I am posting here to ask if I need to add more insulation to my attic because our house feels drafty in the winter. Our house is a 10 year old, 1300 sqft ranch. The ceiling is 9 ft high and all the a/c vents registers are located in the ceiling. HVAC is heat pump and electric furnace. I think the current insulation in the attic is blown-in cellulose (although the home inspector has called it fiberglass), and it’s supposedly 12-16” thick. I was wondering if this meets the R38 to R60 code for our region. We have lived in our current home for nearly two years, the house is very comfortable in the summer but chill and drafty in the winter. I usually set the thermostat to around 68 F to be easy on the heat pump. So far I have made adjustments to ensure the weather stripping is tight around the exterior doors. The windows are double plane and seem to shut tight. So will adding more insulation help in the winter? If so, what kind of insulation and how much of it should I add? Thanks in advance.

Drafts are usually a matter of air-sealing, not R-values.

A foot of open blown cellulose is good for at least R40, as long at it's at least a foot deep everywhere. If it's uneven it's worth raking it smooth to fill in any craters. If you have 12-16" everywhere the problem is not the R-value of the ceiling.

The biggest untreated air leak in most homes is at the foundation sills & band joists. In a lot of quickly-built tract homes there are also big air leaks in walls (tub-surrounds with no wallboard over the wall insulation, etc.)

With AC ducts and air handler in the ceiling the duct boots need to be caulked/foamed air-tight to the ceiling gypsum, and the ducts & air handlers all need to be air-sealed too. This could easily be the culprit for your wintertime draftiness problem.

If the ceiling is a sea of recessed can lights there's a good chance that THOSE are adding up to big air leak too.

Any fireplaces?

Are the plumbing vent stack & electrical chases that run to the attic air-sealed top & bottom?

Full basement foundation, crawl space (vented, unvented?), or slab-on-grade?

Thank you for your detailed response. The insulation is a little uneven. It looks like someone was up there may be to do some repairs. I'll try to level out the lows.

Just yesterday I unscrewed all the ac registers from inside the house and sealed the gap between the gypsum sheets and duct boots with regular duct tape. But today I read that one is supposed to seal them with a different type of duct tape; I hope this doesn't make a big difference. I also plan to go into the attic to spray some gap filling foam between the ac boot and the gypsum. I am thinking the foam will not make its way inside the house since i have put some duct tape from the inside of the house...

The house is on a slab, and the carpet is the cheapest grade you can find. We have a fake fire place, but we do have about 5 can lights, should I spray gap foam around the too? What does one use to seal air handlers?

When I go into the attic, should i not step on the sheets at all costs? will it take some light steeping-on, I weigh about 150 lbs.

you need to get an energy audit - someone to come in with a blower door and FIND your air leaks. As Dana said, the drafts are NOT an insulation problem; they are an air infiltration issue, and in a very leaky house they can easily double your heat loss and your fuel costs as well as making it uncomfortable. A lack of insulation will show up in your fuel use, but that will not create drafts.

Some states will do energy audits for free. Some auditors, use them as sales tools for insulation and heating, but before hiring anyone to change anything, tighten your house.

Tape doesn't work well for sealing duct boots to wallboard. Can-foam works for big gaps. Fiber reinforced duct mastic applied at 1/4" thickness would usually do it if you're sealing a flange to the wallboard. The connection of the boot to the ducts, and any duct seams/joints can be hit with duct mastic too. The seams on the air handler can be sealed with an appropriate foil duct tape with a temperature-rated adhesive (eg: Nashua 324, found at most box-stores, but there are others. No-name tapes without temperature specs need not apply.)


If the can-lights are air-tight insulation-contact rated you can just seal them to the gypsum and you're done. If not, you'll have to build an air tight box over them with 3" clearance to the fixture, and seal the box to the gypsum. Housewrap tape on all the seams of a cardboard box does pretty well, then you can caulk or can-foam the box to the gypsum, then heap insulation over the box.

If the fake fireplace is on an exterior wall, there may be a huge air leak around the back side of it, and possibly no insulation. If it's in the middle of the house somewhere there may be a large leak around the flue (assuming it's gas unit). Can you describe both the unit & installation a bit better?

You definitely DON'T want to be stepping on the ceiling gypsum, even if you only weighed 75lbs, which makes working in the attic pretty tricky. If it's a trussed roof it's fine to step on the truss chords, which are probably buried in the insulation, so you'll be disturbing the insulation as you go, and have to rake it smooth when you back out. If it's joists it's easier to find buried joist tops than truss chords, and you may even be able to lay down 2x10 planks to work from. But fixing all of the air leaks in both the ceiling plane and the ducts & air handler is a primary order of business.

With slab-on-grade to seal the sill-plates/studwall-plates you may have to pull the kick boards and put a bead of can-foam under the bottom edge of the wallboard or something if they seem to be leaky. Working around carpet you probably can't just air-seal them in place without pulling them.

If there is a local company that does blower-door testing it's probably worth fixing the most-obvious stuff then testing the house to find & fix the big leaks that weren't so obvious. You can fix 1000 smaller leaks without seeing much improvement if you've missed a couple of big ones, and there's almost always a few surprises lurking.

Your home is a "cube" with 5 sides exposed to the elements...4 walls and the "roof" (roof being really the ceiling here). Your heat load, therefore, is one part ceiling to 4 parts wall. Your walls are therefore far more liable to be the issue as well as any penetrations. 12-16 inches of insulations is like plenty if it is installed well. Your walls likely have 3.5 inches of insulation vs 4 times that up in the attic. With 1/4 the insulation AND thermal bridging of studs in 4x the heat load of the walls, thus is your big problem.

Heat rises but conduction is faster than convection.

On the other side, plug your holes. Hard to do after its built though. Google air sealing. YouTube airsealing. Get to work. Drafty homes have holes. The average home has a three foot dis hole in the wall due to poor airsealing. Winter has lots of wind and no leaves. Holes in the home are more noticeable due to hugher winds and greater differences in air temperature between inside and out.

In terms of a few surprises....most homes will have hidden areas in the wall with NO insulation. Anywhere there's joined walls, the studbay is wider than 14.5" and therefore likely to have NO insulation. Inspectors dont walk the home and check behind the face stud to see if the Insulation was carried across, hidden from view! No way! They don't check airsealing!! They walk in look around sign the ticket and leave, leaving lots of small poorly insulated and non insulated areas in the walls meeting other walls and ceilings.

A blower door test with airseal analysis will cost $300-400 but it will help you immediately identify the major problem areas so you're not guessing. Best done in winter so thermal imaging is easy to see. Fun stuff.

you said that your heat registers are in the insulated attic, so they are outside of the conditioned envelope and likely insulated to something like R-3. They are also probably very leaky. This seems like a major flaw that needs to be corrected. The duct system should be checked for air leakage, and if at all possible, brought into the conditioned space.

I was discussing my post and your responses with my wife. My wife thinks it's a bit of stretch to say our house is drafty. I think I agree with her. it used to be drafty as the winter was approaching our first year in the house. So, I sprayed foam all along the perimeter of the house under the gap between the base board. The carpet got messed up at a couple of places, that's another story. Subsequently I had our utility company do the energy audit. They did do the blower door test, they said my house was quite tight. They also took pictures of the ac registers with the infrared camera and told me the seams between the boot and gypsum sheet needs to be addressed.
I would say our house is cold and uncomfortable, not drafty. Believe it or not I am having trouble recalling how it felt in the winter only after a few months of warm weather.
Like you guys have advised I will take care of the duct work with duct mastic and foil tape. Sure there could be some gaps in the wall insulation as well. Our fireplace is truly a fake fireplace with fake fire and an electric hot air blower. It is along an exterior wall and it does feel cold around the fireplace. I wonder if there is a easy way to address any potential leaks around it.

Folks, thank you so much for all your detailed input. The suggestions on the energy audit report was pretty scarce.

If you had a detailed energy audit I find it interesting all you got was "its kinda tight"...?? What did the calculation show for your home?

They should have taken pics of every exterior wall in every room.

Posted By madhuxs on 01 Aug 2015 12:07 PM
I was discussing my post and your responses with my wife. My wife thinks it's a bit of stretch to say our house is drafty. I think I agree with her. it used to be drafty as the winter was approaching our first year in the house. So, I sprayed foam all along the perimeter of the house under the gap between the base board. The carpet got messed up at a couple of places, that's another story. Subsequently I had our utility company do the energy audit. They did do the blower door test, they said my house was quite tight. They also took pictures of the ac registers with the infrared camera and told me the seams between the boot and gypsum sheet needs to be addressed.
I would say our house is cold and uncomfortable, not drafty. Believe it or not I am having trouble recalling how it felt in the winter only after a few months of warm weather.
Like you guys have advised I will take care of the duct work with duct mastic and foil tape. Sure there could be some gaps in the wall insulation as well. Our fireplace is truly a fake fireplace with fake fire and an electric hot air blower. It is along an exterior wall and it does feel cold around the fireplace. I wonder if there is a easy way to address any potential leaks around it.

Folks, thank you so much for all your detailed input. The suggestions on the energy audit report was pretty scarce.

So, what was the cfm/50 number they came up with during the test?

Sorry for the delay in replying. I was out of town for a few days.

Blower door test cfm50 number is 1426.

I am pretty sure the auditor did not take infrared pictures of the walls but she has written wall insulation level R5 (vs. the recommended R13), for the floor she has noted R5 (R30 recommended).
The main recommendations were to air seal return ducts and supply duct. I am not sure how she determined they were leaky because she really didn't walk around in the attic, she only took a peek. However, she did image the AC registers in the ceiling. Unfortunately, they did not include the infrared images with the copy of the report they sent me.

Assuming 8.5-9' ceilings your internal volume on a 1300' slab-on-grade rancher would be about 11,000 cubic feet.  1400 cfm is 84,000 cubic feet per hour, so you're looking at 84/11= 7.6 air changes per hour @ 50 pascals , or "7.6 ACH/50 ".

That would not quite meet IRC 2009 code max of 7 ACH/50 (though it's close), and is quite a bit leaker than IRC 2012 code max, which would be 5 ACH/50 for US climate zones 1 & 2, and 3 ACH/50 for all other climate zones.  "Kinda tight" would be only relative to some fairly leaky paradigm case, though there are many many (too many!) 10 year old house that come in above 10ACH/50.

If the walls really are performing at R5 it means either the wall cavities are empty (assuming it's a framed wall, not masonry?) or it had low density insulation that either settled or was mis-installed with lots of gaps & compressions, or it had R7 half-batts that did not completely fill the cavity.  Whichever scenario it is, it's worth dense-packing cellulose or fiberglass over whatever is there into the stud cavities. That alone will reduce any wall leakage by quite a bit, improving your cfm/50 numbers.

If the ceiling is performing at R5 it means there's at-best a couple of inches of blown fiber insulation on the attic floor, or big gaps where there is none.  This is DEFINITELY worth fixing, but AFTER you've air-sealed the ceiling gypsum & ducts.  A competent insulation contractor would air-seal first anyway, but not all insulation contractors have gotten the memo on that yet, so it needs to be discussed in advance.

Which climate zone are you located in?