Clay flue liner: standard, modular and round flue tile

Clay flue liner: what we stock

Clay flue liner sizes and pallet counts

We stock Logan Clay flue lining and sell it by the full pallet. The chart gives Logan's outside size, pieces per pallet and weights for each size on our list, so you can plan the chimney and the truck. Every flue below comes in two-foot lengths.

Figures from Logan Clay's flue liner chart. Logan doesn't list a 15" round, so ask inside sales for its pallet count. Fired clay varies, so sizes are approximate.

Sold by the pallet

Flue lining ships from Monroe by the full pallet, not by the piece. Pallets of the larger sizes run past 3,000 lb, and your forklift unloads them at your yard or job. Ask inside sales about putting more than one size on an order.

What is the difference between standard and modular flue?

Rectangular flue comes in two families. Standard (nonmodular) sizes run on 8.5", 13" and 18" dimensions: 8.5" x 8.5", 8.5" x 13", 13" x 18" and so on. Modular sizes are nominal 8", 12", 16", 20" and 24" dimensions, built to fit modular brick coursing, so a 12" x 16" modular measures about 11 1/2" x 15 1/2" outside. On our list, modular means the 8" x 8" and 12" x 12"; every larger size is in our standard group. Check which family the plans call for before you order.

Chimney thimbles

A clay thimble is the round sleeve that runs through the chimney wall so a stove or appliance connector can join the flue. It fits into a hole cut in the square or rectangular flue and should sit flush with the flue's inside wall, not project into it. Thimble diameter is matched to the connector: in Sandkuhl's chart a 6" thimble pairs with 8" x 8" and 8.5" x 8.5" flue, and an 8" thimble with 8" x 12", 8.5" x 13" and 13" x 13".

Setting flue and what to order with it

• Heat Stop lists ASTM C-315 and ASTM C-1283 as the specs building codes call for on clay flue lining.
• Set flue joints in refractory mortar meeting ASTM C-199; Heat Stop 50 is rated for flue lining inside or outside.
• Finish the stack with a chimney cap: stainless 8"x8" to 13"x17", stainless painted 9"x9" to 18"x18", or galvanized painted 8"x8" to 18"x18".
• Vestal cast iron cleanout doors and Lyemance dampers are stocked for the same chimneys.

Questions about clay flue liner

Where can I buy clay flue liners?

Mason and masonry supply yards carry clay flue lining. Yankocy supplies those yards with Logan Clay flue by the full pallet from Monroe, CT: standard, modular and round flue plus thimbles, delivered on its own trucks across Connecticut and nearby states. Call (203) 261-4955 or email info@yankocy.com.

How many flue liners are on a pallet?

It depends on the size. Logan Clay packs 84 pieces of 8" x 8" or 8.5" x 8.5" flue per pallet, 40 of 13" x 13", 36 of 8.5" x 18", 18 of 18" x 18" and 12 of 24" x 24". Round flue runs from 84 per pallet at 6" to 16 at 12". Yankocy sells flue by the full pallet.

What sizes does clay flue tile come in?

Rectangular flue comes in standard sizes such as 8.5" x 8.5", 8.5" x 13" and 13" x 18", and modular sizes on even 8", 12", 16", 20" and 24" dimensions. Yankocy stocks Logan Clay standard sizes from 8.5" x 8.5" to 24" x 24", modular 8" x 8" and 12" x 12", and round 6", 8", 10", 12" and 15".

How long is a section of clay flue liner?

Logan Clay's square, rectangular and round flue come in two-foot lengths. Logan also makes round flue rings 6" to 18" long for special conditions. Each section is set on the one below in refractory mortar.

What mortar is used for clay flue liner?

A refractory mortar meeting ASTM C-199. Heat Stop recommends Heat Stop 50 or Heat Stop II for clay flue lining, because they are not water soluble in service after the initial set. The premixed Heat Stop is interior-only and not suited to flue. Yankocy stocks Heat Stop 50 in 50 lb bags.

Last updated November 2, 2026

Yankocy sells clay flue lining wholesale to mason yards and dealers, on the same truck as Heat Stop, thimbles and chimney caps. Buying for your own home? Your local lumber or mason yard can order it for you.

Clay flue liner data sheets and sources

• Logan Clay flue liners: sizes, flues per pallet and weights
• Sandkuhl Clay Works wall thimble size chart
• Heat Stop FAQs: ASTM specs for flue lining and mortar

Related to clay flue liner

• Heat Stop refractory mortar
• Firebrick
• Steel lintels
• Lally columns
• All fireplace & chimney