Unfortunately what you are doing is putting a band aid on an open wound.
Putting on tar paper for roofing.
Start at the bottom of the roofline and work up so any water that gets through the roofing material will shed down the tar paper and will not go under it.
These cracks will now open up your roof to the same leak you had originally only now you have an additional problem.
While impossible to know unless you do an expensive analysis the asphalt used to make modern tar paper contains much more oxygen than it should.
The 30 pound tar paper is heavier and has much more asphalt in it.
Some roofers prefer to attach felt underlayment with 1 inch roofing nails or special nails with plastic washers but most codes allow staples which are easier to drive.
Felt labeled astm 15 meets specific standards and is the norm in many areas.
Felt or building paper must be applied to walls properly to be effective.
Roofing felt also known as tar paper serves as both an extra layer of protection between the shingles and the plywood and as a temporary moisture barrier until all the shingles are in place.
Wind driven rain or snow can trap water under your shingles putting your roof deck and inner residence at risk of moisture damage leaks rot and mold.
The roofing felt should be applied in layers that overlap.
Place a final piece of tar paper over the top of the roof attaching it so it overlaps the tar paper on both sides of the roof.
The tar paper made between 1900 and 1980 probably will last far longer than the tar paper made today.
Many builders use standard 15 pound roofing felt.
How to install roofing tar paper.
Whether you re building a new house or putting a new roof on your existing house installing tar paper first helps waterproof the roof and prevent leaks.
Roofing felt helps.
It s important that use the building paper that is recommended for your area.
The idea is to make sure water that falls on the roof drips down from paper to paper and off the roof rather than up under the tar paper potentially damaging the roof s wooden structure.
Before applying roofing you ll need to cover the sheathing with roofing felt also often called tar paper most local codes call for using 30 pound felt.
And while band aids can be useful they are also temporary.