Overlaying Asphalt Roofing

Owens corning produces high quality asphalt coating asphalt sealants and adhesives for asphalt shingles.

Overlaying asphalt roofing.

But before we get started one thing must be clear. Most building codes allow two layers of organic or fiberglass asphalt shingles on roofs with a 4 12 pitch or less and three layers on steeper roofs. If you don t take your roof down to the sheathing you will never know if you have proper underlayment or are experiencing sheathing rot or ice or water damage. Before you reshingle a roof read our step by step guide for adding new shingles over old ones.

When the roofing company you hire tears off your existing roof and then puts on an entirely new roof. Adding new roofing over old sometimes called a re roof is possible only with asphalt shingles also called composition shingles. Since an overlay roof is made up of two layers of shingles it traps much more heat and is prone to issues that can occur between the two layers. Experience the total owens corning roofing system and high quality roofing shingles.

You can t examine the decking to determine if there is any damage that needs repaired. If you are putting a layer of asphalt shingles over an existing layer of asphalt shingles on to a 3 4 inch deck or a plank deck then you should be using 1 1 2 inch nails. Beveled wood pieces called horsefeathers must be laid along the thick edges of the shakes to make a fairly flat surface. An overlay roof will have a shorter lifespan than the average asphalt roof.

It s good to know that you can only choose this option if your roof has not been overlaid previously. Prep work for re roofing over asphalt shingles inspect the condition of the existing roof and roof deck for numer of roof layers soundness of roof decking smoothness of existing roof installation and other factors that determine whether or not you can do a roof over or if a roof shingle tear off is required. California roofing laws cover everything from licensure of the roofing company to the types of shingles that must be used to the slope of the roof. In general it is not a good roofing practice to overlay a traditional asphalt shingle roof versus a complete tear off and replacement with a new roof for the very reason you stated.

If the structure can support the added weight a typical 20 square 2 000 square foot reroof will cost at least 1 000 less than a tear off job. The tear off method is exactly what it sounds like. If your decking is less than 3 4 inch then a 1 1 2 inch nail will suffice. Asphalt shingles can be laid over cedar shakes or shingles however this is a roofing project best left to pros.

You can t do it with wood or slate for example and you should never mix materials such as laying asphalt shingles over cedar shakes. An overlay roof occurs when keep your existing roof as is choosing instead to shingle on top of it.