This document discusses common defects that can occur in wooden roofing materials like shakes and shingles. It identifies 9 main defects: 1) lichen and moss growth, 2) mold and mildew, 3) rotting shakes or shingles, 4) cracks, 5) distorted shakes and shingles, 6) termite attacks, 7) roof leaks and moisture, 8) inadequate ventilation, and 9) roof sagging. For each defect, it describes the causes and recommends remedial and preventative measures, such as removing debris, improving ventilation, replacing damaged materials, and reinforcing structures.

1. Wooden roofing

2. Shakes and shingles: These are used for covering the
top of a house

3. Defects in wooden roofing
1. Lichen and Moss growth
2. Mold and mildew
3. Rotting shakes or shingles
4. Cracks
5. Distorted shakes and shingles
6. Termites attack
7. Roof leaks and moisture
8. Inadequate ventilation
9. Roof Sagging

4. 1. Lichen and Moss growth

5. Causes:
– Lichen and moss can grow on surfaces of roofs,
especially if it is situated in a damp and shaded position,
overhung by trees.
– Debris on your wooden roof can trap moisture and damp
air, causing your roof to grow fungus
– Shady spots and areas that touch trees are more likely to
grow moss as they have an interrupted air flow.

6. Remedial measure:
– Use a hose and gently scrape the moss off of the surface of
the roof. Once all the moss is removed, kill the moss by
carefully using bleach.
Preventive measure :
– Remove debris regularly
– Cutting back branches from hanging over the roof

7. 2. Mold and mildew

8. Mold usually appears as black or greenish-brown patches on surfaces in
humid environments. Mildew is a common term used to describe both
mold fungi and their discoloration to unfinished wood.
Causes :
– Dampness or inadequate ventilation typically results in the
growth of mold or mildew on wood surfaces.
– Moss, mold and mildew in roofs often go together because they
prefer the same growing conditions and help each other to grow.
The moisture the moss retains makes it easier for the mold and
mildew to form and spread over your roof.

9. Remedial measure:
– Once the humidity problem is eliminated, mold and
mildew can be removed by cleaning the wood surface
with one part household bleach mixed with four parts
water.
Preventive measure:
– Remove debris regularly
– Cutting back branches from hanging over the roof

10. 3. Rotting shakes or shingles

11. Black stains and moist surfaces that don’t seem to dry
with the rest of your roof are the signs of rotting shakes
and shingles.
Causes:
– Incorrect shingle placement, clogged gutters and poor
ventilation in your roof can all add up to the speedy
deterioration and the growth of rot on your cedar roofing.
Remedial measure:
– Replace the entire roofing structure, even if only a small
section of your roof has rot, because rot spreads easily.

12. 4. Cracks
• Wood shakes and shingles expand and contract over time so
they must be spaced out and installed with exact
measurements by a professional.
• Too wide of spaces between shingles may cause leaks in your
home and increased humidity and moisture on your roof.
• When shingles are installed too close to each other, they may
not be able to expand correctly and smash into each other. This
can lead to cracks in your shakes or shingles.
Remedial measure: replace the shakes and shingles

14. 5. Distorted shakes and shingles
• Shakes and shingles may deform due to uneven water
absorption and drying – particularly if your building is in
the shade most of the time. This distortion is called
curling if it occurs along the roofing material’s length.
• Cupping is the term used to describe the distortion
occurring along the width of a shake or a shingle.
Causes:
– When nails are improperly placed during construction
Remedial measure:
– Replacing the shakes and shingles

16. 6. Termites attack

17. Causes:
– Although dry-wood termite and subterranean wood
termites will attack a roof if access is made possible
by overhanging branches, air, debris. We can protect
your roof from termites by cutting overhanging
branches
Preventing measure:
– Spray anti termite chemicals
– use termite repellents
– Use wood types that naturally repel termites such as red
cedar, chestnut, juniper, walnut and white oak.

18. 7. Roof leaks and moisture
• Leaks are a serious problem and can be identified by
checking for moisture and damp in the loft.
• When moisture gets under the layers of the roof, this
can cause mold and rot, which will lead to more
extensive problems in the future if left un-repaired.
• This becomes a more urgent issue if the moisture has
spread to the rafters as they carry the weight of the
roof.

19. 8. Inadequate ventilation
• Roof and loft ventilation is an important part of ensuring
a roof will last.
• Vents should be placed at the base of the roof and near
the ridge so that warm air can leave through the top and
cool air can enter through the bottom.
• This regulates the temperature and moisture levels in the
loft – left unchecked, heat and moisture can build up,
potentially causing damage to rafters and insulation, and
can cause mold and damp problems

20. 9. Roof Sagging
• Excessive weight load on a roof is one of the most
common reasons as to why roofs sag.
• A solution to this is to reinforce the roof timbers with
additional purlins andstruts.