Re roofing with 3 tab shingles are pretty straight forward.
How to re roof with architectural shingles.
Instead of one layer laminated or architectural shingles have two or more layers with three dimensional tabs of varying sizes.
Attach each shingle with three nails one in the center and one each on each side.
If you ve got a new roof on your mind there must be something noticeably wrong since these types of roofs come made to hold up for a lot longer than a 3 tab.
Nesting each new row below an existing one keeps the new nails 2 inches below the existing which will help minimize any splitting of the sheathing.
Architectural shingles are durable less prone to curling and hide imperfections better.
As you can see from the photo the architectural shingles will have bumps created by the old shingles which will keep the new shingles from looking flat and smooth.
51 to 124 per roofing square shingles are priced per roofing square which is equal to 100 square feet.
The standard practice is to limit to a total of two layers of shingles.
Mark a chalk on subsequent roof layers upward.
After that you should tear off old shingles before installing a new layer.
Best solution is tearing off the old shingles first.
Architectural roofs should be able to and withstand more damage than 3 tab shingles.
Apply a cover of starter architectural shingles.
You can cut the layered edge of architectural roof shingles and use the cut flat piece as your starter roof single.
The professional answer is no you should not attempt to re roof architectural shingles over existing architectural shingles.
After that correctly positionthe first shingle and properly snap a line of chalk across the roof to mark the top layer of the shingles.