Off Topic - Concrete Counters - Make me an expert

[jstoddard]

I know this isn't the place to post this - I don't care, I want my "regulars' " input .

I'm thinking about doing a bunch of concrete counters in my own house - I want any and all experience... doing it yourself.... subbing it... pros, cons, how it was done...

- pour them in place, (hand-finish the top) --or--- form them somewhere else and pour upside down (hand-finish the bottom)

- What kind of rig to vibrate the form...?

- What did you do (specifically) to colorize the mix ?

- What mix works the best ... at what slump ?

- What did you do after you strip forms.. grinder, sander, nothing... what ?

- Reinforce how? Tie #3 bar? WWM ? What Gauge wire? Both ?

- What would you do differently the next time ? (especially good if you've done it a few times and are still tweaking...)

No offense - but just so we're on the same page - Please don't post links unless it's something:
you have written -- or have actually done yourself -

If you wrote the article - fantastic.
If you routinely do and have success with what's in the article - great.

Otherwise I don't need article links or links to websites on the topic. I've read hundreds of articles compiled ad nauseum and in gory detail .. .and not to brag but I'm pretty good with a trowel myself....I don't need any help with any of that... The problem I'm having is sorting it all out - there is a ton of conflicting info. I want to know what WORKS - not what some editor found in their research.

My biggest questions are "pour in place... or form off-site" ... and

"finish the top, or finish the bottom and let the top 'finish' itself against the melamine form ? "
Or do you use something other than melamine?

I was going to pour a couple of trial runs to use outdoors or somehting - try them a couple different ways. My biggest fear is pouring something in-place and having it all screwed up, and then have to deal with tearing it out. My cabinet layout is a "C" - while I can definitely do it offsite and move it in - it's not trapped between walls or anything - it would really work best to pour in place if possible.

Many thanks in advance. If you're doing something cool with concrete counters we'll turn it into a JLC article with your byline.

JLS

[David Meiland]

I don't make concrete tops myself... got a great sub for that... but I would pour upside down in the shop, use sack mix and colors from Buddy Rhodes or Fu-Tung Cheng, use smooth laminate for forms and not melamine, buy a wet grinder and set up a place to use it, learn how to fill bug holes with slurry, and plan on making a bunch of test pieces before going live. It's probably worth buying a Cheng book.

I would only do pour-in-place if (a) you want a semi-rustic look and (b) you still make some practice pieces first.

[Lavrans]

Joe- I used to work for a guy who loved to do concrete countertops. He always poured in place. I think we did 7 or 8 kitchens & other counters that way. It always came out looking like a poured in place counter. I suppose some could have been ground to look better, but I never liked them all that much.

After that I've done a couple counters poured in a shop setting. One was a phenomenal F-up. Not enough time spent detailing the corners and the platform wasn't strong enough, sagged, etc. After that I have done a couple that came out great. Making sure the form was correct, etc. double stick or glue anything you want to show up on the top to the bottom of the form. Did one with polyurethane fibers- they did sand out eventually, but I'd rather go with a higher cement mix and lightweight aggregate if I did it again.

Vibrator for the forms- borrowed one of the Makita cordless, and that worked really nicely. Good, MDO worked well for forms. Azek works pretty well for molding details.

Second Cheng's books.

I would probably hire someone if a client wanted a concrete countertop, but would make one for my own house. Don't try to make an integral sink unless you're really comfortable with building forms.

edit: basically like the building elsewhere because you don't have as much potential problem if you need to really get in and grind and polish a lot.

[Dick Seibert]

Joe:

Why not wait until the next time you come to the Bay Area and take one of Cheng's one-day workshops?

[MarkMc]

Gotta ask, are you banned from posting outside of the BT forum? )

It'd be far easier to start this the other way round, with what you expect to get [final product/look] and where [site conditions] you expect to get it, otherwise it's a endless either or (but with links).

Forming not in place is far superior IMO.

Small samples will only match large installations when something gets screwed up and you are lucky.

Don't use less than 5k psi. Fibered can work well for whit is but does add to the process.

White melamine and black silicone. Practice your caulking.

Reinforcement will be dependent on what you're making and what it has to do in life, but in general both will be used; buy the flat sheets of wire, you'll thank me later.

Calculate weight before finalizing the layout/sections and make friends accordingly.

Mix the whole room in as few batches as possible - 1 is at least 3x more preferable than 2.

If it's a one timer the sub $100 vibrators from HF will work fine. Vibrating technique will/does change the outcome - color, texture, structure. If it's a lot of area and you are doing large batch you may want more than one on hand.

And so on....

[Joe Adams]

If the concrete countertops are going on your existing cabinets, you will need to evaluate their construction and determine if it is sufficient to support the added weight.

[jstoddard]

No I'm not banned. Read the first sentence of my post. I did post this question a few other places last year (on this site and others). I got answers that ranged from the usual DIY flaming and stupidn turf battle BS to "concrete is a mixture of.... blah blah blah" - and a handful of decent tips. Going back there would be a repeat and I don't think the input was worth the hassle frankly. The feeling I got was more like the part of the "Dog Whisperer" where people first introduce their pooch to Cesar's "pack" of 50 Pitt Bulls and other canine mis-fits at his "Dog Psychology Center" ;-)

I didn't tell you what I'm expecting to get because that's not relevant yet. I don't know what I'm expecting - I want you guys to tell me what I can expect. As we all know, concrete can be used to make everything from a giant gray cow turd you can't move with a Bobcat... to "Falling Water" If we're going to get a JLC article out of this - and for my own knowledge - I need to know not just "How" but also the "Why" and "What" . Lavrans' post has more of the "why" behind his answers - thank you for that.

I'm not a newb McMark -I grew up in this business and just like you guys I've built hundreds of projects - most of which I designed from the first line working with the client, and/or did some or all of the finish work on. I like the craft - all of it - from carpentry to masonry to welding and mechanical and finishing drywall and whatever else people can make or do- that's the reason I got into the business to begin with.

I have Fu-Tung Cheng's books and have studied everything he has written on the topic that I can find. I'm glad he's developed such a fine method - that still doesn't tell me what you guys are doing or why.

Someone said "Laminate (what - you mean HPL- Formica?) not Melamine". Why Not ? Everything I've seen or read they're using sheets of melamine. Why don't you like that - what were the failure points? Seems like a lot of extra cost and hassle to build a Laminate countertop to build a concrete countertop (?)

"Fiber adds to the process "---- what exactly does it add? I would think the last thing you'd want in a countertop would be end-grain of poly fibers. On exterior concrete they can create a point of entry for water to eventually start freeze/thaw and spalling the surface. seems to me there would be absorption issues . Flat mats of wire - obviously when your target is 2" or less any curl would be devastating. What size mesh and gauge is what I'm more interested in - one mat or two? Chickenwire in addition to WWM- or no?

"White Melamine- Black Silicone" Does the concrete care about these colors or is there a practical reason to use them? I'm guessing black silicone so you can see exactly what the caulk is going to do to (for) you. Correct ?

Why is one batch preferable ? Color matching... or something more structural ?

It sounds like everyone is pretty down on forming in place. I can understand that - a surface that is great for a sidewalk still looks like a sidewalk when applied to the top of cabinets ;-) And from what I gather you're not done after using a steel trowel. Counters require grinding, polishing - lots of post-pour mess-making. Correct ?

I was thinking about building a forming table where the table itself vibrates, and is reinforced to remain perfectly flat and controllable. Any time you work with concrete - control is your friend and losing control is definitely your enemy.

Actually - I can tell you what I want - I really want Vermont Soapstone - but the kind you find in the science labs of school buildings from the 1920s that they are tearing down. That deep almost black/greenish tint from 60 years of mineral oil - with the edge worn from decades of kids leaning/scraping on it. If I could get that deep, dark look somehow with concrete that would be great.

JLS

[philthegreek]

I did mine, and as a first run I am pretty happy. I formed mine using melamine particle board. I used a bed mould to give it an ogee type edge. I built a perfectly flat "stage" out of 2x6's on which to pour the molds. I made all the openings in the molds (sinks, cooktop, faucet holes). I used 6x6 mesh for reinforcement, with 3/8 rebar around the sink lip and cooktop. Any handheld concrete vibrator will do, a HF cheapo is just fine. You need to vibrate liberally. I made the mistake of shortcutting on one piece and had to redo it because of air bubbles. I used a medium to wet mix to make sure it flowed into the nooks and crannies. Dry dye mix is now readily available at Lowes, I got mine from O&G concrete in my area. I also used polypropylene reinforcement in the mix and I absolutely did NOT get any fuzzies in the finished product.
Some caveats; Use only silicone to create fillets and seal seams. Any latex or latex/silicone hybrids react with the mix and cause crumbling where they touch. I don't know why, it just does.
Write down your recipe and follow it precisely or the color variation will be noticeable.
Once you pour, cover with plastic and seriously leave the pieces alone for a week.
I used plastic bed mould. If you want to use AZEK, make sure it's formed and NOT machined.
Light colors use white mix dark use grey. Use the 5000 psi mix from HD or Lowes since the aggregate is really uniform.
Use the sealers that Fu Tung Cheng recommends. I didn't and paid the price. My screw up actually caused my counters to have a more "old world" look to them, so I'm not really unpleased but YMMV.
If you can catch a Cheng seminar, do it. He's very approachable and doesn't just try to "sell" himself. I took his seminar at the Remodeling Show a few years back.
Mine are terra cotta red and I found that 3M fire guard caulk was almost a perfect match when finally assembled in place.
Don't make pieces bigger than 2 people can handle, if possible. Of course the design takes precedence, IMHO.

Since I've already taken up a lot of space here, if you want more specifics, PM me. Or I can answer here too.
Hope this helps you with your decision.

phil

[philthegreek]

My kitchen is a work in progress, with twin 19 month olds, I don't get much time to work on it. The "shoe maker's shoes" I guess.

phil

[Dick Seibert]

Joe:

I am having a home designed now with soapstone fireplaces and in other areas (I don't know about counters, apparently he is sticking with granite there), there is a distributor somewhat near you (I think). Soapstone counters.

[David Meiland]

Someone said "Laminate (what - you mean HPL- Formica?) not Melamine". Why Not ? Everything I've seen or read they're using sheets of melamine. Why don't you like that - what were the failure points? Seems like a lot of extra cost and hassle to build a Laminate countertop to build a concrete countertop (?)

The few times I've seen or built forms they were out of gloss laminate. Melamine has a slightly pebbly texture. I would do a test piece with a melamine mold and see if you like it, and I would definitely take Cheng's advice instead of mine.

[MarkMc]

No I'm not banned. Read the first sentence of my post. ... Cesar's "pack" of 50 Pitt Bulls and other canine mis-fits at his "Dog Psychology Center" ;-)

Cat person, huh?

I didn't tell you what I'm expecting to get because that's not relevant yet. I don't know what I'm expecting - I want you guys to tell me what I can expect. As we all know, concrete can be used to make everything from a giant gray cow turd you can't move with a Bobcat... to "Falling Water" If we're going to get a JLC article out of this - and for my own knowledge - I need to know not just "How" but also the "Why" and "What" . Lavrans' post has more of the "why" behind his answers - thank you for that.

A gray or colored cream spatter should be added to the list. Since you know the range, didn't sort of answer the question? And yes, IMO, "it's" always relevant.

I'm not a newb McMark -I grew up in this business and just like you guys I've built hundreds of projects - most of which I designed from the first line working with the client, and/or did some or all of the finish work on. I like the craft - all of it - from carpentry to masonry to welding and mechanical and finishing drywall and whatever else people can make or do- that's the reason I got into the business to begin with.

Neither am I, and I suppose not "regular" enough either. It's great you want to het an aticle out of it, but you are starting with some constraint - your house/location and kitchen. Some of the questions are broad enough to require a book to fully answer, but don't let me give you any ideas )

I have Fu-Tung Cheng's books and have studied everything he has written on the topic that I can find. I'm glad he's developed such a fine method - that still doesn't tell me what you guys are doing or why.

For me each one is tailored to the client/project with all that entails and they rarely overlap much. There are some who do/did volume such as to be able to make standard stock, but that for the most part was a dog.

"Fiber adds to the process "---- what exactly does it add? I would think the last thing you'd want in a countertop would be end-grain of poly fibers. On exterior concrete they can create a point of entry for water to eventually start freeze/thaw and spalling the surface. seems to me there would be absorption issues . Flat mats of wire - obviously when your target is 2" or less any curl would be devastating. What size mesh and gauge is what I'm more interested in - one mat or two? Chickenwire in addition to WWM- or no?

All the usual advantages, and some finishing disadvantages. Some colors and grinds make for more noticeable artifacts and filling. Again, very broad, typ #3 or 4 and 6x6 10/10. Would nver use chicken wire. Metal in counters has pretty much the same req's/limitations as any conc.

"White Melamine- Black Silicone" Does the concrete care about these colors or is there a practical reason to use them? I'm guessing black silicone so you can see exactly what the caulk is going to do to (for) you. Correct ?

Yes

Why is one batch preferable ? Color matching... or something more structural ?

Yes, and maybe yes. The more times you have to mix & pour the more opportunity for deviation/error in your process or the batching of raw materials. If you have two suppliers of sacrete products in your town they may well get product from different plants using differing agg's which could make a very significant change in the result [appearance].

It sounds like everyone is pretty down on forming in place. I can understand that - a surface that is great for a sidewalk still looks like a sidewalk when applied to the top of cabinets ;-) And from what I gather you're not done after using a steel trowel. Counters require grinding, polishing - lots of post-pour mess-making. Correct ?

In place has its place whic is usually where there is no other space for fabrication.

I was thinking about building a forming table where the table itself vibrates, and is reinforced to remain perfectly flat and controllable. Any time you work with concrete - control is your friend and losing control is definitely your enemy.

Have you priced that out yet? They are nice, but expensive when well made and sized to allow for all the parts of a typ kitchen to be poured at the same time.

[Overbuilders]

Back to the thread title...

OK then, we hereby make you an expert. Here's your badge and certificate. Now get to work.

[Dancing Dan]

My concrete guy uses PVA fibers from Nycon to avoid the hairy tongue look of the regular fibers.

Joe- have you ever seen paperstone? The first time I saw it I thought "science lab."

[jstoddard]

I have read about paperstone - never seen it in-person. If you're talking about the pressed-paper product that comes in sheets - You're thinking of it as a replacement for my soapstone comment. Real soapstone is cheaper isn't it? I also understand that if you get the edge wet it comes unglued like MDF - swells up, etc etc.

This is one of those "green" products that you never get any ROI on... probably has all kinds of issues we don't know about yet... and costs two or three times as much as the 'real' material it's replacing. And it doesn't perform well in wet areas - no cut edges next to sinks or other sources of water, etc. I don't see how that would work for a kitchen counter.

JLS