Legrand FD - Manual (Page 4)

4
7. Work Subsequent to Underfloor Duct Installation by Other Contractors
a. Concrete Placement and Curing
1. Reinforced concrete design shall be in accordance with American Concrete Institute Specifications for Structural
Concrete for Buildings (ACI301-72) and ACI Building Code Requirements for Reinforced Concrete (ACI318-83). Any
admixture containing chloride salts such as, but not limited to, calcium chloride shall not be used, as such
admixtures have proven harmful to steel and steel finish.
2. Concrete placement shall follow proper and accepted industry practice and be in accordance with ACI
Recommended Practice for Measuring, Mixing, Transporting and Placing Concrete (ACI304-73). Concrete must be
vibrated at all junction boxes and ducts to insure that the concrete completely fills underneath the system.
However, it is imperative that the concrete not be over vibrated. Over vibration causes segregation of material in the
concrete mix which, in turn, leads to weakening of concrete strength.
3. Concrete curing shall follow proper and accepted industry practice and be in accordance with ACI301-72.
b. After the Concrete Pour
When material or equipment loads that could deform junction box cover plates will be placed on or moved over the cover
plates, install temporary planking that will transfer loads to the adjacent concrete. Cover plates and underfloor duct
that are damaged during construction must be replaced. This will not be the responsibility of Wiremold / Legrand.
c. Excess moisture should be removed from inside the system within 48 hours of the concrete pour. Remove junction box
cover plates where water may have entered to check for water accumulation or condensation. Depending on job site and
weather conditions, cover plates removed on several boxes will help prevent condensation. If water is left in the system,
it may freeze and cause severe damage to the underfloor duct, the junction boxes or the floor slab.
d. Floor Finishes
Stainless Steel or Brass Pans, recessed to hold vinyl Tile or Carpet, are installed on top of the Junction Box Cover Plate.
For Tile Holders: Install Tile in recess, then drill and countersink holes through Tile. Install Escutcheons and Hold Down
Screws furnished with the Pan.
For Carpet Holders: Attach Holder on top of Cover Plate with Hold Down Screws before inserting Carpet. Use double
back tap around perimeter of Holder to secure Carpet and gain future access to Hold Down Screws.