Attic insulation

G-rott

The weight of is not going t be a problem unless you have added a layer of drywall or somthing. In my opinion FG is a waste of money and time. Better than nothing but not an effective air barrier. Cellulose could be installed over glass but the FG can still allow air movement, and leakage.

Garett

ralman

Attic insulation

I have been reading a lot of information about insulation and it is hard to determine what is the best way to go. I currently have 2 layers of very old R-11 fiberglass batts with kraft paper on both sides of each batt. The batts are laid perpendicular to each other. My attic trusses are 2X4 with 24" spacing. The concern of the batts with kraft paper on both sides leads me to believe that they should be removed due to the possibility of trapped moisture within the fiberglass. I have had some estimates done and nobody wants to remove the fiberglass and put cellulose down. They all would like to blow fiberglass over the current insulation. I am not thinking this is the best solution. The blow in fiberglass is a lighter product but doesn't insulate as well. I can't see blowing the cellulose or fiberglass over the existing batts as a good idea either. I have been trying to determine how deep I could blow cellulose between the trusses before weight of the product would become an issue. I sent an email to the manufacturer about that and never received a reply. I also searched manufacturers website but could not find an answer there either. I had read somewhere that there is a limit on how deep the cellulose can be, but I can't find the link anymore. I would appreciate comments/advice from anyone who has used either product pros and cons. Thank you.

Ken Field

Insulation

I don't have all the answers you are looking for but in my opinion, removing old insulation and installing stabilized cellulose is the best way to go. Look on www.applegateinsulation.com for your answers and if you have to call them I think you will be surprised at how helpful they are.

Ken

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joel_19

insulation

Icynene foam best yet

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mel rowe

I agree with JoelB. Removed all my layers of fiberglass, that were a mess, and had a thick layer of icynene foam sprayed in. According to the company, more heat is lost "through the openings" than through the insulation itself. I'd check the foam out first. In my old house, there was no insulation in the walls, so also had foam sprayed in to fill the walls. Big difference. Also had Icynene sprayed all around the joists just above the basement wall, which is a big heat loss area.

Unknown

Say Mel,,,,,,,,,,,,

insulation is something I haven`t thought about in a long-while. Call me "dumb" about this, but I didn`t think you could spray foam into the wall cavities?

ralman

Curious

How thick is the attic foam? Did you put another type of insulation over that? I can't get any companies in my area to do foam. But I have looked at tiger foam and fomo foam do it yourself kits. Expensive when compared to cellulose.

ralman

Thank you.

I had checked their site as well as the Cocoon brand site. I really haven't found information on how much weight my ceiling will hold. The instructions generally state to find how much the recommended R value is for your area, then install the appropriate thickness for that R value. I don't see any cautions about weight on the ceiling in their instructions. I am hearing impaired so I tried to email them. I think your advice to call will be my best solution.

Rob_32

weight limit

There is a weight consideration with cellulose. I just checked my reference book, however, and couldn't find it. Keep looking and asking around. 2x4s might be an issue depending on spacing and ceiling assembly. I'll post back if I find the weight stuff.

mel rowe

Here is a site about icynene foam. http://www.icynene.com/ I chose to use it because I was convinced that it would provide better insulation in the attic. For the walls, a slightly different formulation is used, that does not expand. This prevents creating pressure on the interior walls when spraying into the wall cavity. To fill the wall cavity, holes are drilled into the mortar joints for a brick house, and afterward the hole is filled with mortar. I had to look very hard to find the holes afterward. Of course this is the same if you use cellulose. In the attic, the Icynene is sprayed on the surface, and it expands like crazy, up to a 6-8 in. layer that is tough, non-flammable and solid, which is better for insulation properties. It is a bit more expensive, but I thought it was worthwhile, and I have been very happy with the results.

Unknown

Thanks Mel,,,,,,,,,,,

and that "was" my next question, as I did not know you could get foam that didn`t expand, I thought it was like the stuff sprayed around windows. I`ll check that out! I have this stuff that looks like "rock-wool" they blew into the upstairs of my house in the early 70`s, the upstairs was an addition in the 50`s so it`s all "cross-blocked" on an angle as they used "black-joe" for outer sheathing, and I know they missed alot of cavities. I don`t really want to get-into taking the siding-off if I can help-it! I`m sure what`s there has "settled" alot too, in your opinion, what could a guy use to top this up, or will I have to remove the siding? Thanks Again!

mel rowe

Not sure Dave, as it's not real clear to me what you're dealing with. I do know that some of my wall cavities had some old rock wool type of material. They just filled all the spaces between joists, with the foam. I guess it just encompasses whatever is in there and fills the cavity. Regarding your siding, they need a way to insert a nozzle of about 1 1/2 inches into the cavity, and also a vent hole at the upper part. I know in some cases where they are doing through siding, they drill holes and afterward, fill the holes with same size disc. Probably not very aesthetic, so might have to find some way for them to get under the siding, with partial removal as final option. This all might be a waste unless there is someone in your area who does foam insulation, so I suggest you find out about that first and then you could investigate more.

mel rowe

Sorry, I should have said spaces between the studs, not joists.

D107

what city/state are you in?

HO here who's recently had blown in cellulose from outside. Only a few clapboards are temporarily removed, usually 2 per side of the house, one fairly low, the other about 2/3 way up. They they then drill 2" holes through the sheathing in between the studs and pump up then down until full, then plug the holes with styrofoam or other disks. Sometimes if there are firestops that prevent full fill, they have to remove a third clapboard in between the other two. They then caulk the place near the building corners where they'd cut the clapboards and you'd never know they were cut in the first place. If you already have partial insulation there it could get tricky--you'd have to count the number of bags of cellulose they used to know how much they chould charge you.
(See attached photos.) Before the job I would buy and install the thin soft foam gaskets for any electrical outlets or switches to stop the dust from coming inside--which it will. Plug up areas around the plumbing or rad piping as well.

Foam insulaton around windows is usually slow expanding; I'd personally be wary of pumping in fast-expanding icynene foam into old walls. I plan to do that under my attic eaves and gable walls which are open and leave room for the foam to expand and can then be sawed level if you want.

David

ralman

Do it yourself foam if no contractors in your area.

Available in slow rise pour formula for wall cavities and fast rise spray for open cavities. Expensive but you could order one kit at a time. I have not used either product, but I am considering it. You could do just a kit at a time so the cost could be spread out. http://www.tigerfoam.com/index.php
http://www.fomofoam.com/

Constantin

Neat!

Looks like your energy bills are going be taking a beating as the cellulose and the new exterior sheathing tighten up your pretty house!

As you know, I am a fan of foam insulation. We used closed-cell and open-cell foam in our house and I'm very happy that we removed the little fiberglass we had and replaced it with foam. However, we did not attempt any closed-cavity filling... we had open studs throughout.

One company out of NH not only fills closed cavities with open cell foam (icynene, et. al.) using thermal cameras for feedback, they can even fill them with the allegedly far more tricky closed-cell foam varieties like Corbond that exert greater expansive forces.

D107

Constantin did you ever calc extra fuel costs for

partially heating unvented attic? Perhaps Ross might also be interested in this. If I recall you have an unvented attic and you insulated under eaves and gable walls with icynene? Usually --for vented roofs--the advice is insulate the attic floor (as discussed in this thread) but if you make the attic a partially conditioned space there must be some fuel cost associated with keeping the strongest insulation under attic roof. (well worth it for many reasons but a cost nonetheless.)

Thanks,

David

ralman

Nice photo, thanks.

Just exactly how did they get the board off? My siding is similar. I tried pushing some shims up from the bottom of a board, but I think the board is going to split. I was thinking, try to shim it out again, and sawzall the nails. My house is single story, so I need a board removed under the windows. I plan on catching above the windows by removing the soffit boards. The soffit board came off fairly easy with no splitting. The estimators that I had come by the house refuse to remove any siding or the soffit. I tried to get some companies to remove all the current siding, blow cellulose in the walls, put rigid foam over the plywood sheathing, Tyvek, and reside with Vinyl. Nobody will do that either. They insist that the foam backing on the vinyl is plenty of insulation and they can put it over the existing wood siding.

T_2

Everyone seems to like icyene however I habe been told airkrete is superior any thoughts?

D107

all by sawzall.....

First they make a vertical cut where the end of the clapboard meets the corner, then sawzall the nails of the board being removed AND I THINK the one above it. After they use a nail gun to put it back up. They don't shim it, they just push the blade up a little into the crack between the clapboards.

Don't know where you're located but through some of the web sites mentioned on this thread you might find a contractor near you. No need to remove the siding to put vinyl on, rigid insulation goes right over it and the old siding gives you some slight additional insulation.

But if these guys are telling you that 3/4" of rigid insulation is enough that's just wishful thinking. I'm having siding put on next month--regret covering up the old wood but repainting costs here are prohibitive. The 3/4" will cut back on infiltration a bit but the R13 from the cellulose is very important.

Also we will not be using Tyvek since sheathing already has old black paper on top of it. There is always the possibility of unwanted condensation under the 3/4 insulation but we had it looked at and decided, given some examples from the book 'Cold Climates' by Building Science, that the risk was acceptable.

I don't know your skill level but watching the cellulose guys work I would never attempt to do it myself. There is an art to getting that nozzle just in the right place to make sure the fibers go as high and low as they can.

Note: for vinyl installation I insisted that my contractor make the nailings into the studs to make vinyl more secure. That's the way the manufacturers give their high wind resistanced ratings. Easier for them to just nail where they like. Rigid insulation though is nailed wherever.

ralman

I'll give the sawzall idea a try.

"But if these guys are telling you that 3/4" of rigid insulation is enough that's just wishful thinking. I'm having siding put on next month--regret covering up the old wood but repainting costs here are prohibitive. The 3/4" will cut back on infiltration a bit but the R13 from the cellulose is very important."

LOL

They are NOT talking 3/4" rigid foam board insulation at all. They have a vinyl siding product which has a rigid foam backing on it already, maybe 1/4" thick. There idea is not the way to go so I will be forced to put on my DIY cap once again. I don't have any experience, but I would rather screw it up trying to do it the correct way than have someone else install it improperly.

My concern with vinyl over the wood with rigid foam board and tyvek wrapping is it will bring the wall out past door and window openings too far. So it won't look right unless their frames are redone.

I was thinking with the wood siding removed, cellulose blown into the wall, and a 1/2" rigid foam board with tyvek wrap I would not have to adjust framing at the doors and windows.

If I can get a row of siding off without causing too much damage. I could at least get the insulation blown in and still have the option to repaint the wood instead of going with vinyl. Thanks for the sawzall clarification, I'll try it out next weekend if it don't rain.

G-rott

\"Non Flamable\"

> Here is a site about icynene foam.

> http://www.icynene.com/ I chose to use it

> because I was convinced that it would provide

> better insulation in the attic. For the walls, a

> slightly different formulation is used, that does

> not expand. This prevents creating pressure on

> the interior walls when spraying into the wall

> cavity. To fill the wall cavity, holes are

> drilled into the mortar joints for a brick house,

> and afterward the hole is filled with mortar. I

> had to look very hard to find the holes

> afterward. Of course this is the same if you use

> cellulose. In the attic, the Icynene is sprayed

> on the surface, and it expands like crazy, up to

> a 6-8 in. layer that is tough, non-flammable and

> solid, which is better for insulation properties.

> It is a bit more expensive, but I thought it was

> worthwhile, and I have been very happy with the

> results.

G-rott

Who's smokin' what...Non Flamable???

Rated for flame spread...Yes

Rated class 1 for Smoke Production...Yes

Non Flamable .... Burns Like Crazy if flame is present.

In many applications it must be covered by a fire barrier for jus this reason.

G-rott

FG removal and side wall insulation

FG remaval is a mess any time and many contractors will try to avoid it. We would remove all of it but it does cost. Then install Cellulose after all penetrations into the attic are sealed with spray foam.

The sawsall trick usualy works, we use the thicker remodel style blades as they jam up under the siding better.

Goog luck with your project.

PS where are you..we are in zone 6 and use an R-44 min. with cellulose

ralman

South central pennsylvania

I am not sure of the zone number without looking for the chart. R49 is recommended in attic according to the chart. R38 is the local code recommendation. I think it is going to be too much weight to go that deep. Maybe remove what I have, seal the penetrations with canned spray foam, spread cellulose even with the truss chords, then cover that with rolls of unfaced R25 fiberglass. Maybe I should screw 1X3 to the truss chords to give a little more depth, and still be able to lay boards across chords in case of having to repair anything like exhaust fans later on down the road. Any ideas about that?

Constantin

Hi David!

Nice to hear from you.

The attic is quite small - 2nd Empire Mansard roofs are quite shallow so the surface area difference between the attic floor area and the 3/12 roof is pretty small. IMO, the real benefit became evident two weeks ago... I had a blower door test done and the house came out to 0.20ACH.

For retrofit jobs, it may be easier to insulate between the rafters of the roof deck than pulling up the floor boards to get good access to the void below. But it depends on the house, the local code (which may still forbid unvented roofs), and the local contractors.

Constantin

Airkrete has a couple of things going for it.

IIRC, it's pretty darn fire resistant. Polyurethane foams can be made fire retardant but once they go, they GO! Dense-pack cellulose that was bromide-treated is very fire restant too though.

ralman

2nd Empire Mansard roofs

I had to google that one to figure out what it was. A nice looking architectural style. The foam insulation and sealing work you mentioned in the earlier posts must be working well to get that 0.20ACH. I'll bet it is saving a lot of energy and reducing your bills.

Ron Schroeder

Hi Ross,

What's best depends on how you define "best". Your highest R value for the least amount of money would be to blow cellulose over the existing insulation. You will NOT have a problem with the two layers of craft paper. Unless all of the edges are taped together it is a totally ineffective vapor barrier. As far as maximum thickness, it depends on the direction of grain of the drywall on the ceiling and the drywall thickness. On my house, I have about R70 cellulose over 5/8" drywall attached to 24" o.c. trusses with the drywall grain running 90 degrees to the trusses.

Seal up all penetrations into the attic before you blow in the cellulose.

If you have the money for an expensive retrofit, you could blow foam on the top of the drywall and the bottom cord of the trusses to act as a vapor barrier and then either blow more foam over that or blow enough cellulose over the foam to get the R value that you want.

Reusing the old insulation as part of the total system is usually not a problem as long as you fill the gaps with cellulose and have at least a few inches of cellulose as the top layer.

Ron

ralman

R70... WOW

Your house is insulated. I had purchased one bag the other day to bring home and read all the fine print on the package. I just checked the chart on the package(which only goes to R60) and it looks like a minimum of 16" depth with 100 bags per 1000SF of coverage which puts the weight at more than 2 pounds per square foot. Yours would be heavier at R70. Thanks for your input as I was interested in how other ceilings were holding up. I am not real familiar with building techniques. I have a 60 year old ranch home. Everybody in my area says I have plaster walls. There is a 1/2" drywall type board nailed to the studs with a coat of plaster over that. I will have to dig through some fiberglass later to see which direction it is nailed. How do you handle going into the attic too inspect/repair items?

Constantin

Yes...

Approximately a 4x reduction in heat loss per square foot between the pre- and post-gut stage. Never mind the increase in comfort as drafts stay outside. It's pretty impressive to sit indoors and watch snow going horizontal outside as a blizzard does its thing and not feel a draft or even a tinge of cold.

The main thing with foams or thick layes of insulation is that they become so efficient that thermal telegraphing via the studs becomes a major problem. Mooney walls and the like are an answer, but they are rare.

If zero energy homes become widespread, I imagine that they'll use a lot of mass on the inside, thick insulation on the outside, and careful architectual & infrastructure features to minimize the need to heat or cool.

Ron Schroeder

The walls are R40. Some are Icynene and some are dense pack cellulose. Insulation is cheaper than oil.

My attic access is external, no hatch thru the ceiling for air leaks.

Ron

ralman

Hello Ron.

Sounds like a well insulated home. Great idea about your entrance. With your attic insulation being so deep, do you have some type of platform above the cellulose to walk on? If so, please explain how that is done, Google isn't helping me with that one. I have 2x4 trusses. I want cellulose insulation. I also want to be able to service/replace exhaust fans and inspect roof for leaks. Any options for me?

Rob_35

IAQ?

Neat insulation. Curious. What do you do for IAQ?

D107

Some people build a raised floor above the cellulose

That's one way if you have the headroom. If I really didn't want to raise my floor and needed attic access that a pile of cellulose wouldn't allow, I'd probably take out existing de-rated fiberglass under attic floor and have pros pack under floor space with dense cellulose or polyicinene foam. For cellulose Perhaps lifting floor boards could be avoided by having 2" holes drilled through the boards and pumping the cellulose in.

just saw a 'ask this old house' where they showed how badly even a modern, 10 yr old home had tremendous heating loss via:

1-under roof eaves where the existing soffit gasket --meant to direct air toward peak--allowed outside air to enter.

2-All around attic entrance door which was uninsulated, especially at perimeter. They used a fabricated inverted insulated box to cover that door from above.

3-Attic pipes, bathroom fans, electrical conduits, etc. in some cases they used a little fiberglass as a base, then put foam to seal then the fiberglass batts over that.

4-Worn main door weatherstripping.

This is a good website to buy certain kinds of weatherstripping, gaskets, etc. http://efi.org/

ralman

Thanks, David for the tips

I am trying to figure out the best method of making a walkway through the center of the attic, the entire length of the home. I would like to keep an eye on roof penetrations for rain water leaks. I just had to replace a bathroom exhaust fan and would like to have that option when it fails again years from now. I have some ideas of how to raise a walkway above the truss chords and was wondering if any one else had already invented this "wheel". I don't need an entire floor, I would just like to be able to have the option of laying some boards across the chords to work on something if necessary. I wasn't sure if I should raise the chord with 2X4 laying on top parallel or perpendicular to the current truss. Or is there another method? Great website tip. My attic access is a mess and needs fixed. I have a dedicated finished entrance with stairs and a poorly remodeled hatch by previous owners. I wanted to move it outside of the heated space for different reasons than Ron Schroeder had mentioned. But his idea would be another good benefit for me to move the access. Thanks!

Ron Schroeder

Hi Ross,

I just spiked some 2x4s up against some of the vertical parts of the trusses to walk along. I will probaly add a 16" wide walkway one of these days (in my spare time------Ha)

Ron