Description: Mansard roofs are, for the most part, based on standing seam or batten seam construction.
The lower ends of the pans are typically hooked over an edge strip to form a drip. The ends may alternately attach to the base flashing where a change in roof slope occurs.
The recommended detail for the upper edges of the pans is to fold them out the height of the batten or standing seam and terminate them with a 3/4" fold. The lower edge of the gravel stop or coping flashing is then hooked over this fold (see Details 8.7A and 8.7B).
Special Conditions: Since mansards are inherently used on vertical or nearly vertical surfaces, most of the special provisions for low slope standing and batten seams are not necessary.
Decorative battens may be added in the same manner as for chevron roofs.
If the standing seams or battens are to continue over the top edge of the mansard, special steps must be taken. The pans should be continuous over the top edge. The upstanding legs of the standing or batten seams must be slit where they are bent. After bending, small pieces of copper must be soldered over the legs to restore continuity. The seams are then finished in the conventional manner.
Decking Requirements: A continuous sheathing substrate is required, compatible with the roofing system used.
8.7A. Top of Mansard - Coping Cover
This detail shows a condition where the top of the mansard meets a coping cover. The top edge of the pans are folded out to the height of the standing or batten seam, then bent down 3/4". The coping cover is hooked over this edge, effectively forming a drip.
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8.7B. Top of Mansard - Gravel Stop
The top of a mansard at a gravel stop is illustrated. The top edge of the pans are treated similar to Detail 8.7A, with the gravel stop engaging the folded pan edge.
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8.7C. Bottom of Mansard
This is a typical condition for the lower edge of a mansard. The bottom edge of the pans are hooked over the edge strip to form a drip. The horizontal dimension of the edge strip should not exceed 4" if it is not fastened to the soffit.
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8.7D. Change in Mansard Slope
This detail shows the condition where the bottom of the mansard meets another roof. At the lower roof, the standing seams are laid flat 8" from the roof break, folded 3/4" and secured with copper cleats spaced 12" O.C. Copper locking strips of the same weight as the flashing are soldered to the pans between seams at least 6" from the roof break and engage the base flashing in a 3/4" lock. At the upper roof, the upper edge of the base flashing is folded 3/4" and secured with copper cleats spaced 12" O.C. A continuous locking strip is soldered to the base flashing and secures the mansard roof edge.
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8.7E. Continuous Over Roof Batten Detail
The detail illustrates the installation for batten seams which are continuous over the roof. Standing seams under the same conditions are detailed in a similar method.
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The pans shown are continuous from the face of the mansard over the edge onto the roof. The upstanding legs of the seams must be slit where they are bent. After bending, small pieces of copper must be soldered to the back side of these legs. Batten caps are then added in the conventional manner, except that their legs must also be slit and soldered where they are bent.
For Additional Information:
- Roofing Systems - Introduction, for general roofing system descriptions and requirements.
- Flashing and Copings, under the appropriate sections for flashing details.
- Basic Details for information on seams, fixed and expansion cleats, hold-downs, edge strips and transverse seams.
- Roofing Systems - Standing Seams or Roofing Systems - Batten Seams for information on the respective roof types.
- Roofing Systems - Chevron for additional information on decorative battens.