I measured my concrete floor by using two small (2 inch by 2 inch) piece of 1x2. I placed the two blocks about 10ft apart and stretched fishing line between them (with my assistants holding the line taught on the block). Then I measured at several points along the line. I have included a link to my Comcast webpage that shows the simple graphic I created for the measurements. Note that the H or L annotations are where the floor is High or Low.

http://home.comcast.net/~rtbrick/measurements.html

I would like to either glue or float an engineered product such as the BR111 Triangulo Brazilian Cherry. Please advise and comment on the necessary preparation of my floot. I know I probably need to do more measuring, but the listed measurements should give me an idea of whether I should even attempt a wood floor. If preparation it too extensive I will likely put carpet back down. I don't want carpet, but I do intend to sell this house in just a few years (don't want to spend too much money).

Thanks!

Flatness is critical. 1/8" difference in 6' radius is common specification by manufacturers for both glue down and floating floors.
Self-leveling cement works wonderfully and is expensive.......... but saves on labor and know-how.
Preping a floor with a trowel to meet flatness specifications requires talent, know-how and experience. Put the word Talent in bold...
You may have to grind some high spots.
all flooring needs a flat subfloor surface;;; if not by specification, then by comfort and furniture sitting level.

I wouldn't use a self leveling cement in self leving mode - remember we are looking for flatness here not necessarily level. The problem with self leveling is that if you floor is out of level edge to edge more than 1/2" or so you may be in trouble and this is difficult to determine. Also, the skill level and know-how may not be as high as troweling but a mistake can be extremely expensive to fix and I know people who have made them.

I patch leveled my floor and it was not really that hard. I mean if you can find someone to do this for you great, but in my area I just got quizzical looks and in fact I think many floor installers don't bother. Here's how I did mine -

I measured my floor flatness with an 8' or longer straightedge (level). Just move it in a pattern in both directions overlapping about 3' or so. Wherever you see a gap that exceeds your spec, chalk an outline around it. You may want to add additional lines around the outline because the outline disappears under the cement and you can get confused. Usually they seem to be 1' to 3' or 4' in diameter.

When you're ready to patch, use a cement that can be feathered to zero thickness (Most use Custom leveling cement - don't forget you primer and of course concrete floor must be clean). Mix a small amount for one small patch to get a feel for it. A screed is a must have (Home Depot sells a nice alum screed set - I don't like wood because it may be warped). Use a screed that is larger than your patch. Also, use a rect trowel to help feather the edge. You have to work reasonably fast. Sometimes it's difficult to feather the edge to zero thickness but you should be able to meet your spec. Beware it's a very messy job so cover anything that shouldn't get dripped on. Drips on the slab can be popped off.

The difficult areas are near the edges of your slab because your screed does not have a reference. Don't be tempted to eyeball it here. A couple of possibilities here -

1. Cut a strip of wood such that it conforms to the depression at the edge of the slab. Then the top of the strip of wood is flat and bridges the depression giving you a screed reference. Secure wood, screed, remove and fill hole. Probably to difficult for any thing less than 1/4".

2. Using a straightedge parallel to the wall first build a cement screed reference from deck mud, let it harden and then use that as a screed reference. Note that some may advise against the deck mud because it takes along time to dry and thus is a moisture concern. You could chip it out after you put down the self leveling - I have chipped out basic mortar 24 hours after application quite easily.

Just use my comments as a guideline - I did mine this way and I checked it afterwards and it did appear to meet spec. I couldn't quite get the feather edge and I'm told the better floor installers sometimes grind these out. Imporatant thing is to try one small patch first to get a feel for it.

Did you read this?

http://www.hardwoodinstaller.com/hardwo ... n-prep.htm

Great advise Alex!



You have the knowledge to start your own floor prep business!!

Your right, it is very hard to find any contractor that understands floor flatness and how to achieve it.

A lot of people think that you can just mix up a bunch of self leveling cement, throw it down on the floor and bingo, you have a flat floor. It may not require skill but it requires a lot of know how.

I heard firsthand 2 cases where a floor was botched - once by a beginner and another by a company where they pumped it in.

In the case of the beginner, he did not have enough/any help and he couldn't work fast enough. His floor ended up something like 1/2" higher on one end of the room than the other because the self leveling set up before he was completely done. This wouldn't really matter except that the transistion was not smooth - it happened over a small distance and thus his floor was not level or flat.

In the other case I don't know how it happened but there were several obvious high spots. The company did fix it by grinding the spots down but his wife was cleaning concrete dust out from all areas of the house for months and I think it almost resulted in a divorce!

The difficulty with the self leveling is two-fold. It sets up really fast - on the order of 15-20 mins I think so you pretty much have to complete the entire floor within that time period.

The other problem is that novices think that it has no effective viscosity. Of course it does and your pours have to be done evenly. If you pour 20 bags on one half of the room and 10 on the other half it's very unlikely that it will flow out even if you meet the time requirements.

RT,

Not to belabour the point but if you have a low spot next to the edge of your foundation or a wall (the former seems to be more common) you only need to make a screed support if the low spot is longer than your longest screed (which was my case). Normally you could just put the screed parallel to wall and pull it out towards the center of the room.

Good luck and if you decide to do the work let us know how it comes out. I had virtually no experience with concrete when I did mine. The only thing that would worry me is if my straightedge/level showed spots in the slab that are more than 3/8" of so out of flat but your drawing seems to show much less than that. Also make sure when you check the slab you position the straightedge in both directions (90 deg) in a grid pattern. This way if you have a large depression it is less likely to escape your attention and also as sort of a double check.

I think a glue down on slab install is the hard part of your project but there is plenty of expertise here on that subject.

Thanks for all the advice. Patch leveling does seem like it would be easier (to control anyway). My primary concern is figuring out the actual flatness of my slab. I did the fishing line bit, but I will try another method or two to be sure. Though, I do not want to invest too much money is 10 ft long straight edges (that will then sit in a corner of my garage). Next I'll try a simple string on the floor method (hold string in center and walk the other end around the floor). As well, I'm hoping I do not have to grind. I understand it makes a terrible mess.

I had a couple of guys from the local carpet store (I know, I know) who have been putting down wood for many years. Neither one actually measured the floor with a straight edge, yet said it should be fine. That concerns me. As well, they tested the moisture with an electronic pulse meter (I didn't see it, my wife was home). Is there such a device? So, for Mohawk Lakeshore Oak (looks like other Mohawk named products at $4.30 sq ft), a 3 ply with a decent thickness veneer layer they want $3.98 a sq ft and roughly $3 install to glue down. This engineered looks to be a rotary sawn product. I figure if I DIY float I can easily get a better product ($4 sq ft) and have less money invested. Still have less money if I DIY glue (but I'm a little nervous about gluing). Another online flooring store had BR111 Triangulo for $4. I wonder if hardwoodinstaller would match that, though I'm not sure the special is still on at the other place. As well, how is the Kahrs Builders grade? Any good?

You don't have to use a metal straight edge, you can use a piece of wood. It's just that there is no such thing as a straight piece of wood unless it just came off the jointer. Tool rental places typically have a lot of concrete tools like screed sets etc.. You also need the wood or metal for use as a screed.



I think I stated that most of the installers I talked to never bother to check the slab. After all, why should they? The floor will probably be fine for a year or 2 and by that time the consumer won't even bother to complain or if they do complain the original installer will just patronize them. The carpet stores do such a high volume quality is not their primary concern. I believe Ken has warnings on his site about carpet installers masquerading as hardwood floor experts. Also, Ken has an installer referral service you may want to try. BTW, I got my beater level at Home Depot (a level can also function as a straightedge but using it as a screed may be a little messy) for a pittance.

You need to read about testing slab moisture before you continue. The info is on the NOFMA site or this site. I have seen meters that can measure moisture in drywall and now they have meters that don't have pins that puncture the surface but I'm skeptical that they can measure slab moisture by just pressing a button.

If I were you I would get a quote from one of Ken's recommended installers if he covers your area. A glue down install is not for everyone and I wouldn't do a glued floting install again w/o the Bessy strap clamps and that is a fairly heavy investment.

Doesn't exist. Too much liability and headache involved. All it took was one clown and we know his name. No make that two, but the first one could make ten clowns.