Roofing, Flashings & Chimneys Flashcards
Two main categories of roofing systems
Sloped Roof (steep roofs) 4 in 12 > and flat roofs (low sloped roof) between 2 in 12 and 4 in 12
Roof Pitch
ratio of the vertical rise over a set horizontal run(12 ft) so a 6 in 12 is 6 ft vertical rise over 12 ft horizontal run
Asphalt Shingles
asphalt impregnated felt paper or glass fiber mats, coated with a layer of asphalt and covered with granular material
Asphalt Shingles - Life expectancy
15, 20, 25, 30 or 35 year - manufacturer’s warranty
Asphalt Shingles - wear factor
Exposure (sun) and slop (steeper the slope the longer they last)
Asphalt Shingles - self-sealing shingle
self sealing strip that sticks 2 shingles together to protect shingles from being blown off in heavy winds
Asphalt Shingles - granular material
protects the shingle from ultra violet light
Shingles used for roof pitch between 2 in 12 and 4 in 12
conventional asphalt shingles but first cover the roof with non-perforated, asphalt-saturated felt papers or a waterproof membrane
Re-Roofing asphalt shingles
Can re-roof over one layer but they will perform better and last longer if you remove the old roofing material. Can’t go over 2 layers.
Difference between wood shingles and shakes
Wood shingles are machine cut and typically smaller, thinner and more uniform and thicker. Wood shakes are hand or mechanically split and have a much more uneven surface.
Wood shingles - life expectancy
30 to 40 years
Wood shingles - re-roofing
You can install over a layer of ashpalt shingle but it is better to remove existing shingles to allow wood roof to breathe
Wood Shingles - How much is exposed to weather
1/3 of the wood
Slate Roof - life expectancy
200 years
Slate Roof - Biggest Problem
The nails that hold the slate in place rust and allow the slate to come loose and then water rusts the nails of nearby slates
Slate Roof - reroofing
Slate roofs should never be installed over another layer of roofing
Slate Roof - Flashing
Slate roofs generally outlast the flashing and require a section of roof to be replaced
Concrete Roof Tiles - Replace asphalt
Concrete roof tiles are much heavier than asphalt shingles and may require modifications to the roof structure
Fiber Cement Shingle - Life Expectancy
30 to 50 years
Types of Metal Roofs
Copper, Steel, terne and tin
Metal Roofs and tar
Metal roofs should never be covered with tar because moisture trapped below will cause rust
Corrugated Plastic Roof usage
Generally used over patios and light structures
Built-Up Roofing (Tar and gravel)
They are multiply consisting of two to five plies of roofing felts with a coating of asphalt in between layers. A flood coat of asphalt is then applied on top and covered with gravel to reflect ultraviolet light and protect roof from mechanical damage
Built-Up Roofing - slope
They are designed for flat appilcation with a slope that is no greater than 3 in 12.
Built-Up Roofing - Life Expectency
two ply roofs - 5 to 10 years, 4 ply roofs 15 to 20 years
Built-Up Roofing - Wear factors
If moisture is trapped below or within membranes, blisters and bubbles form
Build-Up Roofing - Water ponding
water ponding on a short roof life by 50%
Built-Up Roofing - Re-roofing
It is common to install over the top of existing, best practice is to remove old roof first
Build-Up Roofing - Leaks
Because of construction of built-up roofs, leaks are difficult to isolate and repair. Water can travel a significant distance before you see the stain on the ceiling.
Roll Roofing/Selvage Roofing
Comes in typical rolls of 18 or 36 inches
Roll Roofing - Attachment to roof
It is either attached with roofing cement, sealed at the seams or nailed at the edges
Roll Roofing - Life Expectancy
5 to 10 years
Single-ply roofing membranes
thermosets, thermoplastics, and modified bitumens.
Single-ply membranes - common problems
seam, flashing and installation problems
Modified Bitumen Roofing - UV protection
By a coating of granules, foil or paint
Single Ply membranes - Re-roofing
Most plastic and synthetic rubber roof membranes are not compatible with asphalt and should not be installed over built up roofs
General Roofing - Max number of layers of asphalt shingles
two
General Roofing - What 4 areas are vulnerable to leakage
Joints, seams, change in roof direction, things that obstruct the flow of water (chimneys, dormers)
General Roofing - Tree Branches
Tree branches will rub the shingle and damage the roof
General Roofing - Ice damning
Is most common on low sloped roof
General Roofing - 4 - Ice daming solutions
increase attic insulation, increase attic ventilation, seal openings in attic floor and seal/insulate attic heating ducts
General Roofing - How does Ice daming occur
Occurs when snow and ice collect, often at the eaves. Melting snow on the upper portion of the roof, warmed by the attic, cannot drain properly as it is trapped behind the still frozen dam at the cold eaves.
Where are flashing used?
They are used where dissimilar materials meet, where a material changes direction, at roof penetrations and at joints in materials - When a roof line changes direction, a ridge, a valley, or a hip is created.
4 materials used for flashing
Steel, aluminum, lead or copper
Difference between an open and closed valley
An open valley has the metal showing a closed valley has shingles covering it
How many layers of roll roofing can be used in the valley for flashing
two
Best material to use for flashing
Metal
What material is used for hip and ridge flashing on asphalt shingle roofs
flexible shingles
Where the flat roof meets the sloped roof the membrane should extend?
3 feet up the roof
What are the 2 types of roof to wall flashing required when a roof slope is parallel to a wall
Counter flashing and “L” shaped step flashing
On roof//sidewall intersection, how far about the roof surface should wood siding materials be?
2 inch
When is a chimney more likely to leak?
When it is installed at the bottom on the roof versus the peak.
What precautions should be taken when installing high side portion of chimney flashing?
The flashing on the high side should typically extend up at least 6 inches or one-sixth of the width of the chimney whichever is greater
What should be installed over the top of a parapet wall?
Cap flashing
What materials are used for flashing around plumbing stacks?
Metal or rubber flashing
What is a pitch pan?
a sheet metal pan round the stack or mast is filled with pitch or tar to a depth of one to two inches.
A skylight should sit on a curb that protrudes how man inches about the sloped roof surface?
4 inch minimum
What is the purpose of a gravel stop?
securing and protecting the roof membrane at the edge of the roof, preventing the gravel from sliding off the roof, and forming a drip edge to keep water run-off from damaging the wood fasci
Chimneys are constructed of?
Masonry or metal
What is a chimney flue
Separate channel for smoke to the outside
What can share a flue?
2 appliances on the same floor of the house
3 common materials used to line a chimney-flue
Clay tile, metal or asbestos cement pipe
Most common element in chimney deterioration?
Water
What would a ring of accelerated deterioration around the exterior of a masonry chimney indicate to you?
There is a gap in the tile liner of the chimney
Chimney Cap
to protect the top surface of a masonry chimney from water usually concrete
Rain Cap
covers the chimney flue to prevent water from entering the flues
Chimney Bracing
Should be on masonry chimneys that are more than 12 feet above last support and metal chimney’s that are over 5 to 6 feet tall
Chimney Height
minimum of 3 feet above the point of penetration through the roof and two feet higher than anything withing 10 feet of them to help ensure good drafts
