New Method Cuts Cost, Boosts Performance Of Strip Oak Floors Over Concrere Slabs

A new cost-cutting method for installing hardwood strip floors over concrete, without rrse of wood subfloors. offers substantial savings to builders and superior floor performance for owners of basementless homes built on concrete slabs.

The system, developed by the Florida Flooring Co., Oak Lawn, Ill., has been employed with highly satisfying results in more than 200 Chicago area homes within the last year. It a-lso has been field-tested in Memphis, Tenn., by the National Oak Flooring Manufacturers' Association, which has ap- proved the method.

Accepted also by the Federal Housing Administration, the technique involves use of a double layer of I x 2- inch u'ood sleepers nailed together, with a moisture barrier of 4 mil polyethylene film between them. The bottom layer of sleepers is secured to the slab by a latex mastic applied with a caulking gun and by concrete nails. The strip hardwood flooring then is nailed at right angles to the sleepers, rvith one nail at each bearing point.

Before the slab is poured, a 4 mrl polyethylene film is placed directly over the base course or fill. This prevents rise of ground moisture into the slab.

Charles Bennett, owner of Florida Flooring, terms the method a major advance over the system now commonly used in rvhiih the flooring is nailed to 2 x 4-inch sleepers arranged in a staggered pattern.

"Formerly it cost us 30 cents per square foot to ready the slab for the oak flooring," Mr, Bennett says. "That perhaps was higher than the figure for contractors in many other sections of the country, since Chicago is among the highest price areas for labor and materials. But according to our information the cost even in the lower price areas averag'es at least 15 cents a square foot. Our cost under the new system is about 7 cents p,er square foot. or less than one-fourth the former figure.

"The savings arises from two factors: I x 2s cost only about half as much as 2 x 4s; the sleepers and the polyethylene film can be put down much faster. In the older approve'd method the moisture barrier installation alone requires far more time. It involves treating the slab first with an asphalt primer, then applying a 'sandr.r'ich' of hot asphalt, a layer of 15-lb. asphalt saturated felt and another coat of hot asphalt.

"As a result of our savings we are able to quote Chicago area builders a complete price of 54 to 58 cents per square foot for strip oak flooring installed over concrete slabs. That price is for 25/32 x 2fu-inch Select grade red oak, and includes sanding and finishing."

Money Saving Possibilities

The money saving possibilities should be especially appealing to project builders of single unit dwellings and to builders cf apartment houses, says Henry H. Willins, executive vice president of the oak flooring group.

"In a 1,500 square foot area, for instance," he points out, "the cost of preparing the slab for the hardwood flooring under the older method rang'es from $225 at the lS-cent per foot cost to $450 at the 3O-cent figure. Mr. Bennett's cost of 7 cents per foot under the new method comes io $105 for 1.500 feet and therefore represents savings from 53 per cent to more than 76 per cent.

on cholk lines 16 inches cpcil, running ot right ongles to the proposed direction of the ook flooring. fhe maslic is purchcsed in disposoble quod tubes. Wood slecperc composed of I x 2-inch noiling strips of convenienl length ore set in fhe mostic. These should be pre-treoted with on opproved rot prese.volive. A l-inch expcnsion spoce is left between sfrips in the same course. The sleepers ore further secured to rhe sfqb evel 24 inches by c 4d spirol concrete noil. which penelrotes 7+-inch into the concrete. Thus rhe sleepers ore held firmly in ploce even before the moslic 3et3.

(lower Photo) A moisture bqrrier of 4 mil polyethylene is ploced over the first loyer of slepers ond o 3econd lef of similor strips is noiled on top of thern, through the polyethylene, with one 4d fiooring noil every 16 to 24 inches. lf rhe polyethylene is in strips rqlher thon one conlinuous rheet, edges should be lopped at least 4 inches. End ioints of the slepcrr in this top loyer ore burcd righrly, unlike those in the bottom loyer. Wood ploster lofh could be usod inslecd of I x 2s for the tcp loyer of sleepers if excessive heighr were of concern.

"On this basis a builder erecting 100 slab-on-ground houses annually and equipping them with oak floors by the older method could effect savings from $1,200 to as much as $34,500 by adopting the new method. The benefits to a small scale builder, of course, would be proportionate. He could save from $120 to $345 per house, depending upon costs in his area."

The system is well adapted to such

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