Attic Insulation Question

AdamZ

AdamZ

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Adam Zucker
Anyone know anything about insulation ( as in the attic kind)? My house was built in the 60's prior to any real concern regarding engergy efficiency. My attic is insulated but very poorly. It is not a truss system so you can walk the legnth of the attic as long as you step on the floor joists, If you miss one leg will be thru the drywall and hanging in the ceiling of the second floor LOL.

I'd like to floor the attic but need to insulate it property. the joist are 2x6s so I only have 5 1/2 inches to fill with insulation. Right now I have a combination of R-19 Batts, R ( Lord knows what batts that are compressed old and thin), some blown insulation that dosen't even fill the space between the joists and insulation blankets that are about a half inch thick with a foil type backing.

So my question is, what do I put in there? Batts and what R value can I get for that size? Blown insulation or something like urea foam if they still do that. Or something else. Keep in mind I'd like to floor some of it. It will never be living space only storage.
 
I looked at a product 2 years ago that was a thin foil like material. Still considering it. Supposedly it reflect heat in summer and insulates warmth in winter. Can't recall the name of the company marketing it, but I'm sure they'll call me in a month or 2.
 
What is the floor going to be used for? Heated living space? Cold storage?

Spray foam is expensive, and can cause off gassing issues (health problems) :eek:

A 2x6 cavity will yield R19 with fiberglass if you only go to the top of the joists. :nono:

You could add 2x4's to the top of the joists to get more insulation (and your floor) and yield roughly R35. That is where you want to be. :yes:

I just built a house with R50 in the attic.
 
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I think the best bet would be to remove the old stuff you have..., and then have pros come in. I expect that if you're going to put down a floor up there that the insulation choice and need for a vapor barrier will be different than if you were just trying to fill the voids and leave the joists exposed.

You should be able to get some good insulation even in only 5 inches of void space to fill, but if not done right you'll end up trapping moisture and probably wrecking the ceiling beneath the attic.
 
In that case your floor will probably just be plywood... I just don't know the proper technique to get the seal you want.
 
AdamZ said:
Larry as per my last sentence its only going to be for storage, Boxes and such would never be living space.
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Do you need the whole floor covered? Or just part of it?

Like Tim said, trapping moisture is a HUGE no no. :nono:
 
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I had a situation almost exactly like yours two houses ago. What I did was:

1) fill the space between the joists with fiberglass batts up to the top of the joists. Do not cram extra insulation in there, as squished batts do not have the same R value as "relaxed" batts.

1a) Be careful laying the batts out near the eaves. Many homes have vents in the eaves and you must allow an air path from the eaves into the air in the attic.

2) I wanted a lot more insulation than that. I carried up what seems like a sqadrillion 2x8's and put them on edge perpendicular to the original joists. Then laid in more insulation. All the insulation so far was unfaced.

3) a layer of Tyvek to make it more or less airtight.

4) plywood. As all of it had to be dragged up the internal stairs to the attic, I cut the plywood into 2x8 sheets and then used that for the flooring.

5) Build an insulated box to cover over the hole in the floor where the attic stairs were.

It worked well.

-Skip
 
TMetzinger said:
In that case your floor will probably just be plywood... I just don't know the proper technique to get the seal you want.
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Yup plywood is the plan.

Geico266 said:
Do you need the whole floor covered? Or just part of it?

Like Tim said, trapping moisture is a HUGE no no. :nono:
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Great question Larry, No I likely don't need the whole attic floored and certainly not the portions close to the soffits as you would never fit there unless you crawled. Even in the portion where you can walk I don't think I need the entire thing floored, that would be a lot of space.

Also Just to confirm the vapor barrier goes toward the inside of the house correct? thats the way it is now.
 
Some considerations (in no particular order)

Make sure there is adequate air circulation/ventilation in the attic, especially the eaves. This will be very helpful in preventing ice dams.

It is my understanding that the vapor barrier must be between the living space and the insulation.

http://www.thisoldhouse.com/toh/video/0,,20051865,00.html
 
Bob Noel said:
Some considerations (in no particular order)

Make sure there is adequate air circulation/ventilation in the attic, especially the eaves. This will be very helpful in preventing ice dams.

It is my understanding that the vapor barrier must be between the living space and the insulation.

http://www.thisoldhouse.com/toh/video/0,,20051865,00.html
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Its even more important in preventing moisture from accumulating inside the attic space, condensing, and leading to mold formation. Must have unimpeded circulation from the eaves to the roof vents.
 
Doggtyred said:
Its even more important in preventing moisture from accumulating inside the attic space, condensing, and leading to mold formation. Must have unimpeded circulation from the eaves to the roof vents.
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Currently I have two gable vents, soffit vents and a mid roof exhaust fan. I will be getting a new roof and closing up the gable vents and removing the exhaust fan and putting in a ridge vent. I do have to spend some time on my belly pulling back some of the batts from covering up the soffit vents.
 
AdamZ said:
Currently I have two gable vents, soffit vents and a mid roof exhaust fan. I will be getting a new roof and closing up the gable vents and removing the exhaust fan and putting in a ridge vent. I do have to spend some time on my belly pulling back some of the batts from covering up the soffit vents.
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Geico...... That attic is breathing better then most.....
 
adam,

check your pm. i have a spray foam insulation company. i deal with these issues daily. gotta help a fellow lawyer out :)
 
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N801BH said:
Geico...... That attic is breathing better then most.....
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Yes, but several posts ago he was talking about covering the attic with plywood. If the attic is well ventilated and only a portion of the floor is plywood it will be able to breath under the plywood.

Add 12" of blow in insulation in the areas without a floor. Go green! :lol:
 
iRyan said:
adam,

check your pm. i have a spray foam insulation company. i deal with these issues daily. gotta help a fellow lawyer out :)
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Adam...... Take him up on the foam option..:yes::yes:..

It is, without a doubt, the hot set up...:rolleyes:
 
N801BH said:
Adam...... Take him up on the foam option..:yes::yes:..

It is, without a doubt, the hot set up...:rolleyes:
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now my boss cant get mad when I check the boards at work! :D
 
N801BH said:
Geico...... That attic is breathing better then most.....
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Ben believe it or not it does not breath as well as it should as the soffit vents are extremely small and much is blocked with insulation and the attic fan only goes on when it gets extremely hot. All the roofers have told me that the gable vents do squat and to move ral air you need soffit vents and a ridge vent. I actually do see some signs of condensation.

The foam is intriguing. I hear with the foam you actually want no ventilation.
 
I own a Foam Insulation company so I might be slightly biased.

however, if you are going to own this house more than 5 years it is safe to say that you should/could justify the extra expense of using spray foam insulation.

If you are going to sell it within 5 years or less then the next best option would be to have it professionally winterized (gaps sealed) and blow in Cellulose insulation (paper). It is about 3.6 R value per inch so 5.5" is about R20 or so.

There are two types of spray foam Open cell R 3.81 per inch and Closed cell R 6.5 per inch. So you can get an R33-34 in the same 5.5" cavity. However closed cell foam is more than double the cost of open cell. So I would spray open cell and just fill over the joist or I would do what is called a sealed attic and spray the roof underpayment.

I just did my retirement house remodel job with Open cell and it cost about $6000-6500 vs about $2200 to have it done in Cellulose.

IMO foam is the absolute best insulation there is. 30% of heat transfer occurs between cracks, holes in the walls for plumbing, electrical outlets which all get sealed with either type of spray in foam.

IMO fiberglass is the absolute worst insulation if you get more than 10 mph winds often. This is due ot the way insulation are measured for R value. When wind blows your fiberglass becomes a nice filter that is why you will see dark spots on fiberglass installed for more than a year. Air goes through it. If air goes through then so does moisture and heat gain or heat loss which ever you are trying to stop.

PM me for any questions. I am in Kansas so probably too far to help you in PA but I am glad to be an some what objective voice.

So let me rephrase it. If you have an equal R value total between Fiberglass, Cellulose and Foam then Fiberglass performs the worst, cellulose is much better and Foam is much much better. Cellulose is the cheapest to have done or do yourself and it is simple but dirty job. Fiberglass is a PITA if you ever had those glass strands on your skin, don't do it any of it without ventilators and eye/skin protection.

Spray foam can be done with Kits DIY but it is cheaper to do most jobs and the performance better if you hire a certified pro. Every manufacturer who sells the chemicals for spray foam requires proof of performance of the installer so it should not be hard to verify if a guy is capable of doing a quality job even if your local gov doesn't require licensing.

Other nice to know facts: 60% of controllable heat loss/gain is through the roof so that is best bang for buck when starting. Second 20% is through the walls but once the walls are finished it is difficult but you can do spray in foam into the walls. Third but 2nd easiest to do is Floor Joist rim joints where the walls meet the foundation or basement walls are normally not insulated in existing homes. You can save 20% doing this small area. it is usually the perimeter of your home x 1.5' so doesn't take much to cover it/ fix it.

Another advantage to using foam is you get the R value quoted but it cuts wind drafts down 100% which saves another 30% over any other insulation rated for the same R value. This is very helpful if you have an old inefficient heater/air conditioner so it can buy you some time before needed HVAC upgrades.
 
iRyan said:
adam,

check your pm. i have a spray foam insulation company. i deal with these issues daily. gotta help a fellow lawyer out :)
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Yay! An expert.

And for Greg, I was recommending pulling the old stuff out because replacing it with newer tech would give better results than just putting additional stuff in - as I read it he had a mishmash of insulation in there already.
 
Adam, I totally agree with Tony...polyurethane foam is the best insulation you can get - it's worth every penny.

If your roof / attic is properly ventilated ( and it should because it really helps keeping temperature under control during the summer ) then the polyurethane vapors shouldn't be a problem ( it's not like you're going to sleep in the attic....)

I insulated my roof with polyurethane foam 10 years ago and I highly recommend it...it made a HUGE difference for us....

My neighbor "insulated" his roof with a layer of pvc bubble wrap covered with aluminum foil ...total crap and way less efficient...
 
A radiant barrier (which you really want as close to the roof surface as possible) can help, but it's NOT a substitute for insulation. There was a company marketing a blow in radiant barrier that they made wild claims unsubstantiated by physics (mostly they point out that spacesuits have no insulation, just a radiant barrier, but of course our houses aren't surrounded by a vacuum).

I will tell you that spray foam is absolutely amazing. Even with the same spec R value, there are NO gaps in the foaming. I've got more R-value in my house in virginia (3 1/2" of the original blown in insulation from the builder plus another 12" of batts) and I can tell you it isn't anywhere as near as comfortable as my house in NC which is spray foamed throughout. About the only stupid thing is that the roofer put in a ridge vent which is completely foamed shut now. The "attic" area is inside the insulated envelope.

It took me a while to figure out why in the summer my Hangar was nice and cool (it's heated but not air conditioned) and the garages were beastly hot. I originally wondered if it was because the hangar sits 6' deeper into the hillside but then I remembered I'd sprayfoamed the hangar and not the garage. In retrospect, I'd have done the garage as well.
 
Armageddon Aviator said:
Adam, I totally agree with Tony...polyurethane foam is the best insulation you can get - it's worth every penny.

If your roof / attic is properly ventilated ( and it should because it really helps keeping temperature under control during the summer ) then the polyurethane vapors shouldn't be a problem ( it's not like you're going to sleep in the attic....)

I insulated my roof with polyurethane foam 10 years ago and I highly recommend it...it made a HUGE difference for us....

My neighbor "insulated" his roof with a layer of pvc bubble wrap covered with aluminum foil ...total crap and way less efficient...
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Well I thought WE'D take on this project the next time you come to visit LOL.

Seriously the foam is intriguing. Although from what I understand if you spray the roof ( rafters etc) you spray over all vents to seal it up and make it "airtight" from the outside anyway. Tony , Ryan am I correct?
 
yes that is correct
 
I also believe foam insulation is the best you can get on the market. It's also VERY expensive for the good stuff (closed cell). One of the biggest benefits of foam is it's ability of stop air infiltration in addition to insulation. If you have the money and a house that can support that kind of expense then by all means.

If you're not sure that you want to spend that kind of money there are some alternatives. For example have the old insulation taken out, not a big deal. Have an inch of foam sprayed (joists not rafters). Then have a bunch of blown in insulation installed and get the same effect for much less.

Last instead of getting wrapped up in just insulation, start with the basics. For example can lights are usually the worst energy wasters. Punching a bunch of holes in your ceiling and pushing a metal can up through the insulation was a bad idea from the start. Many of the older ones are not IC (insulation covered) rated so when you go in the attic you will see pits in the insulation around each can. I retrofit IC rated cans, use 1.5" insulation board cut up to make a box over the can, then spray foam 1" over/around the box, topped by blown in insulation. This is a huge improvement.

Also, check the other obvious places like windows and doors.
 
Airtight cans (in addition to being IC and sealed up they also have rubber gaskets around the trim) can do a bit better than most recessed lights, but you are right, any punctures in the envelope can leak a lot, which is why the spray foam is such a big win.
 
My opinion, backed up by my builder's opinion, is that you would be better off if you could insulate the attic ceiling. leave whatever insulation you have on the floor and plywood over it for a floor. That would give you a more temperature controlled attic and reduce the temperature variance at floor level. This works even better if you have heating or cooling ducts running through your attic.
 
JOhnH said:
My opinion, backed up by my builder's opinion, is that you would be better off if you could insulate the attic ceiling. leave whatever insulation you have on the floor and plywood over it for a floor. That would give you a more temperature controlled attic and reduce the temperature variance at floor level. This works even better if you have heating or cooling ducts running through your attic.
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Ive heard that as well.
 
AdamZ said:
Ive heard that as well.
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More often than not we leave the old insulation in the floor. A trick (well, not a trick really) that we use when we are training a new sprayer is filling the floor bays with the excess foam that is cut off (if it's the open-cell).

If you get me the measurements, I will give you a quote for both foams. The popularity is growing so much, back 40 years ago when my dad started the company, he was the only one in the NE USA. Now there are over 25 just in our main office's area.
 
Would POA mgt. mind if I printed this thread and gave it to my salesmen and potential customers? I am only joking!
 
iRyan said:
More often than not we leave the old insulation in the floor. A trick (well, not a trick really) that we use when we are training a new sprayer is filling the floor bays with the excess foam that is cut off (if it's the open-cell).

If you get me the measurements, I will give you a quote for both foams. The popularity is growing so much, back 40 years ago when my dad started the company, he was the only one in the NE USA. Now there are over 25 just in our main office's area.
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You top the old insulation with closed cell?
 
No, if we are spraying open-cell in the rafters, and we have a new sprayer who applies too much material, they will put the shavings in the floor bays (if the homeowner wants).
 
iRyan said:
No, if we are spraying open-cell in the rafters, and we have a new sprayer who applies too much material, they will put the shavings in the floor bays (if the homeowner wants).
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OK, good deal. Now of course if you're using comp. roofing then the manufacturer will deny any warranty on an insulated roof. It never ends.
 
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