DEAR TIM: The attic in our 4-year-old house creaks, and when it’s windy we hear cracking noises as well. The sounds are very loud, waking us up. It sounds like something is going to come crashing down through the ceiling above our bed. It’s very unsettling. The builder sent a fellow to add two-by-fours to some of the trusses. It did not resolve the problem. We can’t live like this. What’s causing the problem and how can we stop the frightening creaking? – Martha A., Egg Harbor Township, New Jersey
DEAR MARTHA: While I’m not a structural engineer, I’ve built enough wood-frame houses to know that they can groan, creak and moan when the wind is howling. Even my own home, which I didn’t build, creaks and strains when powerful nor’easters batter it.
If your home is creaking and moving with each slight breeze or moderate wind, then I’d say you’ve got a valid complaint. But in severe wind storms, it’s normal for a house to make a few noises.
It’s pretty easy to understand what’s going on if you’ve ever had to carry a single sheet of plywood in a strong wind. I clearly remember a gusty day when I hoisted a piece of plywood and was promptly put on the ground by Mother Nature. I didn’t get hurt, but the pressure of the wind on that single sheet of plywood was far greater than the combined strength of my leg, arm and back muscles to resist the wind’s force.
Structural engineers will be the first to tell you that the combined pressure of a moderate wind is equivalent to thousands of pounds of force.
The mathematical formulas for calculating all of this are complex, but modern building codes have taken all this into account, and the trusses in your home should have been designed to withstand normal weather events and windy days.
As to what’s causing the noise, it’s pretty simple: The pressure of the wind is causing the wood framing to flex.
The wood sheathing could be rubbing against the trusses, and you could be getting noise from wood rubbing against metal fasteners.
The solution, in my opinion, is to stiffen the attic structure so that much more force is required to make it flex or move. Your builder had the right idea in sending a worker over to add more bracing to the underside of the trusses; however, it may not have been installed correctly.
If I were you, I’d hire a residential structural engineer to inspect your attic. The engineer will likely come to your home and take notes and photos, do a detailed inspection of your attic space, and then develop a simple retrofit plan that most carpenters can follow.
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