A non-flat roof can be easy to inspect but often all is not what it seems.
Here I spell out a few tips to help you become an inspection sleuth.
What acts upon and influences performance? Downward forces such as rain, sleet and snow - the latter is very heavy.
Wind can also increase loading potential but it can also reduce stresses by sucking the tiles upward.
What else can affect performance? Temperature fluctuations perhaps caused by direct sunlight or frost/snow coupled with cold winds.
Such roofing can also be attacked by pollutants such as acid-rain, nuclear fallout or anything upon the wind.
I have also seen cases of trees falling on roofs or ice falling from aircraft.
So, pitched roofing is under attack from all sorts of things.
The good news is that most of these sources are predictable and so are fully considered at the design or specification stages of building.
Indeed, all things equal most pitched roofs have a long expected lifespan, sometimes between 50 to 75 years if a good quality concrete tile or natural slate, subject to good maintenance and the exposure rating of the roof to weather extremes.
When all is said and done effective lifespan is determined by (1) the type of covering (2) following Good Practice Guidelines at the construction stage (3) choosing good craftsmen how know their materials (4) well designed support frame and liner details (5) effective loft space ventilation (6) adequate and well placed under insulation, and (7) having the right product for the precise location.
The most robust materials are tiles or slates that overlap one another.
The lower the roof pitch (angle of slope) and/or exposure to strong winds, the greater need for generous overlapping and perhaps pegging down of each tile or slate.
Slates are usually nailed over timber battens whereas tiles can be nibbed (top edge of the tile is turned 90 degrees over the batten which is then covered by the tile above it, and so on up to the ridge or apex: each tiles effectively held in place by gravity).
The verges (side edges) of a roof are attacked by winds and so usually they are sealed with mortar and perhaps clipped with steel brackets to prevent verge tiles being lifted off by the wind.
Perhaps the biggest adverse factor to consider, after exposure to weather extremes, is the human factor.
We do strange things to roofing and often due to our ignorance as we forget to take professional advice or opinion.
For example - if you convert the loft into a habitable room by removing rafters or other supports then it is reasonable to expect that the roof slopes may compact and deflect downwards.
That bowing will cause individual tiles and slates to twist and not sit flush and so allow the wind to begin to affect them further and so the rain can penetrate the gaps created.
Things to verify, that are the hallmarks of a good roof, include the following - 1.
Each slope has an even contour - no bowing, no curves showing.
2.
All tiles are evenly spaced and sit flush with one another.
3.
The tiles or slates are fresh looking - nothing is peeling or exfoliating from upper surfaces.
4.
Moss and lichens are not too prevalent but no plants or creepers have been left to run riot over and through the tiles and slates.
5.
No obvious repairs or replacement tiles or slates can be seen - often such defects are a good indication that fixings are beginning to fail (individual replacement slates are often fixed using a lead strip rather than a nail - the strip is known as a tingle where I operate from in Hampshire, UK).
6.
The slope of the roof is generally between 35 and 65 degrees (depending on multiple factors - often a minimum pitch is quoted at about 10 to 15 degrees).
Every roof type and exposure rating will have a unique calculated minimum pitch to avoid damage, penetration problems or lifting potential.
Pitched roof coverings can be incredibly robust provided they are well maintained and are respected: no DIY unless you have the right degree of knowledge.
Here I spell out a few tips to help you become an inspection sleuth.
What acts upon and influences performance? Downward forces such as rain, sleet and snow - the latter is very heavy.
Wind can also increase loading potential but it can also reduce stresses by sucking the tiles upward.
What else can affect performance? Temperature fluctuations perhaps caused by direct sunlight or frost/snow coupled with cold winds.
Such roofing can also be attacked by pollutants such as acid-rain, nuclear fallout or anything upon the wind.
I have also seen cases of trees falling on roofs or ice falling from aircraft.
So, pitched roofing is under attack from all sorts of things.
The good news is that most of these sources are predictable and so are fully considered at the design or specification stages of building.
Indeed, all things equal most pitched roofs have a long expected lifespan, sometimes between 50 to 75 years if a good quality concrete tile or natural slate, subject to good maintenance and the exposure rating of the roof to weather extremes.
When all is said and done effective lifespan is determined by (1) the type of covering (2) following Good Practice Guidelines at the construction stage (3) choosing good craftsmen how know their materials (4) well designed support frame and liner details (5) effective loft space ventilation (6) adequate and well placed under insulation, and (7) having the right product for the precise location.
The most robust materials are tiles or slates that overlap one another.
The lower the roof pitch (angle of slope) and/or exposure to strong winds, the greater need for generous overlapping and perhaps pegging down of each tile or slate.
Slates are usually nailed over timber battens whereas tiles can be nibbed (top edge of the tile is turned 90 degrees over the batten which is then covered by the tile above it, and so on up to the ridge or apex: each tiles effectively held in place by gravity).
The verges (side edges) of a roof are attacked by winds and so usually they are sealed with mortar and perhaps clipped with steel brackets to prevent verge tiles being lifted off by the wind.
Perhaps the biggest adverse factor to consider, after exposure to weather extremes, is the human factor.
We do strange things to roofing and often due to our ignorance as we forget to take professional advice or opinion.
For example - if you convert the loft into a habitable room by removing rafters or other supports then it is reasonable to expect that the roof slopes may compact and deflect downwards.
That bowing will cause individual tiles and slates to twist and not sit flush and so allow the wind to begin to affect them further and so the rain can penetrate the gaps created.
Things to verify, that are the hallmarks of a good roof, include the following - 1.
Each slope has an even contour - no bowing, no curves showing.
2.
All tiles are evenly spaced and sit flush with one another.
3.
The tiles or slates are fresh looking - nothing is peeling or exfoliating from upper surfaces.
4.
Moss and lichens are not too prevalent but no plants or creepers have been left to run riot over and through the tiles and slates.
5.
No obvious repairs or replacement tiles or slates can be seen - often such defects are a good indication that fixings are beginning to fail (individual replacement slates are often fixed using a lead strip rather than a nail - the strip is known as a tingle where I operate from in Hampshire, UK).
6.
The slope of the roof is generally between 35 and 65 degrees (depending on multiple factors - often a minimum pitch is quoted at about 10 to 15 degrees).
Every roof type and exposure rating will have a unique calculated minimum pitch to avoid damage, penetration problems or lifting potential.
Pitched roof coverings can be incredibly robust provided they are well maintained and are respected: no DIY unless you have the right degree of knowledge.
Source...