The Mansard Roof
Shingles hanging almost vertically? Flat roof above the shingles and not visible? You probably found a home with a Mansard roof. Let’s break it down:
The flat portion: it can be constructed of many different products. Back in the day, it could have been tar and gravel; now products like TPO and modified bitumen membrane are often used. Key to this part of the Mansard roof is drainage. Whether it is internal roof drains, external scuppers, or tapered slope systems to gutters, a flat roof needs to have water easily removed to prevent pooling on the roof. Keeping the drainage systems operating (clearing drains, scuppers, etc. of leaves and debris) extends the life of any flat roof. The longer water ponds on a roof, the faster roofing products breakdown and allow leaks.
Cost guide: flat roof installation is approximately 2-4 times the cost of composition, sloped, shingled roof installation. Why such a variance on cost? There are many variables such as necessary insulation requirements, number of pipes and penetrations on the roof, HVAC units, and drainage issues. Also, maintenance of drainage systems can be a reoccurring expense. Keep the roof clean and it will last longer.
Mansard roof area: Almost any steep slope roofing product can be used for the shingled portion of the roof. Visual appeal usually dictates which product a builder, architect or homeowner chooses. Installation of these products is more complex than a walkable, easy, ranch styled shingled roof. The shingles are not laying on the roof; they are ‘hanging’ from nails or screws. This weight on specific points (the nail or screw) can result in the shingle ripping or breaking over time and falling to the ground. Mansard roof installations generally require strict adherence to manufacturer’s specs on WHERE the fasteners are to be used, and HOW MANY fasteners are to be used. When these guidelines are not followed, the shingles delaminate (come apart) and fall from the roof.
Cost guide: Shingle application on a Mansard roof often requires scaffolding or walk boards to allow the crew to hang the shingles. This can increase roof application cost verses average lower sloped, shingled roofs.
Buying a home with a Mansard roof: we recommend a full roof inspection by a qualified roofing contractor. Knowing the age of the flat roof portion and if it has been replaced with a full tear-off or only had product laid over it is key. Water testing the roof and drainage system is recommended.
Selling a home with a Mansard roof: while many homeowners hope buyers will not ‘find’ problems, we recommend the seller have a full roof inspection prior to listing the home. Often minor repairs can bring a Mansard roof a glowing inspection for a buyer, and large decisions like replacement, allowing funds for replacement, or discounting a listing price due to roof condition can be discussed between the seller and seller’s agent before negotiations.
