The Building Experience DIY Forum > Conservatory foundation advice (and drains)
conservatory foundations needn't be as deep as those for extensions because there is less weight. often they are built on a 150mm raft foundation, with thicker concrete round the edge. if you want to be confident and use a traditional strip, you need to dig down to virgin soil, ie soil that has not been disturbed before. this is easy to find as there will be no builders debri (bricks slates etc) and the subsoil will be homogenous. typically you would find this between 600-800mm down
Tarquin
thanks for that, what i thought of today that i hadnt considered is the inspection cover that would of been inside the conservatory is only about 300-400mm deep so, with the depth of the 100mm concrete floor, hardcore and sand it looks as though ill have to dig foundations and supports to protect the drain - so the new thought is to convert the garage that is at the front of the house for extra living space and build a porch to link the 2 (they are only 2.5m apart) i have rough costed it and to do that and the porch it would be a touch cheaper than the conservatory, then maybe in the future build a conservatory that spans half the back of the house that does go over the drains.
Jason
hi there, i am planning to self build a conservatory (perhaps not the brickwork for the dwarf wall) on the back of my house i have the outlet drainage from the kitchen - 40mm pipe into a surface drain affair, i also have a rainwater downpipe, i plan on having the conservatory 3.5 projection as the ideal 3m would have the wall going over what looks like a rodding point for the main drain. I am aware that the inspection cover which is about a meter from the house will need to be double sealed, thats not a real issue, i am waiting to see when it rains if the rainwater also goes through that inspection area - i guess that would make life easier as i can take the downpipe over the roof and down the front of the conservatory and rejoin into the main drain. on the kitchen waste can i seal this drain and have the 40mm pipe going straight into the drain (water filled so i assume it has a u-bend type affair at present) or is there a reason to have this vented to the air.
Also i plan on trench foundations what depth should these be? i have read 450mm wide as i will be having a 250mm wide cavity wall, but the depth? i will be having them solid concrete as this seems easier than a concrete bit at the bottom and then foundation blocks, or again is this not correct.
sorry for all the questions and the lack of technical terms, i am capable but lacking in the tech side of it all
cheers