B E R O A R C H I T E C T U R E P L L C

A R C H I T E C T U R E S U S T A I N A B I L I T Y P R E S E R V A T I O N

Thirty Two Winthrop Street, Rochester, New York 14607
585-262-2035 (phone) •  585-262-2054 (fax) • contact@beroarchitecture.com (email) 

SOME THOUGHTS ON RE-ROOFING

(MODERN)

Historic materials for roofing include wood, slate, and metal. The following comments do not deal with historic materials but only with modern asphalt shingles.

MATERIALS

1.         Shingles are reinforced with either fiberglass or felt. Fiberglass shingles are fairly new on the market but as far as we know their life and costs are equivalent to the old felt type. A Class "A" fire rating is required by some municipalities, this may dictate the reinforcement.

2.         Shingles are sold by weight as in "300 lbs per square" (a square being 100 sq. ft.). We recommend installing the heaviest (longest lived) shingle you can afford.

3.         Dramatic colors are not generally appropriate on historic buildings; colors of traditional weathered wood and slate are not dramatic. We recommend for most buildings a weathered grey color which matches weathered wood or slate and is compatible with almost every color of paint. This allows you to change building paint colors at will. Be wary of colors which are not historic (white, light grey) or are too distinctive (red, brown, black).

4.         Metal trimmings. Your roofer will probably install a piece of trim at the edge of the roof. There is no reason that this metal has to be white. This trim is available in both brown and black for the asking. White is inappropriate for most historic buildings.

5.         Flashing. When your building is re-roofed the flashing should be carefully examined. Flashing is the metal that bridges between the roof and vertical penetrations such as chimneys and walls. Historic flashing is usually copper or galvanized steel; we recommend that worn out flashing be replaced with copper or galvanized steel. Aluminum is commonly used today because it is cheap and easy to work, but aluminum is very soft and susceptible to punctures and tearing. There is no way to make a permanent, watertight junction between two pieces of aluminum sheet metal but copper and galvanized steel can be soldered.

PREPARATION

Preparation for re-roofing is important. We recommend existing shingles be removed before re-roofing for the following reasons:

1.         Shingles are heavy. Every time you add a layer of shingles you are adding several tons to the roof. The roof was not designed for more than one or two layers. 

2.         Removal of the shingles allows inspection of the roof deck and replacement of deteriorated materials.

3.         Application of shingles over existing shingles is inevitably not very smooth, resulting in poor appearance and shortening the life the new roofing. 

4.         Old wood shingles left on a roof act as a sponge at any leak. They provide a wonderful home for carpenter ants and other insects. 

5.         When roofing is layered, the flashing no longer works properly. Where a roof abuts a clapboard wall, the top layer of roof shingles comes in contact with the siding which deteriorates as a result. There should be a visible gap between the roof shingles and the siding, bridged by flashing..

INSTALLATION

1.         Manufacturers warranty their materials provided that the shingles have been installed in accordance with their instructions. Manufacturers provide instruction sheets for their materials and also print installation instructions on each bundle of shingles. 

2.         Attic ventilation must be adequate or the warranty will not be honored by the manufacturer. 

3.         The cheapest job is not always the best job. It is important to examine other roofing jobs by the contractor under consideration and talk to his recent clients. 

4.         Roofing installation should be coordinated with the installation of gutters. We do not recommend any rainwater collection system where gutter straps are applied by nailing through the shingles after the shingles are in place. We do not recommend the use of spikes and ferrules to attach gutters.