When your house was first built, everything they put into the roof was new, but when you get your roof “replaced” some decades (hopefully) later, you don’t actually replace the whole roof. Or at least, you shouldn’t have to replace everything unless there was some seriously big problems with the construction in the first place.
Unless a roof has leaked seriously enough to damage construction immediately under the waterproofing, re-roofing your home is pretty straightforward. Having said that, a small error in its construction can cause a significant amount of damage, so it’s important to get it right.
Assuming there is no damage to the waterproofing layer
Simply put, the typical roof on a house in Bellevue, Washington, needs only two layers to be replaced when it comes time to take the project on. The first, top-most layer is the one you see. In the past many roofs here were made of plain wood shakes. They were certainly beautiful, and gave the homes in the Puget Sound a certain regional character. The problem is, especially as houses were being crammed in together more densely, the potential for fire to jump from one house to another increased. Washington State codes came into effect more and more, and so, new materials sprung onto the market. You can now buy synthetic shakes that look like the real thing but last longer and are more fire resistant. True, everything has a burning point, but these new materials greatly reduce the chances of your house catching fire from your neighbor’s house fire, so I strongly recommend you go that direction, regardless of Washington State code.
Back to the topic of materials needing replacement: Under the shake (or composite, tile or synthetic material of one type or another) is usually a plastic sheeting that creates a barrier between whatever material you chose for the external covering (shake, composite, etc.) and the framework / roof structure itself. That waterproof plastic (usually plastic, anyway) is the most important layer because no matter what any given slate or tile might do, the waterproof layer with protect your roof infrastructure, and as a consequence, you whole house.
If there is water or other damage under the waterproof layer
No matter how good a roof construction is, the under-layer eventually will fatigue and deteriorate enough for it to fail as a waterproof barrier protecting your roof’s infrastructure. That will happen if for example, you leave it go way past its replacement due date. The constant heating, cooling, dampening and drying breaks down the most stubborn materials. Eventually, it fails, and hopefully it is obvious quickly to the home owner. Unfortunately, though, a leak starts off tiny. Just a little water gets in and over time, even a little bit of water can do a lot of damage. If for example, a small leak sprang in September. A tinly amount of water tricked in through a tiny hole, and kept a small area of the roof’s wooden infrastructure (a few rafters close together, for example) but did not go as far to be visible on the underside of the ceiling, it might be months, or ever years before you saw that there was a problem. That’s why it’s almost always better to consider replacing the upper layers of your roof when a period of time has elapsed. That period of time is what is expected to be the lifetime of the product.
Two layers, and some other pieces
One of the most important areas that must be done properly is where the roof meets a chimney, a skylight or any other protruding part of the roof. Ideally, you do not want water to run from the chimney and under the roof surface material, even though that water is still above the waterproofing layer. Ideally it runs off, and on to the outer roofing material, so you can see clearly that you are still taking advantage of two complete barriers. Should there be any issue with a single tile, for example, only then do you draw on the waterproof nature of the layer underneath it.
Where the waterproof layer is secured to the roof
On top of the rafters is usually a layer of plywood. To that is nailed the waterproof layer, and those nails must perform two functions. Firstly, they must hold the waterproof layer securely in place. Secondly, they must not introduce a new opportunity for water to get through that protective, waterproof layer. If, for example, the guy nailing on the shakes leaves holes in the waterproofing, it might go unnoticed for a long time. This is why, simple and all as many people believe roofing is, it has enormous potential for doing long term damage if the work is done incorrectly.
Washington State code is thorough
It’s understandable that a roofing company (or a plumber, carpenter, electrician) feel frustrated by all the codes that are in place. Aside from having to be licensed, bonded and insured, there are numerous regulations regarding how the work is actually done, what materials are allowed and so on. But, all these regulations apply to every single company that wants to offer roofing services in this state, so the competition all plays on a level playing field: they all have to abide by the same rules!
The state code for roofing companies is for the benefit of the consumer. Aside from the legal requirement that a roofing company must do a proper job, there are also safety concerns for all involved, including the employees and subcontractors that the roofing company engages.
All of the code requirements are why you must choose a roofing contractor that absolutely is licensed, bonded and insured. Even if you think they might do an excellent job, and the price is right, if one of their workers has an accident, you the house owner can be held responsible. When a contractor is properly insured, you do not have that worry.
In many ways, the roof of your house could be described as the most important. Of course, every part of your house can have a negative effect, and the foundation is also critical, but just one seemingly slight flaw in a roof can do a lot of damage.
Check back next week when we’ll talk more about keeping a roof properly waterproof!