A pitched roof turns a shed from a leaky box into a dry, lasting outbuilding, and building one is well within reach for a confident DIYer. So how do you build a pitched roof for a shed? You choose a pitch, work out the rise and rafter lengths, cut and fix the rafters to a ridge or wall plate, then add the deck and covering. This guide walks through building a single-pitch or gable shed roof from the pitch decision to the finished covering.
What this guide covers
Building a pitched shed roof starts with the pitch, because the pitch sets the rise, the rafter lengths, and the angles you cut. The Roof Pitch Calculator turns your chosen pitch into the rise, the rafter length, and the cutting angles, so you can order timber and mark out the cuts before you pick up a saw.
Enter your shed’s span and a chosen pitch, such as 3/12 for a single slope or 6/12 for a gable, in the Roof Pitch Calculator to get the rise, rafter length, and angles, so you can plan and cut the roof accurately.
The job in outline
Building a pitched roof for a shed follows a clear sequence: decide whether it is a single slope or a gable, choose the pitch, work out the rise and rafter lengths, fix wall plates to the top of the walls, cut and fix the rafters, add any overhang and fascia, deck the rafters, and finally cover with felt, shingles, or another material. Add guttering and the job is done. It is a manageable project for a competent DIYer, especially on a small shed.
The pitch decision runs through the whole job, because it determines the rise at the ridge, the length and angle of every rafter, and which coverings will suit. A steeper pitch sheds water better and lasts longer but uses more timber and material; a shallower pitch is cheaper and simpler but needs a covering suited to a low slope. This guide covers both the single-pitch (mono) and gable forms, since those are the two common shed roofs, and shows how the pitch drives each step.
Single pitch or gable
A shed roof is usually built as either a single pitch or a gable. A single-pitch (mono or lean-to) roof slopes one way, from a higher front wall to a lower back wall, and is the simplest to build, with rafters running straight from one wall plate to the other. A gable (or apex) roof slopes two ways from a central ridge, giving a traditional shed shape with more headroom in the middle and better drainage to both sides, but it is a little more work to frame.
The single pitch is the easier and cheaper choice, ideal for a small shed or where the shed sits against a wall or fence, and it lets rainwater run to one side. The gable suits a larger or free-standing shed, sheds water both ways, and gives a peak that adds storage and a familiar look. So choose a single pitch for simplicity and a lean-to-style shed, and a gable for a larger, free-standing shed or a more traditional appearance. The single-pitch roof guide and lean-to pitch guide cover the mono form in more depth.
Choosing the shed roof pitch
For a shed, a common and practical pitch range is about 3/12 to 6/12 for a single slope and 4/12 to 8/12 for a gable, balancing good drainage against material use and headroom. A steeper pitch sheds water and snow better and suits shingles or tiles, while a shallower pitch is cheaper and lower but needs a covering rated for a low slope, such as roll roofing or EPDM. In snowy areas, lean toward the steeper end so snow slides off.
The covering you want also guides the pitch: shingles generally need at least about 3/12 to 4/12, so if you want shingles do not go shallower, whereas roll roofing and membranes cope with lower slopes. The best roof pitch for a shed guide covers the choice in detail, and the shingle pitch guide gives the minimum for shingles. Pick a pitch that drains well, suits your covering, and gives the headroom you want, then use it for all the calculations that follow.
Working out rise and rafter lengths
Once you have the span and pitch, the rise and rafter lengths follow. For a single-pitch roof the run is the full width of the shed; for a gable it is half the width, since each rafter spans from the ridge to one wall. The rise is the pitch multiplied by the run: at 4/12 over a 6 foot run, the rise is 4/12 x 6 = 2 feet. The rafter length is found from the run and rise together, and the calculator gives it directly.
The rafter length is the sloping distance from the ridge or top wall plate down to the lower wall plate, plus any overhang you want beyond the wall. The rise, run and rafter length guide shows the calculation, but the calculator does it for you: enter the run and pitch and it returns the rafter length and the cutting angles. Work these out before ordering timber, so you buy rafters long enough for the slope and the overhang, and know the angles to cut at the top and bottom of each rafter.
Materials and timber
A shed roof needs rafters, wall plates, a ridge board (for a gable), decking, a covering, and fixings. The rafters are usually 2×4 or 2×6 timber depending on the span and load, spaced around 16 to 24 inches apart. The wall plates sit along the tops of the walls to carry the rafters, and a gable adds a ridge board that the rafters meet at the top. The decking is plywood or OSB board, and the covering is felt, shingles, roll roofing, or a membrane.
Size the rafters to the span and expected load, going deeper for a wider shed or a snowy area, and space them closer for a heavier covering. Buy the rafters a little longer than the calculated length to allow for the overhang and the cuts, and choose treated timber for durability. The roof area with pitch guide helps work out how much decking and covering you need from the roof area, which is larger than the shed footprint because of the slope. Good materials, correctly sized, make a shed roof that lasts.
Tools you need
The tools for a shed roof are basic carpentry ones: a saw (hand or circular) to cut the rafters and decking, a speed square or combination square to mark the angles, a tape measure, a pencil, a hammer or nail gun, a drill, and a level. A speed square is especially useful, since it lets you mark the pitch angles for the rafter cuts directly, as the speed square guide explains. A ladder and safe access are needed to fix the rafters and deck.
Nothing here is specialist, which is part of why a shed roof is a good DIY project, though a circular saw and a nail gun speed the work. Set up a safe working area, cut the rafters at ground level where you can, and lift them up to fix in place. Working safely at height matters even on a shed, so use a stable ladder or a low platform and take care. With the pitch worked out and these tools to hand, the framing itself is simple marking, cutting, and fixing.
Fixing the wall plates
The wall plates are the timbers that sit along the tops of the shed walls and carry the rafters. Fix a wall plate level along each wall that the rafters will land on: for a single-pitch roof, one along the higher wall and one along the lower wall; for a gable, one along each of the two side walls. The plates spread the rafter loads into the walls and give a solid, level base to fix the rafters to, so getting them level and well fixed is important.
Bed the wall plates down level, check them with a spirit level, and fix them securely to the top of the walls, into the frame or blockwork as appropriate. On a timber shed the plate ties to the wall framing; on a masonry base it is bolted or strapped down. The rafters will sit on these plates with a birdsmouth notch, so a level, straight plate makes the rafters line up cleanly. Take time here, because the whole roof is built off these plates, and any unevenness carries up into the rafters and the covering.
Framing a single-pitch roof
A single-pitch roof is the simplest frame: the rafters run straight from the higher wall plate to the lower wall plate, all cut the same, sloping in one direction. Mark and cut one rafter as a pattern, check it fits, then use it to mark the rest so they are identical. Fix each rafter down onto both wall plates, spaced evenly along the shed, and the frame is essentially done, ready for the overhang, deck, and covering.
Because every rafter is the same and there is no ridge to align, the single pitch is quick to frame and forgiving, which is why it is the classic shed and lean-to roof. The height difference between the two walls sets the pitch: a bigger difference gives a steeper slope. If you are building the shed walls too, make the back wall lower than the front by the rise you want. The single-pitch roof guide covers this framing in more depth, including mono-pitch trusses for wider spans.
Framing a gable roof
A gable roof is framed as pairs of rafters meeting at a central ridge board, forming the familiar triangle. Each pair rises from the two side wall plates to the ridge, and the ridge board runs the length of the shed at the peak, holding the tops of the rafters in line. You cut the rafters with a plumb cut at the top to meet the ridge and a birdsmouth where they sit on the wall plate, and fix them in opposing pairs so the ridge is supported as you go.
The gable takes more setting out than a single pitch, since you must get the ridge level and central and the rafter pairs matching, but the method is well established. Often the two gable-end frames are built first to fix the ridge height, then the ridge is set between them and the common rafters filled in. A collar tie across each pair, partway up, stops the rafters spreading. The result is a stronger, better-draining roof with more central headroom than a single pitch, at the cost of a bit more work.
Cutting the rafters
Cutting the rafters accurately is the heart of the job, and the pitch gives you the angles. Each rafter needs a top cut (a plumb cut where it meets the ridge on a gable, or the top wall plate on a single pitch), a birdsmouth notch where it sits on the wall plate, and often a bottom cut at the eaves. The angles for these come from the pitch: a speed square set to the pitch marks the plumb and level lines directly, as the speed square guide shows.
Mark and cut one rafter first, offer it up to check it fits the walls and gives the right slope, then use it as a template to mark all the others so they match. This pattern-rafter method ensures every rafter is identical, which is what keeps the roof plane true. The calculator gives the rafter length and the angle, and the pitch in degrees guide converts the pitch to the angle if you set your saw or square by degrees. Accurate rafters make the deck and covering sit right.
The birdsmouth and plumb cuts
Two cuts define how a rafter sits: the plumb cut and the birdsmouth. The plumb cut is the vertical-facing cut at the top of the rafter where it meets the ridge (or the top wall on a mono roof), angled to the pitch so it sits flush against the ridge. The birdsmouth is a notch cut into the underside of the rafter where it crosses the wall plate, with a level seat cut that rests on the plate and a plumb heel cut against it, so the rafter sits down securely and transfers its load to the wall.
Both cuts are set by the pitch: the steeper the pitch, the steeper the plumb cut and the shape of the birdsmouth seat. A speed square set to the pitch marks them directly, which is why the square is so handy for rafter work. Keep the birdsmouth notch to no more than a third of the rafter depth so you do not weaken it. Getting these two cuts right is what makes a rafter sit flush at the ridge and firm on the wall plate, so the roof is strong and the plane is true for the deck.
Fixing the rafters
With the rafters cut, fix them in place onto the wall plates, spaced evenly (typically 16 to 24 inches apart). Nail or screw through the rafter into the wall plate at the birdsmouth, and use framing anchors or truss clips for a stronger, code-friendly fixing that resists wind uplift. On a gable, fix the rafter pairs to the ridge board too, working in opposing pairs so the ridge stays supported and central as you go. Check the roof plane stays true as you fix each rafter.
Even spacing and secure fixing give a roof that carries its load and holds the covering well, so mark the rafter positions along the wall plates before you start and work methodically. Add collar ties on a gable to stop the rafters spreading, and any noggins or bracing the design calls for. Once all the rafters are fixed and the frame feels solid, you have the skeleton of the roof ready for the overhang, decking, and covering. This is the point where the shape of the roof is set by the pitch you chose at the start.
Overhangs and fascia
An overhang, where the rafters project beyond the walls at the eaves (and gable ends), throws rainwater clear of the walls and gives a finished look. You build it by cutting the rafters long enough to extend past the wall plate, then fixing a fascia board across the rafter ends to carry the gutter and close off the eaves. A modest overhang of a few inches is enough on a shed to protect the walls and mount the gutter.
The fascia board runs along the rafter ends, giving a straight edge to fix the gutter to and a neat trim. A soffit board can close the underside of the overhang if you want it fully finished. On a gable, a barge board finishes the sloping gable-end edges. These trims are simple to add and make the shed look properly built while protecting the timber. Plan the overhang into the rafter length from the start, so the rafters are cut long enough to project by the amount you want beyond the wall.
Decking the roof
With the rafters and fascia in place, deck the roof by fixing sheets of plywood or OSB across the rafters to form a solid surface for the covering. Lay the boards with their long edges across the rafters, staggering the joints, and nail or screw them down into every rafter. The decking ties the rafters together, stiffens the roof, and gives the felt or shingles a continuous base. Cut the boards to finish flush with the fascia at the eaves and the edges.
Use a board thickness suited to the rafter spacing, thicker for wider-spaced rafters, so the deck does not flex underfoot or under load. Fix at close centres around the edges and into each rafter across the field. A well-fixed, flush deck is the foundation for a watertight covering, so take care that the boards are secure and the surface is even. Once decked, the roof is ready for the underlay and covering, and the shed is close to weathertight. The roof area from the area guide tells you how much decking to buy.
Felt and covering
The classic shed roof covering is roofing felt, laid over the deck and fixed down to shed water. Roll the felt out across the deck, overlapping the strips so water runs over the joints, and fix it with clout nails or adhesive, finishing neatly at the eaves and edges with the felt dressed over the fascia into the gutter. Felt is cheap, quick, and suits a range of pitches, which is why it is the traditional shed covering, though its life is limited.
For a longer-lasting shed roof, EPDM rubber gives a single-sheet covering with few joints and a long life, and it suits low pitches well, making it popular for modern shed roofs. Roll roofing is another low-slope option. Whatever the covering, lay an underlay if the covering needs one, work from the eaves up so overlaps shed water, and finish the edges so water is thrown into the gutter, not behind it. The covering is what makes the roof watertight, so lay it carefully and to the maker’s instructions for the pitch.
Shingling a shed roof
If the shed pitch is steep enough, usually about 3/12 to 4/12 or more, you can shingle the roof for a smarter, longer-lasting finish. Lay an underlay over the deck, then nail asphalt shingles from the eaves up, each course overlapping the one below so water sheds down the roof. Shingles give a shed a tiled look, last longer than felt, and suit a gable shed well. Below the minimum shingle pitch, though, water can drive under them, so keep the pitch adequate if you want shingles.
Start with a starter course at the eaves, then work up in overlapping courses, nailing each shingle in the correct place so the nails are covered by the course above. Finish the ridge on a gable with ridge shingles. The minimum shingle pitch guide gives the lowest pitch shingles suit, and the low-pitch roofing guide covers the alternatives if your shed is shallower. A shingled shed roof looks the part and outlasts felt, a good choice for a shed you want to keep for years.
Guttering the shed
Finish the roof with guttering to collect the runoff and carry it away, protecting the shed walls and base. Fix a gutter along the lower eaves (both sides on a gable), mounted on the fascia with a slight fall toward a downpipe or a water butt. The gutter catches the water shedding off the roof and directs it to where you want it, often into a butt for reuse, which is handy for a garden shed. Size the gutter to the roof area and the local rainfall.
The steeper the pitch, the faster the water reaches the gutter, so a steep shed roof feeds its gutter quickly in heavy rain, as noted in the steep roof discussion. Set the gutter just below the edge of the covering so water runs off the felt or shingles straight into it, and give it a fall so it drains rather than holding water. A water butt on the downpipe stores rainwater for the garden. With the gutter fitted, the shed roof is complete: framed to the pitch, decked, covered, and drained.
Single pitch shed method
Because a single-pitch shed roof is so common, it is worth summarising its method. Build the shed with one wall higher than the other by the rise you want, fix a wall plate along each, then cut rafters that span from the high plate to the low plate with a birdsmouth on each. Fix the rafters evenly, add an overhang and fascia at the low (and high) eaves, deck the rafters, cover with felt, EPDM, or shingles, and fit a gutter at the low side.
This single-pitch or lean-to method is the simplest way to give a shed a pitched, draining roof, needing no ridge and only one set of matching rafters. The pitch is set by the height difference between the walls, so decide that first from the pitch you want and the shed width. The single-pitch roof guide and the lean-to pitch guide cover this form fully, including how to pick the pitch and frame it. For a small shed, the single pitch is often the best and easiest choice.
Mistakes to avoid
The common mistakes when building a pitched shed roof are these.
Too shallow for the covering. Shingles need about 3/12 to 4/12. Match the pitch to the covering, or use felt or EPDM on a low slope.
Rafters not identical. Cut one pattern rafter and mark the rest from it, so the roof plane is true.
Wall plates not level. The whole roof builds off the plates. Bed and fix them level and straight.
Over-cut birdsmouth. Keep the notch to a third of the rafter depth so you do not weaken it.
No overhang. Without an overhang and gutter, water runs down the walls. Project the rafters and fit a gutter.
Avoiding these means choosing a pitch that suits the covering, cutting matching rafters off a pattern, working off level wall plates, and finishing with an overhang and gutter. Do that and the shed roof will be strong, true, and watertight.
Step by step
The build in order: first, choose single pitch or gable and pick the pitch. Second, work out the rise and rafter lengths from the span and pitch in the calculator. Third, fix level wall plates along the walls. Fourth, cut a pattern rafter with its plumb cut and birdsmouth, check it, and mark the rest from it. Fifth, fix the rafters evenly to the plates (and ridge on a gable), with collar ties on a gable.
Sixth, extend the rafters for an overhang and fix the fascia. Seventh, deck the rafters with plywood or OSB. Eighth, cover with felt, EPDM, or shingles from the eaves up. Ninth, fit the gutter and downpipe. Throughout, the pitch chosen at the start drives the rise, rafter lengths, and cuts, so getting it right and using the calculator for the numbers makes every later step line up. Follow this sequence and a confident DIYer can build a sound pitched shed roof.
Enter the shed span and your chosen pitch in the Roof Pitch Calculator for the rise, rafter length, and angles, and use the construction calculators to work out the decking and covering.
Working out the pitch
Every measurement in a shed roof flows from the pitch, and the roof pitch calculator turns your chosen pitch and the shed span into the rise, the rafter length, and the cutting angles. Enter the run (the full width for a single pitch, half for a gable) and the pitch, and it returns the rise at the ridge, the sloping rafter length, and the angle to set your saw or speed square. That gives you everything to order timber and mark the cuts accurately.
The connected guides help with each part: best roof pitch for a shed to choose the slope, rise, run and rafter length for the rafter maths, using a speed square to mark the cuts, and roof area with pitch to size the decking and covering. The roof pitch tool sits with the other estimators in the construction calculators category, near site tools like the dirt calculator, and the full roofing library is in the roof pitch blog off the homepage. Set the pitch, and the shed roof follows.
How to build a pitched roof for a shed: frequently asked questions
How do you build a pitched roof for a shed?
Choose whether it is a single slope or a gable, pick a pitch (about 3/12 to 6/12 for a single pitch, 4/12 to 8/12 for a gable), and work out the rise and rafter lengths from the span and pitch. Fix level wall plates along the walls, cut a pattern rafter with a plumb cut at the top and a birdsmouth where it sits on the plate, then mark all the rafters from it and fix them evenly. Add an overhang and fascia, deck the rafters with plywood or OSB, cover with felt, EPDM, or shingles from the eaves up, and fit a gutter. The pitch drives every measurement, so work it out first.
What pitch should a shed roof be?
A common, practical range is about 3/12 to 6/12 for a single-pitch shed roof and 4/12 to 8/12 for a gable, balancing drainage against material use and headroom. Steeper sheds water and snow better and suit shingles or tiles; shallower is cheaper and lower but needs a low-slope covering such as roll roofing or EPDM. The covering matters: shingles generally need at least about 3/12 to 4/12, so do not go shallower if you want shingles. In snowy areas, lean toward the steeper end so snow slides off. Pick a pitch that drains well and suits your chosen covering.
How do you build a single-pitch shed roof?
Build the shed with one wall higher than the other by the rise you want, then fix a level wall plate along each wall. Cut rafters that span from the high plate to the low plate, each with a birdsmouth where it sits on a plate, using one pattern rafter to mark the rest so they match. Fix the rafters evenly, add an overhang and fascia, deck the rafters with plywood or OSB, cover with felt, EPDM, or shingles from the eaves up, and fit a gutter at the low side. The single pitch needs no ridge and only one set of matching rafters, so it is the simplest shed roof to build.
How do you cut shed roof rafters?
Each rafter needs a plumb cut at the top (where it meets the ridge on a gable or the top wall plate on a single pitch) and a birdsmouth notch where it sits on the wall plate, with a level seat and a plumb heel. The angles come from the pitch: a speed square set to the pitch marks the plumb and level lines directly. Cut one rafter first, offer it up to check it fits and gives the right slope, then use it as a pattern to mark all the others so they are identical. Keep the birdsmouth to no more than a third of the rafter depth so you do not weaken it.
What size rafters do I need for a shed roof?
Shed rafters are usually 2×4 or 2×6 timber, spaced about 16 to 24 inches apart, with the size depending on the span and the load. A wider shed or a snowy area needs deeper rafters, and a heavier covering means closer spacing. Buy the rafters a little longer than the calculated rafter length to allow for the overhang and the cuts, and use treated timber for durability. Size the rafters to the span and expected load rather than guessing, going deeper and closer for bigger spans and heavier roofs. The roof pitch calculator gives the rafter length from the span and pitch.
Can you shingle a shed roof?
Yes, if the pitch is steep enough, usually about 3/12 to 4/12 or more. Lay an underlay over the deck, then nail asphalt shingles from the eaves up, each course overlapping the one below so water sheds down the roof, and finish the ridge on a gable with ridge shingles. Shingles give a shed a smarter, longer-lasting finish than felt and suit a gable shed well. Below the minimum shingle pitch, water can drive under them, so keep the pitch adequate if you want shingles; for a shallower shed, use roll roofing or EPDM instead, which suit low slopes.
What is the best covering for a shed roof?
Roofing felt is the classic, cheap, quick option and suits many pitches, but its life is limited. For a longer-lasting roof, EPDM rubber gives a single-sheet covering with few joints and a long life, and it suits low pitches well, making it popular for modern sheds. Shingles suit a steeper shed (about 3/12 to 4/12 or more) and give a tiled look that outlasts felt. Roll roofing is another low-slope option. So choose felt for cheapness, EPDM for a long-lasting low-slope roof, or shingles for a steeper shed you want to look smart and last for years. Match the covering to the pitch.
Do you need a gutter on a shed roof?
It is well worth fitting one. A gutter along the lower eaves collects the runoff and carries it to a downpipe or a water butt, protecting the shed walls and base from the water that would otherwise run down them. Mount it on the fascia with a slight fall toward the outlet, set just below the edge of the covering so water runs straight in. A water butt on the downpipe stores rainwater for the garden, which is handy for a shed. Without a gutter, water sheds off the eaves down the walls, so a gutter is a simple, valuable finish to a shed roof.
Roofing safety and accuracy note: Roof work carries a real risk of falls. Only get on a roof when it is dry, the pitch is safe to walk on, and you use proper footwear and fall protection; when in doubt, hire a licensed roofer. The figures here are for general estimating and education and do not replace a structural engineer, a qualified roofer, or your local building code.
Model building codes set minimum roof slopes by material and require confirmation for your jurisdiction. International Code Council →
Roofing manufacturers publish the minimum pitch and installation rules their products are warranted for. Asphalt Roofing Manufacturers Association →