Cap nails are typically made of steel and feature a plastic cap to prevent roof leaks hence their name.
Nails or staples for roofing felt.
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When estimating nail or staple usage for your roofing project you should budget 400 nails or staples per square.
Although staples are allowed in some jurisdictions they do not provide the same holding power.
Use a construction stapler or a hammer.
Put fasteners at least every 8 inches.
Felt staplers are designed for roofing felt housewrap insulation weather stripping light wood assembly and more.
The preferred fastener is galvanized roofing nails with a minimum 12 gauge shank and head diameter of at least 3 8 inch.
When the shingles are installed the felt is not going anywhere.
The reason they want you to use felt nails is to prevent blow offs if left exposed or high wind areas.
Others will tell you that cap nails are more effective.
Roll out about 10 feet of felt and fasten with staples or roofing nails with plastic washer heads.
However always consult your local building authority for exact code requirements.
Both options often depend on the slope of the roof itself.
Staples can be used for tacking it down but not recommended to hold.