General roof maintenance

The most common type of roofing used in new New Zealand houses is galvanised or coated steel, followed by coated metal and concrete tiles.

Some maintenance tasks are common to all types of roof, others are specific to the particular roof type. Some tasks will need to be completed more often if you live close to the sea or in a geothermal area. Check with the manufacturer of your roof for specific maintenance requirements.

Flashings may not last as long as the roof so they will require more maintenance. Anything that penetrates the roof, such as pipes, flues or fixings, needs special care to ensure weathertightness.

If you are not sure about roofing work or you are uncomfortable working at heights, consider using a roofing professional. Make sure your roofing professional passes on their own and the manufacturer’s warranty.

If you are painting a roof, trimming trees, cleaning guttering, replacing spouting, roofing, repairing chimneys and there are power lines nearby, arrange with your power company to disconnect the supply before carrying out the work.

Annual maintenance checks

Once a year you should check your roof cladding, chimneys and flashings by getting up on to the roof. This means using a ladder. Use your ladder safely. Do not work on a wet roof.

Falling and slipping accidents are relatively common when people climb on to a roof to carry out maintenance such as painting or cleaning gutters. On a roof, particularly over 15 degrees in pitch, you generally have little or no chance of catching yourself before the edge if you slip.

Sections of roof that can’t be reached by roof ladder – such as parts of a hipped roof or over dormer windows – need a secure way of fixing safety ropes.

Check that the roof can be safely walked on. Some roof materials cannot support the weight of a human (translucent sheet or severely rusted galvanised steel). Old asbestos roofs and clay and concrete tiles can be damaged when walked on so wear soft soled shoes with good grip.

When working on a roof:

• Ensure the roof is dry – do not climb on to a wet or damp roof as they can be very slippery.
• Walk along the nail lines.
• On roofs over 15 degrees, slope use a roof ladder.
• If possible use an extended window cleaning brush to clean wall cladding, eaves and joinery from the ground.

To avoid damaging the roof and guttering when you are up on the roof:

• Place a timber block in the gutter immediately behind the ladder to prevent crushing the guttering.
• Walk only along the line of nails on steel roofing.
• Step only on the front edge of the tile on tiled roofs - for full inspections use a plank as a walkway. Beware the danger of slipping as angles can be steep.
• Use a cherry picker if there is access around the house for one.

Buildup of salts and dirt

This encourages rust on steel roofs, and moss and lichen on tiled roofs. Most manufacturer’s warranties require regular washing, particularly in areas that don’t get rain washed. Wash the roof down every 3 to 12 months according to the particular product and your location. Consult your manufacturer for specific information.

Concentrate on washing areas that do not get rain washed, such as under the eaves. You may need to wash the roof more often in coastal, geothermal or highly industrial areas to keep salt, sulphur and other deposits to a minimum.

Washing the roof also gives you an opportunity to check the general condition of your roof.

Damaged/unstable TV aerial or receiver dish

The aerial could come loose and fall. A damaged aerial may also affect your TV reception.

There are many different makes and models of TV aerials. You are better off getting the advice of a professional rather than trying to repair or replace an aerial yourself. Although you can replace bent or corroded elements, it is probably only going to be a short-term measure. Look under “Television Aerial Installation” in the Yellow Pages.

Crumbling chimney mortar

Crumbling mortar could be due to moisture getting in. The mortar will need re-pointing and this is a job for the professionals. If the chimneypot is badly damaged you may want to consider replacing it with a metal cowl. If the chimney is no longer used, block off the top to stop birds, rain and draughts.

Corrosion of flue pipe, cowl or fastenings

This could be due to a build up of combustion deposits. Clean the flue, and the roof around it, regularly during the heating season to keep combustion deposits to a minimum. Fires can occur in flues or chimneys that haven’t been cleaned. For existing corrosion, remove the rust and then paint with a zinc-rich primer. Prime with galvanised iron primer and apply roof paint. Replace severely damaged fastenings with hot dipped galvanised or stainless steel fastenings as appropriate to reduce corrosion in future.

Use a chimney sweep. Look in the Yellow Pages under Chimney Sweeps.

Insecure metal flue

This could be due to corrosion of the fixings, especially in areas near the sea.

If the fixings have corroded, replace them with hot dipped galvanised ones. This will only be a temporary solution – you will eventually need to replace the nails, especially if you live close to the sea. Replace or re-fix others, increasing the number if necessary.

Corroded galvanised metal flashings

Corrosion is common in areas near the sea but can also occur in other areas. Flashings protect vulnerable areas of the roof. If they fail, they can affect the weathertightness of the roof allowing water to get into your home.

Remove the corrosion and paint with zinc-rich primer, metal primer and finish coat. If the corrosion is severe, replace the flashing.

Lifted or dislodged flashings

Flashings protect vulnerable areas of the roof. If they fail they can affect the weathertightness of the roof allowing water to get into your home.

Replace loose nails with new nails or screws and increase the number if necessary. Make sure there is timber below to fix the nails in to.

Ponding water

Water ponds when there is insufficient slope on the roof or the roof is sagging. The ponding water will cause the roof to deteriorate. This is most common on flat or membrane roofs.

Before addressing the cause, check if the roof structure is still under warranty. By making changes to the structure of the roof, you may invalidate the warranty. You may also need a building consent.

Consult with a professional if you need to make changes to the structure of the roof to address ponding.

Trees

Trees can cause many problems for roofs of all types. Overhanging branches can scratch and gouge roofing materials when blown by the wind; falling branches can damage or puncture shingles and other roofing materials; and falling leaves can clog gutters causing water to backup or run down behind the fascia.

Trees that are adjacent to the house should be kept well trimmed. Keep your gutters clear of leaves and debris. Consider using a product to prevent leaves lodging in guttering.