Surface area =300 square feet 25 year old ash

If it is near the chimney, it will almost certainly be the flashing although water normally runs down the internal brickwork as well. Unless the wet area is further down the slope from the chimney. Water always follows gravity but can be deviated by just a roof nail in the way. Another thing to check is that you haven't lost the capping shingle that folds over the top of the apex of the roof. That shingle is susceptible to wind damage.

It depends on a variety of factors, including cost, longevity, style, and local climate. Metal is the most durable roofing material, but it can be quite expensive and is not suitable for certain architectural styles. Asphalt shingles are much more economical and typically last 20-30 years, depending on the climate and other external factors. In some climates, asphalt is still the preferred choice because it is better at resisting damage caused by extreme cold or snow. Ultimately, the best option will depend on personal preference and budget.

Lineal feet are straight line feet.
You answered your own question.
25 feet.
Square feet are the surface area.
25 feet X 3 feet are 75 square feet.

Hello Connie

Good to see you back. You still haven't fixed that old roof yet!

You take 36 x 32 and that gives you 1,152 square feet of area. Then you put it into a roofing calculator website and you get this.

To have 10% buffer would require 13 roof squares.
By United States standard, the roof will need:
35 bundles of composition shingles (each bundle will cover ~33 ft2)
12 rolls of roll roofing (~36 in × 36 ft for each roll)
3 rolls of #15 felt (~36 in × 144 ft for each roll)
6 rolls of #30 felt (~36 in × 72 ft for each roll)
Roofing ceramic tiles do not have a standard size. Consult contractors to determine the amount needed.

So you need 35 bundles, but you could probably get away with 32 if it is a nice rectangle.

I helped you before as Andrew Taylor, I changed my name.

https://www.google.com/search?q=calculating+roof+shingles

How to install

https://www.iko.com/na/pro/building-professional-tools/roofing-101/how-to-install-shingles/

and a video, but you really should get someone in to do this for you as I told you in December 2015!

https://www.youtube.com/watch?v=iaDop-7F6Bc

..

Try to scrape off as much as you can without damaging the shingles. If you have moss growing on your shingles, you have a debris (needles)/moisture/lack of sunlight. Diluted bleach with water in a spray canister is the cheapest way.

Cubic foot is a unit of volume. Square foot is a unit of area. There is no direct conversion between them.

A 9600 cubic foot room with a ten-foot high ceiling is 960 square feet. If the roof is eight feet high, the area is 1200 square feet. If the roof is 12 feet high, the area is 800 square feet.

http://www.classaction.org/bp-of-canada-organic-shingles.html