tile flooring,granite counters..reinforced flooring?

I was wondering with all the new tile flooring flooring and granite counters if there should be extra bracing in the sub flooring, sistered Joice’s or any other bracing to accommodate the extra weight?

I just inspected a house that had a complete kitchen redo, granite, industrial grade appliances, island, etc. In the crawlspace I found the floor system had been reinforced, but by a “handyman” as the owner put it. I recommended a stuctural engineer inspect. I had the opportunity to meet with the engineer on-site and it was a great learning experience for me. Engineer recommended the floor system be reinforced, provided the owner with drawings and advised that the repair cost would reasonable.

So yes, depending on the current stuctural conditions and added load, reinforcement may be needed.

they sure should be imo…but often they are not…of course they then wonder why all that pretty tile cracks…:roll:

Sonny, to try and answer your question, floor framing systems for the Residential arena are typically designed for #40 per sq. ft…

Granite countertops weigh approximately 20.625 lbs. per sq. ft.

Ceramic tile weighs approximately 5 lbs. per sq. ft…

In the United States the minimum design floor live loads are usually stipulated in pounds per square foot (psf) by either state or local building codes.
An example of typical design live loads might be 200 or 150 psf for a storage warehouse, 100 psf for a public meeting room, 50 psf for an office and 40 psf for a single family residence.
So, your home most likely has the capacity to safely support a uniform live load of at least 40 psf.
But keep in mind that this design live load is theoretically spread uniformly over the entire floor from wall to wall throughout your entire house.
It is not a maximum load on any given area of the floor, it is just a theoretical average load that is used to design the floor for loads that are initially unknown.
Some people find this confusing because in reality it is not the floor pressure (in psf) that matters at all, it is the floor load in pounds that really creates the stress in the primary structural framing members.

So to make it a shorter answer to your question.


Hope this helps.

Marcel :):smiley:

I guess some snuck up on me while I was typing my message Sonny.

They also bring up good points.

My assumption is that the existing floor framing of a dwelling that you may be thinking of, meets the minimum standard of the IRC.

There is a possibility that these upgrades could occur in a building that does not meet these recent codes.
In which case the framing members in your opinion does not meet the most recent building codes.
Note it as such as a concern, or recommend a building Contractor or Architect to evaluate the upgrade.

Most likely, it is not a crucial problem due the fact that most kitchens are located on exterior wall lines where the capacities of the floor structure is at it’s strongest.

Structural framing might be designed for this theoretical uniform 40 psf but it probably doesn’t reflect the real world loading conditions in any room of your house. The most likely way for a residential wood floor to fail would be because of excessive shear stresses or excessive bending stresses in the floor joists.

What the guys have noted above are all good points to consider.

Hope this helps in providing you an insight to this subject in conjunction with my colleagues above.

Marcel :):smiley:

I think you often have to look at this on a case by case issue…remember the code is the national minimum standard and would generally reflect your average home…some homes are much smaller in size than the average …some much bigger …quite a few years ago i had the contract for the flooring on a good sized home…it included an upgrade to sub floor as 2200 sq ft of ceramic floor was going in a concentrated area of the home …we also had the contract for cabinetry in the home…mid way through construction the homeowner called and said they no longer wanted the sub floor upgrade as it was not necessary to meet the code…i told them it was a serious mistake and would no longer be interested in that portion of their project…I went so far as to quote them estimated repair and replacement costs for the flooring should they decide to take the foolish route they were proposing but they were adamant …they were meeting the minimum standard…when we were installing the cabinets i took note of all of the cracking in the grout lines of the newly installed ceramic flooring and shortly thereafter this new home was up for sale as the homeowner was not able to afford to fix what he had not done right to start with…sometimes the minimum is just not good enough…

To me, it seems like alot of weight concetrated in a smaller area and would need some type of reinforcing.

I guess one other thing too, what would see if there was too much of a load from these upgrads? Cracks in the wall,the floor, deflection in the joist,cabinets out of wack…etc

Thanks Marcel for the help. I’m going to check out the IRC and see if I can find more info.
Thanks to everyone else, this helps out alot.

As far as I’m concerned, minimum means ‘bottom end barely adequate’.

I had one last year where the center island had 3/8 - 1/2 inch deflection across a 12’ span…it was an unusually large island with granite counter tops, roll out drawers loaded with cast iron pots and pans, small frig and lots of can goods.

I asked to see the blueprints and sure enough the builder failed to add a pier that the architect had put on the blueprints under the island. Found some other issues once I went under the crawlspace. In a case like this, regardless as to whether the floor would have been sufficient is irrelevant being that the pier was on the plans.

The client is a lawyer who simply asked the builder to add the pier for which the builder basically told him it wasn’t needed and refused. Needless to say it did not fair well with the builder. What could have been a simple fix for less than $300.00 cost him quite a bit more by the time he had to fix everything else that I wrote up (28 pages).

Strange thing was that they were neighbors…the lawyers said that during the whole building process that everything ran smooth. At the same time the wife was bragging about what a deal they got on the house which led me to believe that the builder under priced the project from the beginning and finally decided to draw a line in the sand. (normally I would feel sorry for the builder but being that I hate low ball builders I could care less)

As Marcel said Sonny,… NO
Standard structural requirements are plenty sufficient for this sort of thing.