Can someone actually explain what thermal bridges actually are?
I have the gist of the idea... but like my structural connections thread, I have found it very hard to find actual diagrams or pictures illustrating what thermal bridges are and how to fight them with thermal breaks.
I GIS'ed, I've browsed... all I get are tons of infrared pictures with descriptions like "HERP DERP, AVOID THERMAL BRIDGING."
I'm assuming in an example of say like a concrete slab protruding out of an exterior wall is a thermal bridge?
And a thermal break would be... like what?
Scoring the concrete deep enough and filling it with rubber or silicone?
UG:
lots of resources on thermal bridging online. it's basically a short-circuiting of a wall/floor/roof/window assembly causing the building to bleed heat (energy).
there is a pretty decent overview from the 2009 passivhaus conference (PDF)
thermal break is something either w/ low conductivity or enough insulation set between two members to reduce or eliminate thermal bridging.
examples:
adding foam insulation (EPS/polyiso/XPS) outboard of 2x exterior wall framing, as the 2xs will short circuit your wall assembly.
quality edge spacers in multipaned windows that reduce loss of heat between exterior and interior layers
cork set between inner and outer leaves of a wood window assembly
So, is it safe to assume that thermal bridging concerns are of utmost importance in light-framed (wood, steel, even concrete) buildings versus more "monumental [heavy]" buildings (concrete, cast iron, stone) that have significant thermal masses?
more so in steel buildings than wood, but still a concern.
definitely an issue in concrete buildings as well, as concrete virtually has no insulating value at all.
regarding thermal mass, it depends on who you talk to. a lot of the passive solar folks from the 60s-80s are big advocates of massive walls (masonry, water) with little or no insulation. which is great, if you live in the desert - boston, not so much.
if the mass you are hoping to use for thermal storage/lag is outside the thermal envelope (insulation) then that won't heat the building.
of course, there are exceptions to the rule (SANAA @ the zollverein, for example) and if you want to go that route, i'd talk to transolar or robert meierhans.
Classic example of a thermal bridge is a balcony. Unless you make your balconies as separate structure, there is not much you can do about this one.
Another detail that architects often get wrong is parapets. You have the insulate the inside vertical surface, or else you will have a thermal bridge.
Doing anything structurally fun is a no-no in climates where thermal bridging can cause damage.
Taller buildings are more prone to show damage from thermal bridges due to a so called 'stack-effect': inward and outward pressures become great in tall structures.
Thermal bridging becomes very dangerous when combined with humidity and dewpoint conditions. I've seen entire brick walls buckle out on buildings 30 years old because the architect decided to run edge of slab to the exterior finishes line.
that's a weird detail. hope you never have to replace the window frame.
You would also want to push the window to line up with the exterior face of the stud. That way you eliminate the yellow (whatever yellow is supposed to be - sheathing?) from turning in at the opening.
If gray is supposed to be rigid insulation, then yes, that's a thermal bridge.
What kind of fucked up framing is brown supposed to represent? Weird.
that is an odd detail... what are you trying to do, UG?
a. the glazing is a unit, look @ optiwin or duratherm's window details for more info. are you trying to reinvent the wheel (don't!)
b. for thermal efficiency, it's better for the window to be in the wall rather that at the exterior face, this spreads the isotherms better. 'innie' or 'halfsie' windows have a lower thermal bridge coefficient, and a better U-value. i know US mfr's like the nailing flange, but this makes for horribly inefficient windows. bronwyn barry's PHNW slide talks more about PH windows (PDF)
c. yeah, if the grey is rigid insulation, that's closer.
UG, if you are interested in thermal bridging calcs, i would recommend DL'ing THERM.
holz. I'm a bit confused about your window placement point. PDF presentation is nice, but I find the details used in there to be very lacking. the ones used on page 8 are downright misleading. Is that rigid insulation? If so, the 'improved' version fetures a massive thermal bridge at the sill, and the 'heat' diagrams are a nice photoshop exercise in detachment from reality.
Details on pages 19 and 20 are also massive thermal bridges. page 21 features a 'euro header'. Detail looks proper, although I can see the construction crew fucking up that one royally.
All of these details are geared towards residential construction. While it's nice that residential industry is looking into building science issues, there is something very 19th century about overall materiality.
In my opinion, lose batt insulation should be used for sound attenuation and little else. Air and vapor barriers should be same product in the same plane. Details shown still have air barrier shown on the inner side of the wall framing. That's archaic.
On second though, the 'euro header' is BS. They don't use wood framing in europe. Therefore they also don't use batt insulation that fits inside studs. Chances are, the building uses concrete block for wall construction, and the header is masonry. Air barrier will be on the outer face of CMU. That detail needs to be renamed to 'fargo header' or something more appropriate.
The framing is some weird system of insulated light framing I found-- obviously half-assed. The window was some window system for applying commercial glazing to residential applications.
When I was looking over the detailing for the windows, I did think the flashing bit was off (as in difficult, expensive, overtly custom. However, I think for intent and purpose it would function as intended.
This was basically like 45 minutes to an hour of reading followed by a 10 minute quick drawing.
Cream white - Gypsum board.
Brown - wood
Blue - metal window framing
Pink - insulation
light coffee - OSB or hardiboard
grey - rigid insulation
Greenish yellow - flashing
lighter red brown - exterior glassing
Oh, I'm just trying to understand detailing a bit more. It seems with the current trend of energy efficiency, you ought to be able to draw at least a wall that would minimize energy consumption.
Just working on my free Masters of Fantasy Architecture. Also, trying to get archinect back to architecture.
the details are ripped from EU presentations, but that doesn't make them any less applicable. the slide on p. 8 is showing that pulling the window inboard of the exterior and wrapping insulation over the edge (thereby reducing exposed window frame) you get a much lower psi coefficient (thermal bridging). PHI isn't putting out protocols w/ thermal bridging in it - there is a separating material under the sill, or it's stainless, to reduce the psi value.
those details work on residential, institutional and commercial projects... i can show you a number of projects if you'd like.
there are a number of instances where you don't want your air barrier to be your vapor retarder. if they're the same product are you using fluid applied? what happens when you penetrate the fluid applied or membrane with fasteners for the facade? you've created hundreds of little holes (if not screwed) that will drive moisture into your wall assembly.
a lot of PH projects are pushing air barrier (typically OSB) to the interior so that you can effectively and efficiently create an airtight building. all of the building sci guys are promoting this as well (e.g. the airtight drywall approach, which can be problematic), so it's hardly archaic.
finally, there are tons of architects using wood framing in europe (a good majority of the PH projects in austria, for example) and they utilize fiberglass and cellulose batts, and wool as well.
I was also reading another presentation where it said you can essentially increase energy efficiency (and minimize thermal bridging) by increasing the amount of glazing.
if the glazing is triple-pane w/ swissedge spacers and a rockin-low u-value this actually makes sense. mostly because frames suck, and US installation psi-values are terrible.
if you are going to have a 4'x8' opening (theoretical) and were going to do one window and frame, as opposed to 3 mulled windows, you would have less thermal bridging and heat loss. frames have lower u-value than choice triple glazing (typically, there are exceptions to the rule)
i don't think you necessarily increase energy efficiency, because if those windows are facing north, you'd still be bleeding BTUs.
I guess my issue with pulling the window inwards relies on having an insulated cavity for it to work. That 'heat' diagram that goes from blue to red would look drastically different if you were relying on rigid insulation alone (blue to red spectrum would be contained in a very tiny portion of the overall wall assembly). In an assembly with rigid insulation only, pulling the window back only creates problems. Thus all commercial grade windows have a very predictable relationship with insulation and waterproofing.
Primary reason for use of lose insulation in residential projects is cost. It's still a magnitude cheaper to dump a bunch of batts in a cavity than it is to properly install an adhered extruded/expanded type.
there are a number of instances where you don't want your air barrier to be your vapor retarder.
I was always though (on professional level) that this is an outdated way to approach waterproofing. Yes, penetrations through a waterproofing membrane are an issue. That can be avoided by proper installation sequencing. Any anchors, cladding supports and penetrations need to be installed prior to waterproofing (regardless if it's fluid applied or adhered).
Having air barrier on the inside of the cavity scares me as anyone trying to mount a TV support on the inside will easily puncture it.
Holz. from your experience, are most PH projects cavity insulated? Are there any good masonry examples in US? If I were involved on a PH project, I would intuitively try to steer away from organic materials, for longevity's sake.
Unicorn, you should tell that poor sap facing a quarter million student loan burden in the other thread about your free Masters of Fantasy Architecture.
It may be all wrong, but your stab at detailing is still much stronger than what a 4th year architecture student would be able to produce.
i think you are correct on the insulated cavity for the innie windows. but i'm not opposed to cavity insulation (lower embodied energy and cost, typically)
i would avoid rigid - only insulation for the most part, but even with SIPs, it's still more efficient to bring the window in from the exterior layer.
i'm not a big fan of petrol-based products (e.g. rigid insulation, spray foam) but i would/have used rigid as a thermal break outboard of a stud-wall, under slab, etc.
by placing the air barrier towards the inside, you allow opportunity to still fix any holes/leaks after installation of WRB/'outsulation'/rainscreen/windows. there are a number of people that advocate air barriers on inside and outside for belt and suspenders approach. air leakage is a huge source of heat loss in most projects, somewhere between 25-40%.
to bypass the TV bracket penetrating the air barrier (one of the reasons i'm not a fan of the airtight drywall approach) you could throw up battens and then GWB inboard of the air barrier (e.g. OSB) - that's what we did routinely when i worked in EU. it also helps alleviate un-plumb walls and moisture issues.
there are a number of excellent masonry-based PH projects (some excellent concrete and CMU projects) but they're all in EU, at least the really successful ones. A few retrofits in US, mainly in brooklyn (look at loadingdock 5)
I also agree with holz about the rigid insulation part.
Most foam makes who produce high-quality foam board fore rigid sheet insulation typically use freon chlorofluorocarbons as a blowing agent to 'inflate' the foam.
Depending on where the vapor barrier lies, those CFCs could be leeched directly into the home which presents a significant health hazard (as do any interaction with completely synthetic compounds). Also, construction rigid foams are treated (brominated) with another more hazard compound (hexabromocyclododecane) that also leeches into the surrounding environment.
In addition, rigid foam insulation often has a very limited, ~10 years, functional operating life meaning the r-value will drop and the sheeting will eventually fail. There's a lawsuit around right now dealing with this.
Historically, fiberglass batts became the preferred choice for residential construction in the late 20th century; it is useful to understand how this evolved, as there is no inherent advantage to batts. [Commercial and industrial construction do not use batts.] In the 1970s, in response to oil price shocks, many US state governments sought to cut home heating oil usage by increasing building code insulation requirements for all new housing. At the same time, Owens Corning fiberglass lobbied intensively to convince the building officials who wrote and administered the four separate building codes then used in the USA. They also aimed to eliminate other kinds of housing insulation material (such as polyurethane) on safety or hazard grounds. The result was that Owens Corning successfully lobbied for mandatory 2 × 6 in (51 × 150 mm) wall framing with fiberglass insulation. This suited timber merchants just as well as it suited Owens Corning. Then, given the predominance of non-wind-proof cladding materials, and the prevalence of sleet (wind-blown ice) during the winters of the northern states, a need was created to ensure the whole 140 mm of fiberglass stayed ice-free and dry at all times. Building code officials also made it mandatory to fix and seal wind-and-sleet-proof sheathing under all claddings. This suited the plywood industry very well, which in turn led to the North American development of its now-massive oriented strand board (OSB) industry. Other insulation materials present advantages in terms of stopping air, moisture migration, and recycling for sustainability not found in fiberglass batts.
So yeah. I've been poking around wikipedia in search of chemical compositions of different insulation types. I think I would have gone into engineering instead of architecture had I not just barely passed chemistry. Chemistry was my learnin' kryptonite in my teen years...
So. Lose batt insulation is a lot more environmentally friendly, especially since it can be largely made of recycled content. Unicorn is correct about content of CFC's and HFC's in rigid insulation, although it's possible to get rigid insulation without any of those.
High-density insulation will have weird chemicals in it, primarily due to its use: below grade foundation insulation (where chemicals protect the insulation from water damage), and horizontal insulation (foot and vehicular traffic).
All petroleum based insulation will give off nasty chemicals in case of fire.
Some rigid insulations will lose their R value as they give off gasses, but will settle at a certain environmental equilibrium.
In 80 or so projects I worked on, I have never dealt with batt insulation (outside of interior sound attenuation). None of the project were single-family residences though. So this is all kind of new to me!
My only personal experience with batts is discovering black mold in a wall cavity of a rental (yuck!), and building out a loft space. For the later, I didn't use a mask, and had a nasty cough for the next 6 months or so. So I may be biased. I've stuck styrofoam (expanded) and blue foam model building foam (extruded) in my mouth many times. To no ill effects! So there!
By the way, I really wish there were more technical discussions on archinect! I feel like I learned a few things tonight. Judging by the number of willing participants in this thread (three), I shouldn't expect too much.
Off to the OMA threads to see if one of those buggers has landed an internship! I hear Rem is a dreamboat come wintertime...
A little more reading, a little more drawing. I think I actually like detailing despite not knowing shit about wall assemblies? I will avoid telling future employers about this little love affair.
Looks close to being right. You need a steel lintel at the point where window meets the wall (as well as flashing). Not sure what the dark gray shape is on the outside. Some kind of stone veneer?
Orange stuff- whatever it is, will be gone. Drywall will be installed onto CMU wall by use of resilient channels (either hat or S shaped).
not quite sure what's happening in the cavity. All you need is waterproofing applied directly to CMU (spray applied bituminous dampproofing works really well in these conditions) followed by rigid insulation (either mechanically fastened or adhered). air space, brick veneer, Done! push the face of glass inwards so it aligns with the face of insulation (standard practice) make sure you draw in weep holes 24 o.c. for bonus points!
You show that the CMU is steel reinforced. There's no need, unless your wall is taller than 9 feet (or around that, a code requirement) or CMU is load bearing (I rarely ever see this, but it's possible).
This is all with assumption that left side is exterior :)
Left side
standard masonry bricks.
White = plaster/mortar fill.
Black things = brick ties
Greenish thin = moisture wick
Grey thing = brick window header
Middle between brick and CMU
Dark blue = wire mesh
Thin pink line between wire mesh and teal = moisture barrier
Teal = polyiso foam sheets
Brown = furring strips
Right (CMU)
medium grey = cmu
Dark grey = header
pink (not really visible but between CMU and orange) = vapor moisture barrier
Orange = sprayed in foam insulation
Brown = studs
cream = drywall
that's way too complex for what is usually one of the most simple of wall assemblies. Also, you should never have insulation on the inner side of waterproofing. You want trapped moisture (due to dewpoint) to go away from the occupied space.
brick, airspace, polyiso, water membrane, CMU, drywall (optional), That's it!
Brick ties would be installed in the CMU coursings, not drilled in. Adjustable brick ties tend to work the best.
You want air space behind the brick veneer, not mortar. Brick is a very porous material, and is best treated as 'rainscreen principle' meaning you want the space behind the brick to be vented. This is where weep holes come into play (they drain out trapped moisture in the cavity).
No need for furring strips (unless you are cladding your facade in plywood).
Insulation will come on the outer side of waterproofing, which itself is applied to the outer side of CMU. The only time you would want insulation and waterproofing on the inside would be if you were designing a meat locker, or similar.
You would not use 'wire mesh' (aka expanded metal lath) unless you were planning a stucco building of some sort.
You can use a masonry lintel (as you have draw it) in lieu of a steel one, but the size of it would be closer to the size of the brick units.
Thermal and moisture protection is a very difficult subject to learn and detail properly. I continue to learn more on a daily basis.
One of the best lessons from a colleague was his challenge to draw both the line of waterproofing and line of insulation. If there were ever a discontinuous line, it was a good sign that there might be a problem with the detail.
The topic of the proper location for the vapor barrier and insulation is debated often in my region. It really depends on your climate and is "easier" for architects in Minnesota and Miami, a little more ambiguous for those around the Mason Dixon Line. (I was thrilled to find out that Grace makes a breathable waterproofing membrane that is more durable than Tyvek. Hurray!!)
Unicorn Ghost: you might want to find out if your local AIA chapter has a Building Enclosure Council (BEC) - they often have seminars on these topics. I commend your efforts for tackling subjects like these.
Tiny bridges made of tinier fires (Thermal Bridges)
Can someone actually explain what thermal bridges actually are?
I have the gist of the idea... but like my structural connections thread, I have found it very hard to find actual diagrams or pictures illustrating what thermal bridges are and how to fight them with thermal breaks.
I GIS'ed, I've browsed... all I get are tons of infrared pictures with descriptions like "HERP DERP, AVOID THERMAL BRIDGING."
I'm assuming in an example of say like a concrete slab protruding out of an exterior wall is a thermal bridge?
And a thermal break would be... like what?
Scoring the concrete deep enough and filling it with rubber or silicone?
UG:
lots of resources on thermal bridging online. it's basically a short-circuiting of a wall/floor/roof/window assembly causing the building to bleed heat (energy).
there is a pretty decent overview from the 2009 passivhaus conference (PDF)
thermal break is something either w/ low conductivity or enough insulation set between two members to reduce or eliminate thermal bridging.
examples:
adding foam insulation (EPS/polyiso/XPS) outboard of 2x exterior wall framing, as the 2xs will short circuit your wall assembly.
quality edge spacers in multipaned windows that reduce loss of heat between exterior and interior layers
cork set between inner and outer leaves of a wood window assembly
So, is it safe to assume that thermal bridging concerns are of utmost importance in light-framed (wood, steel, even concrete) buildings versus more "monumental [heavy]" buildings (concrete, cast iron, stone) that have significant thermal masses?
more so in steel buildings than wood, but still a concern.
definitely an issue in concrete buildings as well, as concrete virtually has no insulating value at all.
regarding thermal mass, it depends on who you talk to. a lot of the passive solar folks from the 60s-80s are big advocates of massive walls (masonry, water) with little or no insulation. which is great, if you live in the desert - boston, not so much.
if the mass you are hoping to use for thermal storage/lag is outside the thermal envelope (insulation) then that won't heat the building.
of course, there are exceptions to the rule (SANAA @ the zollverein, for example) and if you want to go that route, i'd talk to transolar or robert meierhans.
Classic example of a thermal bridge is a balcony. Unless you make your balconies as separate structure, there is not much you can do about this one.
Another detail that architects often get wrong is parapets. You have the insulate the inside vertical surface, or else you will have a thermal bridge.
Doing anything structurally fun is a no-no in climates where thermal bridging can cause damage.
Taller buildings are more prone to show damage from thermal bridges due to a so called 'stack-effect': inward and outward pressures become great in tall structures.
Thermal bridging becomes very dangerous when combined with humidity and dewpoint conditions. I've seen entire brick walls buckle out on buildings 30 years old because the architect decided to run edge of slab to the exterior finishes line.
holz. covers thermal breaks pretty well.
Like this?
Yes/no?
that's a weird detail. hope you never have to replace the window frame.
You would also want to push the window to line up with the exterior face of the stud. That way you eliminate the yellow (whatever yellow is supposed to be - sheathing?) from turning in at the opening.
If gray is supposed to be rigid insulation, then yes, that's a thermal bridge.
What kind of fucked up framing is brown supposed to represent? Weird.
that is an odd detail... what are you trying to do, UG?
a. the glazing is a unit, look @ optiwin or duratherm's window details for more info. are you trying to reinvent the wheel (don't!)
b. for thermal efficiency, it's better for the window to be in the wall rather that at the exterior face, this spreads the isotherms better. 'innie' or 'halfsie' windows have a lower thermal bridge coefficient, and a better U-value. i know US mfr's like the nailing flange, but this makes for horribly inefficient windows. bronwyn barry's PHNW slide talks more about PH windows (PDF)
c. yeah, if the grey is rigid insulation, that's closer.
UG, if you are interested in thermal bridging calcs, i would recommend DL'ing THERM.
holz. I'm a bit confused about your window placement point. PDF presentation is nice, but I find the details used in there to be very lacking. the ones used on page 8 are downright misleading. Is that rigid insulation? If so, the 'improved' version fetures a massive thermal bridge at the sill, and the 'heat' diagrams are a nice photoshop exercise in detachment from reality.
Details on pages 19 and 20 are also massive thermal bridges. page 21 features a 'euro header'. Detail looks proper, although I can see the construction crew fucking up that one royally.
All of these details are geared towards residential construction. While it's nice that residential industry is looking into building science issues, there is something very 19th century about overall materiality.
In my opinion, lose batt insulation should be used for sound attenuation and little else. Air and vapor barriers should be same product in the same plane. Details shown still have air barrier shown on the inner side of the wall framing. That's archaic.
On second though, the 'euro header' is BS. They don't use wood framing in europe. Therefore they also don't use batt insulation that fits inside studs. Chances are, the building uses concrete block for wall construction, and the header is masonry. Air barrier will be on the outer face of CMU. That detail needs to be renamed to 'fargo header' or something more appropriate.
The framing is some weird system of insulated light framing I found-- obviously half-assed. The window was some window system for applying commercial glazing to residential applications.
When I was looking over the detailing for the windows, I did think the flashing bit was off (as in difficult, expensive, overtly custom. However, I think for intent and purpose it would function as intended.
This was basically like 45 minutes to an hour of reading followed by a 10 minute quick drawing.
Cream white - Gypsum board.
Brown - wood
Blue - metal window framing
Pink - insulation
light coffee - OSB or hardiboard
grey - rigid insulation
Greenish yellow - flashing
lighter red brown - exterior glassing
Oh, I'm just trying to understand detailing a bit more. It seems with the current trend of energy efficiency, you ought to be able to draw at least a wall that would minimize energy consumption.
Just working on my free Masters of Fantasy Architecture. Also, trying to get archinect back to architecture.
"UG, if you are interested in thermal bridging calcs, i would recommend DL'ing THERM."
I'll leave architecturing to actual architects. But I will check it out, soonish.
steel,
the details are ripped from EU presentations, but that doesn't make them any less applicable. the slide on p. 8 is showing that pulling the window inboard of the exterior and wrapping insulation over the edge (thereby reducing exposed window frame) you get a much lower psi coefficient (thermal bridging). PHI isn't putting out protocols w/ thermal bridging in it - there is a separating material under the sill, or it's stainless, to reduce the psi value.
those details work on residential, institutional and commercial projects... i can show you a number of projects if you'd like.
there are a number of instances where you don't want your air barrier to be your vapor retarder. if they're the same product are you using fluid applied? what happens when you penetrate the fluid applied or membrane with fasteners for the facade? you've created hundreds of little holes (if not screwed) that will drive moisture into your wall assembly.
a lot of PH projects are pushing air barrier (typically OSB) to the interior so that you can effectively and efficiently create an airtight building. all of the building sci guys are promoting this as well (e.g. the airtight drywall approach, which can be problematic), so it's hardly archaic.
finally, there are tons of architects using wood framing in europe (a good majority of the PH projects in austria, for example) and they utilize fiberglass and cellulose batts, and wool as well.
I was also reading another presentation where it said you can essentially increase energy efficiency (and minimize thermal bridging) by increasing the amount of glazing.
MIND F*CK.
unicorn,
if the glazing is triple-pane w/ swissedge spacers and a rockin-low u-value this actually makes sense. mostly because frames suck, and US installation psi-values are terrible.
if you are going to have a 4'x8' opening (theoretical) and were going to do one window and frame, as opposed to 3 mulled windows, you would have less thermal bridging and heat loss. frames have lower u-value than choice triple glazing (typically, there are exceptions to the rule)
i don't think you necessarily increase energy efficiency, because if those windows are facing north, you'd still be bleeding BTUs.
holz.
great response.
I guess my issue with pulling the window inwards relies on having an insulated cavity for it to work. That 'heat' diagram that goes from blue to red would look drastically different if you were relying on rigid insulation alone (blue to red spectrum would be contained in a very tiny portion of the overall wall assembly). In an assembly with rigid insulation only, pulling the window back only creates problems. Thus all commercial grade windows have a very predictable relationship with insulation and waterproofing.
Primary reason for use of lose insulation in residential projects is cost. It's still a magnitude cheaper to dump a bunch of batts in a cavity than it is to properly install an adhered extruded/expanded type.
there are a number of instances where you don't want your air barrier to be your vapor retarder.
I was always though (on professional level) that this is an outdated way to approach waterproofing. Yes, penetrations through a waterproofing membrane are an issue. That can be avoided by proper installation sequencing. Any anchors, cladding supports and penetrations need to be installed prior to waterproofing (regardless if it's fluid applied or adhered).
Having air barrier on the inside of the cavity scares me as anyone trying to mount a TV support on the inside will easily puncture it.
Holz. from your experience, are most PH projects cavity insulated? Are there any good masonry examples in US? If I were involved on a PH project, I would intuitively try to steer away from organic materials, for longevity's sake.
Interesting topic nonetheless...
Unicorn, you should tell that poor sap facing a quarter million student loan burden in the other thread about your free Masters of Fantasy Architecture.
It may be all wrong, but your stab at detailing is still much stronger than what a 4th year architecture student would be able to produce.
steel,
i think you are correct on the insulated cavity for the innie windows. but i'm not opposed to cavity insulation (lower embodied energy and cost, typically)
i would avoid rigid - only insulation for the most part, but even with SIPs, it's still more efficient to bring the window in from the exterior layer.
i'm not a big fan of petrol-based products (e.g. rigid insulation, spray foam) but i would/have used rigid as a thermal break outboard of a stud-wall, under slab, etc.
by placing the air barrier towards the inside, you allow opportunity to still fix any holes/leaks after installation of WRB/'outsulation'/rainscreen/windows. there are a number of people that advocate air barriers on inside and outside for belt and suspenders approach. air leakage is a huge source of heat loss in most projects, somewhere between 25-40%.
to bypass the TV bracket penetrating the air barrier (one of the reasons i'm not a fan of the airtight drywall approach) you could throw up battens and then GWB inboard of the air barrier (e.g. OSB) - that's what we did routinely when i worked in EU. it also helps alleviate un-plumb walls and moisture issues.
there are a number of excellent masonry-based PH projects (some excellent concrete and CMU projects) but they're all in EU, at least the really successful ones. A few retrofits in US, mainly in brooklyn (look at loadingdock 5)
You could also leave a pamplet in the finished project instructing new occupants to put some good damned caulk in the holes after they pre-drill.
:)
I also agree with holz about the rigid insulation part.
Most foam makes who produce high-quality foam board fore rigid sheet insulation typically use freon chlorofluorocarbons as a blowing agent to 'inflate' the foam.
Depending on where the vapor barrier lies, those CFCs could be leeched directly into the home which presents a significant health hazard (as do any interaction with completely synthetic compounds). Also, construction rigid foams are treated (brominated) with another more hazard compound (hexabromocyclododecane) that also leeches into the surrounding environment.
In addition, rigid foam insulation often has a very limited, ~10 years, functional operating life meaning the r-value will drop and the sheeting will eventually fail. There's a lawsuit around right now dealing with this.
from Wikipedia. I though this was interesting:
Historically, fiberglass batts became the preferred choice for residential construction in the late 20th century; it is useful to understand how this evolved, as there is no inherent advantage to batts. [Commercial and industrial construction do not use batts.] In the 1970s, in response to oil price shocks, many US state governments sought to cut home heating oil usage by increasing building code insulation requirements for all new housing. At the same time, Owens Corning fiberglass lobbied intensively to convince the building officials who wrote and administered the four separate building codes then used in the USA. They also aimed to eliminate other kinds of housing insulation material (such as polyurethane) on safety or hazard grounds. The result was that Owens Corning successfully lobbied for mandatory 2 × 6 in (51 × 150 mm) wall framing with fiberglass insulation. This suited timber merchants just as well as it suited Owens Corning. Then, given the predominance of non-wind-proof cladding materials, and the prevalence of sleet (wind-blown ice) during the winters of the northern states, a need was created to ensure the whole 140 mm of fiberglass stayed ice-free and dry at all times. Building code officials also made it mandatory to fix and seal wind-and-sleet-proof sheathing under all claddings. This suited the plywood industry very well, which in turn led to the North American development of its now-massive oriented strand board (OSB) industry. Other insulation materials present advantages in terms of stopping air, moisture migration, and recycling for sustainability not found in fiberglass batts.
So yeah. I've been poking around wikipedia in search of chemical compositions of different insulation types. I think I would have gone into engineering instead of architecture had I not just barely passed chemistry. Chemistry was my learnin' kryptonite in my teen years...
So. Lose batt insulation is a lot more environmentally friendly, especially since it can be largely made of recycled content. Unicorn is correct about content of CFC's and HFC's in rigid insulation, although it's possible to get rigid insulation without any of those.
High-density insulation will have weird chemicals in it, primarily due to its use: below grade foundation insulation (where chemicals protect the insulation from water damage), and horizontal insulation (foot and vehicular traffic).
All petroleum based insulation will give off nasty chemicals in case of fire.
Some rigid insulations will lose their R value as they give off gasses, but will settle at a certain environmental equilibrium.
In 80 or so projects I worked on, I have never dealt with batt insulation (outside of interior sound attenuation). None of the project were single-family residences though. So this is all kind of new to me!
My only personal experience with batts is discovering black mold in a wall cavity of a rental (yuck!), and building out a loft space. For the later, I didn't use a mask, and had a nasty cough for the next 6 months or so. So I may be biased. I've stuck styrofoam (expanded) and blue foam model building foam (extruded) in my mouth many times. To no ill effects! So there!
By the way, I really wish there were more technical discussions on archinect! I feel like I learned a few things tonight. Judging by the number of willing participants in this thread (three), I shouldn't expect too much.
Off to the OMA threads to see if one of those buggers has landed an internship! I hear Rem is a dreamboat come wintertime...
I am not participating but love the info
A little more reading, a little more drawing. I think I actually like detailing despite not knowing shit about wall assemblies? I will avoid telling future employers about this little love affair.
Better/worse?
Looks close to being right. You need a steel lintel at the point where window meets the wall (as well as flashing). Not sure what the dark gray shape is on the outside. Some kind of stone veneer?
Orange stuff- whatever it is, will be gone. Drywall will be installed onto CMU wall by use of resilient channels (either hat or S shaped).
not quite sure what's happening in the cavity. All you need is waterproofing applied directly to CMU (spray applied bituminous dampproofing works really well in these conditions) followed by rigid insulation (either mechanically fastened or adhered). air space, brick veneer, Done! push the face of glass inwards so it aligns with the face of insulation (standard practice) make sure you draw in weep holes 24 o.c. for bonus points!
You show that the CMU is steel reinforced. There's no need, unless your wall is taller than 9 feet (or around that, a code requirement) or CMU is load bearing (I rarely ever see this, but it's possible).
This is all with assumption that left side is exterior :)
Left side
standard masonry bricks.
White = plaster/mortar fill.
Black things = brick ties
Greenish thin = moisture wick
Grey thing = brick window header
Middle between brick and CMU
Dark blue = wire mesh
Thin pink line between wire mesh and teal = moisture barrier
Teal = polyiso foam sheets
Brown = furring strips
Right (CMU)
medium grey = cmu
Dark grey = header
pink (not really visible but between CMU and orange) = vapor moisture barrier
Orange = sprayed in foam insulation
Brown = studs
cream = drywall
that's way too complex for what is usually one of the most simple of wall assemblies. Also, you should never have insulation on the inner side of waterproofing. You want trapped moisture (due to dewpoint) to go away from the occupied space.
brick, airspace, polyiso, water membrane, CMU, drywall (optional), That's it!
Brick ties would be installed in the CMU coursings, not drilled in. Adjustable brick ties tend to work the best.
You want air space behind the brick veneer, not mortar. Brick is a very porous material, and is best treated as 'rainscreen principle' meaning you want the space behind the brick to be vented. This is where weep holes come into play (they drain out trapped moisture in the cavity).
No need for furring strips (unless you are cladding your facade in plywood).
Insulation will come on the outer side of waterproofing, which itself is applied to the outer side of CMU. The only time you would want insulation and waterproofing on the inside would be if you were designing a meat locker, or similar.
You would not use 'wire mesh' (aka expanded metal lath) unless you were planning a stucco building of some sort.
You can use a masonry lintel (as you have draw it) in lieu of a steel one, but the size of it would be closer to the size of the brick units.
Thermal and moisture protection is a very difficult subject to learn and detail properly. I continue to learn more on a daily basis.
One of the best lessons from a colleague was his challenge to draw both the line of waterproofing and line of insulation. If there were ever a discontinuous line, it was a good sign that there might be a problem with the detail.
The topic of the proper location for the vapor barrier and insulation is debated often in my region. It really depends on your climate and is "easier" for architects in Minnesota and Miami, a little more ambiguous for those around the Mason Dixon Line. (I was thrilled to find out that Grace makes a breathable waterproofing membrane that is more durable than Tyvek. Hurray!!)
Unicorn Ghost: you might want to find out if your local AIA chapter has a Building Enclosure Council (BEC) - they often have seminars on these topics. I commend your efforts for tackling subjects like these.
They do not have a Building Enclosure Council.
And to put it into perspective Just Why, I have like zero non-art-school, non-college-of-public-affairs architectural training.
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