minimum falls of 1:40

a finished fall of 1:80

insulation is installed above the deck

ballast installed on top of the insulation

combined waterproofing/vapor control layer installed

a result of errors in the original construction

Failure in the roof structure

alterations that affect the discharge of water by the intended fall

can attach the surface of the felt

moss can act as a sponge/ it freezes and thaws in the winter

a raised area where there is a loss of adhesion of the roof

This area can fill up with air or water to form a blister

When air or water is trapped in a blister, the weather can cause the blister to grow on a daily basis.

Warm weather will cause the water or air to expand during the day then cool temperature will cause the trapped water or air to contract at night

light surface crazing

variations in surface temperatiure

absence of effective solar reflective treatment

bonding of asphalt to deck construction

asphalt not treated with sand at the time of its installation. lead to bitumen lying on the face of the asphalt

Sulphation expanding brick mortar joints caused by the combination of water and sulphur or other minerals.

ne side of the stack is more exposed to the prevailing wind than the other side. The theory is that the side of the stack exposed to the prevailing wind will dry out more quickly than the other side. The mortar joints on the ‘dry’ side will tend to shrink whilst the joints on the ‘wetter’ side will tend to expand.

ain penetration through the chimney structure

condensation of the flue gasses

where the chimney breast has been removed and no support has been put in place

The nail fixing tiles decay over a period of time and as a result of the corrosion of the metal aided by condensation forming on the back of the tile or slate surface or by water penetration. Results in slates slipping.

failure to adequately support the main rafters of the roof