A native of Wales, Tim Underhill came to the states in 1980 and established Tim Underhill, Roof Renovation, in Baltimore, MD in 1986. This slate and copper repair company continued until 2012.

Tim took over management of The Gummer Slate Company, owned by Wayne Roland of Roland Slate Services, in 2012 Baltimore MD. This slate distribution company gave Tim an introduction to the quarries and quarriers of North America, Spain and Wales. Here he learned transportation logistics and gained business experience from owner Wayne Roland.

Tim spent the next two years working with the most successful slate company in the US. Durable Slate has regional offices in Columbus, Cincinnatti, Cleveland, New Orleans, Rockville and Baltimore. He collaborated with their dynamic approach to slate and copper work, pursuing some of the biggest projects in the country. Tim headed negotiations and sales for the following projects:  All Saints Episcopal Church, Chevy Chase MD; Church of The Blessed Sacrament, DC NW. and residential work throughout the Mid-Atlantic region.

He has taken a strong interest in the National Slate association (NSA), serving on the Board, and for two years as its Executive Director. He is a continuing member of the NSA and the Slate Roofing Contractors Association (SRCA), Roof Consultants International (RCI, Inc), the International Facility Managers Association (IFMA), past member of the Vermont Slate Quarry Association (VSQA).

He has presented to the first International Slate Convention in Madrid, Spain, to Architectural Committees in Baltimore, MD, Glen Ridge and Trenton, NJ, Monson ME, and to the ongoing education conventions of Baltimore and Maryland Association of Home Inspectors (MAHI).

He has written extensively for the NSA publications, Roofing Contractor, Quarry Newsletters and Online Design Magazine. His passion is All Things Slate.

As owner of The Delta Slate Company, Tim has returned to his home town of Baltimore, MD, and is involved with day to day running of the company.