Subfloor standards for a long lasting tile installation.

[HotinOKC]

I will be working on this thread to give essential information required to have a long lasting tile installation. Please read the following prior to your tile installation, and if you have questions, please don't hesitate to ask.

FAQ's

1) Should I tile directly to a wooden subfloor? My handyman said it's ok and he has been doing it for a zillion years.

No, plywood expands and contracts with temperature and moisture changes and could result in your tile/grout cracking. You should always install tile onto a cement backer board or other membrane or mud screed floor.

2) What is "deflection?"

It's the downward movement of your floor when weight is applied. Deflection may occur along the span of your joists or in the plywood between your joists. Excessive deflection will cause your tile installation to fail.

In order to know your floor deflection, you will need to know your floor joist sizes (2x8, etc), joist spacing (center to center), and the unsupported span of those joists. The unsupported span of a joist the length of the joist before it is supported by a foundation wall, post, etc. Once you have your measurements, click here for a handy calculator. Courtesy of John Bridge. Remember, your joists and subfloor need to be even stronger for a natural stone installation. For more information on deflection, click here.

3) Should I remove the existing luan? What type of plywood should I use?

Yes, you should remove any existing luan that is attached to your subfloor. You should be installing your backerboard or membrane onto at least 5/8" thick exterior grade (AC/BC) plywood for ceramic or porcelain tile, and 1 1/4" for natural stone installations. If you have a planked subfloor, install at least a layer of 1/2" exterior grade plywood.

For some technical reading, read this article, which explains subfloor installation and other info.

4) What type of thinset should I use?

I always recommend using a portland based thinset. I do not recommend using anything that comes in a bucket. You maybe tempted to get some of this adhesive, but there are lots of horror stories about failed installations. Portland based thinsets come in 50lb bags, and are usually alot cheaper then the buckets of junk. The only time where I might use anything in a bucket is for a simple backsplash. Be sure to read manufacturers instructions on what type of thinset to use (modified/fortified or unmodified).


Too be continued........more to come.