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Can you build a lean to shed against house siding? Yes, but check five things first: what the wall is made of, where its framing is, what sits on it (windows, vents, meters), where the house roof drips, and whether the shed will move with frost. Then attach it with a ledger, or build freestanding 2 ft away.

All 12 3DSHEDPLANS lean-to shed plans are freestanding four-wall sheds. They do not cover the attached version.

Attached or freestanding: two ways to build a lean-to by a house

Attached. The shed has three walls. A ledger fastened to the house carries the high end of the rafters, and the house wall closes the back. You save one wall of framing and siding, but you cut into the house’s weather barrier and tie the shed to the house structure.

Freestanding. The shed has four walls on its own floor frame and stands 2 ft or more from the house. Nothing is fastened to the house, so there is no ledger and no flashing into the siding. It costs one more wall of lumber and siding.

Question Attached with a ledger Freestanding near the house
Walls you frame 3 4
Opens the house siding Yes, along the ledger No
Flashing into the house wall Yes, above the ledger No
Frost or settling movement Can pull on the ledger Shed moves on its own
Can be moved later No Often, if built on skids

Some towns treat an attached shed as an addition to the house, and many set a minimum distance between a shed and a house, including for fire separation. Check your local permit office before you design either one.

Lean to shed against house: what to check on the wall first

  1. Wall material. Wood lap, fiber cement, vinyl and panel siding over wood framing can take a ledger once the siding is cut back. Brick veneer and stone veneer are not structural, so a ledger cannot hang on them, and stucco is hard to open and patch. On veneer or stucco, freestanding is the practical choice. Solid masonry needs anchors sized by a pro.
  2. Framing behind the siding. A roof ledger sits high, often 8 to 10 ft up. On a one-story house that usually means wall studs or the double top plate; on a two-story house it may land on the second-floor rim joist. Find studs with a stud finder and confirm with small test holes, because each fastener has to hit the center of a 1 1/2 inch stud edge.
  3. Windows, doors and vents. The shed covers the wall from the ground to the ledger. Measure your lowest window sill, dryer vent, bath fan outlet and crawlspace vents. Never let a dryer, furnace or water heater vent exhaust into an attached shed; have a pro reroute it.
  4. Meters, gas and hose bibs. Electric and gas meters need open access, and utilities set their own clearances, so call your gas and electric utility before you build near them. Keep an AC condenser’s airflow clearance from its manual.
  5. Buried lines. Gas, electric and water lines often run right along the house wall. Call 811 a few days before you dig footings or post holes so buried lines get marked.
  6. The house eave. Measure the soffit height and how far the eave sticks out. If the house roof drips or sheds snow onto the spot where your shed roof will be, that water lands on a low-slope roof every storm.

How high the ledger has to sit

A lean-to roof drops a set amount for every foot it runs. The table gives the rise across the full depth of the shed at common slopes. Add it to the height of the low wall to find roughly where the high end of the rafters meets the house.

Shed depth Rise at 2:12 Rise at 3:12 Rise at 4:12
4 ft 8 in 12 in 16 in
6 ft 12 in 18 in 24 in
8 ft 16 in 24 in 32 in
10 ft 20 in 30 in 40 in
12 ft 24 in 36 in 48 in

These are simple rise-over-run numbers (depth in feet times the slope). Real framing adds rafter depth, sheathing and roofing on top, plus a 6 to 12 inch overhang at the low edge. Example: an 8 ft deep shed at 3:12 with a 7 ft low wall puts the bottom of the rafters about 9 ft up the house wall. On a one-story house with 8 ft walls the top plate is near 8 ft, so that won’t fit; a 6 ft deep shed with a 6 ft 6 in low wall lands at about 8 ft.

That height must leave room for flashing and roofing below the soffit and stay under any second-story window. If it doesn’t fit, make the shed shallower or the low wall shorter. Don’t flatten the roof to make it fit: asphalt shingles are made for slopes of 2:12 and steeper, and the Asphalt Roofing Manufacturers Association calls for extra underlayment between 2:12 and 4:12. Below 2:12 you need a low-slope roofing product or metal panels rated for that slope.

The ledger: how an attached lean-to hangs on the house

  1. Cut the siding back. Snap a level line and remove the siding where the ledger goes, so the ledger bears on the wall sheathing. A ledger over vinyl or lap siding crushes it and traps water.
  2. Membrane first. Building Science Corporation’s deck ledger information sheet for the US Department of Energy is written for decks, but the water logic is the same: the ledger fasteners pierce the wall’s water barrier. It shows a waterproof membrane between the ledger and the sheathing. Lap it like shingles: the membrane’s top edge tucks under the house wrap above.
  3. Fasten into framing. Use a pressure-treated 2×6 or 2×8 ledger, at least as deep as the rafters. Fasten it into stud centers or the top plate with 1/2 inch lag screws, through-bolts or structural screws rated for ledgers, staggered. Nails alone are not enough. Since our plans don’t cover an attached ledger, get the size and fastener spacing from your local permit office or a pro, because they depend on the roof span and snow load.
  4. Hang the rafters. Sloped joist hangers on the ledger carry the high ends of the rafters. Use hangers and fasteners rated for treated lumber (hot-dip galvanized or stainless). At the low wall, cut a birdsmouth (a common rule of thumb is no deeper than 1/3 of the rafter) and add a hurricane tie at each rafter.
  5. Flash the top. A continuous metal head flashing goes where the roof meets the wall. Its upper leg tucks under the house wrap and siding, and its lower leg laps over the top shingle course. Leave the siding 1 to 2 inches above the roof surface so it doesn’t wick water. Follow your shingle brand’s instructions for this detail.

If a side of the shed roof runs along a wall, as in the inside corner of an L-shaped house, the Building America Solution Center guide to roof-wall flashing shows step flashing plus a kick-out flashing at the low end.

Caulk is not flashing: sealant fails as the wood moves, and water then runs behind the siding unseen.

Water, snow and frost: the problems that show up later

Roof runoff. A lean-to sends all of its water off one low edge, away from the house. Hang a gutter there and point the downspout away from both foundations. Grade the soil so it slopes away from the house.

Splash and ground contact. Keep siding and framing several inches off the soil and out of the splash zone. The USDA Forest Products Laboratory Wood Handbook explains that wood which stays wet is what decay fungi need. Wood near the ground should be pressure-treated, and wet leaves piled against a wall keep it wet.

Snow from the house roof. A lower roof next to a taller one collects drifting snow, and snow sliding off a steep house roof can hit the shed roof in one heavy load. Snow guards on the house roof hold snow there so it doesn’t slide onto the shed in one load. Snow loads vary by region, so check your local permit office for the load to design for.

Frost movement. Many sheds sit on skids over gravel or on blocks, which can rise and settle a little with frost while the house foundation does not. A shed fastened rigidly to the house fights that movement, and over a few winters the ledger or flashing can pull loose. An attached lean-to usually needs footings below frost depth, which varies by region, so check your local permit office. Our guide to shed foundation options compares skids, gravel pads, piers and slabs.

Inside an attached shed. Leave the house siding in place, add a vent at each end of the shed, and keep gas cans in a freestanding shed, not against the house.

Termites. In termite areas, a shed tight to the house can hide the foundation from inspection, so ask your pest control company first.

Common mistakes

  • Fastening the ledger to brick veneer, stucco or siding instead of framing.
  • Skipping the membrane behind the ledger and relying on caulk.
  • Flattening the roof to fit under a window, then shingling it like a steep roof.
  • Letting the house roof drip onto the shed roof with no gutter above.
  • Building a freestanding shed 3 inches from the wall, where leaves pack in and nobody can paint.
  • Burying the bottom of the house siding with gravel or soil to level the shed pad.

Using a freestanding lean-to plan next to a house

The lower-risk way to put a lean-to by your house is to build a freestanding one with a gap. Set the tall wall toward the house, so the roof drains away from it, and keep 2 ft or more between the walls so you can paint and clear leaves. Our lean-to plans stand 112 to 114 inches (about 9 ft 4 in to 9 ft 6 in) at the tall side.

Measure from the shed’s tall roof edge, overhang included, to the house drip edge: if the soffit is under 9 ft 6 in, keep that roof edge clear of the eave or pick another wall. If that eave has no gutter, add one or lay a gravel drip strip in the gap sloped away from the house.

Because a freestanding shed is not tied to the house, the frost, flashing and siding problems mostly go away. You still need the shed gutter and soil graded away from both buildings.

Plans that fit

Each of these 3DSHEDPLANS lean-to plans is a complete four-wall shed with its own floor frame, framing drawings and material list.

For the full build sequence, read how to build a lean-to shed, and weigh the trade-offs in lean-to shed pros and cons. To compare every roof style, see all shed plans.

What we checked: heights and door sizes come from our lean-to plan spec sheets; slope rules from the Asphalt Roofing Manufacturers Association; ledger and flashing details from the Building Science Corporation sheet for the US Department of Energy and the Building America Solution Center.

Frequently asked questions

Can I build a lean-to shed against my house?

Yes, two ways. You can attach it with a ledger fastened into the house framing and flashed into the wall, or build a freestanding four-wall shed with a gap of 2 ft or more. The freestanding version never opens the siding. Rules for structures tied to a house vary, so check your local permit office first.

How do you attach a lean-to roof to a house wall?

Cut the siding back, put a waterproof membrane on the sheathing tucked under the house wrap above, and fasten a pressure-treated ledger into stud centers or the top plate with rated lag screws, bolts or structural screws. Hang the rafters in sloped hangers, then flash the top edge under the siding and over the shingles.

How much gap should a freestanding shed have from a house?

Leave enough room to walk, paint and clear leaves between the walls, about 2 ft or more, and wider than the house eave overhang so the shed is not in the drip line. A gap of a few inches traps leaves and moisture. Distances from a house vary by town, so check your local permit office.

What roof pitch does a lean-to against a house need?

Asphalt shingles are made for slopes of 2:12 and steeper, and between 2:12 and 4:12 they need extra underlayment, per the Asphalt Roofing Manufacturers Association. Many builders aim for 3:12 or more so water clears the wall fast. Flatter roofs need a low-slope product or metal panels rated for that slope.

Do I need a gutter on a lean-to shed next to a house?

Usually yes. All the roof water leaves from one low edge, so a gutter with a downspout aimed away from both buildings keeps water off the house foundation. Also make sure the house roof does not drip straight onto the shed roof.

Shed building guides