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With this extension, Romanine and Nicolas have doubled the surface of their house. A project implemented in family, with, ultimately, a large living room, a bathroom and a garage.

Wood frame extension

Extension project for the house

In their Breton house, our readers Romanine Guilloux and Nicolas Jaffre were cramped: "With a little less than 50 m² on the ground, we lacked space and especially a large living room. so focused on a 70 m piece2. We added a bathroom of 9 m² and a garage of 17 m2"A project entirely conceived and realized with their own hands, with the help of the family, for whom DIY is a passion.

Crucial step: the realization of the plans: "Working in the computer science, explains Nicolas, I drew them with a 3D architecture software"The building permit was not a problem, especially since our readers had taken care, before the deposit, to inform the neighbors." The project arriving almost in limit of property, we preferred to speak to them about it, especially for the height. "The extension project is with a flat roof, which limits its height.

Wood frame and roof terrace

Realization of a wood frame extension

For the realization of the walls and the frame of the expansion, Romanine and Nicolas do not hesitate a second: it will be a wooden frame. "As my father was a carpenter, that was self-evident.The advantage is that we were able to prefabricate all the panels with his tools, dry, in his workshop." But before manufacturing and laying, we must not be wrong in the calculation of loads, especially since the project includes a flat roof: "Even if it does not happen often here, we took into account the weight 20 to 30 centimeters of snow... "For the cover, the choice fell on a PVC membrane sealing system.
Again, thank you to the family. "On this aspect, it's my stepfather, a connoisseur of these systems, who helped us a lot." The installation requires a great attention to detail. "For the installation of the glue and the membrane in the main part, no problem - it's like carpet, but on the other hand, the part is hard when it comes to the outlets roofing, the realization of tightness is not simple.But we did well, because to date there is no leak! "

Interior and exterior finishes of the extension

The closed and covered insured, the work is not completed so far. Outside, it's time for the facades: "We preferred a composite cladding Cream colored to a wood cladding for maintenance reasons. The implementation is easy but requires time. "Follow the installation of joinery, the establishment of networks with RJ45 plug in each room, insulation with airtightness and finally a large format tile: "I had never tiled. It's a very physically demanding job. "
Once the tiles are finished - "Whew!" -, place to work that our readers consider more interesting: "The installation of the rails, the amounts, the plasterboard and the false ceiling is very fast." The passage of electrical conduits and the insulation took a little more time... And then there is the really nice work: "The strips between the plasterboard, it's my hobby... Except on the ceiling, where my cervicals have been put to the test ", explains Nicolas.

Substructure and slab

Disbanding the land

After tracing the footprint of the extension, the earth is disbursed using a backhoe loader.

Slab formwork

Our reader then tackles slab formwork on land-full. The timber frame being a light structure, it is not necessary to provide heavy foundations.

Pack the raft

The raft is perfectly compacted. Its realization is important: it makes it possible to distribute the loads and the punctual efforts in the field.

Pour the slab

After setting up the trellis and wastewater evacuation - "for the other networks, electricity and water, everything will go through the false ceiling, it's simpler" - remains the casting of the slab. Which will be done with a conventional concrete dosed at 350 kg / m3, with "finishes to the vibrating ruler".

"To fix the wood structure on the house, we put a rail along the wall, that was the only solution: the chemical seals did not hold."

Good to know to make a wood frame extension

The junction between the existing masonry and the extension is a delicate point, it is essential to study well before launching. It starts with risk of differential settlement between new and old construction. If you have a doubt about the nature of the terrain, do perform a soil study. The advantage of wood on this point: its lightness. The water and air tightness between the two constructions is another important point, as well as the attachment to an existing construction whose nature is not always known (a not insignificant detail for the type of fixings of the wood frame).

Wood frame walls

Fit the wood frame

Prefabricated panels are delivered. This is one of the advantages of wood frame construction: most of the construction is done in the workshop. "If we are well organized, editing is fast."

Timber frame assembly

On site, everyone is involved. The first panels are placed on a smooth wooden, itself set up on a masonry concrete blocks, after the earthwork. Under the smooth, a rain barrier prevents rising damp.
Note, the use of a motorized hoist to lift the wood panels..

Timber frame assembly

The framework is made up of concrete trusses (38 x 200 mm), which rest on planks (200 x 75 mm) joined to the walls.
Two central poles consolidate the framework and take over the loads.

Timber frame assembly

The wood panels (4 m high, 1.20 m wide on average) are composed of bastaings of 50 x 150 mm, OSB class 4 and covered with a rainscreen on the outside.

Roof of the extension

Laying the roof of the extension

On the roof, Class 4 OSB panels cover the frame, to which they are screwed. The PVC membrane, 1.5 mm thick, is bonded directly to the wood floor. A slight slope (7%) directs the rainwater to the built-in gutters.

Laying the roof of the extension

"To avoid infiltration, we have raised the membrane on all sides by 15-20 cm, with, for the supports of the wells of day, the realization of a double sealing at the level of the incoming and outgoing corners."

Roof windows in the extension

In addition to the floor-to-ceiling windows overlooking the garden, our readers have planned three roof windows. The heart of the house is so bathed in natural light.

Interior and exterior finishes of the extension

Laying the cladding

Laying the cladding? Just pleasure, if we judge the smile of our reader. "After installing the cleats, we placed the rodent grids and the starting profiles, and the blades then snap open very easily."

Tile in the extension

The size of the tiles (44.5 x 44.5 cm) does not make things any easier, especially as the configuration of the extension imposes many cuts, with a thickness of the joints of 5 mm.

Run the cables through the false ceilings

The cabling will go into the false ceiling, while the electrical panel is installed in the garage.

Laying drywall

Ceiling plasterboard is installed using a lifter.

Painting in the extension

After tiling, place to paint. "No problem for the ceiling, a matt white, neither for both sides in satin white and the side of the glazed chestnut windows.The galley began with the planned wall in red Kenya, with a pink undercoat (white + red glitter.) It took us five layers of red! The final is very beautiful, but it was very long! "

Interior of the extension

The facilities are finished. The large room, very clear, with a contemporary look, is finally invested.

"It took us two years to complete all the work. A few headaches, but a lot of fun. "


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