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Inspecting a Flat Roof

Date: September 30, 2018

Leaks Can Be Devastating

When you’re buying a new property, you have a lot to think about to prepare for your new home. Inspecting a flat roof before following through with the purchase is extremely important.

Even though you may have owned a property with a flat roof in the past, it is still a good idea to inspect the roof and understand how to maintain it.

Leaks can be devastating and expensive if they’re not repaired quickly after they’re found.

Serious Flat Roofing Problems To Look For


These are areas that look like bubbles or where the surface is uneven. There could be moisture trapped underneath the membrane, but more often, it's a result of improper installation.

Ask a roofing contractor if a particular blister on your roof will cause bigger problems.


This could mean there’s a poor structure or bad insulation installation. Even if the membrane was installed correctly, shifting or movement inside could cause a split in the flat roof’s membrane. If this is the case, the flashing in this area will usually fail too.


If the membrane looks like it shifted from its original position, it could be due to the slope of the roof being too steep for the type of membrane installed, poor adhesion, or thermal issues.

This can contribute to ridges, splits, and other roof problems.

Obvious Damage

When inspecting a flat roof and find that it has been punctured or shows other signs of obvious damage, you should bring it to the attention of your professional roofing contractor.


Some membranes have a tendency to shrink. You will see this as an issue if membrane seams look like they’re pulling against a penetration like a plumbing vent pipe, or if the membrane can be pulled away from the eave’s edges.

You may also see “bridging” at angle changes such as parapet walls, against other walls, etc.

Things to Look When Inspecting A Flat Roof

On the Roof

If you don’t see any discolored spots or any other signs leaking inside, it is still a smart choice to have the roof inspected.

There could be cracks beginning to form that will become bigger issues down the road. You’ll want to get these problems fixed before they cause any internal damage to the home.

One thing we would recommend is walking the roof to do a simple visual inspection. To be safe, make sure to be aware of where you are on the roof and never walk backward.

Make note of all the penetrations and don’t put any weight on any skylight covers, they’re not built to withstand the significant weight.

While you’re walking the roof, make a note of how it feels under your feet. If it feels weak, get off the roof safely and as quickly as possible and call a professional roofing contractor.

A leak on the roof could soak the insulation under the membrane. If it feels spongy underneath you, you’ll also want to refer to a roofing contractor. This is also the case if you notice any water coming out of any part of the membrane.

Inspect Penetrations and their Seals

Next, you will want to look at all the penetrations and seals. A large number of leaks start at penetrations and seals, which make up a very small percentage of the total area of the flat roof.

Penetrations, things like pipes and flashings that ‘penetrate’ the roof, are usually enclosed by flashings made from some form of sheet metal. Inspect around these penetrations for deterioration and cracks.

This cracking might not seem to be a big problem, but as moisture gets in, it will expand the crack until it's large enough to cause a big leak.

Seals are where two waterproof materials overlap, coming together in the same spot. Inspect these seals and make sure they’re smooth and still fully adhering.

In the Interior

You’ll want to check each individual room on the property carefully. Check the ceilings for any stains or discoloration. If the roof is leaking, you’ll find a dark-colored ring forming around the water-saturated spot.

stained ceiling from leaking flat roof
This is what a leaking roof looks like from the interior

If you see this, you should contact an experienced roofing contractor before moving ahead with your purchase.

Damage from a leak in one area doesn’t necessarily mean that the leak is located directly above it. Flat roofing systems have layers that might direct the moisture to other areas in the home, many times far away from the source.

The damage could also be from a plumbing or AC leak or, possibly some other source other than your roof itself.

It's also a possibility that the leak that caused the stain was previously repaired but the discoloration on the ceiling was not.

However, to be on the safe side, the best thing to do is to hire a professional flat roofing contractor to locate the source of any leaks.

To Conclude

If you’ve finished your roof inspection and decide you need to hire an experienced commercial roofing contractor, make sure to get several bids to ensure that you thoroughly understand what really needs to be remedied.

Also, if you get multiple bids, you’re more likely to pay a lower price for your roof repair. Your roofing contractor might also be able to help you extend your roof’s lifespan and give you instructions on what you can do for routine maintenance throughout the year.

About Mikku & Sons
Mikku and Sons red repair track with its logo painted on its side- roofing company track wraps
Our roofing company was founded in 2001 by Michael Riutta, who is still part of the ownership and management team. Between Michael, his two sons and co-owners, Devin and Joshua, and our crew members, we have many years of experience to handle any type of roof repair or roof installation solutions you may need.