LEEDS ROOFERS - ROOFINGTIPS 

Most people call on the services of a roofer after spotting a leak in their homes. From there, the roofer must assess the situation during what is known as the initial consultation. Many homeowners have the tendency to discount the value of these consultations, as they do not see any "work" being done. However, it is in your best interests to allow your roofer adequate time to make his diagnosis. Never rush your roofer through this critical stage of the repairs process.
(roofing tips, homedoctor.net).

Proper ventilation in your roof may be the difference between a successful roof or a complete failure in a very short space of time.

Roof Maintenance

It does not matter what your roof is made of. Roof maintenance should be done at least twice a year... Just before the winter sets in is a good time:
If possible and safe to do so, use a ladder and inspect all sides of the roof while you are at gutter level, do not walk on the roof without the right equipment as you could break the tiles or slates. Slowly inspect small areas at a time looking for slipped tiles or slates or any cracks. At the same time clear any debris out of the guttering.  

If it is not possible to access certain areas of the gutter to clear debris, try taking a hose up the ladder and blasting out the debris with water. This may also be done down any downspouts to check there are no blockages.

See below if it is not possible to use a ladder to inspect the roof from gutter level...

Pay particular attention to roof protrusions where different sections of roofs meet or intersect with walls. Most roof leaks develop in these areas. Roof protrusions are anything that sticks thru the roof, such as pipes, vents, chimneys etc. Remove cracked or dried out caulking / mastic and replace with a good waterproof silicone sealant. Use a wire brush if necessary and make sure surface is clean and dry. Seal loose bricks and mortar in chimneys.   

Internal inspection:

Inspect the ceilings and walls on the inside of your home. In most cases a spot on the ceiling will tell you you have a leak. The first sign of a roof leak should be fixed immediately.
(You may only realise that a repair is needed on the roof when ceiling stains are noticed in a room after rainfall. This indicates that water is leaking into the roof space. Always repair damage as soon as possible to stop further rainfall damaging the fabric of the house).

Checking the roof from inside
If your roof is unlined (no roofing membrane behind the tiles and lathe), check for daylight showing through... It may need closer inspection. Check the timbers for water staining. If stains are found on the timber, try to find the source of the stain. Slate will deteriorate with age so check for hairline cracks and look for staining on the tiles or white efflorescent powder. 

Checking at ground level
Look at the whole roof by inspecting it at ground level. You should be able to spot a tile that has slipped as it will be out of line with the rest. Look for any powdery or flaky substance, known as delamination, which shows deteriorating tiles. Check ridges for gaps in the mortar joints. Check flashings at abutments and around chimney stacks. Check for fallen pieces of mortar, slate etc.

Use binoculars to check if you can not see it too well or a modern digital camera with a good telephoto lens.

Checking from roof level
If using a ladder, make sure it is set up correctly and long enough - at least 3 rungs above the gutter. Always work with someone standing near by when you are working at a height.

If going onto the roof always use a correct roof ladder with wheels to avoid damage to the roof. 

If you do not have any equipment mentioned above call in a roofing contractor to check your roof or alternatively you can hire the equipment from a diy hire shop but please follow all instruction for use carefully.

THE MOST COMMON CAUSE OF ACCIDENTS IN THE BUILDING INDUSTRY IS FALLING FROM HEIGHTS

BE CAREFUL - BE SAFE. IF IN DOUBT USE A PROFESSIONAL