If your slab as wet as your described, I would certainly recommend to use MVP or something similar to seal it first, then Floor Muffler, then float your engineered T&G floor on top. I want to talk a more about your floating T&G engineered flooring. These types of multiply engineered wood floorings are usually designed for glueing down application when solid hardwood flooring are not suitable to use, such as in a condo project,basement or main floor slab subfloor. So the tongue and groove are usually not milled tight enough to hold the T&G in place after the edge gluing. So the boards will tend to separate before the glue dries. If it is random length products, installation will be even harder with some boards are shorter. However most of the engineered flooring brands allow to float their flooring to cover more market or applications. To me it may not be a good choice for DIY home owners simply because they are not as easy as the traditional European style longstrip 3 ply floating wood floors to install. Even without Click Lock system, a T&G 3 ply engineered wood floors are very tight to tap the tougue into the groove. So when glue applied in the upper part of the groove, the tongue will stay tight once tapped into the groove. I guess this is the difference between an engineered wood floor and an engineered floating wood floor, which we are asked all the time by confused consumers. So the answer to your quesiton is: If the tongue and groove is tight, you can edge glue without using the strap. If not, you'd better strap them.I hope my 2 cents will help.

If your are using standard prehung door units they come pregapped appx. one inch at the bottom to receive carpet without having to cut off the door slab. If you install the units on top of hardwood there is nothing to take up that gap, unless your trim guy can fashion a way to cut 3/4" off each jamb/casing leg before the unit is set. Even then... trim guys set the hinge side first then either raise or lower the strike jamb to get the correct exposure at the top.... you may have one jamb side sitting up off the floor a bit. When asked I always request that door units be in place before I get there and I cut the jambs off with a jamb saw. It's going to be harder on the floorguy when sanding but I think it looks immensely better not having that huge gap.

A good deal of that info has to do with preventing moisture problems BEFORE the slab is poured. For installing wood flooring for those who aren't pouring a new slab, the author recommends a "fluid moisture barrier" rather than a plastic sheeting barrier, but doesn't say much (anything?) else beyond that. Is he suggesting something like Redguard?

PPF: All materials have a coefficient of linear thermal expansion. Coefficient of linear thermal expansion for concrete is roughly the same as for iron which is why it (rebar) works well with concrete. Expansion/contraction is significant for long linear surfaces such as the large concrete slab with the crack OPs thread. Though there is a much more to material science, especially concrete and types of concrete, hopefully the following excerpt provides an adequate explanation. THERMAL EXPANSION AND CONTRACTION Materials expand or contract when subjected to changes in temperature. Most materials expand when they are heated, and contract when they are cooled. When free to deform, concrete will expand or contract due to fluctuations in temperature. The size of the concrete structure whether it is a bridge, a highway, or a building does not make it immune to the effects of temperature. The expansion and contraction with changes in temperature occur regardless 0of the structure’s cross-sectional area. Concrete expands slightly as temperature rises and contracts as temperature falls. Temperature changes may be caused by environmental conditions or by cement hydration (the exothermic chemical process in which the cement reacts with the water in a mixture of concrete to create the calcium silicate hydrate binder and other compounds). An average value for the coefficient of thermal expansion of concrete is about 10 millionths per degree Celsius (10x10-6/C), although values ranging from 7 to 12 millionths per degree Celsius have been observed. This amounts to a length change of 1.7 centimeters for every 30.5 meters of concrete subjected to a rise or fall of 38 degrees Celsius. Thermal expansion and contraction of concrete varies primarily with aggregate type (shale, limestone, siliceous gravel, granite), cementitious material content, water cement ratio, temperature range, concrete age, and ambient relative humidity. Of these factors, aggregate type has the greatest influence on the expansion and contraction of concrete. Severe problems develop in massive structures where heat cannot be dissipated. Thermal contraction on the concrete’s surface without a corresponding change in its interior temperature will cause a thermal differential and potentially lead to cracking. Temperature changes that result in shortening will crack concrete members that are held in place or restrained by another part of the structure, internal reinforcement or by the ground. Forexample, a long restrained concrete section is allowed to drop in temperature. As the temperature drops, the concrete tends to shorten, but cannot as it is restrained along its base length. This causes the concrete to be stressed, and eventually crack. Joints are the most effective way to control cracking. If a sizable section of concrete is not provided with properly spaced joints to accommodate temperature movement, the concrete will crack in a regular pattern related to the temperature and restraint directory. Control joints are grooved, formed, or sawed into sidewalks, driveways, pavements, floors, and walls so that cracking will occur in these joints rather than in a random manner. Contraction joints provide for movement in the plane of a slab or wall, and induce cracking caused by thermal shrinkage at preselected locations. One of the most economical methods for making a contraction joint is by simply sawing a continuous cut in the top of the slab with a masonry saw.