What's the best way to air seal my house?

RascalOrnery

Hello Heating help friends! This summer I'd really like to do some work tightening up the air infiltration in my 1923 (yr built) 2000 sq ft balloon framed house. I consume from 750,000 to 1.1 million BTU/day in the winter months if temps are between 10-30 average. I am in eastern central PA. Last year I did my best with fiberglass to insulate the rim joist in the basement. However I know that the balloon frame lets air travel through the walls up into the attic very easily.

I notice the second story floors get chilly and I think it's from all the open areas between wall cavities and floor joist areas. Where is a reasonable place to start to slow the air movement? I have a little bit of blown in cellulose in the attic under the floorboards but I would pretty much consider that not doing a whole lot. The house is sheathed in 1" boards with a tarpaper (what's left of it) and then 1/4 blue foam sheeting with vinyl siding. Some I'm pretty open to the outdoor temps and wind. Windows are 25+ yr old vinyl.

I know some people say just spray foam or fill everything up with some sort of blow in, but I'm really not about that. I want to stop air migration and chimney effect before I would even tackle that. I want a secure lid on my house. So 'dams' seems to be the approach my mind takes, dam the channel to the attic, dam the joist ends to prevent more circulation under the floors.

My 1st floor has all original plaster ceilings, the upstairs has a drop ceiling ( I feel this is my best access area to do something)

Another area I really need to tackle is the stairwell ceiling from the 1st to the 2nd floor, I know there is a lot of heat going straight up from 1st floor since like a typical house the stairwells are all on top of eachother. I was planning to rip off the stairs in the attic and either lay down batts or possibly remove several treads and blow in cellulose. How would I air seal the lath and plaster before doing that? Just run a bead of caulking around the edges and seams and call it good?

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Jamie Hall

For the walls, by far your best option is dense pack blown in insulation. It will stop both infiltration through the walls and any chimney effect in the walls. If you're not about that, that's your choice — but that's the only effective way to stop air circulation within the walls.

The attic is another question — and the question there is whether you want the attic to be warm(ish) or cold. That determines where you put your insulation. If you want a cold attic, then the insulation — I suggest fiberglass, but if there is an attic floor blown in between the second floor ceiling and the attic floor works well — goes in the floor. Otherwise, spray foam on the underside of the roof.

There is a caution: if the insulation isn't really tight to the underside of the roof, be sure the attic space can breathe. Otherwise you'll get condensation up there, and that you do not want.

I'm not quite sure what you mean by sealing the stairwell. Are there stairs going directly up to the attic? If so, can you simply put a cover over the opening in the attic?

RascalOrnery

Sorry I tried to upload these earlier, this is the staircase going to the second floor. When I come up the steps I notice the warm air following me (especially when we use our gas stove in the adjoining room (kitchen) in the summer I notice the heat migrates into this stairwell, imagine the winter? So the 'ceiling' is just panelling on old plaster and lath, I want to insulate this from the upstairs attic stairwell. If I just pull the steps and blow in or lay batts down will that be sufficient? I do have a sort of 'lid' I top the entry into the attic with, but I'm sure that's only doing so much, i thought best off to control it as many places as possible.

RascalOrnery

Doesn't blow in insulation often cause moisture problems if the outside of the house doesn't have a proper vapor barrier? I feel like my vapor barrier is pretty bad!

I'm intending to just SLOW air movement in my house cavities, namely the wall and floor joist. Will installing so called 'fire dams' help with that? Am I barking up the wrong tree? Should I just sacrifice my attic storage and blow in 2' of fiberglass and let that do the work?

Jamie Hall

Yes. Blown in wall insulation can indeed cause moisture problems in the walls. Which is why I don't use it in restoration projects. The lathe and plaster wall material is a pretty decent vapour barrier, but it isn't perfect — and later work (particularly electrical) may have compromised it.

If there aren't fire stops in the ballon framing (and the only way to find out is a small hole and a borescope) installing them would, of course, break up some of the convection currents inside the walls — but it would also mean breaking up a lot of perfectly good plaster. I wouldn't recommend it.

Do I take it there is a pull-down type attic staircase? Those are horrible heat leaks. It will be worth building and fitting a reasonably tight, well sealed cover for that which you can pull down and close before you fold up the stairs.

Then yes, the biggest bang for the buck is going to be insulating that attic floor as much as you feel is reasonable. But as I said above, if you do make sure that the attic itself can breathe. Be sure not to close up any eave openings (except with screens to keep birds out) in your enthusiasm to insulate, and make sure that there are either gable vents or a ridge vent.

hot_rod

maybe consider getting a blower door test done. That will identify where the air leakage actually is. How much you have. Before you start throwing money at insulation.

Spray foam is best around rim joists, even a small amount, then fiberglass batts or foam blocks. Fiberglass isn’t a great air barrier.

Look for an energy audit company or see if your utility offers an energy analysis.

EdTheHeaterMan

Not real sure on your house, But I use Caulk on my home.

RascalOrnery

I'm a little in the dark about what a blower test is, I wasn't sure if it was a test with the verdict being "you're house is this number on the scale of air leakage" or if it was like "you've got this much air leakage, and it's coming from, here, there, over there, under there…" because that, I'm willing to pay for because like you said it's just a guessing game otherwise. I'll look into it!

In the meantime make a better fitting door for the attic.

DCContrarian

Ask at GreenBuildingAdvisor.com. The folks there live for this stuff.

Jamie Hall

Blower door tests are, in my humble opinion, a bit iffy. If the house is relatively small, and relatively new, and there isn't much general infiltration, yeah… OK.

Otherwise… depends on who's paying for it. You? I wouldn't bother.

Funny story. We recently installed a fairly large PV array for Cedric's house, and the State requires a blower door test (no I don't know why). Well… Cedric's home is 7000 livable square feet over four usable floors. 19 exterior doors, and we've never counted the windows. Most recent addition 1893, centre section around 1780. The testing company duly arrived… and were completely at a loss. Don't know what they reported back, but they didn't even bother to unload their equipment…

Larry Weingarten

Hi, Another approach is to find local weatherization contractors. Your local utility company likely can help point you in the right direction. The utility may even have a tool lending library, so you could use a blower door at no charge. The weatherization contractors will know what the range of leakage rates is ( usually measured in air changes per hour at 50 pascals), and they will have tools like smoke gun and infrared camera to help find the leaks. There may even be some subsidies 🤑

Yours, Larry

hot_rod

I'm betting a 1923 home probably has excessive air leakage. Infiltration can be a big number in the heat load calculation. Plenty of You Tube videos showing the process.

The blower door will show how much leakage and also where it is by using a smoke pencil.

https://video.search.yahoo.com/yhs/search?fr=yhs-ima-st_mig&ei=UTF-8&hsimp=yhs-st_mig&hspart=ima&p=you+tube+blower+door+test&type=q3000_A1BWP_set_bcrq#id=1&vid=7a102825d670d2ddcb15487bf1b3e354&action=click

JakeCK

FYI, I had an energy audit years ago. They refused to do the blower door test because of vermiculite in the attic. If you aren't aware old vermiculite insulation often had asbestos in it.

Just something to keep in mind with older homes.

jumper

O/P didn't ask but 1924 house has to breath so it must not be sealed too well. That was true problem with UFFI fiasco in seventies. Windows should be sealed but hopefully drainage established because nothing keeps out water entirely. The most practical insulation is siding, especially over pilaster or straps. It is surprising how effective is capping window frames. A method to save with comfort is to turn down thermostat and use electric radiant in rooms where & when wants coziness.

RascalOrnery

So I can do my own blower test by putting a box fan in the window and putting masking tape around the door and then use a smoke pencil to see where air is escaping out of the room, no problem there, I can at least find the MAJOR leaks.

BUT the mysterious challenge for me is how do I stop the air in the wall cavities and floor joist areas from circulating so freely and causing increased temperature exchange with the outdoors? It seems like trying to work from inside the room is kind of second best, shouldn't I be trying to go one layer closer to the outdoors and stop the air movement in there first? Are air dams a good thing or a waste of time all together?

RascalOrnery

Also, would I be smarter to try to find the areas where the ROOMS have AIR INFILTRATION into the ATTIC and then seal those? (put a box fan in every room, facing inward, tape doors shut and go into the attic and see where entry points are?

Is more heat lost:

ROOM> ATTIC > TO OUTSIDE

or

ROOM>WALL CAVITY> OUTSIDE (through soffitt eaves area?)

Larry Weingarten

Hi, A blower door measures airflow, so you can get an idea of how much leakage there is. A box fan doesn't do that, but can work as you suggest for finding leaks. But it needs to be used with a smoke generating device… even a stick of incense, to see where the air is going. If there is a temperature differential, using an IR camera will show you the leaks as well. For example, if it's warm inside and cold outside, depressurize the house and look around inside with the IR camera. It will show you where the cold air is flowing, even inside of walls. Anyplace different materials join is suspect for leaking. Brick fireplace and wall/ceiling intersection is a common leak location. Behind baseboard is often another big leak. Also, plumbing and wiring penetrations often leak both air and mice! … Just install the fan in a window or exterior door and leave all interior doors open. Unless the leaks are huge, that should let you find the leaks.
I'll add that air sealing is best done before installing insulation. It's hard to seal leaks in the ceiling if a bunch of insulation is in the way. It's common to remove the insulation and then seal. Later, replace the insulation or install some new if evidence of rodents is found. 🐀
Yours, Larry

Jamie Hall

Normally in ballon wall construction there was a plate at the top of all the studs. The rafter tails rested on the plate. That plate seals the cavity made by the studs off — so while there will be some air circulation within each wall cavity, there will be no air— or at least very little — escaping from the wall cavity up into the attic, never mind outside.

In some cases, the rafter tails extended beyond the plates to support the roof overhang, and some ventilation for the attic was provided under the roof overhang.

Now how is heat lost? In the case of the walls, it is by conduction through the lathe and plaster, then primarily slow air circulation (convection) within the wall cavity, then again conduction through the exterior wall to the outside. Now there will be some actual infiltration through the walls, primarily around windows and especially window frames. How much is entirely dependent on the quality of the windows and the window frames.

In the case of the room to the attic, again heat will be lost by conduction through the room ceiling. This is usually also lathe and plaster if the walls are, but note that there is no outer wall (sometimes there is an attic floor, but then the attic counts as a room — and the heat loss by conduction will be through the roof sheathing and shingles). Now there may be openings — intentional or otherwise — in the ceiling, and if the attic cold, the convection (in this case exfiltration) of warm air through those openings can be very significant. Particularly bad actors are pull down stairs, but overhead lights in the ceiling can be almost as bad, or around openings for warm air or air conditioning ducts.

So… generally, although not always, the greatest heat losses will be from the occupied spaces through the ceiling to a cold attic. A lot of this is simple conduction through the ceiling, but any openings — intentional or otherwise — will contribute. So insulate the attic floor… and seal up any openings in the ceiling (I might add that if any of the ceiling has been replaced by dry wall, that must be insulated — dry wall might just as well be a sheet of paper, so far as heat loss is concerned).

Remarkably little heat is lost through a balloon framed wall (assuming that it has plates and sills, and it almost always does), even if it isn't insulated — but check those windows and window framing.

I might add that replacement windows, if later, can be particularly bad actors unless the installing carpenters were very careful and sealed (usually foam, older might be fiberglass) between the replacement window frame and the original framing)(I might add that those 25 year old replacement windows may leak like sieves. Old double hungs didn't, but you are stuck with that).

Another common place for significant infiltration is between the rim joist and the foundation itself. How bad this is is very much dependent on the quality of the original workmanship.

Does that help?

RascalOrnery

Thanks Jamie, that is extremely clear and helpful!

RascalOrnery

I have been working at removing window trim and properly caulking or spray foaming around where the window sits in the original wood work, this has helped, and was never done before.

Given the upstairs is all drop ceiling, (about 4") is there any benefit/reasonable way to do some insulating below the original plaster and above the drop ceiling? It's about 900sq feet of area so even blueboard nailed in place with spray foam along edges seems like it would be rather costly, but I don't see the point in laying fiberglass batts over the drop ceiling framework- that seems like it would just add weight and be awkward to get to lay properly.

In the meantime my attic entry door and my basement entry bilco door are GREATLY lacking - I'll start there.

Jamie Hall

I wouldn't even try to get into that dropped celiling. Some things just aren't worth the effort. On the other hand, I'll bet you can get some insulation on top of the old lathe and plaster. Does the attic space have a floor over the joists as well as the lather and plaster? If so, get insulation — fiberglass is good, but blown or poured in is even better. If there is no floor, however… be very very careful up there. You can insulate between the joists anyway, but leave some kind of obvious reminder that if you step off the joists you'll be on the ceiling — and that isn't meant for feet. Trust me.

Also, however, check in that dropped ceiling space — pop tiles here and there — and make sure no one got creative punching holes for wiring in the lathe and plaster, or otherwise damaged that. If they did, seal up the holes any way you can. Foam in a can can be very useful…

RascalOrnery

I did some cellulose blow in, but it didn't make it all the way to the uttermost area where the rafters meet the floor, I was thinking of drilling 2 1/2" holes in each bay and finishing it off. My attic has finish flooring (hardwood floors even in the attic in the 20's, what luxury!) I don't plan on ripping them up, my parents attic is like that and it's always a little iffy going in there to get stuff.

jumper

One measure at a time. That way you'll know what helps significantly. My experience is that sealing around windows makes a noticeable difference. Extra insulation may not because minimal insulation leaves little amount for extra to be significant.

Jamie Hall

Think and examine twice about where the rafters meet the floor. Is there eve ventilation that needs to come up through there? If the attic is cold, it needs to be ventilated.

jumper

»If the attic is cold, it needs to be ventilated.«

A tricky subject.

hot_rod

Another infiltration point is switches and receptacles on outside walls. Sometimes you can remove the covers and get some spray foam around and behind them. Possibly use a jumbo cover if you have to cut some wall covering.

Those boxes show up on IR scans also.

Any place you see a small spiders web, their is an opening to the outside nearby, so the experts tell me.

Dave Carpentier

I increased my blower door test score a surprising amount, according to the tech. He had to stop and reset the range speed on the blower. I dont think it was bs, cause we had great convos (like, an hour after) each visit. Cool guy.

Anyhow.. targeted the older half ('77), sealing all the outlets and switches, anywhere there was infiltration around the windows, and put a rubber gasket with hold-down clasps on my attic hatch. Adding- also increased attic insulation from R12 to R60. Not sure if that would affect blower-door test.. maybe a little. Air can pass thru blown-in insulation but certainly there's some kind of flow resistance value