Although flat roofs are cheaper to build than pitched roofs they have a shorter life span.
Rainscreen detail flat roof.
About ice dams admittedly a concern that rarely plagues homes with metal roofing is to apply 2x4s on the flat on top of the roof sheathing with one 2 4 over each rafter or truss.
Changes to the building code mean that in some parts of canada in particular coastal areas with high precipitation rainscreen detailing is mandatory.
When ventilated properly with a minimum 1 4 gap to the exterior at bottom and top of the rain screen and a minimum 3 8 deep vertical cavity in between the volume of air passing through the rain screen cavity can be measured in the 10s even 100s of air changes per hour.
Having a manual for warm flat roof construction with details and a summary of rules to follow helps.
The rain screen battens can be made from many materials.
A roof is considered to be flat when it is of a slope of 1 5 o to the horizontal.
If the attic is ventilated morgan says a rainscreen detail on the roof is unnecessary.
At that time we used 1 2 pressure treated plywood.
I ve been doing rain screen installs since 2002 when i learned the technique in portland or.
The third and last example is perhaps the most complicated.
Flat roof construction for residential.
The cavity helps wall assemblies dry out.
I ve also used rips of hardiplank and standard 1 4 s.
Cad details document name pdf dwg download all cad construction details 37 1 mb 3 4 mb mc01 identification of roof areas 694 kb 167 kb mc01a single layer underlayment 678 kb 302 kb mc01b double layer underlayment 711 kb 322 kb mc02 vent pipe flashing 626 kb 349 kb mc03 valley.
The basic construction of a flat roof starts with roofing timber that is laid across two upright items usually two walls.
Simply put we built.
I can see the need for this detail with spray foam applied to the underside of the decking but also with any vaulted ceiling system or attics with any type of insulation obscurring the underside of the roof deck.
That will help you remember certain factors and details to build the best possible flat roof.
For an animation on what is a rainscreen follow this link.
Is the topside rainscreen air space detail opened to the outside so that air can circulate through it.
Intercept modular metal panel systems interrupt conventional thought on rainscreen wall systems to inspire spectacular visual results.
The davidson residence above uses a built up flat roof deck at the center portion of the house the portion with the guardrails.
However whether or not the code requires a rainscreen it is a better way to detail exterior cladding of buildings.
