1- Am I on the right track with this idea? Open vs Closed cell in this situation? Will our roofing materials make a difference in choice?

Closed cell for cold climates.

I don't know about cedar shakes, not a roofing material I've

seen here in La. ask foam companies in your area this question.

don't see question #2 (maybe because #3 is several questions?

3- condensed version...so the large gable ends in the attic are exposed brick - do we spray
them too? (will it damage the brick?) Or just do the roof rafters?

2" minimum on gable end walls.

plus of course enough inches of foam to meet code's R-value

requirement for your area.

the above is a huge sticking point...so be wary of anyone selling

product saying stuff like "1" is equal to/performs as R-10"

inches of foam to meet code requirements for your climate.

no benefit from radiant barrier (foil) in cold climates.

when you foam the roof line (hopefully) there will be

no radiant gain.

4- (again condensed) do I need to worry about makeup air before I get to the kitchen stage? Will sealing off the attic make that much difference?

the answer to that is one that I hate, but its true.

it depends.

in my experience old houses are never tight enough to require

fresh air. back then they weren't building with the materials we

have now for air tightness.

best would be to have a blower door test to determine how leaky

the house actually is. IMO you'll be in the 10,000 cmf range of

air infiltration.

but...if the attic access (doorway...hatch) is within the

house's living space...then you can test the foam install for

air tightness. simply test the house (blower door test) with

attic closed...then open the access. difference between the

two readings is leakage from foam sealed attic.

do blower door test at the end of the foam install...

while foam crew still onsite to seal any leaks.

with the blower door running, you can feel the

leakage sites. I mark with spray paint...send the foam

crew back...and run the blower door again. until they

get it sealed air tight.

so keep in mind when you call foam companies...inches of

foam to meet code. air tight seal of roofline to attic floor.

uniformity of install...measure depth of foam in rafter bays

in several areas.

shop around. I like owner/salesman/installer all the same

guy foam companies. no unnecessary sales hype &

(again hopefully) they know construction & the confines

of their products.

best of luck

You may want to stud-out the gable ends before spraying so you have the future opportunity to drywall the whole thing.

One way we add AC to large old houses up here is to run ducts in the attic for the second floor, and ducts in the basement for the first floor,(two separate air handlers and outside units) and leave the first floor AC optional. The natural convection moves the warm air from the 1st floor up to the air return in the upstairs hallway; if it is deemed wise, you could add a large AC duct above the stairs to allow cool air to dump to the first floor. With brick houses it's not as necessary to have ducts on the lower floor.

Casey

Foam is generally very effective because it both seals and insulates, but once sprayed in a cavity it will be very hard to go back and do any additional work within those areas. That means that updating electrical or doing other work is much harder because the foam is so solid. Blown in fiberglass or other insulation is much easier to move out of the way if you need to get access to a cavity.

Bruce

The house is 2 stories plus attic and basement. Since there are no stud bays or siding, we aren't looking to foam or insulate any exterior walls. The basement also has masonry walls. We are mainly looking to foam the roof rafters, and the gable ends in the attic which will never be finished space - even though I'd love it - not quite enough headroom, and we'd have to beef up the joists to carry a live load - plus change the roofline to accommodate windows/dormers - too much work and expense for this house. So it's only attic space - accessed through a hatch, but plenty of room for HVAC. Our goal is simply improved energy costs.

Forget the foam. Too many problems, what happens if you get a leak in the roof? I would use a FSK foil faced batt insulation, stapled in place. Use as thick as you can to fill the cavity of the roof rafters and still being able to staple the foil.

The batts are laminated with an FSK (foil-scrim-kraft) facing, which enables the insulation to carry a fire hazard classification rating of 25/50 or less per ASTM E84 and also serves as an excellent vapor retarder

hire a RESNET energy rater with experience with existing homes.

or a BPI building envelope specialist.

while I can only speak with experience of RESNET energy rater,

providing the homeowner with a plan for improved efficiency is

what we are all about.

best of luck

No Foam. It's way too permanent. As someone else above said, insulation best practices are in a constant state of flux. Don't fall prey to this to costly mistake.

Unless the attic is going to be converted into finished space, there is zero reason to insulate anything except the floor of the attic. Don't insulate the walls, and don't insulate the roof.

But add more ventilation. The last thing you want to do is completely seal the attic up.

Because no matter how well you think you have it sealed, it wont be. Water will find it's way in, and without adequate ventilation it will just slowly smolder into an expensive mess.

I work in a 1930s era brick building owned by the largest organization in the world. For some reason, when this building was renovated ten years ago the inside of the roof was insulated. Now there is a project to un-insulate the roof because of problems. Luckily, it's not spray on foam.

I'll look for an energy rater. I can't get more ventilation into the attic, that's my big problem - I have 5 turtle (passive vents) and one power vent up there now, the problem is there is no way to get air into the attic on the cool side - the eaves aren't vented and aren't accessible and are sided over in aluminum (over the original wood). So the house pulls air from the living spaces. That's why we thought air sealing the attic and bringing it into conditioned space might be a solution.

There has to be a way to get everything vented properly. It will just cost more than you want to spend.

Have you gotten the price tag on sealing everything up with foam? It might likely be more expensive than having the eves vented.

I do understand the appeal of sealing the attic up though. And if new construction, with the intent from the time of conception through blue prints to construction that the attic would be sealed it might make sense.

My .02

We sprayed the floor joists of the house with closed cell. There's no real fear of a leak going unnoticed and it makes the floors more comfortable during winter- also no blowing vortex up the walls and between floor boards (it's ballooned framed). We were advised not to do the roof (from the insulation company- who has a vested interest) because of possible leaks- we have a slate roof. Instead they suggested we use the foil bubble wrap, between roof bays to help with heating and cooling.... plus add more pink stuff to floor of attic. We had a Noticeable increase in comfort level and a noticeable decrease in power usage. There are so many variables including climate, this is what we did in Central VA.

A conventional vented attic, regardless of the type of insulation, will work fine in your Zone 4, 5Marine Climate as long as:

1) the attic plane is tightly sealed;

2) you have the proper ratio of clear soffit vents to peak vents--much more than the ridiculous minimum 1:300 ratio which has no basis in building science, but was simply an arbitrary guess made in 1942;

3) you get rid of that whirlygig sucking conditioned air to the outside.

Instead of putting an air system for cool air in the attic, put it in the basement.

Thanks - problems - my soffit to vent ratio is currently 0:6 ! No soffit vent inlets at all, six 1 sqft turtle vents on the roofline near the ridge (3 windward, 3 leeward in the usual winds) .

There isn't a way to reach the upper floor with ductwork from the basement without doing major changes to the house - walls don't line up, there aren't any closets or dead spaces we can use. I'm adamantly against adding bulkheads to this Victorian. (so the current plan is 2 zones, one from the attic for the 2nd floor, 1 in the basement for the basement and main floor.)

The attic is probably 6-18 months down the pipeline, so I have time to figure out the right solution - obviously there's a lot of opinions out there on what that might be!

Whole house fan is definitely going. I've had it sealed off with fiberglass insulation for years.

Thanks for the reply!

If you're adamant about bulkheads and are certain the soffits can't be vented, then unvented it is.

Unvented roofs in your climate should be insulated with closed cell spray foam and with a Class II vapour retarder under the roof shingles. And be sure the shingle warranty covers your situation.

glad to see you doing research in advance.

I had to laugh about sealing the whole house fan with

fiberglass. when you move that fiberglass, look for

the dirt trails where it has filtered air from attic

into you living space for as long as it has been in place.

it makes for great visual for showing the air movement!

any ductwork in attic? heating equip? water heaters?

do you have recessed lights?

best of luck

I'm sure there's plenty of air infiltration, just less than the open fan would be!

Currently nothing in the attic - no ductwork, hot water heaters, or recessed lighting. Just some electrical runs, and once the 2nd floor a/c goes in there will be an air handler and ducts to the 3 bedrooms, one bath, and the hall. Only thing that enters the attic from the heated space is the DWV pipe headed to the roof and one rouge bathroom vent line (2nd floor bath) that just dumps into the attic (on the list of things to fix - so we just don't really use it). It's just a big empty space - rafters, various misc. insulations on the floor, and two openings - the attic scuttle, and the whole house fan. Ceiling is 9ft high at the peak, 22ft wide side to side, about 40ft long plus a smaller side gable.

Roof is multi-layers - original 1in planks for the underlayment, possibly the original cedar shakes, one or two layers of asphalt, topped with a good quality metal (Decra) roof. I'll double check with the company and be sure closed cell is approved.

possibly the original cedar shakes, one or two layers of asphalt, topped with a good quality metal (Decra) roof.

Whoa! The "beauty" of old homes. (One of many I owned for a few years had a total of five layers of shingles--one cedar and four asphalt.) Standard practice now is to strip and start over.

As noted by building scientist Dr. Lstiburek in my previous link with regard to unvented roofs:

"Asphalt shingles require special attention when installed on unvented
roof assemblies in hot-humid, mixed humid, and marine climates due to
inward vapor drive. To keep moisture out of the roof assembly, a roofing
underlayment with 1 perm or less (class-II vapor retarder) must be
installed under the shingles."

Is that combination of roofing materials able to do the job? I'd also be concerned about the condition of the roof sheathing under that abundance of roofing materials.

if you have no mechanicals or ducts in the attic...then take out the old

insulation & install 2" foam. use blown insulation to bring it up

to R-value for Nebraska.

you'd still get the air sealing benefits of the foam, and cost would

be manageable with conventional insulation.

you should start talking to foam companies in your area

to get an idea if anyone has done this hybrid insulation

and who is familiar with it.

now for the hvac system that you want to add upstairs...

is this a hallway with bedrooms off the hall & a closet

at the end of the hall?

if so, you would quickly re-coup the money it would

take to install the unit in the closet, and fur down the

hallway for ducts to serve each room.

and yes, it would drop the hallway a foot, and you'd loose

part of a closet, but the benefits are long term.

I've never regretted losing half of my linen closet

to put my ducts in conditioned space.

granted yours is a heating climate, and mine is a cooling

climate, but savings & efficiency should work out about the

same.

just food for thought.

best of luck.

The hallway is the stairwell and an entrance hall with 4 doors to the 3 bedrooms and bath (which was the 4th bedroom before conversion to a bath 40yrs after the house was built). Apparently the Victorian era farmers who built this house didn't believe in closets! One bedroom door at the top of the stairs, one across from the stairs, one halfway down the hall (bath) and one at the end of the hall (master). No linen closet, clothes closets are very small. My biggest closet in the whole house is 45" by 54"! And that's the master closet that I converted from a passageway between two bedrooms. Hall is only 3ft wide, so narrowing it further isn't really desirable! The door plus trim at the end of the hall only has about 1" of plaster on either side (30" door, plus 5" trim on either side). We are looking at possibly doing a small duct high velocity system - but I think if I do the 2nd floor system zone from the attic and put the vents in the ceiling, I can go with a standard system.

I will ask about doing a hybrid insulation mix - will that be beneficial if the air handler and main trunk ducts are up there? Or am I putting extra stress on the HVAC equipment - the attic currently gets wicked hot in the worst of the summer - probably easily 130-150 degrees !

worthy - the roof seems to be in great shape. No leaks, no signs of any leaks in the attic, and the workers I have had on the roof for various tasks (roofers, gutter guys) have commented on how solid it is.

fur down would be at the ceiling, not affecting the width of

the hallway, just the height.

building a closet isn't a huge deal if you can give up the

room in the room at the end of the hallway. the pros

far outweigh the cons.

my air handler closet is 24x24, built for specific ahu

installed. the remainder of the linen closet faces into the

bathroom, the ahu opens into the kitchen and the return

is in the living room. just the way my house is configured.

you could build a closet in master, use 2-3' for heating

system, and the rest for closet space.

but you have to want to do it.

as for putting equip/ducts in attic with foam seal

on attic floor, you'd install the system & ducts first.

then the foam & conventional insulation.

some efficiency loss obviously by putting R-8 ducts

into a 130 degree attic but the air sealing the the foam

would provide is the main point in your specific home.

in your first post you asked about make up air.

based on my years of testing & diagnostic work...

you have a lot of air sealing to do before reaching

a point where mua is required.

maybe in 4 cases of caulk...but until some major air

sealing is done...you have plenty of air exchanges.

if you plan on trying to achieve the degree of air tightness

that would require mua, you should start with a blower door

test to show you leakage areas. complete your air sealing

and re-test. close big holes & smaller holes show up.

best of luck

Thanks! Unfortunately, I don't think I can add a closet (other than the small 3.5x4.5 master closet I already managed to get in a room that had none to start.). There's just no wall space - large windows dominate the 3 outer walls (and they are a huge feature of the house, so I'm not giving any up) and the one inner wall is where the bed goes. (really, I'm not trying to be a person who always says "Yeah, but...."). It's just a quirk of the house - The HVAC guys I've had in have all scratched their heads over things like where they can run trunk lines and put in returns.

Thanks for explaining the order of install for floor sealing!

I'm not trying to get to the perfect airtight house - I just wanted to be sure I would accidentally create a situation that would backdraft the boiler or fireplace. No point in having an energy efficient house if it killed us all in our beds. (and yes, I have CO detectors!)

I will definitely look into the blower door tests.

Thanks again!

Hunzi

I'm glad to come across this thread because I'm also trying to figure out whether/how to add blown-in insulation to our attic, and possibly radiant foil. I hope I'm not derailing the thread by tacking on.

Our home is a roughly 120 year old Victorian, and it also has a sprinkling of old insulation in the (sealed) attic, but nothing more. And when I say attic, I should clarify--we actually have a finished attic/third floor but the very peak of the attic, above the ceiling of the finished area, is unfinished. It's like a capital A, where the lower half is the finished portion and the upper half is unfinished. I'm sure there's proper terminology for that but I don't know what it's correctly called.

We use the finished portion regularly, or at least we would if it didn't get very hot up there in both the winter and the summer. In the winter, we can counteract this by closing the HVAC vents so the attic is only heated by the hot air rising through the house, and that works well enough. But in the summer, we add two window units in addition to the house AC (to cool a space that's probably 400 sqft)--the window units are kind of a mixed bag because with the way they're installed, they let in a good portion of hot outside air around them through the window.

We're contemplating replacing the window units with a minisplit system in the attic alone, but I feel like it's worth exploring all the various possible ideas to try to keep summer heat out of the finished portion of the attic before installing a whole new additional system.

Any thoughts or ideas for me?