How deep below Joists

[Basecoat]

Hi All

Back on building my extension. Had to leave it for a while. Started shifting earth. I have hit a pach of wet clay. Difficult to shift. Is there a easier way. Someone told me to keep spade wet.

I would like to know what the acceptable depth should be below joists. I have looked under the hatch in the kitchen. The depth from top of floorboards is 28 inches but varies. (soil)

would it reasonable to have a depth of 30 inches below joists in my extension .Any feedback will be greately appreciated. Breaking off for England match.

 

[Job_n_knock]

I have a similiar situation. I see no reason why 30" would not be enough. Of course make sure you wont end up with a tree coming through the floor next year.

 

[joe-90]

The main thing is to make it below the DPC and any airbricks you are fitting.


joe

 

[Static]

9" below the underside of floor joists is plenty, but you may wish to have more to allow drainage runs to get to the outside walls. 30" is quite large any more and you will need to strap the parallel spaning flooring into the walls.

 

[fitz1]

make it deep enough so us heating engineers can get in. makes our job easier.

 

[Basecoat]

make it deep enough so us heating engineers can get in. makes our job easier.

You guys will love it. I know whats it like to crawl under floor boards in confined places. So 30 inches it is.

 

[fitz1]

dont get personal.

 

[carryoncamping]

9" below the underside of floor joists is plenty, but you may wish to have more to allow drainage runs to get to the outside walls. 30" is quite large any more and you will need to strap the parallel spaning flooring into the walls.

My existing floorboards are approx. 3'3" 1000mm above a concrete skim. I'm thinking of having approx 800mm depth on my extension

What are the straps you speak of, should I get them for my exisiting floor?

Hey Bascoat, have you got any plans or photos of your project so far? My PP & BR should come through soon so I hope to start digging.