Expert: Roger Zona - 9/3/2008

Question
I am resending this because I mistyped my e-mail address the first time :-) Please ignore the original.
*******************************************************
I am remodeling my kitchen and dining room. I have torn out the wall between them (non load bearing) and am about to tile the new open space with 1/4" thk porcelain tile. I am also planning to replace the laminate countertops with 1-1/4" thk granite plus add an island in the middle of the kitchen space. Total granite area of approximately 45 sq ft. Of that, the island is approx 15 sq ft centered in the kitchen. All other counters are along the outer walls of the kitchen. My concern is that I may be overloading the floor joists at least from a deflection standpoint.

My home is a small 3 bedroom rambler (1040 sq ft main floor) in Minnesota. It has a supporting wall running lengthwise down the center. The floor joists are 2 x 8s, 16" o.c. with a span of 11'5" contact to contact. The combined kitchen-dining space is approximately 21'5" long x 11'4" wide. The kitchen portion is 12'3" long. The subfloor in the kitchen is diagonally laid 1 x ? tongue and grove boards topped with 5/8" plywood and vinyl flooring. The dining area has the same tongue and grove subfloor covered with 1-1/2" x 3/4" thk red oak flooring which is then covered with linoleum that has asbestos in the adhesive; that's why I'm tiling over it. I have already laid Hardibacker over the entire area (the cabinets have been removed); I was also going to tile under all the counters and new island but decided against it. Before I continue I want to confirm that I'm not going to end up with cracking tile joints or worse.

The approximate material weights/sq ft I've come up with are as follows:

Granite-average density: 17.5 lb/sq ft
Porcelain tile 1/4": 3.55 lb/sq ft
Hardibacker 1/4": 1.9 lb sq ft
Oak flooring: 2.75 lb/sq ft
Pine subfloor: 2.125 lb/sq ft
Plywood 5/8": 1.875 lb/sq ft

Thanks.

Rich Gundlach

Answer
Rich,

I opened this file after already responding to your 1st transmission.

Your e-mail address is not sent with your inquiry.  If you don't get the first reponse, you may email me at:
askthecontractor@hotmail.com
and I will re-send my answer.

Thanks

Roger