OVERFLOWING gutters and blocked rainwater down pipes can cause serious damp damage to buildings. Autumn is the time to overhaul your rainwater disposal system. Here's what to do:

1. Fallen autumn leaves must be physically removed from gutters. On anything higher than a bungalow this requires a ladder and a head for heights. Don't take risks. Unless you know what you're doing, pay someone else to do it for you.

2. Various types of mesh guard can be fitted to keep leaves out of gutters, but unless you are surrounded by trees, they are probably more trouble than they are worth. A simple piece of chicken wire stuffed in the top of the running outlet will stop leaves from entering the down pipe.

3. Plastic guttering can start leaking after only a few years. Make sure it has enough support brackets to prevent sagging, and that it is fixed at a sufficient slope for the water to drain away. If pigeons are using your gutter as a bird bath then you've got a problem.

4. Watch out for leaks from the joints of plastic guttering. It means that the rubber gaskets are worn and need replacing.

5. Cast iron guttering is much better than plastic. It needs painting every 20 years or so, and the joints should be re-sealed using a mix of putty and oil-based paint.

6. Whenever overhauling guttering, always check the condition of the tim-ber fascia board on which it is mounted, and repaint if necessary.