July 22, 2021
Today was the last day of a 4 day online course with Joe Lstiburek on building science fundamentals that I attended. Below are my short-hand notes. Slides from the 4 day course can be found here for free.
Day 1
- Keep the outside out and the inside in.
- External and internal environmental loads
- Plumbing code came first, then fire, then structure
- Equation: 18-20 rise in temperature doubles the badness
- The ASSEMBLY is far more important than the characteristics/changes of one component
- Flow is from MORE TO LESS
- Warm to cold = 1st approach
- Water is going to be on the cold spot most of the time
- TALK TO OLD PEOPLE
- Buildings are still being built with negative pressure, vinyl wallpaper
- Better not having a vapor control layer than having it in the wrong place
- Thermal control layer as the least important layer, but has the most building codes because it’s the easiest the measure.
- Drainage plane of ONE MM works if it’s CONTINUOUS. Brick association claims 2 inches (2”x4” used behind wall for mortar mess).
- .5 water ratio in concrete to prevent bleed out
- Corner connections = key = continuity
- “Perforated” wrap = beware/don’t use
- Vapor pressure is water vapor density
- Moisture floating on warm air & warm air floating on cold air
- 55 degrees = AC coil temperature (based on freon Thomas Midley & Carrier)
- Plywood performs far better in drying (vapor permeable) than OSB
- Wood is affected by relative humidity more than temperature
- BRICK DIPPING should be done before laying brick to prevent water from getting sucked from the mortar into a dry brick
- Rain screens to prevent hydrostatic pressure (WATER PRESSURE). Even 1/32 of an inch works.
- Door flash pan back dam
- SES spray foam recommendation
DAY 2
- Back-painted siding (lower edge mostly) to prevent capillarity
- Adsorbed water increases with relative humidity
- 80% RH for mold to grow because of “capillary condensation”
- Capillary condensation break with rough surface plaster coating (preventing mold growth on gypsum board)
- Water phase change will release or absorb energy
- Water at 32 degrees is both solid and liquid
- MOLD IS GOLD
- Accuracy of output is an good as the accuracy of the input
- Concrete creep
- Books: Roofs by Max Baker / Roofing Failures by Carl Cash / Building Science for a Cold Climate / John Straube books / Moisture Control for Residential Buildings by Joe Lstiburek
- Small parapets protect roof edges to protect against vortices
- Small parapet, white membrane, air and vapor control layers
- Vented roofs are banned in high fire areas
- Vented roofs blow off more easily in hurricane prone areas
- Sealing perimeter between ceiling and wall before installing walls
- Thermal resistance of wall should be same at upper perimeter (?)
- 300 sq ft area = 1 sq ft of venting
- 400 CFM for an AC unit
- Vented balcony enclosures even in Florida
- 1 degree difference in a vented attic means a lot between sheathing and rafter affects from moisture
- Asphalt shingle blow off can mean nails losing strength
- 20” of snow could mean an R-40 insulation
- Very cold climate has different ice dam causes (siding warms, heat affects roof edge melt)
- Venting a roof with vapor diffusion when using SIPS (insulation paneling)
- Problem with roof leakage in January and July and not when it’s raining due to HVAC pulling in air and blowing out air at wrong direction each of those months
- Isolated material VERSUS assembly
- Humidity affects airplane take off speed, need more speed and lighter weight
- Vapor diffusion port at ridge to deal with hydro buoyancy (works up to climate zone 3) with no combustion appliances and you can bury ductwork in the insulation
- Radiant barrier at attic ceiling in mixed humid climate vented attic = crazy
- Code won’t allow return ducts in closets even when humid closets may need this to resolve mold issues (widen door gap for greater ventilation)
- Return in utility room for condensation on the HVAC unit and make up air from hallway
- Concrete foundation control joints … because if you don’t create control joints the concrete will create them for you (cracks).
- Control joints = more is better for exterior concrete
- Interior insulation at foundation = superior
- Thatched roof idea to manage water
- Rigid insulation or spray foam (2 lb density) ON foundation, and crawlspace underside
- CRAWLSPACES: should be COMPLETELY OUTSIDE or COMPLETELY INSIDE
- Paint or cover new slabs exiting moisture during building.
- MASTIC COATED ALUMINUM over foundation to prevent termite infestation
- Heat loss is radial
- Damp proofing stopping at grade for residential basements
- Mass timber protection during construction = biggest challenge
- Trash chutes should have negative pressure 🙂
Day 3
- OSB: the Spam of wood
- Rainscreen = rain coat for your house
- Stucco with asphalt impregnated paper behind it: felt fibers would absorb moisture and then shrink and create a drainage gap accidentally.
- Problem isn’t stucco it’s the lack of a drainage gap
- Northern OSB Aspen, Southern OSB southern yellow pine (less dimensionally stable)
- Plywood requires a greater skill set to produce (2 plywood producers left in America).
- The 7% to 9% volume increase of water from a liquid to solid
- PPPPP: problem, people, pollutant, path, push/pressure
- Accurate air testing approach is to ask if a specific pollutant is in the air and to test for that, then repeat the process with path and pollutant pressure combination
- Hand = 5 Pascals, Licked Hand = 1 Pascal
- Test & Balance reports don’t measure pressure
- Drop ceiling panels when exposed to water give off buteric acid, which smells like vomit after 1 day, but staining is not always visible. Return air plenums located above the ceiling panels can pull in the odors.
- Gas fire place pilot lights generate soot
- HVAC distribution systems should help compensate for leaky, old buildings by being tightly sealed, having returns at each floor, etc.
- Dilution is not the solution to indoor air pollution
- ERV maintains the temperature/HVAC
- Fireplace make up air from 1-3 partially opened windows and a carbon monoxide detector.
Day 4
- Less than 20 inches of rain annually = “low(er) risk”
- 3 different qualities of brick (historically) used differently at 4 sides of a house.
- “Weather side” of the house should have the highest quality wall
- Brick has different saturation points and irreversible expansion from freeze-thaw happens beyond that saturation point. Discovering that saturation point requires test each individual brick, which require $500-$600 to test each brick.
- Brick Porosity determines capillarity
- Historically we used to focus on where the worst damage from weather would occur (corners)
- Stucco was originally used to patch older buildings
- In Europe, stucco repairing/maintenance are a common staple building material
- A quality built stone residential home these days would cost about 40-50% more than the low ball residential
- Vapor permeable (acrylic latex) paint can actually be good for covering brick with, when maintained.
- If you build with very good materials, you can get away with bad water management for a time.
- Lime-based mortars sacrifice mortar for the brick. Portland cement based mortars sacrifice brick for the mortar.
- Sub-fluorescence 1-2 mm is where the damage can happen
- 25-30 years = re-pointing
- Thinner drainage gaps also contribute to reducing fire
- Capillary breaks can help prevent the need for sophisticated repair methods
- Granite rock doesn’t suck water and can be used as a capillary layer
- Borate/boric acid cylinders inserted into wood to help preserve the wood
- Capillary rise at foundations below 1.5 feet from joists
- Germans: insert hydronic tubing with a moisture sensor and when the moisture gets to a particular percentage the hydronic heating turns on to dry out the area
- Poly modified stucco can’t breathe
- Moisture damage solution for basement floor structure: Cut joists and installed a capillary break as a metal column or angled metal to disconnect the structure.
- Keeping basement to at least 40-45 degrees to avoid heat coming in towards foundation
- Painting all SIX sides of wood siding
- 7.5kW use home = “net zero”
- PVC fascia and trim
- Ultra-violet keeps the coils clean, but not the air.
- Foster 40‑20 (Fungicidal Protective Coating) for mold control
Related:
+ BuildingScience.com
+ The UnBuildIt podcast tribute to Building Science Corporation (35 min)