Attic for light storage only
 

I just finished cleaning out 50 years worth of junk from my attic. The house is 1300 sq ft, built in 1939, with 2x6 joists on 16" centers. Only a small area around the stairs is floored, with 1x6s. I insulated between the joists years ago. It gets VERY hot up there in the summer even with a gable fan and eave vents, so I want to cool it and put down some more flooring for storage.

My questions are:

Flooring: 15/32 plywood OK? I will probably have to cut these to 2' x 4' or 8' to get them up the stairs by myself? OSB would be cheaper but would it be OK?

Insulation of roof between rafters (2x6) and end walls (2x4) : 3.5" roll fiberglass with vapor barrier to inside? Or no vapor barrier?

Thanks in advance.

OSB is fine for areas that stay dry.

Your OSB is fine as is your insulation selection. Although I think paper backed insulation is a little easier to handle.

No vapor barrier under roof but foil backed does add to the value.

As for flooring anything will work. Even 3/8ths ply running across a few joists will support you and a light to medium load. 1/2 OSB is good too and it doesn't really care which way you put it.

Of course you'll land your seams on the joists. No blocking required for what you need.

While it's all open still, you might want to double up some of those joists.
(every second one perhaps? idk)
Use thin strips of https://en.wikipedia.org/wiki/Laminated_veneer_lumber
That will add a lot structural integrity without too much weight.

Pine lumber is mostly water. It will twist into a pretzel when it dries out taking the rest of the house with it.

Put a higher cfm temperature-controlled gable fan in there instead? That one doesn't seem to be doing the job as is.
Or add a few roof turbines?

Curious- 2x6, 16" centers. One very important number is missing.

How far do the 2x6s span?

If you don't have it already, now is the time to add and outlet and lights....Above my garage, I used 3/4 OSB to cover an area 48X 20 ft........Lot's of storage...

what is the span? 2x6's are limited in their ability to carry weight. Even old full dimension wood

What's your largest unsupported span? Up to about 10' you should be good to go with just decking the 2x6's. Above that and you should be selective on where you store things.

I just finished removing some stuff from my attic when my roof was re-roofed with aluminum. Mostly holiday decorations that are only used a small fraction of the year.

Mine gets hot as well - a gable roof with a vent on either end. No eaves venting so air flow is only north-south. The new reflective silver metal should help vs. the old asphalt shingles.

I asked on a different thread about adding a fan on one end controlled by a thermostat but never got a response.

This is the one I was looking at:

Cool Attic CX1500 Gable Mount Power Attic Ventilator with 2.6-Amp 60-Hz Motor and 14-Inch Blade

Thoughts?

12 ft span max on the joists to load supporting inner walls.

If I use paper backed insulation between the rafters, does the paper face the inside of the attic?

Duh, I hate sounding so stupid but the internet is full of conflicting info.

Definitely adding another fan or 2 and some better lights.

I just ordered a recording thermometer with 3 sensors so I can monitor attic temps. I don't even know how hot it gets. And if I add a fan, the thermometer will help me with data acquisition.

I have a low slope roof so not a lot of room but would like to store a few things up there. The heat concerns me.

Sorry, I musta missed that one?

I like em' but not sure how effect they are since I have never tested it with any instruments. When its 120 up in there, every bit of air flow will help is my opinion. I always put those things, or power fan or vents in homes in general knowing every bit helps. I put them in my parent's home. They have high ceilings, almost 10' 1930's Spanish home. I remember, it was cold but relatively cool during the warm months. Once it got near 100, nothing would help. I stuffed a huge amount of insulation in the attic and installed two of those gable fans on a thermo switches set at medium setting. One to draw air, the other would push air through the attic with normal vents on other sides.

By doing so, I was able to reduce interior temp by about 8-10 degrees during summers. What made the huge difference was the new windows, I truly believe. At 85-90 degrees during summer, their AC doesn't come on until after 1-2pm. The house is much warmer too in the winter months. In the past 15 years, their ac has been set on auto at 79 degrees come April until October.

I forgot to mention, mount those fans on rubber or urethane of some type to dampen vibration. I have done it with and without and really notice no difference unless the house is dead quiet, I bearly notice them kicking on.

Glue and nail or screw 5/8 or 3/4 plywood sheathing will make it so much stronger. Blocking it off makes it ever stronger. Other then that, I wouldn't double up on the joist. I really don't think its necessary. Again, I don't know the span. If you really think about it, it will support you up there without any issues, so if you plywood and or block it off, that will distribute the weight evenly. What are you going to store up there, a diesel engine? Just boxes of junk that weight 25 -30 lbs max? It will hold up just fine.

Thanks for chiming in, Jeff. Always appreciate your take on all things construction/home improvement.

I feel the same way - it's gotta provide some relief.

I will be setting up a thermometer to monitor and will report back.

10-4 on the windows. Mine are not that great but will be a while until I get to those.

Thanks again! SmileWavy

Spend a few bucks more on quality Low-e glass, it makes a huge difference. Don't get those " For 25 bucks more, You can have low-e glass" BS.

I can stand under my skylights at 1pm with 100 degrees outside temp. I will feel little heat, very little unless I stick my nose up against the glass. Even then, it isn't hot at all.

+1

You can also run a few 2x6's from joist up to rafter to add some weight bearing support. Make sure you drill thru joist and rafter to attach a carriage bolt, don't use lag screws.

Get a structural steel contractor to install wide flange beams with 1/2" steel plate. Add 8" diameter steel columns on 6' centers through the ceiling and floor to the bed rock. That should do it.

I'll have to wait for my tax rebate check to get here to cover that, unless you will spot me. I'm good for it, I promise.