Deep Dive On Roofing
So you want to know more about roofing? Well, you've come to the right place! Vector construction has been in the roofing industry for a combined 25 years. We have installed hundreds of roofs, attended many conferences, and have had personal training directly from shingle manufacturers, not to mention our litany of training and licenses. So we know a thing or two about the roofing process! As far as the science behind roofing materials, Owens Corning has a track record of over 50 years of breakthroughs in the industry. Not only in roofing, but in the fiberglass industry as well! In fact Vector Construction has done a lot of research on fiberglass and Owens corning and have written a compilation of the history of fiberglass here!
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Back to roofing though, we should probably start with the different types of roofing material. In truth, there are a multitude of materials that have been created and used throughout the years to protect homes from the elements. While we would love to cover all of them, we must limit our coverage to the common types of materials used in our service area in Illinois.
Roof Decking
Roof decking is the first barrier between the inside of your home and the weather of the world. Often times, this decking wears out and rots away from absorbing moisture that gets through the other layers of protection.
When a roof is to be replaced, Vector construction tears everything down to the decking every time. This allows us to inspect the decking and ensure there are no flaws in this layer of defense. If there are areas of decking that are soft or rotted, this material will be replaced with a material of similar thickness and quality.
Typically, we replace the decking with 5/8" OSB which is code required in most of the areas in which we operate. For the areas in which there is no code, we fall back on our manufacturer specifications for decking in which we always fall within even when focusing on code requirements. The decking is installed to your roof with Ring Shank nails in a 6 nail pattern meaning that this decking is here to stay, even in high winds! We did kind of gloss over the cause of the rotting decking though, so let's get into that.
Typically, decking rots around the eaves of the roof. The cause of this is of course, water rolling off of the eaves of your home. As water is a bipolar molecule and wants to stick to itself, so it doesn't just want to fall off of the roof, it will actually curl under the shingles and seep into the wood.
In cold weather, this water will freeze under the shingle layer and causing a backup of water at the eaves of your home. Then when this ice melts it soaks into the decking and causes rot. Luckily we have a solution to this problem in the form of Ice and Water Barrier!
Ice and Water Barrier
High water volume areas have always been addressed in the past, but usually they have been secured by a material referred to as Valley Metal; an aluminum strip that can be bent to fit inside of valleys. For a long time, this was a great way to prevent water intrusion in these vulnerable areas. However, Valley metal still has the issue of condensation from high humidity, so sometimes we find decking rot even in areas that have been covered by valley metal.
The industry needed something better to prevent this issue. Enter Ice and Water Barrier! This material is higher quality and it quickly became code required by many building codes.
Just like with Valley Metal, Ice and Water Barrier is installed in the valleys of your home. However, we take it a step further, as many building codes and manufacturer installation instructions require this material to be installed along the eaves, and anywhere the roof meets a wall. At this point we have established where the material is installed, and why it is needed, but what exactly is Ice and Water Barrier and how does it work?
Ice and Water Barrier is a pliable material with a smooth sandpaper top side, and a sticky bitumen adhesive on the underside. This material is applied directly to the decking under the felt layer. Once it is installed and heated by the ambient temperature, the sticky adhesive backing bonds to the decking and forms a water tight seal. This makes it impossible for water to back up under the shingles and harm the decking as the material itself is made from a hydrophobic oil based material.
Flashing
Flashing is a category that seems over-simplified. In truth, there is a lot of metal integrated into your typical roofing system, and just as many different types of flashing. Flashing in all forms are installed on the roof with nails through the material and should never be reused for a new roof because they will inevitably be the source of leaking in the future. The good news is that when you call on Vector Construction to complete your roof installation, we replace all of this metal in order to provide you with the best defense against water intrusion. All of these types of flashing is vital to the health of your roofing system but let's start with End Wall Flashing.
End Wall Flashing
End Wall Flashing is an "L" shaped strip of solid seamless aluminum that is installed with one half under the siding, and the other half on top of the shingles. The main purpose of End Wall Flashing is to guide water away from the seam where a wall meets the roof section. Water intrusion in these areas could prove extremely harmful and allow interior water damage to your home. With Siding overlapping this flashing which is then overlapping the shingles, water never really has a chance to infiltrate the wall to roof seam.
Chimney Flashing
Chimney Flashing is, as the name implies, flashing for chimneys. Chimney flashing actually comprises of a few different components. End Wall Flashing, Step Flashing, and Counter Flashing.
As before, End wall flashing is installed facing the downward slope of the roof. This protects the seam where the chimney penetrates through the roof surface.
Step Flashing is then installed along the sides of the chimney and is weaved between shingle layers as they step up the roof slope. The stepping up of the flashing is important to direct water away from the chimney penetration.
The last material to be installed around the chimney is called Counter Flashing. Counter Flashing is the only flashing on the chimney that doesn't directly tie into the roof. Instead, it is used to cover up the tops of all the rest of the flashing. In order to make the Counter Flashing water tight, it has to be cut into the bricks and hooked inside of the chimney itself and sealed with an adhesive.
Drip Edge
Drip Edge is an interesting item on this list as most people don't think of it as flashing, it is commonly thought of as finish. However, this material serves the same function as the rest of flashing in this category. It serves to direct water away from areas where it is undesirable to be. Namely, the perimeter edges of the roof. Formerly, we covered the necessity of Ice and Water Barrier to the edges of the roof which prevents water from getting to the top of the decking. Drip Edge prevents water entry to the edges of the decking by guiding the water that rolls off of the shingles onto the fascia, or into gutters.
Many roofing companies will attempt to save money by not replacing this material when performing a roof replacement. While reusing old drip edge may not directly lead to a leak within your home, it will lead to water intrusion around the perimeter which will cause eave rot despite the inclusion of Ice and Water Barrier.
Therefore, it is very important to replace this material every time.
Pipe Flashing
Not the final flashing, but one of note to be installed on the roof is Pipe Flashing. Pipe flashing is installed around the pipes that penetrate through your roof. These pipes are often plumbing vents, exhaust vents and furnace vents. These flashings are separated into two pieces. The aluminum plate is what integrates into the roof decking. The upper half of which is laid under shingles to continue that shingle step pattern. The lower half is nailed to the decking on top of the shingle layer. The second part of this flashing is a rubber ring in the center of the flashing. This is where the pipe goes through. The elasticity of the rubber seal ensures a tight seal around any pipe it is installed on.
Underlayment
The next material to be installed on your roofing system is felt underlayment, or in this case, Synthetic Underlayment. Underlayment in essence is a moisture barrier this is installed directly to the surface of the roof decking, usually with staples. In the past, this moisture barrier was made from hydrophobic oil coated fiber meshes. This material served its purpose well for a very long time, but the main issue with this felt was its flexibility. When we tear off a roof containing 15 or 30 lb felt, this material tends to end up shredding like confetti and blowing away with the wind.
Vector Construction uses synthetic underlayment. This material is like covering your entire roof in a water resistant tarp. Synthetic felt is far thinner, more flexible, better wicking, remarkably resistant to tearing and incredibly breathable! For what it's worth, it's also easier for our installers to walk on as the installation process is under way. For those reasons, we use synthetic felt for all of our roofing projects!
Starter Strip
Starter strip is the starting point for the shingle installation. A shingle lake material is nailed to the edges of the roof, (the rakes and eaves) and has a sticky mastic adhesive facing upward. When starter strip is installed, it usually overhangs the roof by about a half of an inch. This ensures that water is carried over the edge of the roof and hopefully ends up in the gutters.
When the shingles are installed, the underside of the shingle material sticks to the adhesive strip and forms a bond that should never unstick throughout the duration of the roofing system's life span.
Starter also has the benefit of increasing the wind resistance of the entire roof by giving the shingles a solid foundation in which to build upon.
Shingles
Now we get to shingles. What can we really say about them? Vector Construction uses two different suppliers when it comes to our shingles. Atlas, and Owens Corning. The latter of which is exceedingly popular, and we get it. Owens Corning has had quite a history, just read our article on fiberglass!
Owens Corning shingles are great. The Laminated Duration line has a wind rating of 130 MPH because of its Sure Nail Strip. With a 6 nail pattern put directly in the Sure Nail Strip, the vinyl strip will grip onto the nail and prevent it from backing out over time. Then, the next shingle to be installed places their mastic seal strip right on top of this strip which solidifies the installation.
When installed properly, with Ice and Water Barrier, new Flashings, synthetic underlayment and proper Ventilation, your roof qualifies for Owens Corning's 50 year warranty!
Ventilation
Finally, we come to Ventilation. Ventilation is often times overlooked, but not on our watch! Ventilation is the key factor in ensuring your roofing system has a long life. In every roofing system, the ideal condition is that the attic space is relatively the same temperature as the outside air. This is because the material on your roof will expand in the heat and contract in the cold. If the attic space is not ventilated, the shingles would expand on the top and contract or remain the same size on the bottom thus leading to flexing. This flexing can actually end up pulling nails out of the decking. Uneven temperatures across the shingles can cause other damages such as blistering and thermal cracking.
With this in mind, you can rest assured that we will do everything we can to ensure that your new roof is properly ventilated.
Though the math associated with proper ventilation is a bit complicated, Owens Corning has made a nifty calculator that will give you the amount of ridge vent that is needed to ensure that your roof is properly ventilated.