I’m taking notes today at this seminar taught by Building Science Consultant and teacher Mark LaLiberte and thought I’d blog them. Mark LaLiberte is an amazing speaker and I consider him a mentor of mine. I first heard him speak over 10 years ago when I was working in Portland OR and I truly believe his “EEBA Houses That Works” (basically an intro to Building Science) talks I heard him teach in the early 2000’s transformed how all builders build homes today in Portland. Anyhow, here’s the notes from today’s session in Austin, TX.
All buildings need to strive for:
-Heath & Safety
Mark lectures overseas and asks “How long should a building last?” Poland Builders say “Hundreds of years”…
When he lectures in the East Coast people say 150 years
When he lectures in CA people say 50+
So, what causes a building to fail? Remember the Pareto principle 80/20 rule. The most significant challenge to durablilty is WATER and it’s management.
Is 100 years a fair lifespan for a building? YES. So how do we both increase durablity and thermal efficiency.
In general, we have one chance to do water management, insulation, and mechanical correctly for the next 100 years of a house’s life. You aren’t going to insulate differently 20 years from now if energy prices rise.
Have you ever dumpster dove? You find amazing things in the dumpster that really could be re-used. Example; Grandfather was a builder, when he finished a house he walked away with (2) 5 gal buckets of trash. Was he Green? No, he was cheap. Dumpsters are full of $$$$. Let’s move to advanced framing, reduced lumber, reduced waste. This costs less and is more sustainable.
Architectural Relevance – We save buildings that are beautiful! Ugly houses don’t last and aren’t maintained. Architecture is a critical part of residential construction but is often missing. Older houses have “character”. What is “character”? It’s those trim/builtins/craftsmanship/etc. Mark makes a great case for the Not So Big House movement (series of books by Architect Sarah Susanka). Smaller houses with better design, and better built. He also mentions A Pattern Language book as a great guide to designing a house.
|Mark using a folded piece of paper to illustrate a roof from older houses. Slide of a complex roof of a house with problems.|
|Mark then takes the simple “A” roof and crinkles the paper up saying this is how some Architects design roofs today. Big laugh from the crowd on this one.|
Why are furnaces up in the HOT/Humid attic in TX? Do most homeowners know where/if their HVAC system have a filter? If it’s hidden in the hot attic and it’s a bear to get up there you’ll likely not maintain your hvac system. It’ll still work with a 3 year old plugged filter but the efficiency goes way down!
What’s changed in the last 10-20 years in buildings?
-Materials, Sheathing, Insulation, Cladding. All are NEW products! Also, Equipment, HVAC, Processes, Less experienced Trades, Greater expectations for comfort.
|We ask a lot from our walls! By the way, this is from a 1950’s builders handbook. This is not new.|
Why are brick buildings more durable? Design? No, because they have an air gap behind the brick, and any water that migrates through hits an air space and drains/dries to the outside.
Mark has been traveling Texas this week and builders have told him AC tonnage here is generally 400-500 sq feet per ton of AC. That’s WAY too much tonnage. That’s the amount we used in the 80’s. We need to do load calcs, Manual J’s… size equipment correctly! Then we need to air seal, insulate correctly, use better windows… that will lead to 600-700+ sq foot to the TON. (side note from Matt, my houses I build today are usually 700-900+ sq foot per ton of AC)
Where should ducts go? Should we use electricity to cool the air, run the ducts into the HOT attic then cool them down before we run them into the house? NO, ducts MUST be in the conditioned space of the house. Running them in the hot attic is frankly stupid and wasteful. It should not be done even if it’s code. What is code? Code is the minimum legal way to build, we can do better.
How do we deal with indoor air quality? I breath 9000 liters of air a day. Should we provide fresh air? YES, we need continuous fresh air. Don’t just rely on leakiness for fresh air. We don’t want fresh air that’s leaked through fiberglass, or around your doors. We want filtered fresh air, and dehumidified fresh air in our hot/humid climate.
What if a customer watches the cooking channel and decides they want a 6 burner Pro range and a 1000 CFM super sucker range hood? When we put in commercial cooking equipment, we MUST do make-up air. If not, then when they do the 1000 cfm fan the house goes negative pressure and the fireplace will backdraft, the water heater flue will backdraft, etc. NOT good. We must do make up air when we install these commercial cooking appliances.
We should do a hose test on our houses prior to adding cladding (siding/stucco/etc). Put your rain control glasses on and see in your mind what happens when water gets past the claddding. You must look at your buildings critically prior to the claddings. These are the areas that will eventually leak and that’s what will kill the building in time. Maybe not in 2 years, maybe not in 20 years, but eventually that small water proofing issue even if it’s covered with cladding will cause a problem. This is why many houses being built today won’t last past the first mortgage without a major failure of some type.
Here’s a crazy measure of a house’s value… A potential client calls a builder and asks “How much do your houses cost per foot?” That’s the craziness measure of worth. The builder should say “How much was your car per pound?”
You need to ask clients what’s valuable to them?
-Energy Efficiency? What do you expect your energy bills to be?
-How long they expect the house to last?
– How comfortable would you like to be?
Price per square foot is a terrible measure of well a house is built!
Supervision & Oversight is so important to a house construction. The trades (framer/plumber/electrician/hvac) get ZERO days of training a year. We as builders must educated the guys on the jobsite who are actually doing the work. AND the person supervising the work needs trained to know what’s acceptable and what will be a problem in the future for that house. It’s vital to have a knowledgeable and trained trade and supervision crew who knows the basics of building science.
|Photo shows a house with many reverse flashed areas.|
Water and Mold intrusion… Your Builders Business Insurance won’t cover this problem. Your homeowners insurance won’t cover mold/water issues. When we have an issue with water/mold it costs $thousands$ to fix! And no one will cover this. You as the builder are on the line. But what happens when the builder goes out of business. These houses turn into bank owned, crappy houses that are major problems. It’s an ugly cycle. We as builders must do it RIGHT the first time!
Builders must stop using 1/8″ Thermoply in Texas for sheating. I’ve seen SO much Thermoply in Texas as I’ve traveled this week. This passes code but SHOULD NOT BE used! This is a terrible product. Any water that gets to the thermoply will eventually get in and rot/ruin a house.
|NOT From Mark’s slides. I took this photo last week of a house with Thermoply. This house WILL leak air & water. I hate thermoply.|
What is the R-Value of a common wall assembly? The typical wall in Texas is insulated with fiberglass batts, but these have so many requirements to installation to get the stated R value of the product. R-13 batts typically perform at R-6 to R-9 (maybe less). It’s typical to see 50% degradation in the efficacy of fiberglass batts after they are installed.
Question from the crowd: “Can fiberglass batts be installed to the manufacturer’s spec’s to get the stated R-value?” Mark’s answer: NO. It’s not reality. Houses don’t have perfect 14.5″ cavities to install batts perfectly. We do it because it’s CHEAP. Builder in TX using batts must move to a minimum blown-in-blanket insulation. (Mark references Johns Manville Spyder blown insulation)
R-value of OSB sheating = R-.45 . When you have non-insulated OSB sheating with fiberglass batts it’s really easy to get the dew point of the back of your sheathing.
|Mark showing how a typical wall cavity can have condensation and mold issues when temperatures dip to 35 F.|
|Now add 1″ rigid exterior foam to that wall and it performs VERY well!|
|The Rigid Foam outside also brings the dew point up inside the wall sheathing so no condensation can occur.|
|Austin is in climate Zone 2, but we are very close to the diving line for Zone 3. You can see code is moving to higher Rvalues in June when the 2012 IECC will be adopted.|
It’s not so much making our walls thicker, it’s about putting the insulation in the right space.
DON’T EVER PUT THE VAPOR BARRIER ON THE INSIDE OF THE HOUSE in TX. We need our walls to dry through diffusion through the drywall to the inside of the house. Diffusion is SLOW, it means that the water must diffuse through sheetrock/paint. We want no vapor barriers on the inside so that it won’t slow that diffusion (read drying) to the inside on our dehumidified houses.
We want a draining housewrap behind our exterior foam so that any water getting past the foam won’t make it to the house.
Construction Instruction Apple App. Can use this to show crews how to install correctly without words. Shows animations on how to install correctly.
Mark shows a wall assembly with 1″ foam, Tyvek Drainwrap, rainscreen, hardieplank siding. Says this the most ROBUST wall you can build. (Matt’s note, that’s what I’m building! See my past blog posts on this)
Stucco should be installed with rainscreen too. Use a dimple mat with a filterfabric to keep it all drying & breathing. Keene rainscreen example.
Spray foam products: You need to be very careful about the install. The industry is having some problems regarding the quality of install. A few worst cases are getting national press. The foam industry is having lawsuits that boil down to mixing issues and crews that aren’t properly trained. Mark says he’s a fan of selective use of foam. Use it in the key areas. He likes the Hybrid Approach like I’ve showed before in my blog.
1/3rd of a building AC load in TX is based on the SHGC of the windows. We want to always use Cardinal LOW E366 glass which is usually Solar Heat Gain Coefficiant of .22
Does air react like a fluid? YES. Let me ask you this “How tight do you like your plumbing?” We need to tighten our ducts as tightly as possible. Less than 5% leakage must be mandatory in our ducts. Leaky ducts can leak transport moist air to places that will condense on a cold surface. We need ducts to be sealed tenaciously.
Leaky ducts in a traditional attic leak air. When that air leaks the house goes negative. When the ducts up there lose 100cfm of air that air must be made up. 30% of the makeup air when a furnace in the attic turns on comes from the garage. It’s not good all around to put ducts in the hot/humid attic.
Typical recessed can in a ceiling with a traditional attic above leaks at an average rate of 10cfm
|New 2012 Energy code requires a blower door test to be less than 5 at 50 pascals.|
A blower door test at 50 Pascals is equal to a 20 mile an hour wind acting on a house. This tells us how leaky the building is, which translates to the load calculations to size the HVAC system correctly. BUILD TIGHT, VENTILATE RIGHT.
Microperferated Housewraps. Sheets of plastic that are pin punched. These are no good. They are permeable to air and water. Not good.
Quote from John Ruskin. From a carpenters book published in 1945.
“When we BUILD let us think that we build forever. Let it not be for present delight nor for present use alone. Let it be such work as our descendants will thank us.”
|Eric Rauser, Mark LaLiberte, and myself. Always love to get photos with my Hero’s!|
Hardie Siding Mitered Corners Next Post:
Masonry Best Practice – Rock / Limestone with a Rainscreen