Masonry in self-help housing

The realization of the masonry of a simple house represents an important work calling upon particular knowledge and requiring a physical fine shape and a minimum of tools. One can conclude this task all alone for the majority of the operations but an assistance is quite useful in much case: to measure with the decametre, to hoist breeze blocks with the pulley or to install beams. To run a flagstone, it is a whole team which will be necessary.

See: Self-help housing

Foundations

The foundations are an essential component of construction. They constitute a rigid base which supports the mass of the very whole house (of the hundreds of tons) and distributes this load on the ground so that no movement of the building is detectable. They consist of a whole of beams (still called soles ) out of reinforced concrete firmly connected between them. The surface of the foundations is calculated so that the pressure (in MPa = N/mm ²) that is to say lower than the resistance of the ground and this in all circumstances (strong rain, dryness, freezing…). This surface is proportional to the width of the sole and must be given in each place according to the local load to support (wall, flue, staircase, post…) and of the variations of strength of the ground to the pressure. The soles are run in excavations in drains of practically square section dug by the cup of tractopelle. The bottom of the drains must be specific to the moment of cast and the surface of the soles will be levelled in order to facilitate the installation of the walls.

The operation of casting is relatively fast if one calls upon a supplier of Béton any loan. As it is difficult to calculate with just, one will may find it beneficial to envisage a work cased and ready to be cast if there would be a surplus with the foundations. A contrario one can order a little less than estimated volume and supplement with Béton manufactured “ with the main ”. To envisage in this case Sand, gravel, Cement and water as well as a small concrete-mixer. This way of doing can be applied for the casting of the flagstones.

Basement or underfloor space

The difference between underfloor basement and Space is not only one question of hauteur : external access, levelling of the ground, lighting, drainage… are necessary in the case of a basement. This last requires a height between ground and ceiling of at least 2 meters under the lintels. If it is entirely buried one will light it using drips emerging in English course .

It is not rare that a basement is arranged thereafter to be livable. To envisage as of the beginning the flows to install thereafter toilets or a bathroom is not an useless precaution. The openings will be envisaged consequently (drips or window, doors, etc)

A well drained basement should not be wet. However in a heated of a basement and not isolated part can occur condensation which could let accept infiltrations. The ground could be insulated by adding a floor on tie bars if one envisaged a sufficient height from the beginning, but it will be advisable in this case to correctly ventilate the buildings because a floor wood is very sensible to moisture.

Pavement concrete

The realization of a pavement concrete in a basement can be under consideration before assembling the bulk-heading, which makes it possible to work with clean in all the following phases. This operation is made according to the same rules that one is inside or outside :

scouring of surface to reach the sterile and firm ground
so necessary drainage
installation of a Geotextile .
poses sheaths and drains (flow, siphons, glances…)
spreading out of a blocking (hedgehog) of crushed rock (10/50) and stabilization.
poses of a steel fabric if necessary for the places of strong load
installation of rules (tube diameter 40mm) parallel and horizontal by taking account of the finished level and the thickness of the cover of completion. A light slope will facilitate the water run-off towards the possible siphons (generally placed at the center).
casting of a coarse concrete (250kg of cement per cubic meter, sand and gravel 5/15) to obtain a thickness of 10 minimum cm.
installation of a film in polyane (to avoid the increase of moisture).
realization of a cover mortar (sand 0-5, 300kg of ciment/m ³) smoothed or bouchardée or intended to receive a painting, a tiling…

Walls, doors and windows

As the Béton built is out of reach amateur, the walls will be generally assembled in breeze blocks. For the basement or the walls retaining, one will choose a thickness of 25 cm or of the breeze blocks special, known as “ of Formwork ”, which can be filled of Béton furnished with scrap. The stages will be assembled in breeze blocks of 20 cm. Breeze blocks of 15 cm is more delicate to go up and the 5 gained cm are not determining in the choice. The use of bricks (insulating or not) for the walls of the dwelling is possible but more delicate, in particular for the realization of the Enduit S. the gas Concrete is a tempting product by its lightness and its factor of insulation but its cost price is higher. Moreover it is not obvious to carry out a coating frost-resistant to the bad weather and on an exposed wall.

The tools most important are the scaffolding. For a height of stage (lower than 3m) one can manage with piles of breeze blocks and good beams. To finish the pinions it will undoubtedly be necessary to get one of them. Taking into account the weight of the breeze blocks, a serious material is essential.

The walls are of two sortes :

walls external or of circumference, they are bored external doors and windows and generally doubled by an thermo isolation.
cross walls, interiors, they are used as reinforcements to rigidify construction, to carry the beams of the flagstone and partitionner the stage in various volumes. Their thickness is sometimes lower than that of the walls of circumference (15 cm instead of 20 cm for the breeze blocks in Concrete).

The lower part of an opening is materialized by a threshold (for the doors) or by a support (for a window) which can be cast places from there or prefabricated. To take account of the door frames (doors and windows) before running, ordering and to install a threshold or a support. In certain areas the external openings are framed by brick jambs, stones of size…

The upper part of an opening (interior or external) is consisted a lintel resting on the walls and supporting the load of the wall, the flagstone or the frame placed above him. The lintel can be a beam in Béton armed or prefabricated. There exist lintels prefabricated in the shape of formwork (or cases travelling shutter) in which one runs Béton. The upper part of the lintel is sometimes consisted the chaining of the flagstone.

The chaining surmounts the walls and joins together those in a firm way since it is about a whole of beams in Béton armed working primarily with traction. It is often at the same time cast as the flagstone and its reinforcement Marie with the posts of corners, pillars…

At the end of construction, the external walls will be coated, rough-cast or barded (with or without external insulation) for better resisting the rain. It is preferable to await the end of the Carcass work heavy castings to coat the walls because them microscopic cracks which could appear at the time of the stabilization of construction.

The flagstone rests on the walls. So that it is quite horizontal, it is necessary to level the top of the walls by running over all their length a mortar bed of a few centimetres thickness, levelled on the level with water or better, using a sweeping laser of good quality.

Others Material X or techniques of construction are also utilisés :

alveolate brick isolante (still called Monomur, of the name of a registered trademark): the installation out of thin joint allows a time-saver construction, and the insulator addition is not nécessaire ;
gas block of Concrete, even function that the insulating brick
colombage : in certain areas. The vacuums can be filled by gas Concrete, brick enduite ;
pisé : expérimental ; ground walls posed by successive layers, then " tranchée" with dimension ; technique used in Ille-et-Vilaine and in many countries in the process of development in construction traditionnelle ;
framework Wood : for those which prefer the work of wood to conventional masonry.

Floor, beams and hollow block

The realization of a flagstone of compression on a floor beams/hollow block can seem a work of specialist, however there is only the casting which is delicate and at the same time requires to be well prepared (because the ready Béton does not wait) and to have the assistance of a handle of reliable friends.

The study of the floor, i.e. the calculation of the beams, the estimate of the hollow blocks necessary… is carried out by a technician with the service of the supplier of the material starting from a plan with dimensions exact of masonry indicating the places undergoing of the overloads (chimney, large aquarium…), balconies, staircases… The neophyte will may find it beneficial to visit several other building sites, to even give a knack to be prepared or run in someone else. For the preparation of a flagstone, it is strongly advised to be two.

Successive operations for the preparation of a floor beams/hollow block sont :

Checking of the delivery, sorting of the beams according to their length.
Installation of the beams on the flush walls and the lintels. To fold up steel wire to 90 degrees so necessary. The beams rest at their ends on 5 cm approximately.
To distribute the beams by using a hollow block at each end like spacer.
To support in the axis of each span by using rafters partly high and beams on the ground. Not too much not to attach the stays because the prestressed beams have a counter-arrow which they will lose when the stays are removed and will be then about right.
To place the hollow blocks.
To carry out the formwork of banks of flagstone (boards, liteaux, screw clamps of mason…) by taking account of the finished height of the flagstone.
To case the hopper of the staircase and the reservations most important (service shafts).
To reinforce the chaining, the edges of the hopper…
To set up to maintain the reinforcement of the possible balcony and it raised with spacers.
Placer the steel fabric plates some and to attach those with wire.
To check last once the solidity and the level of the formwork.

The thickness of Béton is about 4 with 6 cm but one must raise volume calculated to take account of the shape of the beams (in T) and the hollow blocks. Moreover it the chaining should be run at the same time. One finds in the trade of the very ready elements of reinforcement

The casting itself of the flagstone is a simple but rather delicate operation. So that this one is rainproof (the building site nevertheless will last a few months) it is preferable to run in only once with Béton ready with the employment brought by one or more “ toupies ”. During the ordering of the Béton one will specify that it is about a flagstone. If the operation proceeds at the cold period it is possible to add antifreeze Ideal time corresponds to a temperature of 10 with 20°C, covered but without rain. In sunny weather or very dryness one can fight against the drying of surface while sprinkling gently. Light a scarifying of surface east of no importance. Freezing is more awkward, if the flagstone is not too large one will be able to plan to cover it by a cover.

Although the Concrete “ prenne ” in a few hours, it is preferable not to pose heavy loads on the flagstone before several days. A pallet of breeze blocks represents more than one ton, and even if the shoring is well made the flagstone will bend and fissure. These microscopic cracks are generally not awkward, except if one counts on the flagstone to protect from the rain the material stored in lower part of it. Normally one waits 4 weeks before removing the stays.

Flues

A flue can be used pour :

a chimney of approval (open fire or insert),
a boiler or stove (Wood, coal, fuel…),
a cooker or furnace,
an external barbecue,
a Baker's oven or pizza pie
a generator.

The section of the conduit and the height of a conduit depend on its type of use. The flow necessary to a chimney with open fire is much larger than that necessary for a simple stove. One needs a conduit by type of use and level. To install an useless conduit is much less expensive than to add some after the end of work.

In general the flue is supported against a cross wall or a pinion wall and leads to the roof near the ridge. So that pulling is good, certain rules are with respecter : the stock (left exceeding roof) must dominate the ridge of at least 40 cm and to be rather on the side of nonexposed roof to the wind prevailing, in the trough of low pressure. By isolating the conduit with rockwool until under the roof one decreases the risk of bistrage (condensation on the internal walls of the conduit) and starting is faster because the conduit is heated more quickly.

That the conduit is in Béton or terra cotta, the stock will have to be tight with the infiltrations of rainwater. A preparing in zinc works, boarding, smoothed coating, rough-casts or out of facing bricks made damp-proof after the installation is appropriate in the majority of the cases. The stock is crowned by a plate, a pottery ( miter or baker's boy ) or a brick construction (variable according to the areas) which reduces the effects of the rain. An accelerator of pulling can facilitate the operation of the chimney in the cases of high wind.

The conduit is assembled in several stages and follows the realization of masonry. In the roofs, it is assembled in parallel with the frame. The internal surface of the conduit should not be with less 20 sometimes cm of a beam, beam or flammable Material, this rule (the variation of fire) forces to cant a conduit to make it circumvent a breakdown. If a rafter or a beam is placed such as it should cross the conduit, it is necessary to carry out a bandage.

The design of the conduit must take account of the conditions of brushing:

the trap door of brushing should be in a place which can be dirtied without too much problem, at the base of the conduit. For a very high conduit or clearly canted, an intermediate trap door can be installed.
the access to the stock is done in general by outside, while placing scales punts on the roof. One can envisage hooks at the time of the cover. In Germany, it is frequent to see a true staircase giving access of the chimney sweeper.

The realization of the flue must comply with certain rules which it would be too long to detail here (direction of the bushels, staying of the too high stocks…). If necessary the section of a conduit can be reduced and this one made tight by a casing out of stainless steel. There exist also light and less traditional solutions (but perhaps more expensive) to carry out a flue under particular conditions.

Staircases

To carry out staircases in Béton is not difficult but requires a serious formwork and reinforcement and the compliance with some rules. In certain cases, it is to better install a staircase in Bois (see this section).

To be pleasant and sure in its use, a staircase must be well balanced if it is revolving, with steps whose bosom (the width) is included/understood enters 23 and 28 cm and of which the height of the contremarche lies between 15 and 21 cm. There exists a formula which fixes the ideal (if there exists un about it;?) : the sum of the width of the walk and twice height of the contremarche must be included/understood between 60 and 64 cm. However a bosom lower than 23 cm and a height higher than 21 cm are disadvised. To take account of the thickness of the preparing of the steps and the floor coverings future in the calculation height. The ideal width of a staircase is of 1,2 m but one can go down to a minimum from 0,7 Mr. Penser of the transport of pieces of furniture, stretchers, crossing of people… before deciding working width.

A flight of stairs should not comprise more than one score of steps, beyond it is necessary to envisage one or two stages. Best is to measure dimensions of an existing staircase than one has pleasure to use and to reproduce the principles of them. A winding staircase well balanced is assembled without jolt, it is obtained by a method of tracing calling upon the solid geometry, work a little delicate for a beginner. To check the “ keep with the plafond ” or height of escaped for each walk, it must be of at least 2,05m.

The position of the staircase is imposed by the installation of each level which it serves. The stair-well (volume which it occupies) can be open or closed. In the first case heat, the light, the sounds… will be transmitted of a stage to the other. The intimacy, decoration, the effectiveness of the staircase will not be the same ones.

When surface on the ground is limited one can carry out a spiral staircase using prefabricated steps. It can be preferable to install a metal staircase or in Bois. Another possibility is the scale of miller of which the angle of inclination can reach 60 degrees. These two solutions are makeshifts.

The staircase is one of the dangerous places in a house. It is important to limit the risks of a fall by installing as soon as possible a slope and a railing. The coating of the steps is important : non-skid, absorbing shocks, silencer, easy to clean…

For the inhabited stages one prefers the Bois, heat, of lighter aspect, easier to work… The realization of a staircase in Bois made up of right flights does not pose a particular problem. The steps are carried out in hard Bois like the oak, the silts can be in fir tree. To limit squeakings and the crackings, one can slip into the rabbets and grooves of assembly a polyethylene sheet which will function like a lubricant.

The access to the nonlivable roofs can be assured by a retractable staircase, left collapsible scale. It is a solution which is not advised for a regular use, it is better to envisage as of the beginning the site of a fixed staircase, possibly out of snail.

See: Staircase, Self-help housing

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