Help with a mansard roof

I’m inspecting several (17) apartment buildings with mansard roofs. The shingles are newly installed laminated comp. I’d never seen a second layer of laminated shingles installed on a layer of laminated shingles. Also, the mansard shingles are not hand sealed down, the roofing contractor said he’d use a “hurricane nailing pattern”. Well, I can’t see what pattern was used without pulling off shingles, and some tabs have been falling off the mansards. Does anyone have resourses for these issues. The shingles are IKO, but I haven’t found the info I’m looking for there. Thanks in advance.

Hi Stuart,

Before becoming a home inspector I spent 15 years remodeling apartment complexes. In that time I have never seen a mansard that did not have serious damage from leaks. Be sure to pay special attention on the interior walls in these areas. More than likely there will be plenty of evidence there.


I don’t know what a Hurricane pattern is but shingles on a Mansard Roof (slope exceeding 60 degrees) should have nine nails, five in the nail area and four above the tab corners. I don’t know what IKO requires but this is the norm, with a dab of asphalt roof cement also under the tabs.

I wouldn’t install them over any existing shingles. But I don’t understand why the tabs are falling off.

Are they blowing off?

Dale, no they aren’t blowing off (yet), the tabs at the very top of the mansard look like they were just glued and not nailed. Hundreds of exposed nail heads over the complex. Some plumbing vent collars were reused, and several of those are split. No bad sheathing was replaced, just watch your step. It may just be the small tabs thay the roofer added to make the laminated look carry to the top of the mansard. There is a transition between the 2nd story roof and the mansard skirt that uses drip edging and about a 4 inch metal wrapped fascia.
Greg, these apartments may have interior damage. I wish I could check a few attics, but the owners just want a roof evaluation at this time. The roofing contractor is from out of state, and was here to cash in on a big hail storm we had in March. The owners wisely held back 2/3 of the payment until the job was complete and accepted. The whole 2 layers of architectural shingles and crappy workmanship have the owners a bit worried. How do you get a company 400 miles away to service a workmanship warranty a year down the road? You don’t, you hire a local company. There may be more to this story, the owners may have negotiated a cheap price, and they got a cheap job.
Thanks for the input.

Do you have a picture? Sounds like your saying the laminate strip is falling off which should expose the nailing pattern. They’re probably nailed high. Never a good idea to do 2 layers on a roof even when using 3 tab shingles. And if done one should always use standard over standard, never metric over standard and never anything over laminate. The laminates are too rough and will cause a depression where the nails are. Roofers know this so they usually intentionally nail them high to keep the nails from shooting thru the shingles, and on three tabs it makes the roof look smoother to nail them high. Crossover shingles tend to blister and etch, but would be a better option on mansards since they are one piece.

Hey Stuart. Just saw your last post after I left my post. If you have a picture it will help. A good roofer would not recommend to roof a building like this. I bet the owners told him to do it as cheap as possible and got a crappy job and apparently held back money. A good roofer would have refused to do it this way and walked away. This is the basic stimulate I use on whole roof bids and then add in the details. This way the owner knows exactly what they are getting.
Recommend to:

Remove existing roofing from entire house and dispose of all debris
Install Shingle mate brand felt underpayment
Replace all plumbing pipe boots using custom made copper boots
Seal seams and collars on all metal vent stacks and paint black
Line valleys with ice and water shield
Install year shingles to be secured using nails (not staples)
Install Lomanco ridge vent on all roof peaks
Re-flash all walls, chimneys and skylights using step flashing

Total cost excluding decking=$

Replace decking as needed at $45 per sheet or $3.50 per lineal foot.

Never heard of hurricane nailing pattern. Laminated shingles installed on a layer of laminated shingles? That’s kinda odd. I think it’s better to replace laminated shingles with brand new ones

The most important component in the wind resistance of shingles is the sealant strip, not the fasteners. Often on mansards, because they’re so steep, gravity is insufficient to allow full bonding, and so shingles suffer creasing, tearing, or blow-off. 30 nails won’t keep the tabs from bending back/creasing/breaking off if bonding fails.
If, as you mention, they aren’t hand sealed, if the bonding is inadequate, consider recommending hand-sealing.

Multiple layers is never ideal. How bad it is depends on whether they’re bridged or nested. The less flat they lie on the roof deck, the more easily the wind will tug at them. The roof will also stay hot longer, which reduces shingle lifespan, and installation over an existing layer reduces impact resistance.

Bridged Shingles.png

Nested Shingles.png