robinson!"...

The concern here is, at what point will the structure get pushed past it's limits and collapse? Continuously patching cracks may make things look better but it runs the risk of hiding just how wide the shifting has been. The fact you've got a slab that's 3" off is not a trivial thing to ignore.

Perhaps it's time to pay a structural engineer to come look at the soil and foundation conditions. Yes, this will cost money. But failing to do so may be putting the house and anyone inside at a serious risk. The repair now could be simple, compared to the aftermath of bigger problems.

akimbo 10-10-2013 11:01 AM

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[QUOTE...
Perhaps it's time to pay a structural engineer to come look at the soil and foundation conditions. Yes, this will cost money. But failing to do so may be putting the house and anyone inside at a serious risk. The repair now could be simple, compared to the aftermath of bigger problems.[/QUOTE]
Thanks for your concern, as this was a carport, it is not the same slab as the house though there was one long crack in the basement foundation.This workshop has the original carport concrete floor. I should have mentioned that his house was moved from another location onto a new foundation and basement in 1968. Still that doesn't explain why there are cracks in the ceilings upstairs are returning after repair, but we are talking about 1mm in 5 years. We call our house the "crack house". I asked a building expert who has his own tv show and he said not to worry at all about the cracks. I've noticed them in a lot of other houses. For sure the 1990 construction of this workshop addition was of poor quality. To help shore up the footings, our carpenter added a 2' perimeter concrete wall around the base of the workshop, with 1' below grade, he drilled rebar into the footings to tie in the new concrete. We added perimeter drains too so the workshop is now nice and dry. previously water could get into the space.

akimbo 10-10-2013 05:08 PM

a few more pics...
 
3 Attachment(s)
... of the workshop floor. It would take more than 20 bags of Level Quick (self-leveling compound) to do the job--about $900. My idea was to level it with an application of thin set then 4 parts sand to 1 part portland cement -- as instructed by concrete company, but the contractor is inclined to create a plywood floor using shims to level it out. I have no experience with that, but , as he said it would be warmer.

akimbo 10-11-2013 10:00 PM

...Perhaps it's time to pay a structural engineer to come look at the soil and foundation conditions. Yes, this will cost money. But failing to do so may be putting the house and anyone inside at a serious risk. The repair now could be simple, compared to the aftermath of bigger problems.[/QUOTE]

Thanks. Until a year ago there were no perimeter drains around the workshop, and I wonder if all the water destabilized the footings. The previous owners should not have cheaped out when they walled in this carport but we have shored up the footings as best we can and now just want to fix the floor. I'm retired and on fixed income so I'm not spending the estimated 20,000 to replace the footings. As for the ceiling cracks, we get little earthquakes here, and truck traffic going past our house, but primarily the ceiling cracks were probably caused by the house being moved from another site onto a new foundation. Found this solution which may work for us.
http://www.woodnewsonline.com/DTEW/1...odworker2.html

wkearney99 10-12-2013 04:34 AM

Well, with the revelation of it being a moved structure, it'd make me even more interested in having an engineer's input.


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