Table of Contents
How is a flat roof constructed?
A flat base is required to lay the roof covering on. The sheets of plywood are fixed to the flat roof joists to make a flat base, hence the name flat roof. The panels are laid with the longer edges across the flat roof joists and staggered to offer a more stable surface.
Can a porch roof be flat?
A major benefit to a flat roof is that it’s easier to build and cheaper. If the building is large enough, a flat-roofed porch becomes a more attractive option, structurally. But perhaps the biggest advantage to a flat roof porch is the alternative uses to which you can put the space.
What size timbers do I need for a flat roof?
The joists should be sized using either the TRADA span tables or BS EN 1995. The sizing and spacing will depend upon the loads imposed on them and the required span. Wherever possible, joists should span the shortest distance. Common joists sizes are 200 x 50mm, 175 x 50mm, and 150 x 50mm.
How do you slope a flat roof for drainage?
For drainage purposes, the current building codes require a minimum two percent slope or a one-fourth unit vertical for every 12 units horizontal. In other words, the roof must slope one-fourth of an inch for every 12 inches. The slope is barely noticeable to the naked eye.
What type of roof is best for flat roof?
Let’s get to the 4 best materials for a flat roof replacement. EPDM membrane roofing. EPDM (ethylene propylene diene terpolymer) is a synthetic rubber black membrane commonly used in commercial and medical facilities. TPO membrane roofing. PVC membrane roofing.
What is the best type of flat roof?
EPDM Membranes Quite possibly the best flat roofing membrane, EPDM is a relatively low-cost flat roof material that offers a number of significant advantages. Clean, straightforward installation, incredible strength, a long lifespan, and a smart finish combine to make EPDM membranes a difficult one to beat.
What kind of roofing do I need for a flat roof?
PVC membrane roofing. PVC (polyvinyl chloride) is also a single-ply white membrane used in commercial and residential roofing. PVC is also a great choice for any flat or low slope over a living space or bedroom.
What is the minimum pitch for a porch roof?
The smallest pitch of a roof is 1/4:12, which translates to 1/4 inch rise to 12 inches of run. Such a small pitch can only work with built-up roofing or specialized synthetic roofing. Covered porches that are near trees or in areas with heavy rains should not be covered with a low-slope roof.
How much pitch should a porch roof have?
The minimum pitch for a roof is 1/4:12, which translates to 1/4 inch rise to 12 inches of run.
How much slope does a flat roof need?
A flat roof is generally any roof with a pitch of 1-10 degrees. That means flat roofs aren’t actually flat. It may look horizontal but often has a minimum slope of 1/4 inch per foot. This allows water to run off the roof to prevent damage.
What is the dead load of a flat roof?
Permissible Clear Spans for Flat Roof Joists (to BS 5268-7.2) C24 Dead load per square metre (in kN/m²) supported by joists Not more than 0.5 More than 0.5 but not more than 0.75 38 × 145 3.264 3.013 38 × 170 * 3.903 3.567 38 × 195 * 4.467 4.085.
How far can a 2×6 span on a flat roof?
What is this? A 2×6 rafter can span 14 feet 8 inches when spaced 16 inches apart with No. 1-grade southern pine lumber on a roof with a 3/12 slope or less with a maximum live load of 20 pounds per square foot and a dead load of 15 psf.
How far can a flat roof truss span?
A roof truss can span up to 80′ without support, however in any home that distance would be impractical and incredibly costly. Trusses are designed to span spaces without interior supports, and spans of up to 40′ are the most common in today’s homes.
Can you add a pitch to a flat roof?
You can install a shallow pitched roof over your existing flat roof, add a trussed ranch-style roof to convert to cathedral walls, or even build a new floor and install the pitched roof above that. Either way, your home’s existing design may interfere or affect the changes you can make.
How do you divert water on a flat roof?
Gutters. We’re all familiar with gutters. Another commonly used drainage solution for flat roofs, gutters are also cost-efficient. They simply divert water into a downspout that drains the water far enough away from the building’s foundation that the water will not damage other parts of the building.
How much does it cost to turn a flat roof into a pitched roof?
Evaluating the costs of a project like this can be difficult, as they can range significantly depending on region, season, and current costs of materials. However, our research indicates that as a very rough ballpark figure, you should be prepared to spend upwards of $30,000 for an average-sized residential structure.
What kind of wood do you use for a porch roof?
Plywood is a standard roof decking product for porches. It withstands moisture well and grips nails tightly. Plywood requires trees from old-growth forests. It’s a light, stiff material, though it does sometimes have soft spots due to knots overlapping.
