What is the maximum safe loading for wooden joists?

[JohnJolliffe]

Can anyone give me some advice about the maximum loading for wooden joists? My MD’s office is situated in a converted house on site and he has asked me to look into having it redecorated. His chosen preference for the new décor is dark oak furnishings with a slate floor. So far I have had the old floor boards lifted and replaced them with 18mm T&G chipboard screwed down at 200mm centres (the green moisture resistant type). During this process a visual inspection of the joists was conducted and they were found to be in good condition. The room in question is approximately 2m x 3m with the 9 (150mm x 50mm) joist spanning the 2m length every 360mm. What I need to now is the max safe load I can put on this floor I have calculated the approximate wait of the tiles, adhesive, and desk etc… Please help, as I feel sure that my boss falling through the floor of his office would be bad for my career!

John Jolliffe
(A quality Engineer out of his depth!!!)

 

[rlflower]

Umm... I think there is justifiable reason here to reccomend a licensed civil engineer to take a look at this, weather or not you intend to obtain a permit. You see, there should be a limit to interior decoration without proper supervision when it starts to involve structural elements. Several reasons for this, some of which I mention here:

First, I take note that you mentioned a tile floor; was there a tile floor there originally? A tile floor would be a considerable amount of dead weight on the floor and this would make a big difference in the performance of the floor framing if there was no such tile floor previously.

Secondly, whose opinion are you relying upon to determine the condition of the extisting floor members? The building code has specific regulations regarding such visual observations - these regulations are for your safety.

Third, I hope the "chipboard" you mentioned is in fact plywood.

Fourth, if you are in the United States, I should mention that we work with pounds-feet-inches rather than metric.

I am a civil engineer by the way, licensed in California. Best of luck - an skill - in persuing your project.

-Richard L. Flower, P. E.