More Blogs on Similar Subjects:

  1. I’m buying a ‘50s house with a “gravel” roof. Is the roof going to be a problem.

  2. What are the right words for talking about a roof?

  3. Should I buy a house that needs a new roof?

  4. What is the cost difference between asphalt shingle and metal roofing?

  5. What’s the difference between a roof inspection and a roofing estimate?

  6. What is roof pitch?

  7. What’s the difference between “composite” and regular wood siding?

  8. Should I buy a fixer-upper?

  9. What are “shiners” and why did they make me lose my insurance discount?

  10. What do you look for when you inspect a roof?

  11. What are the most common problems with older houses?

  12. What does “lack of tab adhesion” in an asphalt shingle roof mean?

  13. Why does my insurance company want a roof letter?

  14. I saw some staining on the ceiling. Do you think the roof is okay?

  15. How do I find out the age of a roof?

  16. What is a TPO roof?

  17. What is a “cool roof”?

  18. What can I do to prevent roof leaks?

  19. What are the roof sheathing requirements for a roof replacement in Florida?

  20. How can I be sure my roofing contractor got a permit?

  21. What is the difference between galvanized and galvalume metal roofing?

  22. Does it cost more to roof a hip roof than a gable roof?

  23. What is an H-clip?

  24. Is a ridge board/beam required for a roof framed with rafters?

  25. If my roof is not leaking, why does it need to be replaced?

  26. What causes a lump or dip in the roof?

  27. What are the most common problems with wood roof trusses?

  28. What is the difference between roofing felt and synthetic underlayment?

  29. Why is a popped nail in a shingle roof a problem? How do I fix it?

  30. Are roof trusses better than roof rafters (stick framing)?

  31. What is the difference between roll roofing and modified bitumen?

  32. What is a roofing boot?

  33. Why is there no attic access hatch in the house?

  34. Why is it a mistake to replace and roof not replace its flashings?

  35. What are the hazards to avoid when going into an attic?

  36. What is a “square” of roofing?

  37. Why are most house roofs slanted instead of flat?

  38. What is an SPF roof?

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Welcome to our blog!
We want you to be an informed homebuyer, and each blog post is a question that we have answered for our friends and customers over the years. Hope they help you make a good choice for your next home.

   All asphalt shingle roofs with a pitch of 4/12 or more have an underlayment of 15-lb. asphalt felt paper that is tacked to the roof sheathing before the shingles are installed. Each sheet overlaps the one below it by 3”, called downlapping, and provides a backup layer of protection from water intrusion.

   Roofs between 2/12 and 4/12 are required to have the underlayment more deeply lapped, so that there are effectively 2 layers of the 15-lb felts over the surface. Or, an alternative underlayment for low-slope roofs is a self-adhering bituminous membrane material is also self-sealing. The most popular brand of this underlayment is “Grace Ice and Water Shield.”

   A roof slope of between 4/12 and 8/12 is considered the sensible range for most situations. While a higher pitch than 8/12  gives a home more dramatic curb appeal, there are several downsides. A high pitch increase the homes exposure to lateral wind loads, and the rapid flow of rainwater down the shingles can prematurely scour away the protective granules on the surface of the shingles. Valleys on steep roof are especially prone to premature granule loss, as shown in the photo below. Also, steep roofs are more difficult—and less safe—to maintain or replace. Workers may have to be wear a safety harness while on the roof, which slows them down.

While we hope you find this series of articles about home inspection helpful, they should not be considered an alternative to an actual home inspection by a local inspector. Also, construction standards vary in different parts of the country and it is possible that important issues related to your area may not be covered here.
©2015 - McGarry and Madsen Inspection.


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