Of course re felting the roof correctly will involve the removal and replacement of the tiles anyway.
How to repair felt under roof tiles.
Make sure the tiles are facing the correct way for the prevailing wind.
Take the next shingle and overlap it on top of the first on.
Image description step 2.
If your roof is leaking it is not because of faulty under felt.
Cut each strip into 3 individual tiles as shown.
Cut off a piece of flashing strip to fit the length of the tile you need to repair.
Observe equal distance of each nails approximately 20 inches so they are properly attached to the roof.
It would be far cheaper to fix the faulty tiles than to re felt the roof.
Put a coat of flashing strip primer onto the crack and the area around it.
Where wind driven rain is working under the roof and causing leaks then the felt will need to be replaced.
It is because you have faulty tiles somewhere on the roof.
Bend the shingle over the ridge and nail down firmly.
Fasten the felt on your roof using the cap nails.
To replace a small section of roofing felt involves stripping the tiles from the roof and replacing felt between two joists.
Place the next layer of felt to your tile roof.
Start by giving the area around the crack a good clean with a wire brush wiping away the dust and debris.
The roof felt is merely a secondary emergency waterproof membrane.
Put these nails at the bottom of the felt and leave a small portion available.
This will cost around 460 510 made up of.
When the first length is secured lay the next layer of sarking felt on top so that it overlaps by approximately 100mm.