The Layers of Shingles Matter
Usually when someone buys a property. They do not pay enough attention to the quality of the roof. One of the most neglected aspects is the layers of shingles of a property with a composition roofing system.
Please see the following picture
Do you see how many layers of shingles there are in the picture above? In a one layer roofing system you will see two layers on the perimeter. This is because there is a layer of extra shingles on the perimeter of the roof. This extra layer is called "starters", it's for added protection so rain does not go in into the roof and bring moisture into the roof. So in the above picture you will see four layers, meaning the roof actually has three layers.
Why is this important to know? First, the home inspector will see this, and that is a sign that there are issues with the roof. Maybe you can tell that is does not look right.
In many, cities it is against city code to have more than 3 or more layers.
Also, consider the extra weight on the building. Every square, which is a 10' x 10' area weighs about 165 pounds of one layer of shingles. So in the above house instead of weighing 4000 pounds, the roof will weigh around 16000 pounds. This also affects the ventilation -- meaning you need to spend more money to keep the house cooler. The heat also creates problems on the roof. Particularly on the decking.
It has happened so many times. A contractor gives a price, opens up the roof, calls the real estate investor, saying the price of the job will have to increase. Why? Because the decking has gone bad. So, always be prepared for bad decking if you buy a property with shingles on the roof with multiple layers.
So, a roof with multiple layers is best to consider that you will be paying almost double to replace the roof if the decking is bad. Do not let the contractor just tell you, ask for pictures or be there yourself. Take pictures of the work done to show the home inspector. The good news is it's still cheaper getting the exterior done compared to interior work when flipping houses, and it is less of a headache also.
There is an important exception to this. If you will be buying a property to rent to tenents, and there are no leaks are no leaks the building, and there are less layers then allowed by code, and roof looks in decent condition. If you are on a super tight budget, just doing a layover is an option. This option should not be just jumped into. Its main advantage is will be cheap in the short term, till you make your investment back, and then in later, you will have to change the whole roof, and maybe by that time the decking also. I would only recommend this if there is only one layer already there, and there are no leaks. It would look like this, and will last as long as any other roof.
Also, if you live an area that snows alot. The snow will also add weight to the building. In areas that are hot and sunny, the extra layer will make the building more heated.
Comments (4)
One way to look at it. However, in metal or tile you have ventilation on the roof also, so its not specific to shingles. This is mainly because of the sun,s econd it's around 167 pounds per square and third heat goes up, so all heat gets trapped in attic. This is why its the general rule you need one feet of ventilation for every 150 square feet. So, heat inside the house goes up, and the heat of the sun is on the roof almost 10 hours a day.
I will tell you that 30% of the roofing battle on the roof is the constant heat. The crew has to have a lot of water bottles. If its cold its going to generally be colder than the ground too, especially when its windy.
I should write an article about ventilation in the attic also one day and the costs its saves.
Justin Stanfield, over 7 years ago
Justin, thank you for sharing!
Being not local (I live in Australia), I wonder what type of insulation is customary in the US?
Here in houses being renovated these days it will be as a minimum foil sarking with tiled or metal roof. We don't use shingles here.
So I wonder why several layers of shingles would make the house hotter? Just because they trap heat and release it slowly?
Katrina M., over 7 years ago
A lot of useful information. Great article.
James Syed, over 7 years ago
+1! There is a ton of valuable information that is pertinent to know on this article before securing a house for yourself.
Thank you for sharing :)
Jon Lebron, over 7 years ago