How do I hang a ceiling fan w/light on to an existing light fixture? Do I have to replace outlet box?

pato I'm a construction super in NYC I can give you the answer The box that is up there might not be strong enough to hold up the new fixture if the box is screwed into a beam it might be OK If you hung from it would it come down if its moving around or loose head to the de-pot homede- pot

Bottom line is that a ceiling fan weighs a lot more than a regular light fixture and the added stresses due to a rotating motor necessitate additional support hence the proper "fan/light kit" from your local hardware store, or simply properly supporting a metal box with screws into a ceiling joist or cross member. I have installed plenty. The test I perform to check box strength is to hang from the fan mounting bracket. If it can support most of my weight it will easily support a fan safely. Don't forget to turn off the breaker powering the light fixture before working on it - not just the light switch. Safety first.

Just go to depot and by yourself a fan box.

If the box in the ceiling is plastic, it will not support the fan. Go to Lowe's and pick up a kit. You not only have to worry about the weight, but also the vibration over time.

first is the fan box in the ceiling made of metal and supported by a bracket or just nailed in? if its nailed in you have to replace it. if its has a bracket you dont have to change it. if its a plastic box you definitely want to change it. a fan box with the extendable arm is your best bet so it wont fall.

grab the box is it stiff or does it wiggle a little if it wiggles change it.if its metal it probley good.

Depends on the age of your home. the only true way to find out is to make a larger opening in the ceiling to expose the box. If you have access to the box from the attic, then you can skip this step. You want to see if the box is simply nailed to a stud or it has a cross bar attached to it. Also is the box metal or plastic. If it's plastic you can almost always count on it being too week.

look if the boxx you have is fan rated should have a sticker some fans come with a bracket that can be screwed independant of the box. if you find a joist or wood in the area . if all else fails install a fan rated remodel box , it has a bar you put through the existing hole and it expands tight aginst the joists in the ceiling.