What size rafters do I need for a flat roof?

What size rafters do I need for a flat roof?

If the rafters of a flat roof need to span 18 feet, with a deflection limit of their length divided by 360 (L/360), they need to be 2 inches by 10 inches or 2 inches by 12 inches, depending on the type and grade of timber used. These dimensions take into account a snow load of 20 pounds per square foot (psf).

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 roof beam span without support?

The maximum distance a 2×6 can span, according to the 2018 IRC, for a floor joist, is 12′-6”, ceiling joist 20′-8”, rafter 18′-0”, deck board 24”, deck joist 9′-11”, deck beam 8′-3”, and 6′-1” as for header. Always check the codes for determining factors or consult a Structural Engineer.

How far apart should flat roof joists be?

Wherever possible, joists should span the shortest distance. Common joists sizes are 200 x 50mm, 175 x 50mm, and 150 x 50mm. The joists will normally be placed at 400mm centres but no more than 600mm centres.

What size rafters do I need for a 14 foot span?

Max. Live Load 20 lbs/ft2 (956 N/m2)

Maximum Span (ft – in)
Nominal Size (inches)	Rafter Spacing, Center to Center, OC (inches)	Lumber Grade
2 x 6	12	16′ – 4”
16	14′ – 11”
24	13′

How far can 2×4 rafters span?

Spacing your 2×4 shed rafters at 24” on center limits the width of your roof. For light load roofs, 24” o.c. 2×4 rafters can span up to 7 ⅔’. For heavy loads, 2x4s can span up to 5 ½’.

What is the max span for a 2×6 rafter?

Can you use 2×6 for roof rafters?

2×6 shed roof rafters are enough for nearly any type of shed a homeowner wants to build. While a 2×6 might be nearly double the cost of a 2×4, you can likely space the 2x6s further apart, negating the added expense of increasing your lumber width. An SYP 2×6 rafter at 24 O.C. can span up to 13’4”.

What size rafters do I need for a 18 foot span?

Max. Live Load 60 lbs/ft2 (2873 N/m2)

Maximum Span (ft – in)
Nominal Size (inches)	Joist Spacing Center to Center, OC (inches)	Lumber Grade
2 x 10	24	11′
2 x 12	12	18′
16	15′ – 7”

What is the maximum span for a 2×4 rafter?

Can I use 4X2 for ceiling joists?

4X2 would be more than adequate for what is required.

How far can roof rafters span?

Max. Live Load 20 lbs/ft2 (956 N/m2)

Maximum Span (ft – in)
Nominal Size (inches)	Rafter Spacing, Center to Center, OC (inches)	Lumber Grade
2 x 8	24	17′
2 x 10	12	27′ – 6”
16	25′