The pitch of the sheathing under the corrugated sheet on the wall: how to calculate and avoid mistakes

Covering walls with corrugated sheeting is a popular solution for garages, hangars, change houses and even residential buildings. But in order for the material to last for decades without corrosion or deformation, you need the right frame for sheathing. Mistakes at this stage lead to wavy walls, squeaks in the wind and rust in the fastening areas. The main question that arises among masters: what lathing pitch for corrugated sheeting on the wall to choose for a specific case?

The answer depends on three key factors: grades of corrugated sheets, climatic loads and type of insulation. For example, for wall corrugated sheets C8 or C10 the step can reach 1 meter, and for heavy brands NS35 or H60 - no more than 60 cm. Moreover, in regions with strong winds (for example, Primorsky Krai), even light sheets require a reinforced frame with a pitch of 40–50 cm.

In this article - step-by-step calculation of the sheathing, tables with recommended values for different brands of corrugated sheets, as well as analysis of typical errorsthat beginners admit. We will not talk about “standard solutions” - instead, we will show how to adapt a step to your project, taking into account SNiP and the practice of professionals.

1. Why do you need lathing for corrugated sheeting on the wall?

The sheathing is a load-bearing frame that evenly distributes the load from the profiled sheets onto the wall of the building. Without it, even the strongest metal will deform over time under the influence of:

• 🌬️ Wind loads - especially relevant for tall buildings (hangars, workshops) or buildings in open areas.
• ❄️ Snow pressure - if corrugated sheeting is used on gables or upper parts of walls.
• 🔥 Temperature expansions — the metal “plays” with changes from –30°C to +50°C, and the sheathing compensates for these movements.
• 💧 Condensate - the correct step provides a ventilation gap, preventing corrosion from the inside of the sheet.

In addition, the sheathing performs leveling function. Even if the wall is curved (brickwork with differences or a log house), the frame allows you to mount the corrugated sheets evenly. And for insulated walls (with mineral wool or expanded polystyrene), the lathing serves as the basis for attaching the vapor barrier and the insulation itself.

⚠️ Attention: If you ignore the sheathing and attach the corrugated sheet directly to the wall (for example, with self-tapping screws to the brick), after 2–3 years waves will appear on the sheets, and corrosion will begin in the fastening areas due to lack of ventilation.

2. What does the lathing pitch depend on: 5 key factors

There is no universal step value that would suit all cases. The calculation is carried out individually taking into account:

1. Brands of corrugated sheets - the higher the wave (for example, H60 vs C8), the greater the rigidity of the sheet and the less often you can install the sheathing.
2. Metal thickness - standard sheets of 0.4–0.5 mm require a pitch of 40–60 cm, and thin (0.35 mm) – no more than 40 cm.
3. Installation directions - at vertical installation the sheathing pitch can be increased if horizontal - just reduce it.
4. Climate zone — in windy regions (for example, the Kaliningrad region) the step is reduced by 20–30%.
5. Availability of insulation - if the wall is insulated, the lathing is made in two layers: the main frame for insulation + counter-lattice for ventilation.

🔹 Example: For corrugated sheets S20 0.45 mm thick in the Moscow region for vertical installation without insulation, the optimal pitch is 50 cm. If the same sheet is laid horizontally, the pitch is reduced to 40 cm.

⚠️ Attention: Manufacturers of corrugated sheets (for example, Grand Line or Metal Profile) in technical data sheets indicate maximum permissible sheathing pitch for your products. Do not exceed these values ​​- this will void the warranty!

3. Table: Sheathing pitch for popular brands of corrugated sheets

Below is a table with recommended pitch values for wall corrugated sheets for vertical installation (the most common option). The data is relevant for regions with a temperate climate (wind load up to 30 kg/m²).

Brand of corrugated sheet	Metal thickness (mm)	Lathing pitch (cm)	Notes
C8	0.35–0.45	30–40	Only for walls without insulation. In windy regions - no more than 30 cm.
C10	0.4–0.5	40–50	Suitable for outbuildings. For horizontal installation - 30 cm.
S20 / S21	0.45–0.7	50–60	A universal option for residential and commercial buildings.
NS35	0.5–0.8	60–80	For high walls (from 4 m) or buildings in coastal areas.
H60 / H75	0.7–0.9	80–100	Used for industrial facilities. Requires reinforced guides.

🔹 How to use the table?

1. Determine the brand of your corrugated sheet (indicated in the certificate or on the sheet’s protective film).
2. Check the thickness of the metal (measured with a caliper or indicated in the documents).
3. Choose a smaller step value if:
• 🌪️ The building is located in a windy area.
• 🏗️ The wall is higher than 3 meters.
• 🔄 The corrugated sheet is mounted horizontally.

4. Vertical vs horizontal installation: how does the pitch change?

The direction of laying profiled sheets directly affects the requirements for the sheathing:

🔹 Vertical installation (sheets are attached from top to bottom)

• ✅ Benefits: visually lengthens the building, drains water better, and is easier to install.
• 📏 Sheathing step: you can use the maximum values from the table (for example, 60 cm for S20).
• 🔧 Mount: screws are screwed into the lower wave, which increases strength.

🔹 Horizontal installation (sheets are attached from left to right)

• ✅ Benefits: original design, suitable for low buildings (eg fences).
• ⚠️ Limitations: sheathing pitch decreases by 20–30% (for example, for S20 - no more than 40 cm).
• 💧 Risks: If installed incorrectly, water accumulates in the joints, which leads to corrosion.

📌 Important: For horizontal installation, be sure to use longitudinal joining strips and seam sealant. Without them, even the correct pitch of the sheathing will not save you from leaks.

What happens if you exceed the pitch of the sheathing during horizontal installation?

With a step of more than 50 cm for corrugated sheets S20 the sheets will begin to bend under their own weight, especially at the joints. After 1–2 years, waves will appear, and the fastening screws may break out of the sheathing. In windy weather the wall will “buzz” like a drum.

5. Step-by-step calculation of lathing for your project

To avoid making a mistake with a step, follow this algorithm:

1. Measure the height of the wall (for example, 3 meters).
2. Determine the brand of corrugated sheeting and find in the table maximum step (for example, for S20 - 60 cm).
3. Adjust your pitch taking into account:
   • 🌬️ Wind load (reduce by 10–20% for open areas).
   • 📏 Installation directions (horizontal - minus 30%).
   • 🏗️ Wall heights (if > 4 m, the step is reduced by 15%).
4. Calculate the number of guides:
   • Wall length / adjusted pitch + 1 (for example, 300 cm / 50 cm + 1 = 7 guides).

Add reinforced racks in places:

• 🚪 Doors and window openings (on the sides).
• 🔧 Fastening drainage systems or visors.

📝 Calculation example:

Wall 3.5 m high, corrugated sheet NS35 (step according to the table - 80 cm), region - Leningrad region (increased wind load).

1. Basic step: 80 cm.
2. Wind adjustment: 80 cm – 20% = 64 cm.
3. Number of guides: 350 cm / 64 cm ≈ 5.5 → 6 pieces (including top and bottom).

Have the wind loads of your region been taken into account?|Has the evenness of the wall been checked (differences of more than 2 cm require leveling)?|Are additional racks planned for fastening heavy elements (air conditioning, lighting)?|Are galvanized guides used (for wet rooms - with anti-corrosion coating)?

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6. Typical mistakes when installing sheathing

Even experienced craftsmen sometimes make mistakes that negate all the benefits of corrugated sheeting. Here are the most common:

• 🚫 Ignoring the ventilation gap — if the sheathing is close to the insulation, condensation accumulates inside. Solution: use a counter-lattice (20x40 mm slats).
• 🚫 Savings on fasteners — self-tapping screws “pressed” or without gaskets lead to rust. Solution: only galvanized screws with EPDM gasket.
• 🚫 Uneven frame — if the guides are not in the same plane, the corrugated sheet will “lead”. Solution: check each rack with a level.
• 🚫 Lack of antiseptic — wooden sheathing without treatment rots in 3–5 years. Solution: use Senezh Ultra or analogues.
• 🚫 Lathing step "by eye" - even a slight excess leads to waves. Solution: Make markings using a laser level.

⚠️ Attention: If you are installing corrugated sheets on metal frame (for example, for a hangar), check that all welds are cleaned and processed Zincol or similar composition. Otherwise, rust will transfer to the profiled sheets.

🔧 Pro tip: Before installing the corrugated sheeting, stretch the sheathing between the outer posts nylon thread - this will help identify frame deflections and correct them before laying the sheets.

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If you are attaching corrugated sheeting to the wall of a house with insulation, use vapor-permeable membrane (for example, Tyvek). It will protect the insulation from moisture, but will allow the wall to “breathe”.

7. Lathing materials: what to choose

The lathing can be made of different materials. The choice depends on the budget, climate and type of building:

Material	Pros	Cons	Recommendations
Wooden beam (50×50 mm, 60×40 mm)	Cheap, easy to install, low thermal conductivity.	It rots, requires treatment, and may wilt when wet.	For dry rooms (garages, sheds). Process Senezh or Pinotex.
Metal profile (CD-60, UW)	Durable, does not rot, can withstand heavy loads.	More expensive than wood, requires welding or riveting.	For industrial buildings, hangars. Use galvanized profile.
Aluminum profile	Lightweight, does not rust, long service life.	Very expensive, difficult to find in the regions.	For objects with an aggressive environment (for example, chemical shops).

🔹 Which timber to choose for wooden sheathing?

• 🌲 For walls up to 3 m - 50×50 mm (step up to 60 cm).
• 🏢 For walls 3–6 m - 60×40 mm or 75×50 mm (step up to 80 cm).
• 🏭 For industrial buildings - metal profile 0.7–1 mm thick.

⚠️ Attention: If you use a wooden beam for sheathing under corrugated sheets on damp façade (for example, a bathhouse or a sink), choose only coniferous species (pine, larch) and process them hot drying oil before installation.

8. FAQ: Answers to frequently asked questions

🔹 Is it possible to attach corrugated sheeting to a wall without lathing?

No, this is a gross violation of technology. Without sheathing:

• The corrugated sheet will follow all the irregularities of the wall.
• Corrosion will begin at the points where it is attached to the wall due to lack of ventilation.
• Sheets can be deformed from wind loads.

The exception is perfectly smooth concrete walls with pre-welded fasteners (but even in this case, a counter-lattice for ventilation is recommended).

🔹 What lathing step is needed for C20 corrugated sheeting on the garage wall?

For S20 thickness 0.45–0.5 mm for vertical installation:

• Standard step: 50–60 cm.
• If the garage is in a windy place (for example, a steppe zone): 40–50 cm.
• If the wall is higher than 3 m: maximum 50 cm.

For horizontal installation, reduce the step to 30–40 cm.

🔹 Do you need vapor barrier for corrugated sheets on the wall?

Depends on the type of wall:

• 🏠 For insulated walls (mineral wool, polystyrene foam) - required. Use membrane type Izospan B.
• 🏭 For cold walls (garage, shed) - not needed, but a ventilation gap of 20–30 mm is recommended.

🔹 Is it possible to use N60 corrugated sheeting for walls?

Yes, but it's overkill for most cases. H60 - this is roofing corrugated sheeting with high load-bearing capacity. For walls it is used only:

• In industrial buildings with high loads.
• In regions with hurricane winds (for example, the Far East).
• If maximum rigidity is needed (for example, for the walls of a shooting range or training ground).

Sufficient for residential buildings or garages S20 or NS35.

🔹 How to attach the sheathing to a brick wall?

Work order:

1. Mark the wall taking into account the pitch of the sheathing.
2. Drill holes for dowels (depth of at least 50 mm for brick).
3. Secure direct hangers (as for drywall) or anchor plates.
4. Install the batten guides, leveling them.
5. Secure with self-tapping screws or rivets (for metal profiles).

🔧 Advice: For brick walls, use dowels SX or GB with a diameter of 8–10 mm.