I am remodeling my two small second story bathrooms(160 sq ft,) by removing flooring and drywall and adding marble and natual stone. The stone weighs about 9lbs per square ft which will be added to the floor and walls. I am concerned about the weight. The floor consists of 2x10s on 16" center with a span of 13ft. The flooring wll consist of 3/4 inch plywood and 1/4 inch durrock.

Is the floor stron enough to support the added weight?

Thanks.

KK

 

I'm not sure I agree with that being fine. The recommended total thickness for natural stone underlayment is 1 1/8". The durarock does not count since it is not a structual material but a bonding agent. 13' is starting to get a little long too. I would feel better about it with a 1/2" ply subfloor on top of the 3/4". Remember once you have the stone down that's it. Would be a real bear to fix later. Especially if it's in a small area it's not much more work or material to add another layer. Not like it will fall through or anything with but I would be worried about cracking.

 

Kay - Your not fine for natural stone. You don't come close to L720 at 13'. You need to either shorten that span by supporting it from below or possibly sistering the floor joists. You do need a second layer of plywood (at least 1/2") for natural stone. Adding the plywood helps with deflection between the joists, but does not help with deflection along the length of the joists.

Doug - where are you coming up with - yep your fine?

I hope Kay comes back to look at this cause shes not fine.

 

HeresJohnny,

Where did you come up with L720 at 13'?

I will accept my error and stand corrected if you can help me understand this.

 

Doug - you need L720 for natural stone. The longest span you can go for 2x10's and achieve L720 is about 10'. No way 13'.

 

Got it. I did some checking - my error. I will delete my previous posting to ensure Kay is OK.

Thanks!

 

kkay3, you'll be fine to follow Heresjohnny's advice.

Doug, as always, you show how gracious we all should be.

 

Tilebri,

Thanks - I'm not perfect but I strive to be better with age.

 

I should try that cause I'm certainly not aging better

 

I'm glad someone else came on and backed me up a bit. I almost said I would asister the joists up as well but that may be more than a little difficult and I didn't want to be the voice of doom lol. I did a job recently in a kitchen where the home owner wanted mexican tile. The house is turn of the century with true dimension lumber and diagonal slat substrate. It was also on a full 16' span. Not much question what had to be done there.I tore it down to the bones sistered all joist. 3/4" TG + 1/2" + 1/4" wonderboard. Tec fullflex thinset and I was still worried about it. I went by not long ago and 0 cracks in about 2 months so everyone's happy