Two estimates land on the table. One proposes a tear-off. The other proposes going over the top, and it is meaningfully cheaper.
The second one is not simply a discount. It is a decision about the roof after this one, and it is worth understanding before the price decides for you.
What the municipalities say
Michigan caps layers. Sterling Heights states that only two layers of roofing may be applied. Clinton Township re-roof documentation prohibits installing more than two layers. Michigan code provisions restated by other jurisdictions bar re-covering where the existing roof already carries two or more applications of any type of roof covering.
The practical consequence is simple. One layer now means you may overlay once. Two layers now means your next roof is a tear-off, and there is no choice in it.
A permit is required either way. Sterling Heights states plainly that a permit is required whether the work is a complete tear-off or just adding a second layer. See what a Michigan roofing permit covers.
Why the limit exists
Weight. Asphalt shingles are heavy, and a second layer roughly doubles that dead load on framing designed for one. In a climate where roofs also carry snow, the margin matters. Ground snow load is 25 pounds per square foot across Macomb and Oakland counties under Michigan rules.
Heat. Two layers hold heat between them. Both layers age faster than either would alone, which is why overlaid roofs frequently do not achieve the life the shingle rating suggests.
The deck is never seen. This is the one that matters most and gets discussed least.
What an overlay hides
A tear-off exposes the roof deck. The crew sees soft spots, delamination, rot around a chimney, damage from an old leak nobody knew about, and repairs what needs repairing before anything goes back on.
An overlay covers all of that. Whatever condition the decking is in, it stays in that condition, with more weight on top and no way to inspect it for another decade or more.
If there has been any history of leaking, condensation or ice damming on the house, an overlay is covering the evidence of it. That is a genuinely bad trade.
The ice barrier problem
Metro Detroit building departments require ice barrier from the roof edge to at least 24 inches inside the exterior wall line. That membrane is designed to seal to a clean deck.
Over an existing shingle surface it is bonding to granules and to an uneven plane. How the eave detail is handled on an overlay is a specific question worth asking, given that this is the single most important waterproofing detail on a Michigan roof. We covered why in the 24-inch ice barrier rule.
The surface is only as flat as what is under it
New shingles follow the contour of whatever they are laid over. If the existing layer is cupped, clawed or buckled, the new surface inherits that shape from day one.
Which means an overlay is only defensible where the existing layer is flat and sound — and a roof that is flat and sound is usually a roof that did not need replacing yet. The roofs people most want to overlay are frequently the ones least suited to it. See reading the shape of a shingle.
Finding out what is on your roof
You do not need anyone up there.
- Look at the edge of the roof at the eave or the rake from a ladder. Layers are countable at the edge.
- Look at the height of the shingle edge against the drip edge and fascia. Two layers sit visibly higher.
- Check permit records with your municipality. Previous roofing work under permit is documented.
- Ask the seller if you are buying, and ask for the permit record rather than a recollection.
When an overlay is reasonable
Rarely, and in narrow conditions:
- There is exactly one existing layer
- That layer is flat, with no cupping, clawing or buckling
- There is no history of leaks, ice damming or attic condensation
- The decking is known to be sound
- The framing can carry the additional load
- You understand that the next roof is a tear-off
If all of those hold, an overlay is a legitimate way to defer cost. If several do not, the saving is borrowed against a bigger bill.
The arithmetic over time
An overlay saves the tear-off and disposal cost once. But the overlaid roof tends to run shorter than a properly installed single layer, and when it goes, two layers come off instead of one, which costs more than removing one would have.
Over twenty years the overlay frequently does not save money. Over five, if you are selling, it does — though a buyer with any sense will ask about layers, and the answer affects their number. See what a roof inspection tells a buyer.
Roof repair across Macomb County
Much of Macomb County housing stock is now old enough to be on its second roof, which is exactly the point at which the layer question becomes decisive. If the first replacement was an overlay, the current one is a tear-off regardless of what anyone would prefer.
See roof repair in Michigan, or find your city.
Common questions
Can you put a new roof over an old one in Michigan?
Michigan municipalities permit a maximum of two layers. Where one layer exists an overlay may be allowed; where two already exist it is not, and a permit is required either way.
How do I know how many layers my roof has?
Count them at the roof edge from a ladder, or check permit records with your municipality.
Is an overlay cheaper?
Today, yes, because tear-off labour and disposal are avoided. Over the life of the roof the saving often disappears.
Will an overlay affect my insurance?
Insurers take a view on roof condition and age. An overlaid roof at the end of its life is not in a stronger position than a single-layer roof of the same age.
We will count the layers first
Any estimate from us states how many layers are on the roof and whether an overlay is even permitted at your address. If it is permitted and genuinely sensible, we will say so.
Book a free roof inspection, or read about residential roofing across Metro Detroit.
Sources: City of Sterling Heights Building Department FAQ; Charter Township of Clinton re-roof permit application; City of Grand Rapids roof assembly requirements handout citing the Michigan Residential Code; Michigan Administrative Code R 408.30515 ground snow load.
