Shimming the plank as required. Threaded Rods and Plates are also used to clamp the plank prior to grouting. A lightweight gypsum floor underlayment is often applied to the top of the plank to eliminate plank surface irregularities. All camber issues and concerns should be discussed with the plank supplier and erector.

Yes, plank has been used on hundreds of high end properties. A high strength gypsum underlayment topping product is recommended. Thickness can vary depending on plank span length. A 2" concrete topping can be used for structural reasons or when there are large expanses of a brittle floor finish (i.e.: ceramic tile).

Rebar is suggested to be #4 x 2'-0" long spaced at 24" 0/C max, and these reinforced cells require block outs. As for intermediate cells, grout has to be able to flow to create a monolithic system. EOR is the sole determiner of how much reinforcing is required and how often.

It depends upon the diaphragm loads and if they are needed for erection (see Girder Slab Intl. typical details). Consult with your local hollow core supplier for availability of weld plates, alternative details may be suggested that will meet the engineer's requirements.

One method is that the hollow core supplier provides these cut outs in the plant and then provides a core plug to stop the grout from flowing more than required into the cell. Another method is the saw cutting of the top of the hollow core in the field and then removing the cut outs and placing them in the hollow core of the slab.

A concrete topping is not required for the 2 hour unrestrained rating. A 1-1/8" concrete topping is required for the 3 hour restrained rating.

This is a decision for the EOR and the erector. Each building is different. It involves stability; the amount of permanent bracing which is installed and the use of temporary bracing such as tie beams, cables, and or angles temporarily fastened to the columns and floor slabs. Some engineers and contractors will call for weld plates in the bottom of the plank, and field tack weld to the Di-Beam. This technique is used so that in the event of freezing weather erection can continue while the grouting is postponed until weather conditions are more favorable.

Consult with your local plank supplier about his tolerances. Plank should be carefully detailed around steel columns to assure proper bearing and avoid interference. Clip angles are often added to columns for plank bearing. NOTE: Some engineers will stop steel bracing short of the "work point" to simplify plank & grout installation. A Plank detailer familiar with steel and plank projects is recommended.

If you have a choice, grout first then weld.

This is more a question for your precast supplier and we would advise you to check with them. We would suggest however, that no slots parallel to the Di-Beam be any closer than 18" to the center line of the Di-Beam.

Please discuss vibration, deflection, and differential camber ramifications with your local hollow core supplier.

Various hollow core plank suppliers throughout the country will have different options. Generally speaking; for curves with radii of 10ft. or greater, the hollow-core plank can be factory cut in straight lines to approximate the curve. Some additional minor trimming in the field will also be required. For curves with smaller radii less than 10ft. it may be better to provide rectangular plank augmented with cast-in-place infill.

We encourage steel fabricators to bid this “entire” scope. Our system is often an alternative to cast in place flat plate concrete. When builders compare the two, having an entire package price is beneficial. A certain amount of wood form work, bent plate, angles or light gauge pour stop is always required around columns, block outs or edges prior to grouting. Who is including this: you, your subcontractor or the builder? Filler material or mesh will be required for small openings; larger openings may require a temporary plywood form. As you know the Di-Beam and hollowcore plank must be grouted together to develop the “composite action”. Be sure to discuss this and agree with the hollow core supplier how their plank will be prepared (opened) for reinforcing and grout. The FAQ’s on our website (these pages) discuss various methods. Additionally ask about “weep holes” in the plank. Are they required? You should also check to see what plank embeds are needed, curtain wall framing, wall panels etc. are these all shown? Will some have to be done in the field? If your project is located in New England (or other Northern climates) you can minimize the cost/delays of “Winter Conditions”. If you anticipate erecting in the winter months ask the recaster to supply some weld plates for the bottom of the precast. Install the temporary and permanent bracing then weld the plank to the Di-Beam. This may be sufficient to stabilize the building and allow you to continue erecting. On a mild day you can go back and do the grouting. Each building is different so be sure to consult with the structural engineer. For more information on this subject please read the article "Let's be Plank" from the September 2007 issue of Modern Steel Construction. You can find this article under the Published Articles section of our website.

Structurally, yes; after grouting is complete (SEE Girder Slab Intl. DESIGN GUIDE FOR SPECIFICS) the composite action will develop between the precast hollow core slabs and the Di-Beam. Note, if the architect is specifying UL K912 for fire resistance, the precast hollow core suppliers should be sure they can comply, not all suppliers are specifically mentioned in these UL numbers.

The use of a light weight material on top of the plank, ½” to ¾” will make it suitable for most all flooring applications; tile, carpet, parquet, etc. After the leveling coat is applied, the door sill is applied, and the shower base goes down. The difference in elevation from the top of the shower (tub) base to the sill can be 2” +/-. A Sloping mud bed is applied for the tile base, so the tile can remain ½” +/- below top of shower tub. We believe the ½” is code acceptable for Handicapped areas.

All types of finished floors; carpet, tile, hardwood, "engineered" hardwood, can be installed over precast hollow core concrete slabs. Your architect will specify a proper leveling material over the precast hollow core slabs. Located in the sidebar of this page is a helpful publication called "Hollowcore 101 - Finished Floors".