The honest answer is that it depends on how quickly you need leads and how long you intend to be in business. Here is the actual trade-off.
Paid Ads: Fast, Predictable, Rented
Google Ads produces leads in days. It is measurable, controllable, and scales up the moment you increase budget. It also stops completely the moment you stop paying, and roofing clicks run $40 to $80 in competitive metros — meaning a qualified lead frequently costs $80 to $250.
SEO: Slow, Compounding, Owned
SEO produces nothing for the first month or two, meaningful movement by month three or four, and durable positions by month six. From then on the cost per lead falls every month, because the asset keeps working without incremental spend.
How to Choose
If you need work booked in the next thirty days, run ads. If you intend to be operating in five years, run SEO. Most established contractors run both: ads for immediate volume and storm response, SEO as the compounding asset underneath.
The Mistake to Avoid
Do not run either one into a website that does not convert. Doubling conversion rate is cheaper than doubling either budget, and it improves both channels simultaneously.