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Hi i am designing a conservatory for my house. The house's floor is approx 30 cm above the concrete floor outside. I want the conservatory floor to be flush with the house floor. i need to dig up 4m squared of grass and soil for necessary foundation. The area of the conservatory is 40m squared. I would like to know if anybody has any ideas on the required dimensions for the foundation? i am confused with so many different types of foundation constructions. I repeat, the current floor to build the conservatory on is 60% then 40% dug up grass, soil. also, which necessary materials i should use for the foundation? the materials used to construct the conservatory will be brickwork with 75% of the whole construction being glazed. does anyone know what good books are out there to help me with the detailed construction drawings for the conservatory and the foundations? please help.

Hi, In answer to your question let me explain first that if the conservatory is going to be bigger than 30m2 ground floor spce you will nee building regs then you will have to get the building inspector involved. You will also need planning as under normal circumstances you are only allowed to extend your property by 70m3 and as yours is going to be over 2metres high clearly you have exceeded the permitted development regs.Right now on to the base construction you will need to level the ground outsid the house about 350 mm then do strip footings at up to 1 metre deep depending on the ground, if the soil is hard then you may only need to go down 600mm dig the footings approx 300 mm wide fill with concret to about 1 brick below ground level and then lay your engineering class b brick to damp central on these footings, bear in mind the inner course of bricks is only decorative not load bearing so these can be laid on the slab once the slab has been laid. I normally the put about 125mm compacted hard core then blind this with sand at about 50 mm.I use a 1200 guage membrane which overlaps the bricks at dpc then I put 50mm insulation on top then 100 mm concrete, this is best finishing about 40mm below dpc, The reason is when you do the screed this comes about 30mm above the bottom of the door so reducing the threshold height.Once you have got this far all you need to do is build the outer skin and inner skin to the required height. Just a tip if the conservatory is not square ask your conservatory supplier to supply the cill made up and all you have to do is follow this template.Hope this helps. Les

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