Recently moved into a 90+ year old house, in central KS, and found NO insulation in the small (16×14) attic directly over the master bedroom–though insulation was obviously blown into the walls of the house many years ago!?
I’ve purchased bags of cellulose but am not sure of exactly how, or if I need to, ventilate the attic. It presently has no ventilation and no interior evidence of any moisture problems (maybe plenty of inadvertant ventilation?). Do I need to put in soffit vents plus ridge vent–or maybe gable vent in place of current window? I have some of the styrofoam Durovents to put between the rafters, but am not sure how to get air INTO them, from the soffits (see pic).
And of course, the $64,000 question–what about a vapor barrier between the plaster and lath ceiling and the cellulose?
Many thanks.
Thon
Replies
NOW, I see how to get the pics here. :-)
Your attic looks just like mine (used to).
This summer I had the lath & plaster of a bedroom upstairs in my 1931 house taken off, and even though I know Dad had insulation blown in in the '60s there was almost nothin there.
So.....
Besides the rewiring, I foamed in all the holes in the top plates where the knob & tube go down to their respective switchs and light boxes, insulate with rigid foam and seal the areas under the floor between the joists, and now I'm putting 3/8" plywood over where the K&T wiring runs.
The entire area is being covered with R-40 (suitable for my area, but you will probably want R56) and then the drywall goes on.
Since I'm doing a retro reno, I'm putting 6 mil vapour barrier in and, oh yea, adding 2x4 studs to the 2x3 there now, so that I can get R-28 into the stud cavity.
Next year, the other bedroom upstairs.
Taunton has a couple of good books in weatherizing your home. Go to the library and check them out.Quality repairs for your home.
Aaron the HandymanVancouver, Canada
I love your load- bearing soffit in your attic photo- I just remodeled my 1915 house with the same cantilevered roof- system where the weight of the roof was bearing out in the yard... Sorry- had to throw that in...
Yea, I have no idea how common it is but it sure makes putting in roof/soffit ventilation a pain. Do you have soffit vents?
Thon
I'd say by the dust in that attic and the condition of the wood framing that it's pretty dry most of the time.
Try laying just a blanket of insulation with your cellulose and don't worry about ventilation for the time being.
No sense fixing what ain't broke.
Gabe
Like Arron suggested, it would be a good idea to seal the wire holes in the partition wall top plates, and if there are any ceiling boxes, try caulking a poly box over them, or do something to seal them up as this is where the bulk of your air leakage will occur. These things are going to be a lot easier now than after you put your insulation in. The next area of concern as far as vapor barrier would be the area along the bottom plates of your exterior walls. Trying to put a sheet of poly in now would be a waste of time, since there is no way you could continue it to the walls properly, better to just seal up the lath/plaster to all the envelope penetrations.
If you want to use your styrofoam vents, you could drill some holes through the blocking between the rafters then cut the chutes in half (2 feet long will be plenty) to fit tightly against the wood block so your insulation doesn't plug up your new vent holes. I've done this before with a 2-1/4" holehawg bit on an extention. Also remember that you're going to need to make sure your soffit is ventilated as well, as well as the ridge. This could end up becoming quite a bit of work :) but remember once your insulation is is (especially if you're putting R40 or greater) this would be a lot more work later on.
Edited 10/13/2003 2:18:17 PM ET by SledBC
<you could drill some holes through the blocking between the rafters then cut the chutes in half (2 feet long will be plenty) to fit tightly against the wood block so your insulation doesn't >
I'm guessing you mean drill holes in the 1 x in the picture,that runs horizontally across the ceiling joists? That's going to take a lot of holes, drilled all the way at the back of that 1 x , at quite an angle, right? I wondered if the styrofoam vent could be attached at its top, and then run all the way down to the soffit--on the INSIDE of that 1 x ? Then I'd make cut-outs for grilles, in the soffit, as you suggest.
Any thoughts on cutting in a ridge vent vs replacing the gable end window with a vent?
Thanks for all the replies.
Thon
What would venting achieve? It doesn't look like you have any moisture problems up there now (if that's a representitive photo), so I'd advise not fixing what ain't broke. Venting the roof might add a year or two to the life of the shingles, but probably not. The amortized savings, if any, probably aren't worth the effort. Air seal with expanding foam, upgrade any exposed knob and tube wiring to Romex, and blow in a foot or more of cellulose. Whap, done, warm in the winter, cool in the summer.
Andy Engel, The Former Accidental Moderator
What about in the summer? I haven't run the numbers, but it seems to me you can't help but get less heat in the house if you keep the attic temperatures somewhere down around ambient rather than 160F or whatever hellish temperature you get in an unvented attic.
As I understand it, the dominant heat transfer mechanism in attics is radiation. Ventilation isn't a very effective way to remove radiant heat. Cellulose is mostly opaque to radiant heat transfer, making it quite effective in these circumstances. Having a pile of it in my own attic, I can attest to its summertime effectiveness. And as someone else said, venting an attic can introduce negative pressures that induce conditioned air to leak from the house to the attic, which can actually increase the likelihood of moisture problems along with carrying an energy penalty. Insulate, but don't vent. It's not usually needed, and is a code carryover from about 1947.Andy Engel, The Former Accidental Moderator
Andy,
"As I understand it, the dominant heat transfer mechanism in attics is radiation." Be careful of generalizations. Are you talking about transfer of heat from the conditionded space below to the attic, or the transfer of heat from the bottom of the roof sheathing to the attic? People insulate their attic floors to slow down the transfer of heat from the conditioned space to the attic. In that direction, there isn't much radiation going on, since there is, after all, a ceiling. (If someone leaves the attic hatch open, of course, radiation has a very direct path. But then again, so does convection.) The heat transfer mechanisms that matter are conduction (from the ceiling, the ceiling joists, and from the top of the insulation to some extent), convection (via any unplugged air leaks), and, to a very limited extent, radiation (that is, radiation from the top of any exposed joists and the top layer of insulation). However, if insulation has been installed, the top surface of the insulation shouldn't be very hot, so radiation should not be much of a factor.
Martin Holladay
Good catch Martin, and good to see you here. What I should have said is that the dominant heat transfer method in attics in the summer is radiation. I don't think radiation matters much in attics in the winter. I was assuming summer because the conversation seemed to suggest ventilation as a means of cooling the attic.
You know, another approach would be to foam the rafter bays.Andy Engel, The Former Accidental Moderator
It ain't broke now, but also ain't insulated! :)
My fear was that adding a gob of insulation might cause moisture problems. Seems I've read similar here, and elsewhere, but maybe that only applied to adding vapor barriers. Since the planets apparently aren't aligned quite right my search attempts here only yield the 'no matches found' or Cu pipe thread. :)
Thanks.
Thon
If there are no air leaks, the insulation will not contribute to moisture problems.
The insulation won't add a vapor/moisture problem unless it has a
barrier and you put it over an air leak that is currently letting moisture escape. I would suggest dumping in some loose fill cellulose.
In the pic of your house, just to the right of the upper window, I see what looks like mildew on the soffit.
The summer attic temp is a real A/C energy eater. Soffit vents, a ridge vent, and adding a radiant barrier to the under side of the roof rafters (foil side to the attic)can get your attic temps down close to out-door air temp.It does require a good air path.
Do you have any duct work in the attic?Energy Consultant and author of Practical Energy Cost Reduction for the Home
No duct work in the attic, K and T wiring has been replaced.
The dark spots in the picture are peeling paint . You can't see it in the pic but it's also happening on much of the siding. I was initially concerned about interior moisture doing this, but it's happening on wood that has no connection to the interior so I'm leaning more towards poor prep work/paint, a long time ago. (?)
So, if I don't ventilate, can/should I run the insulation all the way to the edge of the joists--completely covering the soffits? Also, should I spray foam around the only ceiling box?
Thanks again.
Thon
Thon,
If you have looked very carefully at the underside of the roof decking, all the way to the ridge,and have not found mold, then you must not have an attic moisture problem. In the attic picture, I see a grey area on the roof decking. Can't tell if it's dust or mold.
I am a believer in attic ventilation. I don't like to carry a heat load over night in the attic.
That said, and the fact that you recently moved in, you might want to take some attic temp readings next summer.
If you do decide to ventilate the attic, I would not remove the window, but would install a gable vent over the other windows and put in a thermostaticly controlled exhaust fan. The attic will need a lot of air intake. The fan box will advise you on how many sq. in. are needed for that cfm capacity. Be very generous with soffit vents, and be sure you have a good air path into the attic from the soffits.
Do not over power the attic fan, as you will create negative pressure in the house envelope and pull house air out.
A simpler alternative would be to put a $20 box fan in the gable window and see what effect it has in summer heat. Once again, you will have to provide the attic with soffit air. Pulling the air from behind a radiant barrier would greatly increase cooling efficiency.
The peeling paint may be an indication that moist house air is escaping into the walls and soffits.
I would like to see more pic of attic interior and layout of attic floor.Everbody is trying to give you good advice, and the more facts we have, the better the feedback . Paul
Energy Consultant and author of Practical Energy Cost Reduction for the Home
My climate is temperate rain forest (think of Seattle without quite so much rain). I don't live in extremes, like Tab A, but even here, the norm is 1 sq ft/300 sq ft ventilation to roof area.
Like him, my soffits are not open so I can't understand why they will be adding these vents when I re-roof. According to the Taunton Winterize & Weatherize book just published, an open skylight in an upper floor room will pull hot air in (towards the basement) in the summer. Would roof vents in a closed roof do the same?
One benefit I could see to the insulation project might be the reduction in ice dams, which is NOT a problem here.Quality repairs for your home.
Aaron the HandymanVancouver, Canada
Aaron,
An open skylight is in the building envelope, and since hot air rises,it will pull in replacement air from the least path of resistance.
That opening could be anything from a window in the same room as the skylight, or an opening in a basement. Another force acting to pull air out of the house is wind. As it blows across an opening, it creates a vacuum which will pull in air behind the vacuum to equalize the pressure.
Roof vents on a roof with no other source of entry into the attic (such as soffit or gable vents) will create some negative pressure in the attic below. The hotter the air temp in the attic or the greater the wind speed over the roof, the greater the vacuum effect. If there are openings from the attic into the house envelope, such as wiring, vent stacks, flue pipes,partition walls, etc., then some air flow will leave the conditioned space. Have you heard the damper in a bathroom exhaust fan flap open and shut on a windy day? That same negative pressure is affecting the attic to a much larger degree.
If you have roof vents, it would be wise to provide the attic with an air source, such as soffit vents or gable vents to satisfy the negative pressure without using house air. Some houses have gable vents and no soffit vents. That is OK, because air will flow out of one vent and suck air in the other.
The 1 sq ft per 300 sq ft is to provide enough free air ventilation to eliminate a condensation problem.
Much of the consulting I do is to reduce energy costs, so I am seeking ways to rapidly change the attic air in high cooling load geography, and to prevent high heat buildup in the attic. You do not have a large A/C load from a cooling degree day standpoint, but you may have a large humidity load in you temperate Canadian rain forest.
Hope this is helpful to you.
Paul
Energy Consultant and author of Practical Energy Cost Reduction for the Home
Paul,
Not sure if these are what you need but here are a couple more pics of the attic. I don't see any mildew anywhere--just lots of dirt/dust. :-)
We moved here in late spring and I actually did check some temps in the attic this summer. When it was about 100 outside the attic was always less than 120--which kind of amazed me. A/C bill was never over $75--which I attributed to being able to frequently open the house at night, to outside temps of 70 or less. With KS being the windiest state in the union, having cooling 'breezes' at night isn't really a problem!
< but would install a gable vent over the other windows>
The attic has only the one (gable) window. Other windows in the picture are upstairs bedroom. I haven't yet accessed the tiny space above that bedroom. Presume it has no insulation, and guess I'm going to have to tear into the ceiling to find out.
Also, don't think I got an answer: Is it OK to foam around a junction box in the ceiling, from which a ceiling light is hung?
Thanks to all for the help.
Thon
(Guess I won't post pics, as Prospero's being perverse again.)
You can foam the gap around the box. Do not get foam IN the box, however.
To seal the various holes in the box itself, I use caulk. Those fiberglass pieces that come with newer light fixtures are pretty much useless. Sealing the box itself really works. Make sure the box is up to code, and of proper volume.
Let's see if the pics will load today:
Thanks for the pics.
I thought I had sent a reply about your foam question, but I can't find it now, so, yes, you can foam around the exterior of a connection box.
You would benefit from some added insulation.
Hope the walls of the room that is surrounded by attic are also well insulated. At 120 deg in attic, the room is in an oven.
If it was my attic, I would add ventilation with at least gable vents.
Your uncluttered attic is also easy to add a radiant barrier.
You might ask some of the framing pros on this forum to comment re; adding some collar ties to the roof rafters.
I would staple a product called Solar Shield across the rafters starting about 3" above the insulation final depth. I would go up one side across the bottom of the triangle formed by collar ties, and meet the shield coming up the other roof side.
This would channel all the hot air to the "triangle" between the roof peak and the bottom of the collar ties. A gable vent in one end of the triangle would let the majority of hot air out.
You would need another vent, either gable or soffit, to let air into the attic space below the solar shield. Once accomplished, a natural convection current of air would flow into the attic, pass into the chambers formed by shield/roof deck, and into the "triangle" to exit the gable vent. The hotter the air between the roof deck and shield, the greater the pull for more cool outdoor air.
This arrangement would let your attic approach out door air temp, would greatly lower the cooling load on the attic surrounded bedroom, and provide a radiant barrier for all the attic under the shield. When the sun goes down, you will be amazed at how fast the attic cools, because you will have eliminated the radiant cooking effect on joists, rafters and even insulation.
PaulEnergy Consultant and author of Practical Energy Cost Reduction for the Home
<Hope the walls of the room that is surrounded by attic are also well insulated. At 120 deg in attic, the room is in an oven. >
Prior to this week there was no insulation in any of the upstairs 2 bedroom (I guess these would be called dormers?) walls. :) On the other hand, there has never been any heat or A/C to the upstairs either.
Now that there is wall insulation, this leads me to my next question: The 4-5" open space you can see in the pic is the roof over one of the upstairs bedrooms, and the other is similar. I'll now have the FG you see, in the wall, and cellulose at the base of that wall (the attic floor) but am not sure how I can get insulation in the ceiling of these 2 bedrooms. I'm thinking my best bet will be to tear off the interior 12" tile ceiling and start over? How best to get close to R-40, given that rafters are 2 x 4's?
Thanks again.
Thon
Are the ceilings cathedral in these up stairs bedrooms?
You are not going to get R-40 in 4" of space. If you removed the tile ceiling, and had 4" to the roof deck, you could have closed cell poly foam sprayed in which would yield R 28. Being all foam, that would be a very efficient insulation.
If you wanted more, you could give up some ceiling height and put 2x4s across the ceiling rafters thus adding another 1 1/2" of depth. That would yield r-40 if all in foam. It would also be overkill in my opinion compared to 4" of solid foam.
A third plan would be to spray in the 4" of foam, then put 1/2" of foam board, followed by 1/2" sheetrock. That would isolate the roof rafters by providing a thermal break between the sheet rock and the roof.
PaulEnergy Consultant and author of Practical Energy Cost Reduction for the Home
The ceilings are dropped, and covered with those staple up 12" tiles. I wouldn't necessarily mind getting rid of the dropped ceilings, though.
I like the idea of sprayed in foam but don't think it's likely to happen here for a couple of reasons. The closest installers would be a couple hours away, and financially I want/need to be able to do the labor myself. So, I'm trying to figure out how to get the most R-value I can, myself, in those wimpy 2 x 4 rafters. :-)
BTW, I blew the cellulose (40 bags) yesterday onto the attic floors. Guess I was just lucky that late Oct. temps were close to 90! :-P One dirty miserable job--but it's done! :-)
Thanks.
Thon
What is the total depth you have from ceiling to roof deck if you remove the drop ceiling?
Understand need to DIY. Best bet may be to fill from below with poly wraped non itch roll batt, and then a 1/2" foam board. (String works to hold batt from excessive droop).Well seal so that you get all you can in r-value, then sheet rock.
Blowing cellulose is a grubby job, but not as dangerous as fiberglass. I have done it with a powerful box fan at a gable with a spun glass filter on back of fan. Working from fan backwards kept clean air flowing to me, and dust pulled away. It still leaves something to be desired.Energy Consultant and author of Practical Energy Cost Reduction for the Home
<What is the total depth you have from ceiling to roof deck if you remove the drop ceiling?>
Not sure I'm on the same page with you here. :-) I haven't removed the stapled up tiles yet, but am thinking when I do, the depth will vary--greatest in the center where rafters peak, and only 4-5 inches, I'd guess, at the sides of the ceiling.
What I've been thinking I'd like to do, is use 3 1/2 inches of FG between the rafters, as you suggest, but then use up to 4 inches of foam board below the FG. Don't know if that's feasable, or technically how to attach it or finish the space, if it is.
Might be simpler to just leave the dropped ceiling and put 12" or so of FG on top of it. Only problem I see with that is at the edges of the room where there won't be anywhere near 12" of space.
Thanks.
Thon
I remodelled an entire house over the last few years.
My rafters are 6" deep which means I could only put an R19 batt in between all rafters. I live in Pittsburgh, Pa and the recommended R value for the ceilling is R 39. I had several choices sister a 2*10 next to my old rafters and reduce my ceilling heighs by 4 inches, my ceilling were only 7'6" heigh so that was not an option. My second choice was to just put in a regular r19 batt. I was not satisfied with either option. So I did research on the web and I realized that the most important thing to have was to reduce the air infiltration in my home.
A regular built home has around 1 to 2 air exchange per hour. If you seal the envelope your air infiltration can be reduced to .2 to .5 air exchange per hour. No more drafts which means you can lower your thermostats and save money.
From my experience I went from my home before remodeling with a heat loss of 60,000BTU/H to 20,000BTU/H that is a big difference. LESS OIL TO BUY FROM THE PERSIAN GOLF.
I opted for 4 inches of Icynene in the attic and in the walls. Cost me $1.45 for 4 board feet (one square foot 4" thick). That was a bargain compare to installing 3.5 inches of Fiberglass with tyvek on the outside.
Any questions let me know.
Damien
Hello,
new to the site last week so please excuse me if this is becoming redundant...much discussion around insulation and vapour and air barriers...I have posted several questions regarding my renovation of 1928 brick veneer school house in Eastern Ontario...information so far points to utility of cellulose but I am still concerned about damaging the structure of this building with moisture...
I am looking to blow cellulose down into the balloon-framed 2x4 walls from the attic~R12 and R40 into the attic (twinned 1x6 ceiling joists) when finished, baffling and sealing where appropriate to redirect air flow for gable vents already in place, and reduce air flow from the interior into the envelope.
What to do with interior wall surfaces? Some lathe and plaster removed already but much intact and solid, plus, it is strapped onto 1" horizontal planking sheathing the 2x4 frame...too much work to remove I believe. best to seal as well as possible, draft boxes for electrical, caulking and good coat of paint sufficient?
Fair extremes summer and winter here and basement will likely be damp for a little while until I manage to get to working on the footing drainage and damp-proofing of the foundation.
Appreciate your indulgence
I am not considering myself an expert in the field. I chose Icynene because my whole house was gutted and I had access to open stud bays.
I do not know what the building codes are in Ontario. My recommendation is that you contact your buiding inspector and ask him what option you have. At the same time you can go on the web and do some research on : House Insulation, Humidity Control and Ventilation. You can also go to your local library and read books on the same subjects.
My phylosophy has always been do it right the first time and you will not have to do it again later.
Check the Icynene wedsite : http://www.icynene.com or to http://www.formor.com. The later site offers possibilties for the do it yourself
Good luck
Damien
Sorry upon second look that might be very difficult in your situation with the 1x on the flat that i somehow overlooked previously. As far as the ridge vent, that is a good way to go, the problem is it doesn't do much good if theres nowhere for the replacement air to enter (eaves). Like was mentioned before, don't worry about poly, seal up the penetrations in the plaster from above.
Venting can cause a new set of problems. If there is no warm moist air coming from the living space, no venting is required to flush it away. Focus on sealing the air leaks from the living space. This is treating the problem, instead of the symptoms!
Sealing is even more important than the insulation itself.
Attempting vapor barrier is not a good idea. Plaster is 'low-perm' enough.
Attic moisture problems come from air leaks, not water vapor migrating through plaster.
As mentioned, do not bury knob & tube.
Best of luck.
Be sure you don't cover any knob and tube wiring with thermal insulation - that';s a fire hazard.
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