petitefrancaise

So, I was looking at the insulation in HD today when a penny dropped. My attic has blown in insulation. No rolls between the joists and no humidity barrier. There just happened to be a builder next to me when I realised and probably swore (ok, I did swear). I asked him if that was even allowed and he said yes..... and they regularly did this in older houses - just sprayed in the blow in stuff. The only batts that are there are about R2 placed around the attic opening. So what to do? I am tempted to scoop out what is over the girls' bedrooms (won't take long), seal any gaps and place the batts in myself. Then spread the loosefill stuff back over the top. thoughts?

ddsrph

That would work. With no present vapor barrier I would buy the craft paper covered batts, scoop out all the blow in in area being fixed and put the paper side down against the ceiling sheet rock. Any other insulation that you may later place on top of the first batt should be unfaced. In other words only one vapor barrier and always facing the interior heated space. The batts come sized for ceiling joist on 16 inch or 24 inch center. You probably have Two by six joists and a 6 inch R19 batt would be the one to use. You could later roll another unfaced R19' batt over the top of the first, preferably at a 90 degree angle. Our TN southern building codes now require attics to be R38 for new construction. Run the batts slightly into the soffit area just enough to cover the exterior wall, being sure not to block the air movement thru soffit vents.

anotherlimey

Here is the attic wiring, that box is still powered.

petitefrancaise

I like ddrsph's idea with the electrical wire tracks.
I've been investigating more about the vapour barrier after a headsup from Pulaski. It is not deemed necessary in my climate which is primarily dry and sunny and hot. The attic is (will be) well ventilated with ridge vents and when I've cleared the blown-in insulation away from the roof and installed (more) baffles.
Still torn between rolls and blown-in... Blown-in is fine until you have to do something in the attic and I've also got the airhandler in there. I wish I could start from scratch and just get the roof insulated to turn the attic into conditioned space. ah well.
Next job though is to put the baffles in at the girls' bedroom end and then rake/add more insulation. I might do as Pulaski suggested and do a mix of things. It would work if I raked out the blown in to cover over the joists and then add the rolled stuff over the top. I would also like to seal up the gap between the drywall and the outer wall - "great stuff pro" seems to be the choice there with possibly caulking some isoboard over the top.

ddsrph

You are right about the vapor barrier. Its not a big deal in the attic. A few years ago some codes departments mandated plastic sheeting for vapor barriers through out new houses. This turned out to be a disaster as they tended to trap moisture in the walls and ceiling. In your case I would consider smoothing the blown in stuff flush with top of joist, even it it meant buying more, then placing unfaced, R19 fiberglass batts on top. You could cut a piece of plywood to use as a walk board for support as you lay down the batts. Once that was done inspect the duct work, probably mostly the silver flexible type, for leaks and maybe cover it with more batts. It is probably only R5 and makes both heating and cooling inefficient. On the R19 determine how much you need for whole house, price at Lowes and HD, then call some large insulation contractors and get a quote for the material only. I got some much cheaper than Lowes or HD that way.

anotherlimey

Turns out the insulation is non-existent in a corner of the house that gets the most sun.

anotherlimey

Anyone used spray insulation? I have some vertical walls in the attic to do and spray foam looks easier than batts.

ddsrph

It's very expensive and messy. You can find several videos on Utube of how to do it with kits you can buy. When I was insulating my new house project I bought a large quantity of polyiso insulation boards that came off a commercial re-roofing job.
They were 2 1/2 inch thick 4 by 8 feet R-15. I paid $4 per board versus the new cost of up to 10 times that. Very labor intensive, but they cut very smooth on a table saw. This is the same stuff as the spray, just in sheet form. I bought too much, and resold a lot of it but saved enough to do my 2 by 6 framed detached garage, that I will be building this spring. It will have R30 walls. I want it well insulated, as I will be installing one of those thru the wall heat pumps like you see in motel rooms.

RICH

My lines are closer to 50ft than 15ft, but when it comes to complete replacement, a redesign might be in order. The blower is nowhere near central in the building, and the outside unit is on the opposite side, but near the electrical panel. When I moved in I ran a new electric cable from the blower to the panel more or less following the refrigerant lines. Quite challenging as the roof is only about 3 foot above the attic floor at the apex.

Had a peek inside the inside unit when the guy was here, and I would definitely have a go at the the install, except for the fact it would take me a week and will no doubt be the middle of summer when needed!

Still, good to know it is in the $3-5k region and not $10-20k as I feared.

Thanks all. Of course the last few days were practically frosty in Tampa Bay so it all feels a bit moot

ddsrph

Rich
In the meantime check out diy-chatroom website. There is a section on HVAC and you can learn a lot from the many pros and knowledgeable homeowners, engineers who frequent the site. I used the site a lot as I was building my new house.
Is it possible to post photos on BE from my ipad? I can post to my email and many websites but not to BE. I have tried photobucket to store photos for posting and can't even make that work.

anotherlimey

Is there a good way to attach batt insulation to a wall if there's no studs to staple it to?

I have a wall in the attic, the end of a vaulted ceiling, but the wall is plywood with a steel frame.

Pulaski

Not that I know of, anything is going to be a fudge. You could put eyes in the plywood at intervals and tie it in place, but that would certainly leave gaps, or drape part of the batt over the vaulted ceiling, and leave part hanging over the end - maybe then drape another batt laterally over the ends on the vaulted ceiling to hold the pieces in place.

Nutek

We used to use these self-adhesive spikes when I was in the trade (many years ago, so might be something better now but they worked ok.).

Asg123

A guy at the diy store gave me a 3M spray adhesive can and I sprayed and pressed and it stuck.

ddsrph

Rich
I would look into mini split heat pump units. They use no duct work, but a outside compressor feeding one to four small air handler units that hang on wall near ceiling. They are very efficient units plus you have the advantage of no duct work in a hot attic. The Japanese units are probably the best. As I understand it the refrigerant lines have screw type fittings for easy installation. There is much info available on Internet about sizing and installation.