New Quote: Two Times is a Charm!

No, I don't care what you say; I'm changing it from three to two!

Today, I looked at two houses with the same inherent construction problem, both attributable to contractor ignorance or amateur construction.

It's called failure to provide a structural ridge "beam" to support a cathedral ceiling  (rafter-framed) roof.

In conventional rafter-framed (stick-framed) construction,

two times is a charm
In this diagram, the downward force of gravity is shown on a rafter construction with a ridge board, not a ridge beam. Since there are no ceiling joists, the downward push of the weight of the roof pushes the exterior walls outward and causes roof sag.

the rafters span from birds-mouth cuts bearing on the exterior stud walls up to some board called a "ridge board"---just a board---not a beam!!!

If we remove the critical ceiling joist ties and expect the remaining rafters and non-structural ridge board not to move---we are idiots for not understanding why this doesn't work.  In rafter construction, the peak ridge board is simply a convenient faceplate to mate opposing rafters at the ridge/peak from opposite walls during roof construction.  The ridge board is not structural...just a convenient component of rafter-framed roof construction.

When we use this common, simple method of roof-frame construction, we must have complimentary ceiling joists connected to the opposing rafters at their base, at their birds-mouth cut bearing on the exterior stud walls, and these ceiling joists continue across the home to the opposite exterior wall and connect to the opposing rafters.  The ceiling joists create a critical "structural tie" across the home and prevent the rafters from pushing down and out---spreading the supporting exterior walls.

two times is a charm
When a ridge beam is used, the weight of the roof is supported correctly and will not result in roof sag or outward lean of exterior walls.

If we remove the critical ceiling joist ties and expect the remaining rafters and non-structural ridge board not to move---we are idiots for not understanding why this doesn't work

So today, when I saw the consequence of this ignorance at two separate houses --with sagging ridge boards and outward-leaning exterior walls (the gable roofs looked like saddles!) I felt compelled to write this article and bring this important information to everyone's attention.

Moral to the story:

"Ask your contractor to explain the difference between a ridge board and ridge beam.  If he says he doesn't understand your question or says there's no difference, tell them you just got an important text from God and must leave now!"

Or, take the four-foot level you used to read outward lean in your great room walls, and bop them across their heads!

What causes Cracks in Crown Molding?

What causes Cracks in Crown Molding?

Are these cracks in crown molding being caused by foundation movement?

Many foundation repair contractor salesman will point to crown moldings and wood casing cracks and separations and say that they indicate foundation movement or floor sag, and structural repairs are needed. There is nothing farther from the truth. So, why do cracks and separations appear in crown moldings?

It's pretty simple, wood is hygroscopic and every piece of sawn or milled molding has a unique and specific direction or orientation of wood grain. The physical characteristic "hygroscopic" means that wood will always try to reach moisture equilibrium with the surrounding atmosphere. It will either absorb moisture (from the air) during periods of high humidity or off-gas moisture into the air during periods of low humidity. The wood moisture content is constantly changing throughout the year due to the changing seasonal weather conditions. And depending on where the molding was cut out of the tree or limbs, the molding has a specific wood grain pattern (the pattern of the tree's annual growth rings). The two most common grain patterns that arise from the production of sawn lumber and milled moldings are flat-sawn and cross-grain. Wood expands and contracts with changes in wood moisture content, swelling when wetted and shrinking when dried. These movements in wood take place tangentially and radially to the wood grain. This results in the distorted shapes shown in the attached figure. Flat grain lumber tends to warp and twist, while cross-grain lumber tends to maintain a stable profile. Hence, long, relatively thin pieces of crown molding with flat sawn grain are always wanting to distort according to their grain patterns as the moldings dry during the winter time (heating season) and take on moisture during the spring through fall (cooling season) and when windows and doors are often left open causing the interior humidity levels to rise along with the outdoor conditions.

What causes Cracks in Crown Molding?
This illustration shows how wood can warp and twist during the drying process after it's been cut. The distortion that takes place through shrinkage can cause cracks and gaps in your crown molding.

After multiple attempts or years of caulking and painting wood moldings, the paint/caulk usually form a flexible covering which is strong enough to withstand the movements in the crown moldings due to humidity changes inside the home. This is because the crown moldings will eventually reach a stable or "mean" (average) moisture content throughout the year, based on each homeowner's unique living style, such that the ensuing wood movements that do occur, due to humidity changes, results in such little movement, that the caulked joints do not tear open or crack.