Hi Everyone,

Great site.

I'm planning to install solid hardwood floors on my 15 year concrete slab using the method and prep work that was discussed by "VP" here http://www.hardwoodinstaller.com/hardwo ... light=slab back in November. I thought that the solution you all helped him come up with, while labor intensive (what part of laying HW isn't?) would give me the result I am after.

While my slab does not have any dips over 3/16in, the slab has settled over time resulting is a hairline crack, maybe 1/16" wide running through the width of the foundation. This crack results in the slab sloping about 3/4" over 10 feet on one end of the room to the wall.

I'm wondering if I can build up this end of the room by layering felt paper and additional layers of plywood which is the method discussed here http://www.hardwoodinstaller.com/hardwo ... r-prep.htm or if I would be better off leveling this potion of the room using mortor?

Another thought was to just leave it since the boards will be running in the same direction as the crack, resulting in a very gradual slope appearance that probably won't be noticable. At the slab appears now, one does not notice any sloping from one end of the room to the next. The only reason I found the slope was by using a straight edge.

My amateur skill set is as follows. Have installed HW upstairs using the NWFA and NOFMA standards. Have constructed in-the-wall book cases and have build some Shaker tables for the house. I've have plenty of tools for the task.

Anyway, thanks in advance everyone. And again...GREAT SITE!!!

Best...Stan in Atlanta.

layers of felt won't work. You might try a cement patch.

Skaady:

Sorry for the late reply. Been pretty busy. Yes, 2x8 sheets work great for closets, bathrooms and the kitchen with all the corners. Much easier to carry in and fit for smaller spaces. Used full sheets for larger rooms and that sped things up a bit. The feel of the floors is great. They are noticeably softer than glue down but not overly so. Warmer than glue down too, in the winter (such as it is in Phoenix). When the actual flooring was laid, it stiffened up the plywood sub-floor just a bit. The floating aspect really provided a dry sub-floor with no worry about moisture seeping through. Only thing different I would do is to kick the family out for a month, store the furniture and go full bore for that period using a couple day helpers. Project took much longer than expected. Don’t they always? Flooring is down but I am still working on the molding. Like someone mentioned, I have lots of rounded corners. Absolutely love the Mirage pre-finished product. You really do get what you pay for! Tolerances at Boa are very tight! See that HardwoodInstaller.com is now carrying this product (they weren’t when I purchased). Would have been cheaper using unfinished but being completely done (except for the molding) after finishing the nailing was a big plus. Spent far more time on the prep part than nailing. Nailing part was faster not to mention far more rewarding. You do have to be careful to not scratch as you nail or in my case staple. Saved several big squares of carpet and they came in handy. Moving our dining hutch was a pain. Day helpers were worth their $ in this case. For your ¾” dip I would highly recommend the thin set method I used. Perhaps two or three separate screeds will be necessary. That much dip in 10’ would be a little work but once poured and screeded you will not even see the difference under the ply. The floating aspect also compensates for any further cracks that might appear once the floor is level AND flat. I had about the same amount of dip in one room that was an addition. It is our workout room and the floor had been poured over the old concrete garage floor. The concrete sub flattened but did not level over the long measurement (23’). As just about everyone knows except the sub, garage floors are supposed to slope and rooms aren’t! This room took three separate applications. With thinset, you will get a gritty feel if you walk on it much before you lay the poly/ply but that won’t affect the leveling quality. For part of my install (entry, kitchen and breakfast nook), I was able to bypass pulling up some old oak engineered flooring. Instead of pulling it like I thought I was going to have to do, I simply used it as my first layer of plywood. Since the ½” thick engineered floor had been down for well over 10 years with absolutely no moisture problems, I took a chance and used it. Second ply layer and felt went over it just fine. Saved mucho labor not to mention the ply cost. Guess in these limited areas I have a combo glued down/nailed down installation! Well, that’s about it. Good luck with your project!! Pictures to follow when I get a chance...

I agree with the other posters, flatten that area using a cementious patching compound. You may need a couple of appplications.

Thanks, VP and Gary,

Regarding the thin set mortar, how many days/weeks should I let pass to allow it to fully set up and elimanate and moisture that may remain in the mortar? Are there any tutorials you can recommend that I can review to help me through the process?

VP, since your new floor is raised an inch and half, did you have to "shave" the bottoms of your doors to accommdate for the added floor height?

Thanks again and dying to see photos of your work.

Stan

If you use a floor patch, a couple of days will be fine. This isn't concrete but fast setting cement, more or less. Always double check with a moisture meter.

Let a heavy thin set layer dry for a couple days before applying another or covering it with the poly. Like Gary said, check with a moisture meter before laying anything else on top of it. As to the jambs – yes, the increased height of your wood will mean big changes for your molding, doors, jambs and the fireplace hearth if you have one. I removed the floor molding completely. Once the plywood was down, used scrap flooring with a power jamb saw to undercut the doorjambs to the right height. Bought a super unit from toolsforflooring.comthat cut through them like butter. They shipped fast and were a pleasure to deal with. This saw also cut the bottoms off the doors (in place) with ease. Be sure to check your exterior doors! That is where you will likely have problems. Cutting the door bottoms to raise them for the floor means you will also have to raise the threshold so it will work correctly with the reinstalled weather stripping. Don’t forget about the dishwasher also. Luckily I had a Miel with lots of height adjustment. Floored under it and lowered the feet. Even still, I had to cut a trim piece off just under the cabinet top. You could floor right up to it locking it in. But then when it goes out, you’ll be cutting into the countertop (assuming it is not granite). Undercutting the hearth with a masonry blade (one was included but you will need more!) allows you to slip flooring into the resulting “slot” and avoid using less professional looking shoe molding on the brick or stucco. I got a Crain 820 that was on sale from the place mentioned above, a few months back. The handle on this baby folds back a little allowing it to get into tighter spaces than the 812 and it is less money. I used the vacuum port and connected it to my shop vac. That seemed to help the wood dust a bit but the masonry stuff still went everywhere in spite of the plastic sheeting tent I carefully erected. Use extreme care with this saw! It cuts through just about anything else with ease too and the blade guard is not as effective as one on say a regular circular saw. By the way, I racked my first 3' of install and then went to just nailing down with a little pre-positioning. Found that the Mirage was so nice, it was easy to get a random look. I highly recommend this brand! Here’s a picture of the garage room that has the multiple thinset layers. Is almost finished with only the shutters and molding to go. Note the black felt & poly sticking up slightly around the edges, gap between wall-flooring and the satin finish. Family member in the picture really likes it!

(CLICK HERE for larger version)

Nice job, VP. I know you used two layers of 1/2 inch plywood as your subfloor without nail it into the slab for a floating floor effect. How does it feel and sound when walking on it? Do you think the whole floor will move since it is not nailed to the slab or will the floor be fairly secure once you put furniture on it as weight.

Again, very nice job.

Stan

Stan:

As I mentioned, the floor is very slightly “soft”. I have 1-3/4” total of wood over the concrete so just with that it would be softer than say ½” of engineered that is laid down directly on a thin coating of adhesive over concrete. Compared to the old oak Bruce glue down flooring that I used as my first layer in a couple of rooms (mentioned above), it very slightly but noticeably softer underfoot. Of course with only ½” of wood between you and the concrete, that was understandable. Comparing them is like apples to oranges. Also, the new flooring is Beech instead of Oak so that could be part of it too. I like this effect and combined with the satin finish the new floor almost invites one to walk on it (barefoot). As to the movement later, only time will tell. I bet $20K and spent lots of leveling/flattening labor to ensure that it would not move much! The weight of 1-3/4” of (almost) solid wood combined with the furniture will tend to prevent this, I hope. I left between ¾” and 1” of space all around in each room but this was for the expansion possibility, more than to compensate for movement. Molding is installed to the wall and not the floor per instructions to allow for this normal expansion. Speaking of expansion, I installed the flooring only after letting it sit in the house for a week or two. Carried more inside from the garage as the other was used and let it sit before using it, too. Was also careful to do the actual install while keeping the house at a constant 75 degrees. Humidity is hardly ever a problem here especially this time of year. There is a discussion of this topic elsewhere on this board. As a DIY'er, I figured why not acclimate? The Mirage instructions/box mentions expansion and shrinkage percentages at lower/higher temps and humiditys. Being in Phoenix we keep our house somewhere between 72 (winter) and 80 (summer) most of the time. I noticed on one really cold morning of 50 degrees (again this is Phoenix) that the newly installed floor creaked/snapped just a little when first walking on it in an empty but newly completed and unheated room. This was pre-furniture and the temp was a little lower than the install temp. Figure that in this case it was installed at a 25 degree higher temp and some shrinkage is normal. Logic says that is what causes the "creaking". Humidity does not change much around here except for 3 weeks in late summer. Given an install over a more typical sub-floor I would bet this would still happen. After all this stuff is not one-piece plastic or laminate. In my book the unique wood floor sounds prove it is real if one cannot tell just by looking!

Tips: 1) If installing in a bathroom, use/install the extra long toilet hold-down bolts when doing the plywood. Then when you come back with another ¾” of flooring, resetting the toilet is a snap. You might need to use either an extra thick wax ring or two of them together because of the added toilet height above the opening. 2) Plan out your nailing order/direction ahead of time to make the best use of your nice flooring stapler. When you inevitably get backed into a closet/alcove or have a closet section that “doubles back” on you, use a reversing tongue. Reversing tongues are easy to make by ripping squared ¼” molding on your table saw. When purchasing it, take a scrap of your flooring to make sure you get the right thickness of molding. If the fit is tight, don’t bother gluing. But opinions vary on this one.

Good luck with your project!

Great feedback, VP. Thank you.

S.

The double layer of 1/2" can be a good method but the height issue can be a big deal in some houses, particularly the kitchen. In addition to the dishwasher, you need to carefully check for refridgerator and trash compactor clearance. Also, keep in mind that the cabinets are designed with a 4" toe kick space. If this gets to be too small, it is a pain to work in the kitchen. 1 3/4" nearly cuts it in half. You need to determine if thats enough room for your toes.
I like floating floors but you can cut it down to 1 1/2" with 3/4" ply nailed over a moisture control system. Just another option.
You really need to think through all the height issues!!