We have nail down very thick solid wood prefinished floors (13 years old). While the surface is still very nice in most areas, we have cupping and gapping in certain areas (guests would not see it but we do). Husband is adamant about doing a glue assist engineered floor (he is a GC) when we reno the whole main floor.

It will cost you less to glue directly to a slab versus installing a subfloor and nailing the floor down. Texas has a funny weather system. I would use engineered flooring, since temps can soar into the upper 90's or low 100's. You will need 1-2 coats of a moisture barrier, rated 15lbs to 85% RH applied, before gluing. The rain there is ridiculous.

If you are on slab, I'm not sure what you would be nailing TO. Adding in a sleeper subfloor would be very expensive and will still require a vapour barrier underneath.

*Technically a glue down SOLID hardwood can be done on slab - but it isn't recommended unless your HIGH END flooring installer has done it successfully in the past. A glue down engineered floor is technically "more stable" in the widths they are suggesting, but I would question a comparison to a 2.25" solid hardwood. Especially if the solid NARROW strip hardwoods are rift or quarter sawn.

The same adhesive would be used regardless of plank structure (solid vs. engineered). The RIGHT adhesive (aka. EXPENSIVE glue) MUST be used over slab in TX. And then the proper SPREAD RATE must be used (lots and lots of the expensive glue will be required) as well as the PROPER TROWEL profile/depth will be required.

These expensive adhesives ($100/gallon is common) will achieve 30-50sf per gallon. These adhesives will be the vapour barrier. The most expensive ones will have "limitless" moisture content as one of their key features.

Even with the TOP adhesives, the installation will still be cheaper than a sleeper subfloor + nail down installation. The sleeper subfloor would mean a lower priced flooring professional can be hired to achieve the nail-down installation. The glue down method will require the higher skilled professional with all the knowledge required to install a glue down wood floor PROPERLY.

And the next issue is the HVAC system. Regardless of the installation method, your HVAC will have to have the ability to maintain a CONSISTANT level of humidity. Sometimes A/C isn't enough in high-humidity environments. Sometimes a whole-home dehumidifier is required in extreme humid areas.

Please review your HVAC system's abilities to TIGHTLY control humidity (somewhere around 40% is PERFECT...and it must be maintained 24/7 for the next 25-60 years). Start there. Spend more money for the upgrade on the HVAC system so you can have the wood floors - regardless of width/composition.

The COST of the MATERIAL (unfinished engineered wood plank in WIDE plank presentation) is what is driving the price - not the installation method. The unfinished engineered product is a PREMIUM product. It is rare, highly sought after in certain areas. Because the product is expensive to produce (it is more expensive to MANUFACTURE layers of wood than it is to cut down a tree, throw it through a mill and then let it dry) AND IT STILL requires the EXPENSE of a flooring professional to sand, stain and finish the product ON SITE. You still have to pay to have it finished.

Are you saying you will build a subfloor REGARDLESS of the product being installed? What type of subfloor? Is it being GLUED to the concrete slab or is it a properly built sleeper subfloor (2"x6" laid over plastic sheeting that is then covered with TWO layers of subfloor grade plywood)?

Thank everyone for the reply so far. The site stained glue down engineer floor is by La Madera. Has anyone heard of this product before?