I am adding two bedrooms and a bathroom on the 2nd story....?

Question

My question is, do I need to reinforce the current ceiling joists before I lay a floor? Right now, it is just a wide open attic space. The house was built in 1920, so it is pretty solid. The ceiling joists for the first floor are 2 X 6, not 2 x 4. Some people are telling me the ceiling joists were made to only hold the weight of the plaster/lathe, and not to support weight from up above. I was just planning on putting down some 3/4 tongue and groove plywood, and then start framing walls. The attic is about 1000-1200 sq ft. Any help is appreciated!

Answer 1

with the weight of a tub, better to use 2x10 for a floor

Answer 2

We have converted many attic areas into living space. I have advised several people in this forum on what to do.

Make a floor plan of your first floor walls. Now make a floor plan of the walls you propose to build on the 2nd level using onion paper ( thin paper). Lay your 2nd floor wall paper over top of your first floor wall plan. Do both of these on 1/4" = 1 foot scale.

With 2" x6" ceiling joist on first level - you can easily span 8-10' without a problem. check your spans and note any areas that are more than 10'.

It is likely that a lot of your first floor walls will be located close enough to let you go ahead and install flooring in the attic.

On longer spans - see if can locate an upstairs wall in the middle of these spans. Take some 2" x4"'s and nail them alongside the attic roof rafters, let them extend down alongside the attic floor joist and nail then into the sides of the attic floor joist. This will help strengthen the floor in the attic by transfering some load to attic rafters.

Remember to re-route electrical wiring that may now be on top of the attic floor joist. Don't just notch existing floor joist if they are covering a large span. You can notch the joist if they are close to or right over a downstairs wall.

Glue and s***w your 3/4" tongue and groove subfloor down on the attic floor joist.

If you insulate the sloped attic ceiling be sure to use styrofoam insulation chutes in the rafter spaces, this lets air flow through the rafters, install fiberglass insulation over the chutes. Keep these chutes continuous from unused attic space all the way up to where you flatten out your attic ceiling.

Install gable vents in the space above your flat ceiling to allow hot air to escape from attic. You need to ventilate this area good or you will be in on oven all summer.I would highly suggest a power roof vent fan.

Try to line 2nd level bath over the lower bath for an easier plumbing job.

Remember if you run your knee walls from up alongside the attic rafters down alongside your floor joist - you are actually increasing the load the floor joist can carry. You will need to put blocking between the wall studs at the top and bottom since you will not have a top or bottom continuous plate.

Take your time - do a good job.

Put an egress window (window large enough for people to climb out of) somewhere upstairs. Purchase a rope ladder or some other type of emergency escape system for occupants to get out and down.

Answer 3

You really need an engineer to look at this. I doubt you will be able to get a permit to do the work without doing this.