image of old roofing material


Good morning – to every Baltimorean living in Hampden on down to Federal Hill !

Today we are going to share some professional insights on what to look for when inspecting your Baltimore City flat roof. To learn about different types of Flat Roofs. If you need a Baltimore roofing specialist, Contact Four Twelve today.

Below are 3 things to look for, which are the most common problems we see on a daily basis with when repairing and replacing flat roofs in Baltimore City.


image of roofing workers cleaning roof

1. Layering

The first thing we do at Four Twelve, when climbing on a flat roof in Baltimore City, is pull back the gutters and inspect the number of layers of roofing material present on top of the roof. Many rowhomes were originally constructed with a sheet of tin metal roofing. Over time, these tin roofs were covered up with layer upon layer of black roofing material taking various forms – tar, rubber, asphalt, etc. In Baltimore City, it is not uncommon to see the original tin roof peeking out from under 6 layers of material. If your roof has been building up many layers over time, it is not a bad idea to get a roofing professional out to your home to take a look.

A few layers is common, but to overdo this practice – by adding 3+ layers on a roof, leads to other negative side affects. One, the sheer weight of 5-6 layers of roofing material puts serious strain on the structure of your home. Additionally with each successive layer of roofing material, the install is less effective. If your roofing material has ripples and you lay next layer perfectly on top of this layer, it does not even matter. The underlying ripples will force the new layer to pop up, as it is in the photo below. The glue is not strong enough to combat the underlying materials defects.

Rowhome roof in Federal Hill. The original tin cap is rusted orange underneath. On top are between 6-8 layers of rubber, tar and torch down roofing material.

2. Alligator Skin

If you own a rowhome in Baltimore City, it is a +90% bet that you have what is called a Torch Down Rubber Roof on top of your home. This material is a quality product, but over time the rain and sun can degrade this product by stripping it of its asphalt coating and drying up the rubber material. When this happens to Torch Down Rubber Roofs, the material begins to splinter and crack – a symptom we call Alligatoring, as it starts to look like the skin of an Alligator. Prolonged cracking and splitting of rubber roof material means that your roof is nearing the end of its life cycle.

If you are able to catch alligatoring before it spreads, you can do what we call a silicone coating (learn more about this product here). But if the alligatoring is too pronounced, like it is in the photo below – then you will have to tear off and replace it the roofing material. The way to determine this, is to take a walk on your Baltimore flat roof and see if the paper is dried up and cracking under foot. It will have lost its adhesion from UV exposure and not be firmly secured on the underside. If the paper is crunching and giving underfoot – then the material is susceptible to punctures and silicone coating is no longer an option.

a pic of a damaged flat roof

Alligator Skin, a symptom every Baltimore City homeowner should be aware of. If you see this, it means that your Flat Rubber Roof is nearing the end of its life cycle.

3. Ponding Water

Torch Down Rubber Roofs must be installed properly in order for the homeowner to realize its full benefit. Oftentimes, a subpar install will create valleys of poor drainage and water may pool behind a skylight or chimney. While rubber roofs are thick, AND shed water effectively (when sloped), they can be porous if exposed to ponding water for extended periods of time. This is the 3rd no-no of rubber roofs – make sure there are no spots where water is ponding.

The spots that are most susceptible to ponding on Baltimore City flat roofs are behind skylights, chimneys and any other roof penetrations. The best way to prevent ponding next to a roof penetration, is to have your roofing build what is called a “cricket” behind the penetration. A cricket is a little triangular hill that sits on the upslope side of the penetration, and aids in the movement of water as it rolls downhill on your flat roof.

image of a flat roof in Baltimore done by Four Twelve

Ponding water is defined as water that sits on your roof’s surface for more than 48 hours. Flat roofs have difficult draining, as they don’t have great slope to shed water. Ponding water must be addressed early if spotted.

Let Four Twelve Be Your Solution
For Baltimore Flat Roof Repairs and Replacements

I can’t tell you how often I hear it – people can’t seem to find the right solution for their flat roofs in Baltimore. The flat roof is inherently a tricky product – with little to no slope – they don’t shed water or debris as effectively as sloped roofs, also there is significantly less margin for error when installing a flat roof.

If you have a flat roof in Baltimore we’d love to help you. Let us come out, inspect it and provide a professional opinion, complete with photographs and a free estimate for the repair or replacement necessary to get your roof in good working order.

All work we perform on flat roofs comes with a 3 year warranty on workmanship and a 15-20 year manufacturer’s warranty on material. Every one of our flat roof installations start and finish within 1 week. We also benefit from being a small business with less overhead, allowing us to be competitive in our pricing for roofing services.

When it comes to your roofing needs, whether flat roof or pitched roof, you can depend on Four Twelve Roofing for assistance. Aside from that, we also specialize in other property improvement and renovation services, including but not limited to gutters and skylights. Contact us today or visit us at 10 E North Ave, Baltimore, MD 21218 for a personal consultation!

Call Four Twelve Roofing Today for a FREE ESTIMATE
Baltimore’s Local, Trusted Roofing Contractor.
(410) 989-7343


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