KEY FACTORS FOR SLATE SELECTION

Color
or
Blend

color_sm blend_sm

Random
or
Constant

random_sm constant_sm

Size
&
Thickness

size_sm thickness_sm
 

COLOR SELECTION

Weathering slates will change color as they age with most weathering occurring in the first 1 to 3 years but can continue to change infinitely. Weathering slate provides the natural earth tones of bronze, browns, buffs, cream colors which eventually become a blend on the roof. Colors tend to be on the lighter end of the spectrum with light grays, greens which can provide a more natural “country cottage” or “old world” look to a home.Almost all domestic slate weathers to some degree.Non-Weathering slates as their namesake states hold their colors and tend to be the darker colors of blacks and grays. Non-Weathering slates are most visible on the more formal structures in Georgian and Gothic styles of architecture.

Existing slate roofs on residences are probably about 50% Weathering vs. 50% Non-Weathering, commercial (churches, courthouses, universities, ect…) are about 20% Weathering vs. 80% Non-Weathering. This percentage changes on the region. For instance: Weathering is more common on homes in the North East, while Non-Weathering slate is more common in the South East.

 

WEATHERING OR NON-WEATHERING

weathering
non-weathering
Weathering
vs
Non-Weathering

Weathering slates will change color as they age with most weathering occurring in the first 1 to 3 years but can continue to change infinitely. Weathering slate provides the natural earth tones of bronze, browns, buffs, cream colors which eventually become a blend on the roof. Colors tend to be on the lighter end of the spectrum with light grays, greens which can provide a more natural “country cottage” or “old world” look to a home.

Almost all domestic slate weathers to some degree.

Non-Weathering slates as their namesake states hold their colors and tend to be the darker colors of blacks and grays. Non-Weathering slates are most visible on the more formal structures in Georgian and Gothic styles of architecture.

Existing slate roofs on residences are probably about 50% Weathering vs. 50% Non-Weathering, commercial (churches, courthouses, universities, etc.) are about 20% Weathering vs. 80% Non-Weathering. This percentage changes on the region. For instance: Weathering is more common on homes in the Northeast, while Non-Weathering slate is more common in the Southeast.

 

SIZE & THICKNESS

Sandard Width Slate Roof
vs
Custom width slate roof
Standard
 
Custom

Expressed as
Length Width Thickness

On residential slate roofing projects:
16″ to 18″ random width, 16″ x 8″ or 10″, 18″ x 12″, and 20″ x 10″ constant width are the most common sizes.

On commercial slate roofing projects:
16″, 18″ and 20″ random are often seen, but 20″ x 10″ and 24″ x 12″ are more common on large formal projects.

The standard thickness of slate is 3/16″ to 1/4″ for smooth textured products and 1/4″ to 3/8″ for heavier textured stone. About 90% of all slate projects use standard thickness, but the other 10% can range from 3/16″ all the way to 1″. A “Graduated thickness” slate roof is an installation where the lower sections of the slate roof have “heavy” or extra thick slate and then the slate goes down in thickness as it progresses up toward the peak. These installations are somewhat more complicated but can provide a more dramatic texture on the slate roof. “Graduation” tends toward the more natural and is almost unseen in combination with constant width jobs.

Weight Consideration:
Most homes, where slate is a consideration, can support the weight of standard thickness slate roof with out modification. Standard slate weighs about 8 lbs. per square foot, but varies with color and texture. In situations where the weight is too high, bracing of rafter spans is usually relatively inexpensive.

We can provide guidelines and recommend roof structure consultants to determine the feasibility. In the end it is “better to be safe than sorry” so if the house is not designed for the weight of “hard roof products”, it should be investigated.

 

RANDOM OR CONSTANT

RANDOM WIDTH SLATE ROOF- Random width is the combination of two or more widths of slate roofing tiles randomly installed to provide a “broken” or random pattern of key way spacing the side space between the slate in one horizontal course. Random width is most common on residential installations and tends to the more natural look.Installing a Random Width Slate Roof:For a Random Pattern Slate Roof use the narrowest widths for the hip and ridge and the widest widths for the cuts in the valleys. For a 16” random, use only 16×8 for hip and ridge, not 10” or 12”.In the body of the slate roof, you should not see the keyway spaces lining up (or referred to as bonded) on a random width slate roof.To start, add up the piece counts on each pallet for each size. From the total count, deduct 100 pieces of 16×8 for every 25 linear feet of hip and ridge. Then divide the number of slate tiles for each size by the total number of pieces for all sizes added together to get the percentage of each size. You must do it by the number of pieces, not the number of total squares of each size.For example on a 16” Random with 52% of 8”, 27% of 10” and 21% of 12”, you would pull (20) pieces of slate at a time to go on the roof. For each (20) pieces total, pull (10) of the 8”, (5) of the 10” and (5) of the 12”. Then lay them in a total random pattern. For instance lay (1) 12″, (2) 10″, (2) 8″, (1) 12″, (3) 8″, (1) 10″, (2) 12″, (3) 8″, (1) 10″, (1) 12″, (2) 8″, (1) 10″. Once they get the first course right, then they just put the slate tiles down randomly to keep the keyway spaces 3” apart from the row below and keep them from lining up on every other row.Lay out 3 rows of 20 on the ground to get the idea before you start. It is much easier to lay out the slate this way, once you get started correctly. Trying to line keyway spaces on every other row is tedious and time consuming.

CONSTANT WIDTH SLATE ROOF- Constant width installations are where a single width of slate tile is installed on the roof. In this case the key way spaces in alternate horizontal courses line up to create a more uniform pattern on the roof and provide a more formal style. Constant width is often seen on commercial projects, churches, courthouses, educational/ institutional buildings and large very formal residential projects.