this is what I thought was going on here. your pictures just confirmed it.
now you understand the link I posted in relation to your situation?
so you actually have two situations of bump outs.
one at fireplace & one at cabinets (??)
that neither of the bumpout walls are insulated, contributes to the temp diffrences.
so you have choices as to how to deal with them.
easiest would be just to foam from basement where cantilvered joists exit
walls. this would stop air movement, but still leaves a big uninsulated area of wall.
harder would be to open the bump outs..fireplace from under deck at floor of bump out..
then foam the walls, fit foam sheating to bottom of bump out, air seal and replace osb sheathing.
then from inside basement do the final air sealing.
the other bump out..no access from underneath? then take off vinyl open wall
foam, foam sheath opening & air seal then replace osb, re-install vinyl.
just as you seal joists thru bottom of wall..you have to check at top of the
bump outs for the same situation.
foam insulation would be faster & easier, but I beams at openings make it
easier to seal than space joists. if you use foam sheathing you fit it tight
& caulk it in place. so, I disagree with your energy rater on that one.
and not now..but later explain the radiant barrier in pic five.
good stuff hearthman, I was thinking about you when I wrote my post!
what is that material you use on walls of fireplace..looks like radiant barrier??
Deb I think we're on the same page with the weatherization schedule. I see they have a foil-backed vapor barrier used over the poured concrete walls in the basement, which is quite common in this region. This house is about 90 minutes south of me, west of Baltimore. It doesn't do much good when the perimeter isn't sealed but it looks cool.
I don't really use any sort of radiant barrier per se around factory built fireplaces since their listing allows clearance to ordinary construction. My main thing is to use products that block air infil/ exfil that have a reasonably low fire spread and are not good food for mold and do not disintegrate as soon as they get wet. That's why I love T-ply and hate drywall in dogsheds and chases. Some installers will sit the unit on a piece of Homosote board as a thermal energy break to the subfloor but that's really only a major problem with concrete floors. Doesn't hurt on frame construction but you do have to make that 1/2" adjustment to your facing materials.
Dirty insulation= air flow. The mixed bag of fiberglass batts in those joist bays are essentially cosmetic and do almost nothing to insulate. Remember, unless insulation is encapsulated on all 6 sides it does not meet its stated R-valve by a long shot.
thermo ply? I remember seeing pics of it from your postings.
"I see they have a foil-backed vapor barrier used over the poured concrete walls in the basement, which is quite common in this region."
interesting...does it actually do anything as far as radiant heat, or is it the vapor barrier properties
that it is used for?
I see this cantilevered situation often..the things you notice when you drive around..LOL!
most common in new construction is at porches & balconies, cuz we don't have basements
yeah..basic weatherization would have benefitted this builder, but at least
homeowner on on the right track now.
I guess some salesman told the builder this foil-backed insulation is better than just Kraft paper. It also picks up spills faster than Bounty and slices fruit not to mention trims inches off your waist! This is almost like saying I have insulation in my home--I have a big pile of it lying on my living room floor but I'm still cold. Mis-application of technology or incomplete application. About like using Tyvek without the tape on the seams.
yeaaaaahhh man, Thermo-Ply and Thermo-Sheath. Cool stuff. I use it as fireblocking, draft stopping, protecting floors from work, and of course, my favorite chase wall sheathing material. If you have a chase/ dogshed less than 8ft. tall, you can wrap the inside like a Jiffy Pop with two sheets with one seam horizontally. You measure and cut for two horizontal sheets and bend the sides at 90* but don't cut them into separate pieces. You should have a sheet with three sides that can slip into the chase like a glove. Nail it to the framing with roofing nails or roofing caps. Seal the central horizontal seam with Iron Grip UL 181 tape and pookie the perimeter joints to the framing and subfloor with duct mastic--Done and tight as a duck's rear end. T-ply is thin so I can usually use it without encroaching in my clearance to combustibles the way 1/2" drywall can. If a AHJ forces you to line a chase with drywall, beg them to allow you to use MR board. There is no need for type 'X' fire resistance board unless you are in a commercial application such as a "shaft"---not a chase as in over 4 stories where the full building code then requires fire rated construction. T-ply is fast, light, easy to work with once you've had a little practice and meets all my criteria. There are typically 4 grades in strength but the lowest is fine for weatherization work.
I am looking for a small unit spray foam applicator but most I see that call themselves "spray" and just glorified can foam in jugs with a funky applicator nozzle. I want to batter walls and joints and not just filling voids. Any suggestions? TIA
Thanks for all the feedback. hearthman, you're correct, that foil backed insulation is what's wrapping my concrete foundation. It's in pretty much all the houses around here from the mid 90's on. I have to reattach it in some areas, it's fallen down due to me resting things against it.
I'll call FireSide to have them look at my fireplace chase. I've already had a fireplace shop out (located in Rockville MD) and they said not to do anything with the chase. The guy said I needed to maintain clearances and I can't add any insulation because it would cause the chase to overheat. Then he said I needed to bring in air elsewhere to keep the fireplace from being drafty. They were out right before I had the ventilation system installed. Basically the guy agreed with my energy audit company and said my house was too tight. It did seem like he had a point though. When he opened the window next to the fireplace the draft from the fireplace stopped. After I installed the ventilation system and pretty much nothing changed with the fireplace draft is one of the main reasons I posted here.
This is why I've been all over the place! And also why I really appreciate all of your help!
The bump out in the kitchen does have insulation in the walls. I checked it by opening the electrical outlets and pulling out the dishwasher and making a small hole in the drywall. So I'm not 100% why it's so drafty. I think since the cantilever is just like the fireplace cantilever, fiberglass batts shoved between the joists that's the main problem. The energy audit company did identify a draft up each corner where the plywood butted up against each other. She suggested I spray foam under the gap between the corner vinyl j-channel and the plywood.
So it sounds like the best course of action is to:
1. Have the upstairs attic unit duct blasted.
2. Seal unit upstairs accordingly
3. Have the fireplace chase opened from the outside and properly insulated with Thermo-ply and Thermo-Sheath.
.... How do you completely seal it when you're doing it all from the outside. There is no access now from the inside.
4. Spray foam/rigid foam the cantilever for both the fireplace and kitchen bump out.
... So should I use rigid foam on the bottom of the bump out instead of plywood like there is now? Or more likely: rigid foam then the plywood? Except that means the bottom may stick out too far.
Does this all sound right?
Just made an appointment for duct blasting. Tomorrow at 2pm. Got the name of the company off of the http://www.resnet.us/ site.
Thanks again. Hopefully they find something!
When you open a window, you are changing the Path of Least Resistance. Since the rest of the house is like Tupperware, the leaks at the fireplace and bay window were the only substantial leaks left. The air needs to come in regardless so its just a question of whether or not you're going to control where it infiltrates and how much or is nature. It's T-ply or T-Sheath-not both. Foam/ caulk/ seal then insulate, then interior sheathing with the T-ply/ T-Sheath in lieu of drywall.
As for weatherizing from the outside, it helps to do like Steve Martin and "get small". Otherwise, it's a fun day. I typically cut a large access in the outer sheathing big enough for me to crawl in like a window. I vacuum/ wipe down the unit with citrus solvent. Then foam/ caulk/ seal joints and gaps. Next, insulation. I prefer Roxul mineral fiber insulation, not for any fire rating but I think its a lot easier to handle and keep my full loft and fill the bays with it. It's great chinking the cutout for the gas line wherever it enters the chase. Use a serrated bread knife to trim it. Then T-ply with UL 181 butyl-backed tape over the seams or mastic. To seal the "window", I cut some T-ply about 1" bigger than the footprint of the window and bend tabs in so it resembles to lid of a shoe box. Run two straps across the inside face of the framing as a backer. I shove this into the stud bay so the T-ply is essentially flush with the rest of the chase liner then nail the tabs to the framing. The straps help keep the "lid" from going in too far or falling into the chase. Once in place and secured, I pookie the joints with mastic, insulate, replace plywood/ OSB sheathing and caulk the seams where I cut it out. Replace the house wrap using approved tape, then replace the siding and pat yourself on the back. When done celebrating, tackle the cantilever or you can do it concurrently. I block off the joist bays over the foundation wall with T-ply, duct board or rigid foam board and pookie all joints with mastic. Again, pookie all the seams from below, insulate then sheath. You really should use a CDX plywood underneath. This is an area prone to condensation and rot. If you use OSB or even my beloved T-ply, it may soften and allow rodents to enter. Some builders will cover the undersize with either vinyl siding or aluminum coilstock. I reccomend against the impervious sheet aluminum. You want this area to breathe and dry out. Plastic siding is a suitable inexpensive alternative. When you go to install the plywood against the underside, you run beads of latex caulk around the perimeter for a removable airtight seal. Don't use silicone caulk. You want to be able to remove that plywood in the future God forbid.
As for the driving force of your depressurization, what about upper level leaks? We discussed the duct work but what about the attic penetrations? Attic stairs/ hatch, recessed lights, mechanical chases, speakers, bathroom fans, etc.?
I've been following this thread for a bit but haven't replied because I just didn't have enough time to type everything I wanted to say. At this point most of it has been covered but just wanted to stress that for all that infiltration at the lower levels there has to be ex-filtration at a higher level. I suspect the duct blaster is going to identify that.
One more thought is the roofs of those bump-outs. I've seen problems there, the wall sheathing not continuous with soffit vents basically venting through the wall.
All in all sound like you are on the right track and look forward to hearing how it works out. We can all learn here and especially liked hearthmans approach to the fireplace chase. I would like to see him doing that!
I've been following this thread from the start. Lots of really good thoughts from everyone. The OP has indicated the major "air in" spots, but I have not heard any good ideas on the "air out" spots. The "air in" seems to occur regardless of whether or not the HVAC air handler is on, and I don't see stack effect causing so much "air in". My intuition is for wind driven air infiltration/exfiltration. Some homes are just in wind tunnels, caused by terrain and the homes that surround them. I've had one homeowner who has her bar-b-que grill blown all across her yard with the propane tank still attached because of this wind.
A simple smoke pencil should determine where the "air out" is, since we know where the "air in" spots are. Infrared would work also. The use of a manometer for pressure differences between rooms/hallways/attic/basement would be useful also.
Air in = Air out, and visa versa.
The answer is there, it's just hidden; that's what testing equipment is for. Even a piece of tissue paper can be a testing instrument. Walk around with one and hold it near windows, light fixtures, bathroom exhaust vents etc..., and see if it blows out or in. Air in = Air out.
tipsrfine, I heard the same thing about air in must equal air out. That's why I was really trying to focus on the upstairs before tackling the bump outs. It stinks because those two bump outs are in the two most heavily used rooms (family room/kitchen) making them really drafty and uncomfortable.
I thought driven wind as well at some point but we're fairly well protected by trees and other houses. My friends neighborhood a few minutes away sits up high and the houses there are always loosing siding and roof shingles. When sitting on his deck you'd get big gusts throwing paper plates and cups of beer :-). Unless there's a storm coming we've never had issues with strong winds.
I agree, I think the issue is just hidden, but damn it, I'd like to find it! I'm really hoping the duct blasting today will give me that smoking gun. If it doesn't, I'm not even sure what to try next!
hearthman, almost all of the ceiling penetrations that were identified on the audit report were sealed with caulk and expanding foam. The bath fans (they were really bad!), recessed light (only one), attic hatch, almost all electrical boxes, almost all plumbing penetrations and a mechanical chase were all sealed up. The only item left was the top plates, I tried to seal some of them, but it was just too difficult.
The worst part, it felt like sealing those items didn't make a bit of difference. I know using my hand isn't scientific or accurate, but that breeze felt pretty much the same the night after I did the sealing.
I've somewhat verified the ceiling penetrations by walking around with my black and decker temperature gun. The bath fans, recessed light and attic hatch are now at the same temperature as the ceiling around it.
Thanks, and I'll post back with what the duct blasting company finds.
looking forward to duct testing results.
make sure that return leakage is seperated from supply leakage.
what to expect..in case you don't know.
each supply grill will be covered, return will be covered with duct
blaster & sealed off air tight also.
then ducts will be depressurized to 25 pascals.
this will give you the amount of leakage.
what I like to do, is once the leakage #'s have been recorded,
to reverse the air flow of the fan. going from depressurizing,
to pressurzing the duct/return system.
then go into the attic with a roll of tape to mark leakage sites.
supply take offs on plenums, plenum to equipent connections,
return to return framing & framing to framing members & attic floor
should all be felt around for air leakage.
the duct blaster isn't measuring now...its just blowing, don't expect
the readings to tell you anything. you are simply finding the leaks.
you want to be in the attic, verifying & marking the leakage sites.
then address as in my garden web post.
ask the tech to do this. if they haven't done this before...its a
real eye opener. instead of just #'s you know where it leaks.
to me the whole equiv leakage area doesn't mean much if you don't
know where the leaks are.
as you seal your high leaks & low leaks your mechanical ventilation
system will provide the air changes per hour as needed.
hearthman & I seem to be on the same page as to opening the
bumpouts & sealing them. this is basic weatherization, done right.
sometimes it is close quarters, but if you have the want to do it, and
a plan...it works out well.
you'd be amazed at how much you can do by cutting a 2'x3' hole in the wall.
having spent many a day inside return air chases...you learn it helps to
have someone 'outside' to hand you sheathing materials.
best of luck.
energy_rater_la, thanks for the information! I wasn't 100% sure what a duct blasting entailed. I will definitely ask them to run the test in reverse to locate the leaks. Again, I'm so appreciative of the help, I wouldn't have even thought to ask them about this!