#Insulating plaster and lath walls how to

My advice to people as they add insulation is always “turn off the humidifier.” If the house is still too dry, find out where the air leaks are and plug those because that’s what causes dry air.” Much of it ends up in the attic where it can rot out your roof. Moisture finds the tiniest cracks and holes and moves into spaces like the walls and ceilings. And yet, I see very tight, new homes, being built with whole house humidifiers that dump gallons of water into the air. The more you tighten and insulate your home, the less you need to use humidifiers. Humidifiers can destroy a home and make you sick. Instead, they were lazy and there’s a big hole with fiberglass draped over it – that’s worse than useless! #1a – Turn off the humidifier

If you use a ridge vent, you MUST have an equal or greater volume of air coming in to the soffits.Īnd that picture at the top of this post? That’s a wet mess of insulation caused by the builder neglecting to put an air and moisture barrier behind the bath tub. If you use gable vents, it’s best to have two of them – one on each side of the attic to provide a good cross flow of air. I personally don’t care whether you use gable vents or properly matched soffit and ridge vents, just do it right. Maybe you got away without proper attic ventilation in the old house, but as you tighten things up and insulate, it becomes increasingly important to have good attic ventilation. But, you want extra protection in the system because some moisture is inevitable. Air sealing reduces the amount of moisture that that can get into the attic, reducing the chance that you’ll end up with a mold problem. This is one of the main reasons that energy efficiency experts tell you to air-seal the attic where the insulation will be installed and ensure bath fans are properly vented before insulating. This makes the attic colder and a colder attic with moisture leaking from the house can result in condensation, mold and wood rot. Warm spaces have less condensation risk than colder space so when you add insulation to the attic floor, you’re intentionally blocking some of that heat from keeping the attic warm. This allows a lot of heat up to the attic. Many homes are leaky and have insufficient insulation in the attic. If you’re not, you could end up with an unhealthy, moldy attic. If you’re lucky, you’ll get away with this.

Just throw some pink stuff up in the attic and you’re good to go, right? Wrong. #1 – Insulate the attic after air sealing and reducing moistureĪdding insulation is one of those jobs that people think can be done blindly.

#Insulating plaster and lath walls how to

That’s why you’re here reading this now – you want to learn what not to do when insulating and how to do it right. The problem is, people familiar with building science are extremely rare, as are the chances of finding a builder who knows how to make a healthy, energy efficient home. Renovations are even worse because people often hire unqualified “low-bid” contractors to do the work without realizing that the few thousand dollars that they save on construction may cost them tens of thousands to fix or even send them to the hospital due to mold or poor indoor air quality. Unfortunately, unlike boats and submarines, homes today are often built in the cheapest way possible, with little regard to physics. A submarine had better be water tight and structurally sound or you’re going to drown and get crushed by the intense pressures of the ocean. A log raft is leaky, but it’s forgiving because it floats by virtue of the logs. There’s a science to building and the tighter and more energy efficient you make a home, the more important it is that you do things “right.” It’s like the difference between making a log raft and a submarine. We both adhere to a similar do no harm philosophy of “if it’s worked for decades as-is, don’t mess it up!” It’s something that we both feel passionate about because homes get ruined and people get sick when innocent people follow this bad advice. The topic came around to bad advice that “experts” give about insulating. The other day, I was talking with a friend of mine – an energy auditor who was a builder for decades. Sometimes insulation hides bigger problems.