Choosing the right roofing system for your new meal building is a very critical part of the
planning process. The wrong decision could mean leaks or unsightly damage.
Welcome back. In this installment we will explain the different types of roofing systems available for your new prefab metal building kit.
There are wide-ranging options for roofing systems in the metal building market-place. Finding the right choice for your new building kit is our next task.
Many of the pre-engineered steel buildings can have very low slopes – as low as ¼ in 12. This means that you will require a roofing system that can direct the water off the roof quickly without having the water back-up through the roofing seams and into the building interior.
Generally speaking metal building roofing systems can be divided into four categories:
This is the most common and most economical roof system. You will have
seen this system on agricultural buildings during your drives through the
The roofing material is generally a light gauge metal sheet with a low profile pattern. Most metal roofing comes standard as galvanized or galvalume. Colored coatings are generally optional with some premium colors available.
This type of system fastens directly through the sheet with color matching fasteners. The sheet is screwed down tight and there is no allowance for expansion and contraction.
I would not recommend this roofing system on a very low slope (under 3 in 12) or in an area where there is a great variance in temperature to cause expansion and contraction.
For example in the northern U.S. and most of Canada there will be freeze-thaw cycles every year. Temperatures can range from the high 90's F to 0 F. This temperature range can cause expansion and contraction stress which can loosen the fasteners.
Loose fasteners = leaks!
For many utility type buildings with higher roof slopes and more moderate temperatures this system is just fine.
This type of roofing system has the joint or seam between two roofing
panels raised up or standing as the name implies. This means that any
flowing or standing, or backed-up water is below the actual seam.
Standing Seam roofs come in a variety of profiles. Some are mechanically seamed while others are not. Many architectural roofing panels have standing seams – see below.
Mechanically seamed roofing systems have an added benefit. A tool called a seamer or roof-runner is positioned over a standing seam. When turned on it slowly moves up or down the seam folding the seam tightly similar to the lid of a tin can.
Another big advantage for this type of system is the fact that there are no fasteners through the roofing membrane. This system typically has clips that hook on to one panel and gets fastened into the roof purlin. The next panel is then put into place ready for the seamer to do its job.
Clipped standing seam roofs have the added advantage of being able to move slightly when expansion or contraction occurs. This is especially required when you have long roof panel runs. The panel can slide on the clip as the roof panel stretches or shrinks from temperature change.
Standing seam roofs come in plain galvanized or galvalume and also with colored coatings depending on your supplier.
Where snow is a concern, this is your best option. Snow and ice can build up but as the water flows, it will be below the ice and snow on top of the roof panel. No chance for water damage here!
Architectural roof panel systems are generally for steeper pitched
roofs – roofs that you will see most of.
These panels come in many different profiles. They can be screw-down or a standing seam style.
Most are colored to compliment the architectural features of the building – hence the name. Many are available is premium colors – again for a premium in price.
Architectural roof panels are often more expensive than the types listed above but they can add a tremendous punch in terms of aesthetics.
Insulated roofing systems have panels with two metal "skins" – an
interior skin and an exterior.
Between the two layers of steel is a foam insulation core. This core can range from 1" to 6" thick and sometimes even thicker depending on the manufacturer.
This type of panel is also used in the manufacture of cooler and freezer rooms – which tells you how efficient they can be.
Most of these panels are tongue-and-grooved. They are often held in place by special clips that are fastened to your structure. The clips do not touch the outer metal skin so there is little or no thermal transfer from the outer skin to the inner skin.
The panels come with colored coatings on the inside and out. The skins can have the same color or different colors inside and out.
Again, these roof panels are more expensive however you have the added benefit of insulation and an interior liner both of which will be discussed in a later installment.
When deciding on your preferred roofing system keep in mind these few tips:
Pre-engineered metal building are generally "economized". Unless specified otherwise by you, the slope will likely be fairly flat – as low as ¼" in 12" for a standing seam roof. You will therefore see very little of your roof.
Galvanized or galvalume are your best price options.
For higher pitched roofs you may wish to use an architectural roofing panel to add aesthetic appeal to your building.
Consider what equipment might be placed on the roof. This may dictate which system is most suitable.
You can often purchase extended perforation warranties for certain roof types.
Make your roofing system choice and then check out our next installment in this series.
Step 3 Planning and Constructing Metal Building Kits – Siding Options
What to Do Next
· Check out the other articles relating to metal building kits and residential building packages on our Metal Building Kits Articles Map
· Check out the merchants relating to metal building kits here.
New Series! How To Plan and Build Your New Metal Building Kit!
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