DuraVent Ceiling Support Box Features
- One for Every Ceiling Type: Flat for a standard ceiling, cathedral for a vaulted or pitched one, and an 11 inch box that ships with its trim collar. The box carries the weight of the chimney above and gives your stovepipe a finished transition below.
- Triple-Wall Insulated Construction: Two separate insulating layers, a ceramic blanket plus a ventilated air space, keep the outer wall cool while holding flue gases hot inside. A hotter flue means stronger draft, less creosote and a stove burning closer to its rated efficiency.
- Rated to 2100°F for Chimney Fires: UL Listed to UL 103 HT under file MH7399. Built for continuous operation at 1000°F, then tested a full hour at 1400°F and through three separate ten-minute chimney fire tests at 2100°F.
- Only 2" Clearance to Combustibles: Passes through framing, ceiling and roof with just two inches of air space, so it fits standard 16" on-center construction without reframing the opening.
- Twist-Lock Connection: Sections join with a precision twist-lock, no locking bands or fasteners. The ceramic blanket is held in position rather than loose-filled, eliminating the hot spots and settling common to poured insulation.
DuraPlus Support Box Specifications
| Available Types | Flat, cathedral / pitched, 11" box with trim |
| Part Numbers | 6DP-FCS, 6DP-CS24, 6DP-CS11 |
| Diameter | 6" |
| Finish | Painted black |
| Construction | Triple-wall, all-fuel |
| Inner Liner | .016" 430 stainless steel |
| Intermediate Liner | .018" aluminized steel |
| Outer Wall | .018" galvanized steel |
| Insulation | Ceramic blanket plus ventilated air space |
| Connection Type | Twist-lock |
| Clearance to Combustibles | 2" |
| Listing | UL 103 HT (MH7399), ULC S629 |
| Continuous Flue Temperature | 1000°F |
| Chimney Fire Rating | 2100°F |
| Approved Fuels | Wood, oil, coal, gas |
DuraVent DuraPlus Installation Manual
Download the full manufacturer installation instructions before you begin. Installation must follow these instructions and your appliance manual to stay code compliant and keep the warranty valid.
DuraPlus Ceiling Support FAQ
Flat or cathedral, how do I choose?
If the ceiling is level where the chimney passes through, use flat. If it is vaulted or sloped, use cathedral. The cathedral box is built to sit at an angle and still hold the chimney plumb.
What is the 11 inch box for?
It is a taller square support box that ships with its trim collar, useful where the ceiling assembly is deeper or you want the finished collar included rather than sourced separately.
Does the support box hold the whole chimney?
It carries the chimney above it, which is why it is required rather than optional. Above roughly 5 feet of exposed chimney above the roof you will also need a roof bracket.
Will this work with my wood stove?
If your stove has a 6" flue outlet, yes. Wood stove manufacturers call for a chimney listed to UL 103 HT (2100°F), which is exactly what DuraPlus carries. Drolet, for example, specifies a 6" HT type chimney in its manuals without naming a brand.
Can I connect this to another brand of chimney?
No. Class A chimney systems use proprietary locking joints and are listed as complete systems, so DuraPlus will not join to DuraTech, Selkirk or Ventis. Everything from the ceiling support box to the cap must be DuraPlus.
What is the difference between this and black stovepipe?
They are not interchangeable. Black stovepipe is connector pipe for the exposed run from stove to ceiling only and cannot pass through a ceiling, wall or roof. DuraPlus is Class A insulated chimney, which carries the flue through the building and outside.
How close can this be to framing and insulation?
Two inches of clearance to any combustible, the entire length of the run. Where it passes through an attic you also need an attic insulation shield. Never pack insulation against the chimney even though the outer wall runs cool.