Harvia WHP-ASSYM Chimney Roof Accessory Kit for Flat Roofs & Barrel Saunas, Stainless or Black

The Harvia WHP-ASSYM symmetric roof accessory kit contains everything needed to take a Harvia steel chimney through a flat roof or barrel-sauna roof plate: rain cap, symmetric rain flange with clamp, smoke pipe, lead-through flange, and lead-through insulation with protector. Choose stainless steel (WHP-ASSYM) or black (WHP-ASSYMM) to match your chimney.

Features

• Complete lead-through and weatherproofing kit for flat roofs and barrel saunas
• Symmetric rubber rain flange for horizontal roof surfaces
• Stainless steel or black steel components
• Pairs with Harvia WHP chimney modules (4.6 in smoke path)
• Limited 2-year warranty (consumer use); limited 1-year warranty (commercial use)

What’s Included

• Rain cap
• Symmetric rain flange
• Rain flange clamp
• Smoke pipe
• Lead-through flange
• Lead-through insulation and protector

Specifications

Compatibility

Combine with a Harvia WHP insulated chimney module, or buy the chimney and this kit together as the WHP1000500 package, also listed at Sauna Marketplace. For pitched roofs use the tilted kit (WHP-AS).

Planning note: Harvia’s WHP steel chimney system installs vertically only and is designed for wood-burning sauna stoves in standalone outdoor sauna buildings. Keep at least 4″ (4 in) of clearance between the insulated outer casing and any combustible material, and confirm your installation with your local building authority before you build.

Good to Know

Is this the right kit for a barrel sauna?

Yes, barrel saunas are vented through a flat roof plate, which is exactly what the symmetric rain flange is designed to seal.

What is the difference between WHP-ASSYM and WHP-ASSYMM?

Finish only: WHP-ASSYM is stainless steel, WHP-ASSYMM is black steel. Both contain the same components and fit the same chimneys.

Does the kit include the insulated chimney?

No, it is the roof accessory set. Pair it with a Harvia WHP chimney module, or choose the complete WHP1000500 package that bundles both.

Designing a Harvia Chimney System

Every part on this page belongs to Harvia’s modular WHP steel chimney system: a 4.6 in (4.5″) smoke path inside a 8.7 in (8.6″) insulated casing, assembled with slot-and-lock joints. Here is how a complete system comes together:

1. Start with the chimney. For pitched roofs, the WHP1500 kit (59.1 in chimney plus rain cap, tilted rain flange, smoke pipe, and ceiling lead-through set) is the core of the system. For flat roofs and barrel saunas, the WHP1000500 package bundles the chimney with the symmetric roof kit.
2. Connect the stove. Bridge the stove collar to the insulated chimney with 4.6 in WZ smoke pipes (7.9 in, 19.7 in, or 3.3 ft). Add the WZ115030SP damper plate at the stove to control draft while firing, a WZ115120 reducer where pipe sections step down, or the WZ115155 adapter if you are transitioning to 6″ US Class A pipe.
3. Reach your height. Add WHP500 (19.7 in) or WHP1000 (39.4 in) extensions. Stay within Harvia’s limits: 16.4 ft total chimney height, no more than 6.5 ft above the last support, lateral supports every 9.8 ft.
4. Go through the roof. Choose the roof kit that matches your roofline: WHP-AS for tilted/pitched roofs, WHP-ASSYM for flat roofs and barrels. Replacement rain collars: WHM22 (tilted) and WHM24 (symmetric). Add a snow barrier above the chimney where sliding snow can load the flashing.
5. Seal and control. The WHM25 vapor barrier restores the vapor-tight layer where the chimney passes the sauna ceiling; the WHP270 insulated damper closes the flue after the fire is fully out so the sauna holds its heat.
6. Finish the stove side. Stone-filled covers (WL300 for Legend stoves, WL300PC for Cilindro) absorb radiant heat from the smoke pipe and significantly reduce its required safety distances.

Key clearances and rules: vertical installation only; 4 in (4″) from the insulated casing to combustibles; 19.7 in (stainless) or 14.8 in (black) from non-insulated smoke pipe unless shielded; designed for wood-burning stoves in standalone outdoor sauna buildings. Confirm your plan with your local building authority, and if you would like help speccing the system, talk to us; we design these daily.

Shop the Complete Harvia Chimney System

1. Start with the chimney

• WHP1500 Chimney Kit, 59.1 in (stainless or black), the system core
• WHP1000500 Complete Chimney Package for flat roofs & barrel saunas

2. Connect the stove

• WZ Smoke Pipes, 4.6 in (7.9 in / 19.7 in / 3.3 ft, stainless or black)
• WZ115030SP Stove-Side Damper Plate (draft control while firing)
• WZ115120 Reducing Pipe (joins mismatched pipe sections)
• WZ115155 Adapter, 4.5″ Euro to 6″ USA (hybrid Class A transitions)

3. Reach your height

• WHP500 Chimney Extension, 19.7 in
• WHP1000 Chimney Extension, 39.4 in

4. Go through the roof

• WHP-AS Roof Accessory Kit for tilted / pitched roofs
• WHP-ASSYM Roof Accessory Kit for flat roofs & barrel saunas (this page)
• WHM22 Replacement Rain Collar, tilted roofs
• WHM24 Replacement Rain Collar, flat roofs & barrels

5. Seal and control

• WHM25 Chimney Vapor Barrier (seals the ceiling penetration)
• WHP270 Insulated Smoke Damper (retains heat after firing)

6. Finish the stove side

• WL300 Smoke Pipe Cover for Legend stoves (cuts clearances)
• WL300PC Chimney Cover for Cilindro stoves (cuts clearances)