Nails to hold CHIMNEY CHASE “top hat/cover” on
edwardh1
| Posted in Construction Techniques on
My house has a 2 storey chimney chase, made of wood with Hardie lap siding.. it has a metal top hat/top that sits on top of the chase. Its held on by nails, Chase is about 5 ft x 3 feet. there are two nails thru the metal at the end of each side, so 4 nails total on each side 16 nails total.
if Mr hurricane visits, will 4 nails on the 5 ft side (again 2 at each end none in middle) holds it on,? say 135 MPH winds,? seems light to me. What would an architech specify?
Replies
Typically, the architect follows manufacturer's specifications and augmented if necessary by code requirements for your area and wind zone. Since many caps are of custom design, attachment may vary. For chimneys framed in wood, it is most commonly recommended that a standard design chimney cap is affixed by both galvanized screws with wide-based washers and adhesive sealant. Nails, even of the ring-shank type, are not recommended as suitable attachment.
In high force winds it may not matter, however, if the design of your cap doesn't possess sufficient built-in uplift protection, causing it to break apart rather than become detached.
No, under any condition that's not enough. Replace those screws with at least a #8 X 2" galvanized hex head screws. I would have 5 screws per side on the long side and 3 on the short sides.