I build an extension of 20 m2 in stones (on inner dubbing in hollow bricks of 8 cm) leaning on an old house in stones: should it be joined at home and how? It will be built on a screed and the walls on classical foundations. The house has no foundations.
The work you plan to do is a professional affair, if only for the installation of the expansion joint between the two parts and for the waterproofing between the two roofs. Only undertake it if you have the technical "baggage" and sufficient equipment to carry it out safely.
The anchoring of the new masonry in the old way must be done by means of sealing irons inserted every 2 or 3 rows of stones in the new masonry on the one hand and in the old on the other hand...
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