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To heat the common room of this country house, the wood was naturally obvious because easy to find in the area. A solution all the more obvious that the owners had a stove "colonial" in perfect condition. It remained to create the evacuation pipe...

Make a masonry duct

Practical advice

The installation of a flue must comply with the requirements of DTU 24-1 dealing with building work.
- Make sure to respect the minimum distance of 16 cm between all combustible materials (framework, paneling, etc.) and the inside wall of the bushels.
- Two elbows are tolerated on the path of a conduit. The maximum deviation angle may not exceed 45° if the height of the duct is less than 5 m and only 20° if it is greater.
- Bushings must be erected using lime-cement-sand bastard mortar and not plaster.
- The stump must exceed the ridge by at least 40 cm.
A drying time of three weeks is recommended before lighting the first fire and this, gradually.

In an existing construction, the installation of a masonry conduit can not be improvised. Especially if you also have to go out on the roof! To obtain a good print, the design of the stump is as important as the choice of the conduit itself and its path. After study, the master of the room decides to mount a duct in bushels of terracotta of 30 x 30 cm (H. 33 cm, section int 20 x 20 cm). Handyman accomplished but aware of its limits, he reserved the interior part of the site. For the strain, more difficult to achieve because of the height and technicality (removal of slates, sealing...), he found it wiser to entrust the work to a craftsman.

A well studied course

The location chosen for the stove is in the middle of a gabled wall, made of rammed earth 60 cm thick. The device (from the 70's) has a high outlet of Ø 200 mm, to be connected to the masonry duct by elements of fumistery (metal pipes and elbow) of the same diameter. There is no point in having the duct leave the foot of the wall; the most rational thing is to start at the height of the ceiling.
However, the presence of a large beam along the wall at this point prohibits the first bushel in the ceiling, unless a large transformation (resize the beam, open a hopper...). It is however easier to circumvent the piece of wood from the back respecting, between it and the inner wall of the conduit, a minimum distance of 16 cm according to the rule in force. This is the chosen solution, which will require digging a "well" in the masonry to connect the common room to the attic. In the first part of the course, the duct will be fully recessed then, at the outlet in the attic, it will tilt slightly to finish its course in apparent. The path will be made substantially in the axis of the wall pinion, so that the output is at the ridge tip.

Well

The digging of the well, 40 x 40 cm section, begins at about fifty centimeters from the ceiling. The nature of the wall allows easy work with the chisel and the pick. By opening into the attic, the trench slopes gently towards the interior of the room so that the pipe out of the wall gradually and leans back to finish its course vertically. The rubble is evacuated as and when in plastic bags provided for this purpose.
The assembly of the conduit can be done only if the seat is stable. A reinforced concrete footing (6 cm thick) is cast at the bottom of the well and surmounted by a solid brick base laid flat. Similarly, before mounting, an opening of Ø 205 mm is made on one side of the first plug to connect the stove pipe and allow the sweeping.

The bushel assembly

The sealing mortar is prepared at the rate of two volumes of sand for one pre-mixed lime-cement mixture ("Multibat" from Lafarge). The water is added and the product kneaded until a creamy paste is obtained. Terracotta being very absorbent, it is recommended to wet the bushels before mounting (by spray for example) to avoid a quick setting of the mortar.
Once the plinth is mortar-coated, the first bushel is placed level with its circular opening towards the room. Each element carries a mark (an arrow) indicating the laying direction: male part at the bottom, female part at the top. It is always the latter that must be lined with mortar as the elevation. Two bushels are enough to leave the base and lead into the attic. The inner seal is smoothed by hand for a good seal: on the outside, it is trowelled.
The third bushel is inclined a little forward, which corresponds to a seal pinched side room and open at the back. At the level of the fifth bushel, the duct is raised to lean against the wall and rise vertically to the right of the strain. The angle of cut determined in situ with a false square and a bubble level, the base of the plug is cut to the grinder equipped with a disc material.
The weight of the bushels is important, especially in the sloping part, cantilevered. To prevent any movement, it is necessary to tie the pipe with flanges made of flat iron of 20 x 3 mm. Two flanges per meter, every three bushels, are enough. When approaching the rampant, it is necessary to delimit the passage to be cut in the plasterboard doubling. A ruler, placed successively on each edge of the last bushel, makes it possible to trace the opening which is then cut with the cutter. The jigsaw is not recommended because its blade could hit the rafters. The latter laid bare, it is still necessary to make the trimmer to mount the stump and finalize the site.

The exit of the roof

The trimmer is a hole in the roof to ensure continuity between the pipe and the stump. Two rafters (the one of bank and the following) are first cut, then a 5 x 5 cm cross is placed in the lower part to strengthen the future opening. It is sealed at one end in the gable wall and bolted to the other on the third chevron. The underside of the frame thus formed is then closed by a wooden panel cut in the format of bushels. This panel is fixed with lag screws Ø 6 x 30 mm, to facilitate the formwork of a concrete sole that will be cast from the outside around the duct. Its role: to strengthen the influence of the strain on the roof.
The craftsman's work consisted in:
- to discover widely the slates at the outlet of the conduit;
- cut the leaves and rafters at the location of the trimmer;
- carry out the strain, in the extension of the conduit, with two bushels terminated by a mitron;
- pour the concrete footing (thickness 5 to 6 cm) into the formwork;
- put zinc bibs around the duct;
- coat the stump and rest the slates, making the necessary cuts.

Finishes

Before connecting the stove pipe, the duct inlet is closed by a 3 cm thick door. Made of concrete, incorporating a metal cuff Ø 200 mm, it is fixed with four Ø 8 mm TF screws in a 40 x 40 mm angle frame sealed in the wall. This removable door facilitates the sweeping and recovery of soot fallen inside the base. Important: the door sleeve and the inlet of the first plug must be on the same plane for the pipe-conduit connection. The visible part of the duct is finally covered with two coats of plaster, with a floated finish. The product is identical to the laying mortar but of a more liquid consistency.

Dig the well

Dig the well

The pickaxe is the most practical tool for digging the "well" in the thick adobe wall.

Make the trench

Make the trench

Beginning about 50 cm from the ceiling of the common room, the trench passes behind the awkward beam and ends with a sloping floor at the outlet in the attic.

Consolidate the bottom of the well

Consolidate the bottom of the well

The bottom of the well is consolidated by a concrete footing of 6 cm, armed with four twisted irons Ø 8 mm. It receives a brick base that forms a small receptacle for soot sweeping.

Open the first bushel

Open the first bushel

The first plug must be open on one side to connect stove pipe. A series of tangent holes is pierced on a circle of Ø 205 mm, then the fall is detached with the flat chisel and the hammer.

Adjust and smooth the socket of the bushel

Adjust and smooth the socket of the bushel

The first bushel sits on a bed of mortar spread over the bricks of the base. Plumbed by directing the circular opening towards the workpiece, its male socket is smoothed recto-verso.

Climb the bushels

Climb the bushels

The following bushels are mounted by depositing a bead of mortar on the periphery of the element already laid. Inside, the joints are smoothed by hand and outdoors, trowelled.

Bridging the wall-ducted space

Bridging the wall-ducted space

Before assembly, the bushels are wet with a garden sprayer. As the elevation increases, the space between the wall and the duct is filled by plaster falls that are tied to the mortar.

Bridle the leads

Bridle the leads

As soon as the duct begins to tilt, it is recommended to restrain it. After identification, the sealing holes are drilled with an impact drill equipped with a large drill bit or drill.

Seal the stirrups

Seal the stirrups

The stirrups are simple flat irons of 20 x 3 mm folded in the vice. They end with two legs "carp tail" to seal mortar. A clamp holds the flange while holding the cement.

Find the vertical of the duct

Find the vertical of the duct

To find the vertical of the pipe, it is necessary to cross the base of the bushel following. The angle is determined using a false square adjusted until a perfect horizontality.

Cut the bushel

Cut the bushel

The angle is transferred to the base of the bushel, tracing it to the felt on three sides using a classic square. The cutting is then carried out with the grinder provided with a diamond disc.

Bridle and put the bushel

Bridle and put the bushel

The resized plug is laid like the others by generously filling the mortar joint. Before proceeding with the installation, it is necessary to restrain it in turn because of the deviation.

Delimit the opening

Delimit the opening

The opening to practice in the plasterboard is delimited by projecting the angles of the bushel with the aid of a batten. Once cut, the dressing will be removed carefully to be rested at the end of the building site.

Coat the bushels

Coat the bushels

The crossing of the roof and the stump to be carried out a little later, the wait is put to profit to coat the bushels apparent in two passes: a layer of hook and the finish talochée.

Fix the panel

Fix the panel

The trimmer and the pierced roof, the last bushels are set up. Before finalizing the strain, an indented panel in the shape of the conduit is fixed on the underside by lag bolts.

Seal

Seal

The strain consists of two bushels, wearing a mitron. At its base, waterproofing is provided by zinc flaps taken in the concrete sole.

Formwork removers and remodeling

Formwork removers and remodeling

Formwork is removed after three to four days of drying. The final touch-up of the plaster can then be done and the plasterboard placed under the creeper.

Adjust the door

Adjust the door

The door consists of a concrete slab with a rimmed metal opening for connecting the stove pipe. It fits on an angle frame assembled by arc welding.

Wedge the frame

Wedge the frame

The frame has on the back four welded nuts of Ø 8 mm to screw the door and two bolt-on lugs on each side. It is set perfectly straight, and in the same plane as the wall.

Check the axis of the opening

Check the axis of the opening

Before sealing, a piece of pipe is introduced into the opening to ensure that it is well in the axis of the first bushel. If this is not the case, it must be disassembled and rectified.

Finishes of the door

Finishes of the door

When the mortar is dry, the door receives a finish identical to that of the wall.


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