by Mike Quigley | Mar 23, 2014 | Blog
The answer is a resounding “it depends.” The theory is that the gable vents may disrupt the airflow from the soffits to the ridge. In theory yes, it should work. So why is it not working? The ridge vents are exhaust vents and the soffit vents are intake vents. The goal of a venting system is to remove heat and moisture from the attic. Let’s start with the ridge vent and work our way down.
1. The ridge vent is rarely installed properly. If the roofer remembers to cut the plywood at the ridge, more often than not the cut is not big enough, or he/she will only cut one side. (fig 1)
2. When the actual ridge vent is installed, it is typically a rolled style vent that completely collapses when the roof caps are installed providing little if any exhaust. (fig 2)
Soffit vent chutes: For whatever reason someone either forgets to install the vent chutes, or they collapse the chutes or they block them with insulation. (fig 3)
Soffit vents: (fig 4) The soffit vents provide intake air. The example shown is a standard two inch aluminum strip vent.
Here is an experiment for you. Take an ordinary box fan and place it in your open bedroom window. Turn it so that the air is being exhausted out of the room instead of blowing into the room. Open the bedroom door. Now turn the fan up all the way. Now shut the door. The fan speed slows down. It’s trying to exhaust, but there is no place to draw air from. The purpose of the intake or soffit vents is to draw or allow air in. Everyone installs a ridge vent when a new roof is installed, but no one is installing soffit vents.
If an attempt is made at installing soffit vents they usually fall the way of the ridge vent and are almost always installed incorrectly. (Fig 5) This is due to a lack of training and simple economics. A good quality and correctly installed venting system costs more money.
So now back to the original question. The answer is; the gable or roof vents may be making up for the improperly installed soffit and ridge vent system and in most (but not all) cases should be left in place and uncovered. Every house is different and no one procedure will work on every home.
by Mike Quigley | Mar 8, 2014 | Blog
Attic mold usually starts at the rear of the house.
- The front of your house faces the street and the back faces the woods. Because of the location of your driveway and street, there probably aren’t as many trees in the front. Less trees equal less shade.
- The kitchen and baths are usually located at the rear of the house. This means your high moisture areas are located under the shadier, cooler section of the house.
- The pull down staircase is usually in the hall, right outside the bathroom and right down the hall from the kitchen. Any excess moisture from these areas will naturally be drawn into the attic around gaps in the cover. This upwards movement of air is called convection. In the summer when the attic is hotter, the downward movement of air is called migration.
- If you have an attic staircase, it should have a cover equal to or greater than the R-Value of the insulation.
When the sun comes up and starts to heat up the attic, the sunny warmer side pushes accumulated moisture in the attic to the cooler shadier side. Mold needs water to grow. If the plywood stays damp enough for long enough mold growth will begin. If you have a good attic ventilation system, that excess moisture will be drawn out of the attic. If you have a poor ventilation system water will condense on the roofing nails and eventually drip down on to your insulation.
If you combine mold spores, an edible surface (your attic plywood) and water you will grow mold. If left unchecked the mold spores will spread to the gable ends and eventually to the front section of the attic.
Here is a list of the common conditions leading to attic mold:
1) Cooking and showers.
2) Gas appliances.
3) Excess humidity from clothes dryers.
4) Fish tanks and plants.
5) Wet basements including open sump pump pits, dirt basements and foundation cracks.
6) Efflorescence caused by water infiltration into the basement usually due to improper yard grading.
7) Inadequate ventilation in the attic due to:
A) Blocked, missing or undersized soffit vents.
B) Blocked, missing or undersized ridge vent.
C) Blocked, missing or damaged soffit vent chutes.
8) Leaking ductwork due to improperly installed HVAC systems.
9) The bathroom fan venting into the attic or soffit.
10) The kitchen stove exhaust fan venting into the attic.
11) Improperly installed insulation including missing vapor barriers.
12) Ice dams.
13) Missing or undersized attic staircase cover.
14) Open chasses around pluming, light fixtures or chimney.
15) A lack of solar drying (trees and shrubs.)
16) Roofing, vent pipe flashings, skylights and chimney flashing leaks.
17) Plumbing and heating system leaks.
by Mike Quigley | Feb 21, 2014 | Blog
Ice dam formation is the result of continuous freezing and thawing of snow due to escaping heat from the house or from gutters being backed up with frozen slush. When this occurs, water may be driven under the roof which may cause ceiling, wall, insulation and gutter dam ventilating the attic. To help with water intrusion into your home, make sure you have six ft. of ice and water barrier under your roof shingles (measuring from the gutter line up.) Try to keep the edges clear with a snow rake. Install electric elements to help melt snow and ice on high roofs. Ice dams can be prevented from forming by: Installing a vapor barrier above the home’s warm space, insulating the attic floor and ventilating the attic.If water has found it’s way into your attic, you will probably see mold starting to grow along the lower edges of the roof. Do not let this go unattended as it will continue to migrate up the sheathing. Have the insulation and ventilation system upgraded and make sure you install an ice and water barrier if you are replacing the roof.
by Mike Quigley | Feb 19, 2014 | Blog
Why is there a hump in my floor?
There is a definite hump in the floor that is normally found in older homes. In older homes the foundation sinks leaving the center of the house higher. But this is a different problem.
Let’s say your house was built in 1985.Builders were combining engineered lumber with conventional lumber. Engineered lumber doesn’t shrink like conventional lumber. If you start with a 2 x 9.5 inch LVL (laminated veneer lumber) beam, 20 years later it’s still a 2 x 9.5” beam. However if you start with a standard 2×10 (which is really only 1.5” x 9.5”), 20 years from now it shrinks to 1.5” x 9.25”. So now your floors are all ¼” less than the height of the beam. The plywood that is nailed to the floor and stretches across the beam will now be humped up over the beam.
The solution is to remove the plywood directly over the beam and fill that area in with floor leveler or a thinner piece of plywood. Problem solved.
by Mike Quigley | Feb 18, 2014 | Blog
Well it is black mold, but it isn’t THE black mold that you think it is. The black mold you are referring to is STACHYBOTRYS CHARTUM.
In 1993 there was a story in Cleveland Ohio about infants dying from pulmonary hemorrhage and hemosiderosis. This was apparently caused by the introduction from the heating system of a mold called “STACHYBOTRYS CHARTUM” known today as the black mold. The hot air heating system return was located in the basement. The basement had water damage and the sheetrock in the basement grew mold. The mold spores were drawn into the system and distributed throughout the home via the supply ducts.
DEF: Stachybotrys is a slow growing, dark mold that grows well on cellulosic (paper-containing) building materials. It can produce a number of different macrocyclic trichothecenes which have been described as being toxic to humans and animals.
Stachybotrys is bigger than other molds, usually around 5.7 microns. (A micron is a millionth of a meter.) It is thick (think of tar), and it looks a little like shoe polish. It is aggressive and will dominate other molds. It is not readily airborne and is typically brought into the house on the bottom of your shoes. Typical mold spores are about 3.5 microns. To put that into perspective a human hair is about 75 microns thick. Cat and dog allergens along with dust mites are in the 0.3 to 1 micron range. Bacteria and lead dust are in the 1-3 micron range and skin flakes and pollen come in at around 3-10 microns.
Back to your problem, mold on the attic sheathing. Typical black mold in the attic, CLADOSPORIUM, (0.84-0.88%) is usually caused by vapor migration from the living space below (known as AW or water activity.) ALTERNARIA (0.89%) is typically from bath fans venting into the attic and ULOCLADIUM (also 89%) is typically caused by water leaks from around chimney and vent pipe flashing’s. I have never found stachybotrys growing on plywood. It simply isn’t the right substrate for encouraging this type of mold growth.
I say typically because attics seem to suffer from “all of the above.” It is usually a combination of vapor migration and under performing ventilation systems that allow mold to grow on the substrate (attic sheathing, plywood or boards.)
Mold cannot grow without water. Solve the water problem and you will solve the mold problem.
by Michael Quigley | Dec 19, 2013 | Blog
The Radon Debacle
On a recent home inspection the radon test came back high at
7.3 pCi/L (picocuries of radon per liter of air.) The EPA has set a national action level of
4 pCi/L (picocuries of radon per liter of air) for indoor air. The average indoor radon level is estimated to be about
1.3 pCi/L, and about
0.4 pCi/L of radon is normally found in the outside air.
The property seller had the home tested for radon when she bought the house
three years ago. The level at that time was
1.6pCi/L, well within the acceptable range for radon in the air.
So what happened?
The home-owner had an indoor foundation drain system installed. The system consisted of a series of floor drains around the perimeter of the inside of the basement. Radon that was trapped below the floor was now released into the environment. Additionally, new windows, insulation and a ridge vent were installed along with bathroom exhaust fans as per the recommendation on her last home inspection. This increased the energy efficiency of the home but created a high negative air pressure area in the living space. The exhaust fans and ventilation system were actually “drawing” air out of the basement and subsequently radon was being pulled out of the ground and into the living space.
Before the radon test came back I noted a secondary and potentially even more dangerous issue. There is approximately 250 gallons of home heating oil in the oil tank located directly over a floor drain. A drain tied to a sump pump that discharges to the front yard right in front of a storm drain. Can you imagine if that tank ever leaked and all that oil was pumped outside?
A radon mitigation system works by soil suction and pulls radon from beneath the house and vents it to the exterior. In order for that to work, the new foundation drain system will have to be filled in with concrete. That solves the oil into the drain scenario but leaves her with the original problem of water in the basement.
Recommendations: Fix the gutters and drainpipes along with improvements to yard grading. Install flashing behind the gutters to keep them from leaking and extend the drainpipes three to ten ft. away from the house. Slope the yard significantly away from the foundation and if necessary install a curtain drain around the exterior of the home. Fill in the floor drains and install a radon mitigation system.
Conclusions: Everyone did their respective jobs properly. The windows, insulation, ventilation system, exhaust fans, and foundation system were all done professionally. But the house needs to be treated as a whole unit. If you change one system in the home it could affect other systems. In this case a floor drain led to radon problems and a potentially disastrous oil spill. The foundation drain installer probably knows nothing about radon and most likely didn’t even give a thought to the oil tank. The energy efficiency team that did the windows, insulation and ventilation systems did not realize that the increased “tightness” of the home could lead to increased radon levels.
So who is supposed to know how the home works as a system? A really good Home Inspector does. The next time you plan a major renovation, consult with a professional Home Inspector to make sure the systems you are installing are working in harmony with one another.
Photo of oil tank near floor drain
