Expect the slate roof cost to land at 3 to 5 times what a full asphalt roof costs on the same house. Around Ellicott City, asphalt typically runs $6.00 to $9.00 per square foot installed, so slate sits well above that. The gap comes from the stone, the weight and the skilled labor.
The short version
- Natural slate typically runs 3 to 5 times the price of architectural asphalt.
- This Old House puts natural slate at $10 to $30 per square foot (opens in a new tab) nationally.
- The framing may need to be strengthened first, which adds to the bill.
- Synthetic slate costs less to buy, but the National Park Service says the total installed cost is only marginally less (opens in a new tab) for artificial slate.
- Slate can last for generations, so the price is spread over a long time.
How much does a slate roof cost per square foot?
Natural slate typically runs 3 to 5 times asphalt, which is the range we use around Ellicott City. This Old House says natural slate tiles cost $10 to $30 per square foot (opens in a new tab) of roof, and that a slate roof costs about $30,000 for a 1,500-square-foot home.
Roofers often talk in “squares” instead. One square is 100 square feet of roof, so a 2,000 square foot roof is 20 squares. The table shows what asphalt typically runs here, so you have something to multiply from.
| Roof size | Architectural asphalt, around Ellicott City | Natural slate |
|---|---|---|
| 1,500 sq ft (15 squares) | $10,500 to $13,500 | 3 to 5 times asphalt |
| 2,000 sq ft (20 squares) | $13,500 to $17,500 | 3 to 5 times asphalt |
| 3,000 sq ft (30 squares) | $19,500 to $25,500 | 3 to 5 times asphalt |
| 4,000 sq ft (40 squares) | $25,000 to $33,000 | 3 to 5 times asphalt |
Those asphalt figures are area ranges for the full system, not a quote. A typical Ellicott City replacement is a roof of about 3,580 square feet, which runs roughly $25,200 in asphalt. Slate on that same roof is a different conversation.
What pushes the slate roof cost up?
Labor, pitch and anything hiding under the old roof push it up the most. This Old House says labor makes up 50% to 60% of new roof installation prices (opens in a new tab), and slate is slow, careful work.
On any material, these also raise the price:
- A steep pitch, over 8/12, where crews work slower and need more care.
- A cut-up roof with many valleys, dormers and corners.
- Poor access, such as a wooded lot where the truck cannot get close.
- Historic district rules, which limit your choices.
- A second layer of old roofing to tear off.
- Chimneys, skylights and other places that need new flashing.
Flashing is the metal that seals the roof where it meets a chimney, wall or valley. On slate it matters more than usual, because the metal should last as long as the stone. The National Park Service says to choose materials with life spans comparable (opens in a new tab) to that of the slate, such as copper or stainless steel nails.
Will my house need extra framing for slate?
Often, yes, and it is the cost that surprises people. This Old House says the weight of slate often calls for additional structural support (opens in a new tab), and puts reinforcement at $1,000 to $10,000 (opens in a new tab) added to the total.
When we find framing trouble after a tear-off on any roof, an engineer’s letter typically runs $600 to $1,500. The fix itself can add $3,000 to $15,000 or more, plus days or weeks of delay. With slate, get the framing checked before you sign, not after the old roof is off.
Is synthetic slate much cheaper?
The tiles cost less, but the finished roof does not always come in much lower. This Old House says materials made to look like slate come at a much lower cost and weight (opens in a new tab). The National Park Service, writing about artificial slate, says the total initial cost is only marginally less (opens in a new tab) because labor, flashings and tear-off cost the same either way.
Those two sources are describing different products, so do not treat them as a fight. Ask any contractor which material they are quoting and get the weight in writing. If weight is your worry, a lighter option may be the better fit, and our piece on how much a metal roof costs shows where metal lands. Standing seam metal typically runs 2 to 2.5 times asphalt.
Does a slate roof pay for itself?
It can, if you stay long enough. The National Park Service says slate roofs last 60 to 125 years or longer (opens in a new tab) depending on the type of slate, and that when the cost is spread over the roof’s life, the cost can be reasonable (opens in a new tab).
In Maryland, asphalt shingles realistically last 18 to 25 years. So one slate roof can replace several asphalt ones. If you may sell in ten years, the math is harder, because a buyer may not pay back what you spent. We lay out the good and the bad in slate roof pros and cons.
How do I pay for a slate roof?
A bill this size is worth planning, and you do not have to find it all at once. Our financing page explains the payment options through our partner, without any numbers promised ahead of time. Insurance only comes into it if storm damage is the reason for the new roof, and then your policy and the adjuster decide what is paid.
Common questions
Is slate roofing worth the money?
It is when you plan to stay and the house can carry the weight. This Old House says a slate roof costs more than most other roof materials (opens in a new tab) but adds value to your home. If you may move soon, asphalt usually makes more sense.
How much does it cost to repair a slate roof?
It depends on how much is damaged. This Old House says cracked or chipped tiles are easy to fix if caught quickly (opens in a new tab), but extensive damage gets expensive fast. The National Park Service says that when 20% or more of the slates (opens in a new tab) are broken, cracked, missing or sliding, replacing the roof usually costs less than repairing it piece by piece.
Why is slate so expensive?
You pay for the stone, the weight and the skill. This Old House calls slate one of the most expensive roofing materials (opens in a new tab) and says it needs professional installation. Not every crew does slate, so ask before you book.
What to do next
If you are weighing slate against asphalt, start with the numbers for your own roof. We measure it, check the deck and the flashing, and tell you what a replacement would take. Our roof installation page covers what a full replacement includes, and our free roof inspection comes with a written report and no obligation.
