slimpickins
Well-known member
+1 on making this a sticky!
The Concrete Underground's Guide to Floor Slabs
- Thread starter ConCretin
- Start date
PNWguy
Well-known member
Getting closer to my pour, so I'm reading this again (3rd or 4th time?). Greta stuff, and it makes me think that I can ask the right questions to the contractor and the concrete subs.
Two questions:
My slab will be 40' x 84'. It's a smallish house attached to a garage, woodshop and auto/metal shop. Because of the different uses in different areas, I basically have a 22x40, a 30x40 and a 32x40 area. Would it make sense to pour 3 different slabs, rather than 1 massive one? I'd like to have the absolute minimum number of expansion joints in the living space (22' x 40'), but I'm less concerned about them in the other spaces.
I'm installing Pex in the slab for radiant heat. Will the concrete guys destroy it if I prop up the mesh the Pex is attached to with 2" dobies?
Two questions:
My slab will be 40' x 84'. It's a smallish house attached to a garage, woodshop and auto/metal shop. Because of the different uses in different areas, I basically have a 22x40, a 30x40 and a 32x40 area. Would it make sense to pour 3 different slabs, rather than 1 massive one? I'd like to have the absolute minimum number of expansion joints in the living space (22' x 40'), but I'm less concerned about them in the other spaces.
I'm installing Pex in the slab for radiant heat. Will the concrete guys destroy it if I prop up the mesh the Pex is attached to with 2" dobies?
I'm glad you found the guide helpful!
Since we are primarily worried about cracks resulting from shrinkage rather than expansion, there really isn't a benefit to separate placements but there would be the added cost of forming construction joints and more placements, pumps, etc. I'd place it all at once.
Are the floors in the living space covered? If so, you could space your control joints fairly wide (or even eliminate them entirely) and let the floor covering hide any random cracks you get. After all, your control joints are just hiding cracks, not preventing them.
For exposed floors, you could increase control joint spacing considerably if you pay some extra attention to controlling shrinkage. 1 1/2" aggregate in the concrete, a mid range water reducer, fiber rather than steel reinforcing (yea, I know. This raises some other questions), placing in cool weather and proper curing would probably allow you to space your control joints out to 20' or so. One down the middle and 3 across, which you could even hide under your demising walls.
Concrete finishers will destroy everything they can. lol. I'm admittedly not an expert in hydronic heating theory but I like to staple the pex down to the rigid insulation and keep it out of harm's way. I'm not sure if it's less effective but I sleep better knowing there is a layer of reinforcing keeping it from floating up into my saw cuts or any anchors I might need in the floor.
Since we are primarily worried about cracks resulting from shrinkage rather than expansion, there really isn't a benefit to separate placements but there would be the added cost of forming construction joints and more placements, pumps, etc. I'd place it all at once.
Are the floors in the living space covered? If so, you could space your control joints fairly wide (or even eliminate them entirely) and let the floor covering hide any random cracks you get. After all, your control joints are just hiding cracks, not preventing them.
For exposed floors, you could increase control joint spacing considerably if you pay some extra attention to controlling shrinkage. 1 1/2" aggregate in the concrete, a mid range water reducer, fiber rather than steel reinforcing (yea, I know. This raises some other questions), placing in cool weather and proper curing would probably allow you to space your control joints out to 20' or so. One down the middle and 3 across, which you could even hide under your demising walls.
Concrete finishers will destroy everything they can. lol. I'm admittedly not an expert in hydronic heating theory but I like to staple the pex down to the rigid insulation and keep it out of harm's way. I'm not sure if it's less effective but I sleep better knowing there is a layer of reinforcing keeping it from floating up into my saw cuts or any anchors I might need in the floor.
PNWguy
Well-known member
Thanks for the quick and detailed reply. Stapling directly to the insulation sounds really good. That should also allow me to keep the Pex away from area where I will be bolting equipment to the floor.
I'll discuss the rest of your ideas with the concrete guys.
SkeetShooter
Member
I looked through this thread and didnt see an answer so I figure I'll ask here since LLWillysfan seems to be a font of wisdom... I am going to likely build a detached garage next year and will wait until climate is acceptable for a pour. I have been reading and looking at other detached garage builds and pours and there seems to be a few out there that recommend a foundation pour because we are in the north east. I'm located in south-Central CT. The garage is likely going to be a 16x30 or a 20x24 (Not sure just yet) Stick built. Will not be heated but will be insulated. I may possibly move my 4-post lift in there.
Looking for a 6 in slab. What is your opinion. Is it necessary to get a foundation pour in the Northeast? I've also seen slab pours and then 2-3 rows of cinder block on top before framing...
Thoughts? Appreciate it!
Looking for a 6 in slab. What is your opinion. Is it necessary to get a foundation pour in the Northeast? I've also seen slab pours and then 2-3 rows of cinder block on top before framing...
Thoughts? Appreciate it!
If you soils are stable and drain reasonably well i.e. you are not building in a swamp, you can build a detached structure on a monolithic slab. I have a 28 x 32 on a slab in Maine and it works just fine. The major reason to build on frost walls is if you are connected to another frost protected structure.
You can protect your slab from frost movement if you want by placing rigid insulation under the slab and extend it out 4' or so around the perimeter or you can just let it 'float', which is what I did.
Mine is a 4" slab with a 12" thickened haunch around the perimeter. I used #4's at 24" in the slab with 2, #5 bars in the bottom of the haunch. I prefer rebar in a mono-slab to hold everything together if you happen to get some differential movement.
I formed the outside perimeter of my slab with 24" high form panels. After I placed the slab I set a 12" form on the inside and placed a concrete curb wall against the top of the perimeter form. It's a very efficient way to construct a foundation. Hope that helps.
You can protect your slab from frost movement if you want by placing rigid insulation under the slab and extend it out 4' or so around the perimeter or you can just let it 'float', which is what I did.
Mine is a 4" slab with a 12" thickened haunch around the perimeter. I used #4's at 24" in the slab with 2, #5 bars in the bottom of the haunch. I prefer rebar in a mono-slab to hold everything together if you happen to get some differential movement.
I formed the outside perimeter of my slab with 24" high form panels. After I placed the slab I set a 12" form on the inside and placed a concrete curb wall against the top of the perimeter form. It's a very efficient way to construct a foundation. Hope that helps.
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SkeetShooter
Member
Thanks so much LLWillysfan. This is super helpful. I was really dreading having to pour a foundation for the cost reasons. My area drains very well. I'm basically on top of a mountain.Adding that thickened section around the perimeter shouldn't be a major encumbrance regarding additional cost. When you talk about rigid insulation, are you talking about like extruded foam insulation board or is this a special concrete insulation?
Thanks again. total newb when it comes to this.
Thanks again. total newb when it comes to this.
We can't all be experts in everything. That's why we have the GJ. I've learned a lot from those more knowledgeable than I in many other areas. I'm happy to share what I can in my profession.
With regard to under-slab insulation, You can use either XPS or EPS as long as it meets ASTM C578. EPS is typically less expensive and although 25 psi Owens Corning pink board (XPS) has been the standard in commercial construction for some time, there are studies that suggest that the EPS actually performs better. Either should be readily available at your local Home Depot, Lowes, etc.
With regard to under-slab insulation, You can use either XPS or EPS as long as it meets ASTM C578. EPS is typically less expensive and although 25 psi Owens Corning pink board (XPS) has been the standard in commercial construction for some time, there are studies that suggest that the EPS actually performs better. Either should be readily available at your local Home Depot, Lowes, etc.
SkeetShooter
Member
Thanks mate. That sounds like a plan. I can't wait to tell my wife the good news (well for me that is) She is not sold on the garage being built, but if we are staying in this house, I need just a bit more space.
Jagmandave
Well-known member
How big does the slab need to be to require saw cuts? Is there a general rule of thumb?
I'm getting ready to do an addition to my house for a shop that will be roughly 25X25, should it just have a 4 square look when done - ie 12.5' in each direction? What if those saw cuts intersect or cross where I want to put a lift?
I was thinking doweling into the existing slab where the two pads meet would be a good idea? Actually, I guess I would be doweling into the foundation wall on the house - would this be a good or bad idea? I want the two surfaces to match up level so I can roll stuff between the old and new without a step.
I'm getting ready to do an addition to my house for a shop that will be roughly 25X25, should it just have a 4 square look when done - ie 12.5' in each direction? What if those saw cuts intersect or cross where I want to put a lift?
I was thinking doweling into the existing slab where the two pads meet would be a good idea? Actually, I guess I would be doweling into the foundation wall on the house - would this be a good or bad idea? I want the two surfaces to match up level so I can roll stuff between the old and new without a step.
Recommendations for CJ spacing start at 8-12' but with some attention to overall crack control, you can spread them out to 10-15'. So yes, for your 25 x 25, one cut in each direction would be fine. If the location of a CJ happened to be to close to a lift post, you could move it as needed. If the ruined symmetry of the joint layout bothers you just add another cut and space them at 8'-3".
Doweling to the existing slab is a good idea but i would use smooth rods, which will permit lateral movement to permit shrinkage but limit vertical movement, which would create a step.
Doweling to the existing slab is a good idea but i would use smooth rods, which will permit lateral movement to permit shrinkage but limit vertical movement, which would create a step.
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Bigblockyeti
Banned
I just found this and I also really think this needs to be a sticky! Regarding compaction, jumping jack or plate compactor for 16'x22' shed base prior to pouring a 4" 4ksi pad? I'll have mesh across the whole area and rebar in the full depth 8" thickened perimeter.
cjcocn
Well-known member
I am not a concrete expert by any means, so I will merely share what I have done in the past (in consideration of the conditions - soil etc - in my area).
A plate compactor should work as long as you do not go beyond 6" layers of aggregate thickness before compacting.
I added about 18" of aggregate for my garage pad (after stripping away the top layer of overburden) and ended up doing four layers of aggregate/compaction.
I felt better doing it this way with my 200 lb plate compactor ..... just in case my little compactor didn't quite have the capacity to adequately compact 6" of aggregate.
Also, I built on clay so to prevent the clay and aggregate from mixing I started with a layer of geotech (after the overburden was stripped there was only clay and no other forms of aggregate/soil underneath).
Hope this helps.
I can't add much to what cjcocn has offered. I generally prefer a heavy plate compactor (with forward and reverse) over a jumping jack. They seem to hit harder and cover a larger area.
It sounds like you've got the basics covered on your slab, Bigblockyeti. Good luck with the rest of the project.
Bigblockyeti
Banned
I did research on my own right after posting and saw where a guy on youtube (I know, the advice is worth the cost) comparing a plate compactor to a jumping jack to a hand tamper. The jumping jack offered greater compaction but the plate compactor left a smoother surface which might be more desirable for pavers but matters none under aggregate beneath concrete. I also posed the question to my cousin who's a CE working as a project manager on many large projects around the port of Charleston. He may be of no value if not comparing a 30T lambs foot to a 25T dual drum roller to a 25T rubber tired roller, we'll see. They both cost the same for a day so that part is a wash.
That's interesting. I don't question your info but I wonder what size plate compactor they tested. The smaller units, which tend to be one-directional don't pack nearly the punch of the larger reversible units. In any case, I'd stick with a plate compactor based on coverage alone.
Bigblockyeti
Banned
Didn't look like a big plate compactor, honestly I haven't used a big reversible one. I know the compactor would certainly be faster and more likely to use straight gas vs. premix. Given the small 16'x22' size, either won't take too terribly long. I really need to research the manufacturers specs of what the rental yards actually have available.
Concrete pros:
Thanks for this informative thread! I’m near Boston MA and am having a 25x35 attached garage built later this spring. It will have Radiant heating and be used as a play/basketball area during the long winters we have here. Please see my questions and proposed steps below:
1) fiber reinforced concrete
2) 2” rigid foam that I’ll staple the PEX to
3) should the slab bump up against the frost wall or should rigid foam be between them?
4) I want to install a flush mount floor lift in the future. Should I do the form work now for the 2 pits or just have them cut out later? What about the conduit for the wiring?
5) Anything else I need to get ahead of?
Here’s a picture- excuse the blurriness. Thanks in advance.
Thanks for this informative thread! I’m near Boston MA and am having a 25x35 attached garage built later this spring. It will have Radiant heating and be used as a play/basketball area during the long winters we have here. Please see my questions and proposed steps below:
1) fiber reinforced concrete
2) 2” rigid foam that I’ll staple the PEX to
3) should the slab bump up against the frost wall or should rigid foam be between them?
4) I want to install a flush mount floor lift in the future. Should I do the form work now for the 2 pits or just have them cut out later? What about the conduit for the wiring?
5) Anything else I need to get ahead of?
Here’s a picture- excuse the blurriness. Thanks in advance.
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Congratulations on your upcoming project; I'll respond to your questions but hopefully others will have some thoughts as well.
1) fiber reinforced concrete
Fiber reinforcing is fine but it's value is limited on s residential slab. It's only purpose is to limit early age shrinkage cracks but since you'll need a few control joints anyway, you aren't gaining anything. For similar cost you might consider wire mesh instead. It won't limit cracking but it will hold cracks together including those in the bottom of your control joints.
2) 2” rigid foam that I’ll staple the PEX to
Differing schools of thought on this but I like your method. Place your vapor barrier under the foam so you don't poke it full of holes with the staples
3) should the slab bump up against the frost wall or should rigid foam be between them?
I'd use 1/2" expansion material with a removable top strip that provides for the installation of sealant. It will isolate the slab from the wall and provide a thermal break while looking better than exposed insulation.
4) I want to install a flush mount floor lift in the future. Should I do the form work now for the 2 pits or just have them cut out later? What about the conduit for the wiring?
It's obviously less work to do it now rather than cut it out later but you'll need to select your lift to get all the dimensions and rough-in information.
5) Anything else I need to get ahead of?
See Post #1
1) fiber reinforced concrete
Fiber reinforcing is fine but it's value is limited on s residential slab. It's only purpose is to limit early age shrinkage cracks but since you'll need a few control joints anyway, you aren't gaining anything. For similar cost you might consider wire mesh instead. It won't limit cracking but it will hold cracks together including those in the bottom of your control joints.
2) 2” rigid foam that I’ll staple the PEX to
Differing schools of thought on this but I like your method. Place your vapor barrier under the foam so you don't poke it full of holes with the staples
3) should the slab bump up against the frost wall or should rigid foam be between them?
I'd use 1/2" expansion material with a removable top strip that provides for the installation of sealant. It will isolate the slab from the wall and provide a thermal break while looking better than exposed insulation.
4) I want to install a flush mount floor lift in the future. Should I do the form work now for the 2 pits or just have them cut out later? What about the conduit for the wiring?
It's obviously less work to do it now rather than cut it out later but you'll need to select your lift to get all the dimensions and rough-in information.
5) Anything else I need to get ahead of?
See Post #1
Congratulations on your upcoming project; I'll respond to your questions but hopefully others will have some thoughts as well.
See Post #1
Hi LLWillysfan:
As I referenced in the other thread, my build is finally going to begin. As a reminder I'm just outside of Boston MA.
I'm most likely going to install the in-ground flush lift later on when I recover from the cost of this build. But I do want to install the conduit when the slab is poured. Questions:
1 - what material should I use for conduit for running hydraulic hoses and wires?
2 - what do you think about running said conduit from the future "pits" that will be cut out of the slab to a corner of the slab, and then have it turn up and exit the top of the slab? I'll cap the conduit until the day comes to install the in-ground lift. Will the building inspector allow a conduit to exit the slab like this? Or should I just have the conduit come up to just below the slab surface, take good pictures and measurements of that spot, and then cut a circular hole in that area of the slab to access the conduit when it's time to install the lift?
3 - PEX that goes through the garage foundation / frost walls and into the boiler room that is in the house's basement: what should I do to keep the foundation/concrete guy happy? Do we need to put conduit around the PEX where it goes through the wall?
4 - I'm *thinking* of building and installing a power swing gate next to the driveway. Should the conduit for the power lines run from the house and around the footprint of the garage, rather than under the garage slab?
5 - re-entrant corner in the garage - could you explain a little more about the "diagonal" joints referenced in one of your other threads? I'll likely install plastic tiles or porcelain tiles in the future, but still want to avoid uncontrolled cracks if possible.
6 - I'm building a new family room about 5 feet from the shallow end of an in ground swimming pool. We are tight on space out here! There will be a full basement under that room. What steps would you take to ensure a dry, comfortable basement that we will eventually finish? The general contractor did a walk-through with the guy doing the excavation and they are not concerned with the integrity of the pool being jeopardized by the basement work and vice versa. The GC said rigid foam will be placed around the foundation, a weeping drain will go around the perimeter to daylight in the yard, and I asked for a sump pump (maybe even 2) be placed in the basement. What do you think?
Thank you so much! I'm exhausted just typing that - I don't know how I'll be able to endure this construction work!
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My thoughts are as follows; As always, others are welcome to weigh in.
I'm most likely going to install the in-ground flush lift later on when I recover from the cost of this build. But I do want to install the conduit when the slab is poured. Questions:
1 - what material should I use for conduit for running hydraulic hoses and wires,
The safest plan would be to research the installation instructions for the lift you intend to install. My Rotary two post in-ground lift required a 2" PVC conduit for hydraulic and air lines
2 - what do you think about running said conduit from the future "pits" that will be cut out of the slab to a corner of the slab, and then have it turn up and exit the top of the slab? I'll cap the conduit until the day comes to install the in-ground lift. Will the building inspector allow a conduit to exit the slab like this? Or should I just have the conduit come up to just below the slab surface, take good pictures and measurements of that spot, and then cut a circular hole in that area of the slab to access the conduit when it's time to install the lift?
I would just install and cap the conduit in the base material under the slab. Maybe even bed it in sand to make it easier to find and uncover.
3 - PEX that goes through the garage foundation / frost walls and into the boiler room that is in the house's basement: what should I do to keep the foundation/concrete guy happy? Do we need to put conduit around the PEX where it goes through the wall?
Typically the pex is turned up to supply and return manifolds somewhere on the slab perimeter. Do you need to do something different?
4 - I'm *thinking* of building and installing a power swing gate next to the driveway. Should the conduit for the power lines run from the house and around the footprint of the garage, rather than under the garage slab?
There is no reason you can't run a conduit under the garage slab. Run it in the base material under the slab rather then in the slab itself..
5 - re-entrant corner in the garage - could you explain a little more about the "diagonal" joints referenced in one of your other threads? I'll likely install plastic tiles or porcelain tiles in the future, but still want to avoid uncontrolled cracks if possible.
This is an example of a re-entrant corner;
[https://i2.wp.com/dudleyengineering.../Reentrant-Corners-300x278.png?resize=300,278
It is very likely a re-entrant corner will crack. You could hide the crack with a control joint but if you are going to cover the floor anyway, it's not a big deal.
6 - I'm building a new family room about 5 feet from the shallow end of an in ground swimming pool. We are tight on space out here! There will be a full basement under that room. What steps would you take to ensure a dry, comfortable basement that we will eventually finish? The general contractor did a walk-through with the guy doing the excavation and they are not concerned with the integrity of the pool being jeopardized by the basement work and vice versa. The GC said rigid foam will be placed around the foundation, a weeping drain will go around the perimeter to daylight in the yard, and I asked for a sump pump (maybe even 2) be placed in the basement. What do you think?
For a finished space within, I'd consider a membrane type water proofing system including drainage board on the exterior.
I'm most likely going to install the in-ground flush lift later on when I recover from the cost of this build. But I do want to install the conduit when the slab is poured. Questions:
1 - what material should I use for conduit for running hydraulic hoses and wires,
The safest plan would be to research the installation instructions for the lift you intend to install. My Rotary two post in-ground lift required a 2" PVC conduit for hydraulic and air lines
2 - what do you think about running said conduit from the future "pits" that will be cut out of the slab to a corner of the slab, and then have it turn up and exit the top of the slab? I'll cap the conduit until the day comes to install the in-ground lift. Will the building inspector allow a conduit to exit the slab like this? Or should I just have the conduit come up to just below the slab surface, take good pictures and measurements of that spot, and then cut a circular hole in that area of the slab to access the conduit when it's time to install the lift?
I would just install and cap the conduit in the base material under the slab. Maybe even bed it in sand to make it easier to find and uncover.
3 - PEX that goes through the garage foundation / frost walls and into the boiler room that is in the house's basement: what should I do to keep the foundation/concrete guy happy? Do we need to put conduit around the PEX where it goes through the wall?
Typically the pex is turned up to supply and return manifolds somewhere on the slab perimeter. Do you need to do something different?
4 - I'm *thinking* of building and installing a power swing gate next to the driveway. Should the conduit for the power lines run from the house and around the footprint of the garage, rather than under the garage slab?
There is no reason you can't run a conduit under the garage slab. Run it in the base material under the slab rather then in the slab itself..
5 - re-entrant corner in the garage - could you explain a little more about the "diagonal" joints referenced in one of your other threads? I'll likely install plastic tiles or porcelain tiles in the future, but still want to avoid uncontrolled cracks if possible.
This is an example of a re-entrant corner;
[https://i2.wp.com/dudleyengineering.../Reentrant-Corners-300x278.png?resize=300,278
It is very likely a re-entrant corner will crack. You could hide the crack with a control joint but if you are going to cover the floor anyway, it's not a big deal.
6 - I'm building a new family room about 5 feet from the shallow end of an in ground swimming pool. We are tight on space out here! There will be a full basement under that room. What steps would you take to ensure a dry, comfortable basement that we will eventually finish? The general contractor did a walk-through with the guy doing the excavation and they are not concerned with the integrity of the pool being jeopardized by the basement work and vice versa. The GC said rigid foam will be placed around the foundation, a weeping drain will go around the perimeter to daylight in the yard, and I asked for a sump pump (maybe even 2) be placed in the basement. What do you think?
For a finished space within, I'd consider a membrane type water proofing system including drainage board on the exterior.
Thanks for the detailed answers, Willysfan! I was thinking of placing the manifold and circulating pumps in the adjacent basement's mechanical room:
1) to maximize space in the modest garage for working on cars + playing sports
2) because it'll look better, and be safe from potential damage as I hope the kids can play ball in the garage during the long and cold winters here.
I'm not sure why it's not but I believe this should be a Sticky in this section
like2wheel
Well-known member
menkarran
Member
Thank you for sharing your knowledge and experience!
Blinkerfluid6
New member
sbelles
Well-known member
Wrong place
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M1TCH
Well-known member
Hi I used a product here in the UK called Flo-Crete, Its a Tarmac product. The truck backs up to the fill area and shoots it in as per normal.
Then the guy from the concrete firm gets in with wellies on and using a what looks like a Zimmer walking frame with arms out to the side starts at the furthest point and agitates the wet mix until he reaches the fill point, that's it took him at most ten minutes to do a 10m square. walk on it the next day drive on it in two days but left it a week.
I was amazed being an old school Carpenter and doing hundreds of shuttering jobs how easy it was, no tamping or coming back to float. wherever you put a 2m level its bob on they guarantee +/- 1mm mine did not need steel as its got fibreglass strands in it, been down two years now and no cracks or movement.
I did put expansion fibre board around the perimeter pre pour and its between 125/200mm thick in places as I got fed up with in filling with aggregate and compacting so paid a tad extra for the wet and sloppy.
Hope this helps.
Then the guy from the concrete firm gets in with wellies on and using a what looks like a Zimmer walking frame with arms out to the side starts at the furthest point and agitates the wet mix until he reaches the fill point, that's it took him at most ten minutes to do a 10m square. walk on it the next day drive on it in two days but left it a week.
I was amazed being an old school Carpenter and doing hundreds of shuttering jobs how easy it was, no tamping or coming back to float. wherever you put a 2m level its bob on they guarantee +/- 1mm mine did not need steel as its got fibreglass strands in it, been down two years now and no cracks or movement.
I did put expansion fibre board around the perimeter pre pour and its between 125/200mm thick in places as I got fed up with in filling with aggregate and compacting so paid a tad extra for the wet and sloppy.
Hope this helps.
Cairo94507
Well-known member
What a great read. We are getting ready to begin construction on a 1550 sq. ft. garage and I want to have a polished concrete floor. We decided to go 6" thick so we can install our lift where ever we want. It will have radiant heat to keep it nice year 'round.
Stuntmonkey
Well-known member
@LLWillysfan thanks for this great write up. We are going through the design stages for a 2800sq ft mountain home in the rockies, and my wife keeps bouncing between large format tile and polished concrete in the house. I'll be picking your brain once I know what I need to be asking haha!
trailblazer85
New member
Good information--thank you all. I'm almost done with a 45'x54' shop. The concrete guy didn't want put down plastic and I probably couldn't have afforded it--if I insisted. I'm pretty happy with the outcome but am noticing some chipping (possibly de-laminating) on the surface in the large shop where I'm doing most of my work. It is 30'x45' and I have a 4 post (movable) lift. The damage is not caused by the lift but probably moving large equipment or dropping stuff. If money wasn't an issue, I'd consider epoxy flooring. What other recommendations do you guys have? Yes, I'll get better and try to drop stuff on my boot--instead of the floor. 
The slab is 6-8" thick thanks to errors by the general contractor when he graded. Thankfully the concrete guy made the general pay the extra and not me. I don't think, I'm getting moisture up through the slab although I do bring in snow/water when I park inside--NW Montana. I do mop that up.
The slab is 6-8" thick thanks to errors by the general contractor when he graded. Thankfully the concrete guy made the general pay the extra and not me. I don't think, I'm getting moisture up through the slab although I do bring in snow/water when I park inside--NW Montana. I do mop that up.
Ole Slewfoot
Well-known member
Not quite a slab, but an interesting study in reinforced concrete, I give you my ode to the SS Palo Alto, ferrocement ship age 103.
I wrote a longer post on it here.
I'd also like to thank llwillysfan for this info dense thread. Helped with confidence as I upgraded my driveway double wide, and made screed chairs for the first time.
I wrote a longer post on it here.
I'd also like to thank llwillysfan for this info dense thread. Helped with confidence as I upgraded my driveway double wide, and made screed chairs for the first time.
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Cairo94507
Well-known member
Very glad to have found this thread about concrete. We are getting ready to start a 2K sq. ft. garage build and want a nice concrete floor with a burnished finish.
@LLWillysfan and the other concrete whisperers here:
My 2-year old garage has about 20” of exposed concrete stem wall above grade. I live in Massachusetts. The stem walls were not insulated during the build, so now I’m thinking of insulating from the interior.
Question: i need to attach wood strapping to the concrete walls using Tapcon screws. Will that cause cracks to grow from the screw holes over time, since they will be stress risers?
Thanks.
My 2-year old garage has about 20” of exposed concrete stem wall above grade. I live in Massachusetts. The stem walls were not insulated during the build, so now I’m thinking of insulating from the interior.
Question: i need to attach wood strapping to the concrete walls using Tapcon screws. Will that cause cracks to grow from the screw holes over time, since they will be stress risers?
Thanks.
Thanks for replying! Please tell me about the “metal or plastic Z furring”. Never heard of it.
Yes, I plan on putting some type of wood or composite over the rigid foam insulation. The plan is to make the garage a multipurpose fun space for our family.
Yes, I plan on putting some type of wood or composite over the rigid foam insulation. The plan is to make the garage a multipurpose fun space for our family.
@LLWillysfan
Will this assembly work: stem wall >> continuous EPS rigid foam >> plywood. Then screwing Tapcon directly through that sandwich into the stem wall. Then I don’t have to use any furring strips.
Will this assembly work: stem wall >> continuous EPS rigid foam >> plywood. Then screwing Tapcon directly through that sandwich into the stem wall. Then I don’t have to use any furring strips.