Insulating 85yo attic – need advice
philjohnwilliams
| Posted in Energy, Heating & Insulation on
Hi, I am hoping somebody here can help me out with this.
I have an 85 year old house that is in need of attic insulation. I want to bring the insulation level up to R40 (to make my calculations easier, I assumed that current levels were R0, which judging by my heating bills may not be far from the truth) and have narrowed my choices down to blown in cellulose or fiberglass batts. The cost for the cellulose would be in the area of $400 while the batts are hovering around $1000. Being the budget conscious (cheap) person that I am, I am leaning towards cellulose, but was wondering if anybody out there had any thoughts.
thanks in advance
philjohnwilliams
Replies
philjohnwilliams First to blow in the insulation you need to make sure that the sofit vents have card board or something to keep the insulation from blocking the vents. Thatsaid Iwould put cardboard strips 12in. long stapeled to rafters spaced 6 feet or so apart through out the space so you can guage the depth through out. This will keep it level and avoid over use of insultion.Then starting at you'r furthest piont blow in the insulation at a depth of 16in .Make sure you get around all webbing and other obstructions to get full coverage. All so if you have any can light's you need to cover them with 2in. stirofoam box or otherto protect from fire.Hope this helps Idid min three years ago and have all ready paid for it.Jimbotg
Check out Soythane.com. I am looking into using the product for the first time so I can't speak for the company but I'm going to go with them.
You will be burying lots of electrical and mechanical items.
Mark the electrical junction boxes, j-box positions for ceiling fixtures on the rafters or decking above. Mark pipes, fans, etc. with similar labels.
As mentioned, baffle soffit bays, can lights and fans, extend the scuttle hole sides with plywood.
You will have a need to enter the attic for inspection or service so build an elevated catwalk and entry portal landing to maintain the loft of the cellulose. Once the cellulose is crawled over it is compressed and losses R-value.
I did mine with catwalks 15 years ago and my daughterss rehab this year, plus six or seven other customers through the years.
Some other customers that did not buy the catwalk deal cause "there will be no body up in the attic" have found that eventually some one will crawl through the cellulose.
Cellulose is the best shot you have, better than fiberglass for a number of reasons.
Have some good help on hand, set up good lighting, and wear a good tight fitting dust mask! Don't quit till your done!
...........Iron Helix
philjohncellulose...only R-60 instead of r-40and iron helix had a lot of good pointsMike Hussein Smith Rhode Island : Design / Build / Repair / Restore
Before insulating, seal all openings where pipes, wires, etc. come through the ceiling. They all act as chimneys allowing great quantities of warm air to escape. A couple cans of spray foam will have a tremendous payback not only in energy savings, but those leaks once covered with insulation can lead to condensation which will ruin the insulation and lead to rot and mold.
PHILJOHN,
Make sure you split your attic up into equal spaces and use the speced number of bags per section.It is real easy to over fill when you are just guessing, then you end up short on the other end.
Moe
For me experience with cellulose is that it settles to much myself i would go with the batts maybe more expensive but in the long run it may be worth it ......What size are your joists or rafters? dont forget to leave airspace to the roof for ventilation 12" bats are R38.....Chris.....
Edited 1/4/2009 12:26 pm ET by C_Evensen
chris.....what does settle too much mean ?
the r-value for attics is based on settled density....1.4 lb/cf.....
if you watch your bag ( bale ) count, you know just what r-value you are getting
if you use batts.... how do you figure your r-value ?
Mike Hussein Smith Rhode Island : Design / Build / Repair / Restore
phil
Everyone has made good points.
Also look for open stud cavities, from interior and exterior walls, that are open to the attic. I am assuming you have some form of insulation in place, rockwool batts?
where you have an interior wall pull that insulation back and look for openings. These are huge air leaks.
Seal with styrofoam and expanding foam.
I like the catwalk idea, and I have done that too.
I would use cellulose, you get a more complete blanket of insulation and it is easier.
Order 10-15 extra bags, it won't break the bank.
Rich
if those are the only two choices, the cellulose wins, hands down
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A great big thanks to all who have taken the time to reply. I think i am going to go with the cellulose, but will follow the suggestion of building catwalks, as well as marking the location of junction boxes. A few minutes spent doing this will undoubtedly save me a lot of time in the future.
A question I have for those who have done this is how big is the blower for the insulation? I seem to recall years ago seeing a professional blowing insulation years ago (I don't know if it was cellulose or something else) and the blower unit took up most of a mid sized cube truck. Is the thing I'll be renting this big or are the units more portable?
thanks again
philjohnwilliams
for open blow.... the rental machines are relatively smallMike Hussein Smith Rhode Island : Design / Build / Repair / Restore
Glad to hear it.
-philjohnwilliams
85 yr old house...Is this a balloon-framed house where the wall bays are open to the attic? If so you need to deal with that before blowing, or all will be for naught, as you will still lose tons of heat through those open wall bays.And the air sealing of everything else is critical too. But cellulose is the way to go. Just make sure you take care of all the other issues first. You don't want to have to wade back into it after you've done it.Steve
Is this a balloon-framed house where the wall bays are open to the attic?
From what I have seen the wall bays seem to have been blocked off in some previous attempt at insulating. If I can open them, could i blow insulation in there as well?
-philjohnwilliams
I have a similar problem. Not just the stud bays, but I have big voids like this one above a closet. You can see all the open lath and interesting ventilation paths. Are there any good ways to deal with these? I've been putting sheetrock panels across the big ones.
For holes upto 1-2" you can used canned foam.For larger areas you can get foam sheets (blue board/pink board) and cut to fit and then seal with the canned foam..
William the Geezer, the sequel to Billy the Kid - Shoe
Here are an interest series of video's.http://www.taunton.com/finehomebuilding/video/how-to/home-energy-audit-overview.aspxI have not been through all o them yet.This is blowing an attic with chopped FG using a machine and material
from the home horror stores (don't remember which).http://www.taunton.com/finehomebuilding/videos/index.aspx?id=102792&c=1Just note the warning at the very end..
William the Geezer, the sequel to Billy the Kid - Shoe
>>could i blow insulation in there as well?<<If you can get to them easily enough to work a hose down them, that would be great. They are usually under a pretty shallow pitch and it can be a pretty hard on your scalp scraping it on the roofing nails over and over again. If you can access them from the attic, you would want to dense-pack the walls, which is a specific technique for gettin gthe cellulose in at a high enough density that it effectively stops any air movement through the insulation or settling. Do a search here under "dense-pack" or cellulose.Steve
FHB or JLC didan article recently about the downsides of using modern insulation and sealing techniques with old housing. The problem they noted was that while these old house were drafty, this draftyness kept down the interior moisture too. The article noted that several houses that had stood for centuries were destroyed by rot after being updated.
I don'thave an answer for you, just that note of caution. Other brighter bulbs here might hopefully chip in better info for you on this matter.
Tu stultus es
Rebuilding my home in Cypress, CA
Also a CRX fanatic!
Look, just send me to my drawer. This whole talking-to-you thing is like double punishment.
>>FHB or JLC didan article<<Got a reference? I don't remember seeing that.As with any house that you are trying to seal up, you've got to have the moisture in the house under control. An older house that has too much moisture will hold up better than a new one under the same conditions. The wood in newer houses is garbage compared to older wood. But yes, you do need to address any moisture issues you may have.Steve
Edited 1/6/2009 7:12 am by mmoogie