I am finishing the design phase of a new home in Massachusetts. We are looking to build a center entrance colonial with attached family room. We are trying to follow the PGH concept although the size is double the PGH standard. The issue I am having is attic storage. I would like to have a pulldown ladder so that I can use the attic to store seasonal items but our designer said that they can be very problematic when it comes to air sealing. I was hoping to get some suggestions from the board. Thanks!

I built a rigid foam cover with soft foam air seals around the edges. Seems to work well.

I don’t realy think it is a good idea for storage. First off it is likely to see temps that range as high as 140° and as low as 0 with widely varying humidity. This is hard on just about everything. Secondly, I see lots of stuff in attics I work on. 95% of it is crap that has been there for years and people are too lazy to get rid of. The best place to store extra stuff is the town dump.


If you decide to do it anyway, you need to insure 3 things. First is that it is air sealed and second that it is insulated to a reasonable degree, third that any loose fill insulation does not fall down the hole. If you don’t you will have a leaky uninsulated hole in the ceiling.

Since you quoted pretty good house standards you are likely going for R60 ceiling insulation. A standard truss or ceiling joist is not going to permit that so you will need to build a platform, on top of the joists that will raise you up another 10-12 inches so you have room for the extra insulation under the platform. Plan on that early as it is a PIA to add risers to the floor later when the drywall is in place. An easy way to do that is us I-joists run perpendicular to the joists. You also need to make sure the loads are accounted for as many trusses are not speced for extra weight on the bottom chord.


You will need to build a dam around the attic hatch, higher than the insulation, level with the platform you constructed . Make it out of ¾” plywood and then glue 3 layers of 2” poly iso to it and foam it in place. Now make a top out of 2 layers of ¾ plywood and glue 3 layers of 2” polyiso to the plywood. Lastly use foam tape or epdm gasket to make the airseal between the lid and the dam. The double layer of plywood should keep it from warping and helps weight it in place. Use something to latch it in place.
done

Cheers,
Eric

Air sealing is the primary issue, and Eric's design may work, although it will be very heavy to lift. Plus, site build doors are difficult to seal. One alternative is to build a small insulated, sealed room in the attic accessed by the stair, and have an exterior insulated gasketed door from there which goes to the remainder of the storage space. Attic trusses can be made with a 16" floor cavity to give you sufficient insulation.

Store it above the garage, basement or shed. How can you possibly try to follow the PGH standard and then want to punch a gaping hole in your envelope?
There are some products out there if you must, and your truss or ceiling design load needs to be checked with high insulation dead load plus storage loads.

Posted By greentree on 24 Aug 2014 01:02 PM
Store it above the garage, basement or shed. How can you possibly try to follow the PGH standard and then want to punch a gaping hole in your envelope?
There are some products out there if you must, and your truss or ceiling design load needs to be checked with high insulation dead load plus storage loads.

Yep above the garage is the best option ...... Having your attic access in the garage area wont punch a hole in your envelope. Have the Trusses/garage framing designed to carry a storage load. One thing I'm still fighting to figure out is a cheap design option to utilize heavy cellulose insulation over the conditioned area without causing my flat smooth finished drywall ceiling from sagging from the heavy cellulose.  Netting with batten strips 16" o.c. is the only option I have seen that should work well against ceiling sag but is very labor intensive so its expensive.

Wet sprayed cellulose is supposed to lock together and eliminate most of the load on the drywall.

I'm thinking about the cheapest way of supporting R60+ in the attic area would be attaching a strong tight knit fiber mesh to the topside of the ceiling joist. Would require a lot of labor intensive patch work around objects which project above the ceiling joist line.

What do you think?
http://www.jrproductsinc.com/shop/pc/InsulWeb-c31.htm

I know the underside would be the best scenario for the mesh attachment but it would require furring strips.

Here is an idea I have had to help support heavier loads of cellulose insulation: Roll out and staple galvanized 2" poultry netting to the top of the ceiling joists or roof truss bottom chords cutting to fit around braces as necessary. Then after the drywall is hung, have stabilized cellulose sprayed through the netting to the desired R value level. The lightly wet sprayed stabilized cellulose with water activated adhesive will essentially form a monolithic mass with the wire mesh embedded near the bottom. As the damp cellulose drys and shrinks somewhat, the wire mesh will support the bulk of it and there will likely be very little load on top of the ceiling gypsum board. The cost for the poultry netting is ~$0.10/sq ft. This could be installed after wiring and plumbing is roughed in and before drywall is hung.

http://www.amazon.com/308476B-48-Inch-50-Foot-Galvanized-Hexagonal/dp/B000XFX6TY

I just did a quick search and found a better deal here at ~$0.06 / sq ft for a 6'x150' roll:

http://www.truevalue.com/product/72.../17041.uts

Sounds like an electrifying idea....lol

Given that one is trying to reduce, not eliminate load on the gypsum, I expect that damp sprayed/stabilized cellulose is stiff enough to bridge enough weight to the joints/trusses that mesh isn't needed. Plus it it supposed to yield a slightly higher R value.

It's not clear there is any issue when 5/8 gypsum is used (see here). But it would be nice to see some actual test data on the different options.

We install an air barrier (Majpell) on the bottom cord of the trusses, then strap the ceiling with 1x3's, 16" OC. Have never had any issues with weight of the insulation. (20" cellulose)