Methods to stop mould in your attic

Melissa: I’m just as discouraged as you are. Much of the information on the internet about home improvement, maintenance, and the simple physics of houses is wrong. You can’t imagine how many questions like yours I get on my website. Other homeowners like you are frustrated and confused about what to do in all sorts of situations.

There are many reasons for the misinformation. First and foremost, you don’t need to have any formal education to work in the construction and remodeling industry.

A scary and growing trend is any hobby blogger you come across on the internet. These are people with normal day jobs who have an interest in home improvement, or they have painted a bedroom and think that makes them an expert.

The true definition of a professional is someone who works for others for a fee and has been doing so for years and gaining a lot of hands-on experience. Always look at the About Us page on any website and make sure the website owner is a professional.

Then you have the workers out there who have been doing things wrong for 30 years and polluting the minds of young workers. Some of these bad eggs leave comments on websites or have their own websites.

Finishing concrete is a perfect example. Some pavers feel like you should add water to the concrete when you place and finish it. It makes it easier to ladle, I’ll give you that!

However, the added water dilutes the portland cement on the surface, causing the concrete to flake and fail long before its time. I could give you hundreds of examples of other incorrect building practices, but let’s talk about attic ventilation.

If you want to know the best way to ventilate an attic in a new home, just head to the land near where you live in the south. I am sure you will find a chicken farmer in a short time.

Check out the gable ends of a huge chicken house that houses thousands of chickens. The entire triangular ends at each end of the roof are almost always completely louvred. The farmers need as much air as possible through the attic to keep the chickens cool.

You can’t have too much roof ventilation is the simple answer. Air constantly flowing through an attic prevents mold. Your old home never had mold because old houses were so drafty that water vapor was constantly being transported outside or evaporated from the cladding surfaces before mold could grow.

The continuous ridge ventilation rage continues to dominate the ventilation discussion. The only problem is that the hot air doesn’t go down. All ridge vents are designed like an S-trap for pipes, which causes the hot air to sink down before it goes up. This defies physics.

If your new home has gable ends, install large angled louvers. You also want great full-length reveal openings. Turbine vents, rotating with a breeze, suck large amounts of air from attic spaces.

You will never solve the heat problem in attics due to the physics of infrared heat. When the sun hits a roof, it warms the shingles, wood cladding, and the attic. The temperatures of these things are easily approaching 160 F. I know when I measured the temperature of my own roofing materials.

These building materials act like toaster coils. They radiate heat into the attic. You can only stop it if you use some kind of radiation barrier under the frame that directs the heat back outside.

The radiation barriers work great for about a year, but once they get dusty, their efficiency drops like a rock off a cliff. You can try cooling an attic with huge roof fans like the chicken farmers use. It takes tens of thousands of cubic feet of air per minute passing through your attic to make a small difference, and that air is exactly the same as the outside air temperature.

Forget the solar powered roof fans. They just don’t move enough air to bring the temperature down in an attic. I know how I tested several.

Do you need an answer? All of Tim’s previous columns are archived for free at You can also watch hundreds of videos, download quick guides, and more.

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