Structural Uninsulated Triple-Wythe Brick Wall
I have been very interested in using a 12″ thick triple wythe brick wall for all structural walls in our “forever” home. We are located in West Alabama, just a couple miles above the warm-humid line. The wall would be structural, uninsulated, and the finish surface inside and out. The method was mentioned in a recent Fine Homebuilding magazine. I have watched several videos by the builder, and he is quite convincing, even going so far as to have Clemson University do some testing on heat transfer through the wall. The wall seems to perform much better in the summer than most models would indicate. However, the data is incomplete, and I have reservations how this type of wall would perform through our very damp, cloudy winters. The simplicity of using only one material in the wall, combined with its strength, durability, resilience, and beauty have compelled me to try to study it out. I can find very little data online about this type of mass wall in our climate. Any thoughts? Am I crazy for even considering it?
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When it comes to certain building techniques there are a lot of hand wavy arguments as why it will work better than standard construction.
The thing that really matter is specific heat (the amount of heat it can store) and the R value/inch.
So your triple brick, is around R5 (R6 if the interior finish is installed over strapping) and has similar specific heat capacity as concrete but slightly less density, so it is equivalent to a 9" concrete wall.
So, not much R value, which is fine in warmer climates, and a fair bit of thermal mass.
If you don't have a lot of humidity and your climate has big diurnal temperature swing than the thermal mass can make a big difference on cooling load.
If you are paying for it, I don't think this is a very cheap construction. If you are looking for thermal mass, my guess is ICF walls would be significantly cheaper and much higher R value.
A standard well insulated wood structure would definitely be WAY cheaper than either of these.
Thank you..
One thing I had wondered is if the air gap between wythes would help with the r value? Of course it is bridged by a bond every 6 courses. Would moisture work its way to the interior in prohibitive amounts in such a wall?
Our climate is very humid. Summer diurnal swing is only around 20 degrees. Winter is less predictable, but of course is not as high as I the southwest.
Instagram is @1000yearhouse, if you're interested in seeing his arguments
The R value above was including two air gaps between the wythes. The bond course does reduce the R value a bit, maybe takes an R0.5 off the whole wall.
Brick does a very good job of transfering and storing moisture. If it is humid outside all the time, it will be humid inside as well. Unless day and night time dew points really change a lot, the moisture buffering capacity of the brick won't matter.
Generally with climates with a lot of latent load, you'll need AC anyways, the brick would probably add a bit to this.
20F is not much swing. For thermal mass to make a big difference, you want 30F to 40F (desert climate).
Houses last because of good details and proper maintenance, look at the half timber construction in Europe, nothing magical to make a house last a couple of centuries.
"Houses last because of good details and proper maintenance".
Look at Detroit. Many of the most beautiful, and well-built houses are ruins now, along with their more modest neighbours. If houses aren't wanted, no matter what their construction, they go to hell surprisingly quickly.
A big part of that was thieves would steal metal siding, copper cutters, and certain roofing materials. If you remove big chunks of the siding align with water management details, the structure is going to have big problems in short order.
Baltimore has seen a LOT of renewal in the inner harbor area. They run into problems sometimes with structural decay of shared brick party walls between row houses. That can be interesting with the “who pays” arguments. A friend of mine out there renovated his basement and found that his neighbor’s furnace’s gas line ran through his basement, which resulted in some exciting discussions with their local gas company to get resolved.
Even well maintained structures can have issues when they get to be very old.
Bill
A lot of those rowhouses were built as rentals and the landlord owned the whole row. So niceties like property lines were not a big consideration.
I used to live in a rowhouse that was built around 1870 and the same family owned the row until the 1950's. It was only when they went to sell that they learned the party wall was 3' off of the property line.
I've lived in a couple of brick houses. Hot in the summer, cold in the winter, drafty and damp. A modern, tight, well-insulated house is so much better.
I live in one of these homes. It’s 115 years old. It’s beautiful. It seems indestructible (Though, I pray we never have another earthquake though). But, it’s a lot do maintenance and it can be cold in the winter.
We gutted the second floor, framed out the interior walls and sprayfoamed everything. Otherwise, it was an enormous energy hog. There are way better ways to build in most climates.
It sounds like I would want a wood stove for the dry heat, and a whole-house dehumidifier at the minimum. And even then I could expect it to be an energy hog.. I am not interested in compromising comfort. I would possibly consider slightly less than pretty good house efficiency, but not by much.
Dry heat is also a very common misconception. No such thing. Wood stove / gas furnace / heat pump are the same.
About the only way a furnace can effect the humidity of the house is if the combustion exhaust is not connected properly and is dumping combustion gases into the house. Besides CO (which you really bad for you) it will add humidity to the house.
Badly installed HVAC systems can however dry out houses if they depressurize rooms or have have leaky ducts in the attic. Since this is pretty common, thus the misconceptions about humidity and heat.
Can you explain why you think solid brick makes a better house than modern construction? Even some links or cut-and-paste? I went to the Instagram page you cited and it was all pretty pictures with no explanation, and I couldn't find the Fine Homebuilding article you mentioned.
https://youtu.be/d50xTNITvDg
This is his lecture at Notre Dam. It's an hour long.
http://www.artisantrades.com/hope-for-architecture#
His website.
He was guest on the Modern Craftsman podcast (#89) Also long...
I apologize I couldn't find a concise summary to link to. But in short, he believes he had overcome many of the cost hurdles and can offer a brick home for a competitive price. He says that his homes perform at a much higher efficiency than traditionally believed possible with masonry in locations such as Atlanta, and Carlton Landing Oklahoma. The authenticity and longevity of the structure are points he often lifts out. He speaks compellingly enough to prompt me to seek help filtering the science and facts from sales pitch.
Thankfully the laws of thermal dynamics don't change because of personal beliefs, hand wavy arguments about efficinecy don't effect the actual physics of buildings.
Triple brick is a low R value high thermal mass building. It would work very well in a desert type enviroment.
If I had my heart set on a masonry construction, it would be brick veneer over cinder block with a thick layer of rigid insulation between the two. This gets you all the "benefits" of triple brick but much higher thermal performance and significantly cheaper to build.
P.S. If the gentleman has figured out a way to do brick cheap, I would love to hire him. I'm in the land of all brick houses and getting any brick work done is very expensive.
Once again, this is not something I'm set on doing for our house. It was very interesting though, but I struggle to make sense of the conflicting data. I have attached Clemson's numbers, pulled from one of Chapman's videos. He is very careful with with the air sealing, and I would understand that he over insulated the roof. But again, I worry about the moisture through our winters..
I read his website. Where I'm left unpersuaded is his focus on longevity. I've owned old houses, I've lived in old houses, I've renovated old houses and I've demolished old houses. For the most part houses don't get torn down because they wear out, they get torn down because they are functionally obsolete: the purpose they were built for has changed.
Let me give some examples. Until the end of the 19th century, most houses were heated by burning firewood or coal in either an open fireplace or a not very tight stove. Such fires were hot and hard to modulate. Houses were built quite loose because otherwise your house would be hot, smoky and stuffy in the winter. (A staple plot device in 19th century fiction is a draft blowing out a candle. Think of how drafty your house has to be for that to happen!). Modernizing a house that was built to be drafty to be almost airtight typically means practically rebuilding the whole house.
Older houses tend to be a warren of small rooms. There is a practical reason for this, in that the builders were limited in the spans they could achieve with the materials and methods of the day, so there were more bearing walls. Converting a house like that to the open floor plans preferred today also means rebuilding the house.
Older houses had no space set aside for mechanical systems. I've lived in houses where indoor plumbing was added decades after the house was built. It becomes very difficult to meet modern codes without rebuilding the house.
Where real estate values are growing, higher utilization of land makes economic sense. Often that means going up. However, most houses are engineered for the size they were when they were built and the foundation won't support going up.
Finally, the bones of house -- the frame -- accounts for a small portion of the cost of a house, maybe 10%. If you have a house and you're looking at a new roof and siding, new interior finishes and new mechanical systems it's only a little more to start fresh and build the house you really want.
The way to make houses last longer is not to build them out of more durable materials -- that just means more to cart away when the building becomes obsolete -- but to make more durable designs. This is harder than it sounds because it means predicting the future. I live in a house right now that was built about fifteen years ago. The builder thought he would "future-proof" the house by installing telephone, ethernet, cable TV and audio cables to every room. Of course soon after it was built WIFI came along, and smartphones and streaming audio and video, and none of that wiring has ever been used.
And I'm not going to even touch the "thermal mass" issue. "Thermal mass" is not a term used in science or engineering.
The last thing I want is a damp home, and the second worse is an energy hog. Considering that in the light of everyone's input, I will steer clear of structural masonry.. Thanks!
I have lived in a triple-brick wythe home for five years and there are a lot of things mentioned in this forum that haven't been an issue living in my house.
My house is a 150 year-old two-story brick farmhouse with radiant baseboard heat and no central air conditioning. The walls are triple brick with 1" spacing between each layer and 2x4" interior framing on 16" centers with batt insulation. Total square footage is 2600. The house is located in Wisconsin where we see extreme weather regularly (-55 degree temps in the winter. 95 degree temps in the summer. Extremely dry in the winter. 90% humidity in the summer. Winds approaching 60MPH year-round. Downpour rain on a consistent basis). I mention all this because Alabama should be a picnic in comparison.
During the summers, we run two window air conditioners that easily keep the house at 65 degrees even on the hottest days. We only run the air conditioners in July and August. Our electrical bill while running the units is $190 per month. It normally is $130 per month.
My parents live in a ten year-old house that is standard stick construction. They live in the same location - house is 1900sf. They keep their house at 65 degrees during the summer. They have central air. Their electrical bill is $240 per month. They run their A/C is on from June to September.
I've never seen another house that stays cool like this house does. We get cool nights here in Wisconsin, and the brick radiates the cool temps throughout the entire day.
Moisture has not been a problem either. As I mentioned, humidity is high in Wisconsin. We run a dehumidifier in our basement. The rest of the house never smells damp or feels damp. Much of this has a lot to do with how well a house has been waterproofed. Brick soaks up water and will ooze moisture, which means you need a waterproof barrier behind the brick. Many old double or triple brick houses have plaster nailed directly to the brick. This means all the moisture from the brick gets transfered straight to the wood and plaster, which also gets no sunlight because it is on the inside of the house - this immediately starts to cause mold problems. Build your house with an interior water barrier and you won't have an issue.
During the winter, we go through roughly 850 gallons of propane. My parents go through 600 gallons of propane in their newer house. But what many people don't discuss is how much more important ceiling insulation is for keeping heat in.
My parents house has R-49 cellulose insulation in the ceiling. I have R-30 batt insulation. Cellulose is far superior. If you're concerned about heat in the winter time, don't skimp on your ceiling insulation. Also be aware that a ranch-style house won't perform nearly as well as a two-story house in the winter. Ranch houses have significantly more ceiling space, which means more upward heat loss.
I just wanted to give everyone an apples-to-apples comparison between an actual stick-built house and a triple brick house.
Here are some other advantages that I've noticed from owning a triple-brick home.
Mice have a much more difficult time getting in. Brick is set directly on the concrete foundation. This means there is a solid barrier that mice can't chew through. Mice can easily chew through wood, insulation, rubber, and vinyl siding. Maybe this isn't a problem where you live, but it's a big problem here. I always laugh when my neighbors in their newer houses complain about mice when I don't have any in my 150 year-old farmhouse.
Much less noise penetration. If you live next to a busy road or loud neighbors, having walls nearly two-feet thick keep much more sound out.
My walls measure 22" from outside to inside the dry wall. This makes for extremely deep window wells. This increases the amount of sunlight coming into rooms and makes for a really unique conversation piece. Everyone always comments on how thick our walks are. Not super important, but it's always fun to show off your home to guests.
Increased longevity - and yes I agree that many houses are torn down because they outlived their purpose or because someone didn't take care of them. But brick doesn't rot, isn't phased by termites, doesn't shrink, doesn't twist, and doesn't expand. After 150 years, our house has level floors and straight walls. I've never been in a 150yo stick house that had level floors.
Each building style has advantages and disadvantages. None are perfect, but don't let people fool you into believing that "modern" construction always means better. In many cases, it simply means "cheaper".
We bought an old 1916 brick house in Wilmington DE. I since learned that the only way to insulate such a balloon architecture house is by wrapping it, while still giving the bricks enough space to dry. So, in a first step we’ll just finish renovation of the interior, close all “visible” gaps, and see how the winter goes. I’ll keep you all posted about my heating bill and comfort-level…
I came across an interesting new old concept recently: Dr Erwin Thoma has developed a wall assembly made of 100% wood, without glues, nails, screws. He’s been building these houses for years now and gets rave reviews! Way easier to heat and cool than anything else, no pathogens in air, total comfort feeling… i don’t know the cost yet, but i guess it’s shifting some of the cost from house-technic and finishing towards the actual structural part of the house. Well, the walls, ceilings, roof structure are also the finish , i.e. visible, touchable surface. So, having the structure amount to 20% of the overall cost shouldn’t be a problem, when the rest gets cheaper…
I can’t explain it well, but you can google him, if it’s of interest.
Now, that is for sure my choice for a foreverhouse!
Btw: i am a bit surprised that GBA is completely ignoring the environmental impact aspect of the “green” ! Polysterene takes from 50+ million (!!!) years to never to break down. Using this material lavishly in buildings that are obsolete in a very short time (as some of the commenters point out) seems to me to be really, really dirty and not green at all! Wood100 structure does not need any polysteren!
Well I did it I took the plunge and put my money where my thoughts were and here is what I got. I built a simple 22x42 triple Wythe brick 2 story federal style cube shaped home right out of an 1896 correspondence school book. Here’s what I changed ...beefed up the footer with damp proof membrane and lots of eps foam in the crawl space and around foundation — R 56 on the crawl space floor—- single hung $125.00 each big windows fitted and sealed tight. —- takes a long time to get those $750.00 windows to pay you back kids—- I capped off the place with r96 batt insulation and taped 1/2 inch silver coated eps foam. Covered it all with t&g pine ceiling cause drywall can’t hold up enough insulation to do crap so don’t waste your time or money. —- living in central Ohio —- 13 seer Hvac and gas heat. —- keep things solid set on 68 in summer 72 winter. I don’t change the temps. My energy costs are as follows. Winter coldest $200 month gas bill least month cost $38.00 for the base not using rate. Highest electric bill just had it for July 2021 of $210.00 gas of course was the lowest. After averaging everything your looking at $200.00 a month for energy costs.. probably about like a standard 2x6 house. What would I change ? Bigger air conditioner. Fact is nobody knows how to size this so I sized the heat pump as a 2x6 house. It runs all the time when it’s hot. I will be upsizing 25% next time might even do 50%. The heat I upsized 25% and it’s about correct... variable speed anything with this application helps like variable burners on the gas side. I will be upsizing all heating and cooling and going more efficient on that side next time as I might try all electric and am worried the heating is gonna get pricey. Converting btu’s I probably would have had a $600 electric bill Jan-feb if all I had was electric. I have had zero moisture problems, zero humidity problems. It’s a wonderful comfortable house. I will build like this again for sure. Same cost as a 2x6 house ....I count 12 steps in standard construction for the walls counting each coat of paint as a step. On triple wythe your material is more but your labor is way less. It totally evens out I paid everyone that worked here minimum $30.00 hr. Jump in it’s fine...upsize your heating and air conditioning and insulate what you can outside of your walls to passive house standards and you will come out fine. And one last thing as far as cost goes this thing is bullet proof and won’t need much upkeep at all over the years. A few thousand years of masonry knowledge should not have got thrown out the window in the early 1900’s with the advent of a good sales pitch and the skills to sell people junk construction materials that never were intended to last. Send your questions glad to help where I can.
Ran across this thread, and thought I would add my own digging into a structural brick wall, and why I ended up not going in that direction. I engaged an engineer to help think through it conceptually. I spent way too much time thinking about this, so perhaps someone else may find a useful nugget here.
To have exposed brick on both interior and exterior, and meet energy code, I landed on a brick veneer tied to structural brick wall, with insulation inbetween. I wanted an insulated wall, cause you know, physics.
The interior brick wall would be structural, and I spent way to much time looking at the requirements for reinforcements required by code for brick, with all requiring rebar. It might be possible to do get an engineer to do the calculations on a composite wall, basically the veneer and interior brick wall working together to provide structural integrity. But, the most straightforward way to make the brick wall structural was to embed rebar in it.
Installing rebar in a standard brick core is possible, but labor intensive. You have to have 1/4” opening around the rebar in the brick core (with fine grout, 1/2” with course grout), and get a brick that has a big enough core to allow that. I did find some standard bricks that had a 1 3/8” core, so workable, in theory. You also needed brick with a certain compressive strength, which seemed to be met by most standard bricks.
The brick mason I discussed this with definitely mumbled some insults under his breath, but said they could make this work. Also, working in the support for interior structures would mostly likely be internally supported, kind of like a SIP/timber frame, but in theory could be supported on the structural brick.
For longevity purposes, rebar is certainly tough, but I ran across various articles criticizing concrete and rebar construction (commercial, bridges, etc...) where the rebar is failing early due to corrosion and other issues, and at least adds some question to the longevity of a engineered single wythe brick wall dependent on rebar. If it was a 3 wythe brick wall, no rebar, and no earthquakes, I can see that lasting a long time, but that doesn't really meet the rest of modern requirements.
Lots of wood structure houses (the way I went, surprise surprise) have lasted a hundred plus years, and a ventilated brick veneer should be a pretty durable exterior to protect the structure, with the details done right.
If I want brick interior, you can still build that in, as an interior veneer….
Where I ended up from a wall assembly, but did not end up pursuing, inside to outside:
- brick with grouted rebar, and appropriate brick ties set for the veneer
- fluid applied weather barrier
- rigid mineral wool insulation (think as practical, code here in Georgia was easy with a mass wall)
- brick veneer, same bricks as interior, just no rebar.
Perhaps this all would have worked out better back when random length lumber was $1600, but thankfully we can afford a 2x4 now that our southern yellow pine house house is about done with framing. I did get my exposed structural beams, though :)
FYI, for any other dreamers.
Something I've tossed around in my head is similar, but with Foamglas as the middle insulation layer -- your whole wall would just be cemented together solid blocks of "stuff". At R-3.4 per inch it's not too bad, about 12 inches of foamglas for PGL-level insulation.