Proposal for Conservation of Rowhouses
Academy of Building Conservation
(Draft - 2/23/16)

Question: What is the difference between a rowhouse and a townhouse? Answer: About three zeros.

The above may point out a truth about the power of perception and marketing, but also can suggest it perhaps is time to
take a new look at the humble rowhouse. With two existing warm walls, insulation on the roof, insulation front and rear,
reconditioned windows, heat recovery ventilation (HRV), and renewed plaster, a row house can be an energy efficient
structure at modest cost. The Healthy Rowhouse Project estimates that for the minimum of the $300,000 it takes to build
a new affordable house in Philadelphia, between 14 and 30 homes can be improved. Preserving rowhouse blocks builds
on architecturally significant assets. Preserving existing resources is environmentally sustainable. The most sustainable
home is the one that already exists.

The first step is to evaluate the building for structural integrity from foundation to roof. What repairs are needed? What
is the condition of existing joists? walls? windows, etc. How many layers on roof? What is the scope, sequence and
critical path of work?

Roof- A flat roof on a row house may present an opportunity to cover the roof with a green roof which keeps the house
cooler in summer, warmer in winter, extends the life of the roof and helps with storm water management and climate
change. Using light weight growing mats over an EPDM membrane, we can position Darby as a leader in the green

France is now requiring green roofs for all new construction and we can look at the possibilities.

Example of sedum roof blanket  

Other technologies

Heat Recovery Ventilation is a way to warm incoming air coming into the house which reduces the heating load (not
having to raise incoming 30 degree air so far to a comfortable level) An air intake at the top of the house can gather
heated, stale air and then send fresh, warmed air to the basement where it will rise. Triangular tubing at the cornice
where the wall meets the ceiling be decorative AND functional, exhaust heat in the summer so that only fresh, cool air is

Wooden Window repair - Wooden windows are good windows. Historic windows, particularly those made before the 1940’
s, are from old growth wood which is denser and stronger than modern equivalents and are built with components (stile,
mutton, etc) that can be repaired or replaced…..which means less waste going to a landfill with equivalent efficiency,
better cost savings, and better aesthetic appeal.

Insulating Plaster- Diathonite is a rediscovery of an ancient method and is a type of insulating plaster made from
diatomaceous earth, hydraulic lime, cork and clay which breathes and has excellent dehumidification and sound
absorption qualities. Non-toxic, it can be used for interior or exterior applications and can be sprayed on. It is rated 3.2 R

Dry Ice Basting  is an approved media by the EPA, FDA and USDA. It also reduces or eliminates employee exposure to
the use of chemical cleaning agents. Dry-ice blasting

This is a "Modern Marvels" video showing how it can be used

Plaster is in virtually every building built before 1940 but people trained in the skill of plastering are rare, so quality work
may be prohibitively expensive. Tearing out plaster instead of repair results in more expense in disposal of plaster and
lath, with a less aesthetic, fire-resistant, sound absorbing result. The best way to learn is through hands on training
under experienced supervision. The Academy offers an opportunity to learn, and upon completion of the module, to
train newer students.

And finally,
Act 135 which can be a tool for acquiring properties