Why Not To Add A Second Lkayer On A Roof

This will force you to replace your roof earlier than expected.

Why not to add a second lkayer on a roof.

If the existing roofing is not flat the bumps will show through the new roofing and will contribute to sideways water movement which will result in a leak. Most people want to add another layer to their existing roof to save money. The savings you re going to see may be in the range of a modest 25. Doing a second layer right means a lot of prep work goes into the overlay anyway and flashing which remember is the most vulnerable point on your roof is harder to guarantee.

Two roof layers can work if the existing roof is in good condition but you shouldn t put more than two layers of shingles on your roof because of the weight. Installing a second layer is only advisable if. The existing layer of roofing is extremely flat. The second layer of shingles will trap heat which can result in the decomposition of both roof layers.

Plus depending upon the size of your roof you ve added multiple tons of weight which could pose a big problem if there is significant snow accumulation. Reroofing a home is something ambitious homeowners can do and you can save time and energy by installing the new shingles over the old ones. However this is a particularly short sighted approach once you realize that layering roofing can often void the warranty. In snowy climates most new roofs these days get an ice and water shield a rubbery moisture membrane applied to the sheathing along the eave to protect against ice dams.

In fact the extra layer can reduce your roof s lifespan by up to 40. You re essentially adding a second roof on your house and that added weight puts stress on the roof decking which is especially worrisome in our climate that gets heavy rain and snowfall. Reasons why you should not add a second layer of shingles it will shorten the lifespan of your roof. That second layer of shingles won t last as long.

Manufacturers believe that layering the roofing diminishes the overall performance of the roof. Flashing around roof penetrations and sidewalls can be compromised. You cannot afford to remove the existing roofing.