jimnyboy

We are going to be casting a suspended floor slab with steel mesh inside with an overall thickness of 200mm. We have been told that we need an overhang of 150mm on the foundation, so all good there. Overall floor size is approx 4 x 3m. On the 3m span all is good with the thicker bars of the rebar getting there full 150mm overhang. Problem is on the 4m span on one foundation I can get the 150mm overhang but the other one I am only getting approx 100mm. Before I speak with the BC or SE will this be acceptable as I have the thick bars of the mesh both on the required 150 mm overlap or will I be expected to get the full 150mm on all four edges?

I have an issue were i need to run a wall to meet an existing one and basically need a 100mm high first block to enable me to then run standard blocks on top to line up with the existing wall. Issue is we are in Suffolk were no builders merchants can supply Dolly blocks. So suggestion is would it be acceptable to hire in a table block saw ( not going to be fun as I will need to cut about 100 blocks ) and then cut standard blocks down to give me my 100mm high first level ?

We are having to put in a suspended concrete floor with two sheets of steel mesh as we have a small amount of clay on site. Our SE has told us that we need to put in Shear links at 100mm spacing using H10 rebar. How does this sit in relation to the mesh, does it lay inside between the two sheets ? If anyone has any pics that would be very useful.

Dolly blocks seemed to be an option but it appears that no one in the East of the country can supply them, its a West country thing for hills not a very flat Suffolk. So two more options again still for below DPC sitting directly on top of concrete foundations. Attached is a picture where I have just placed the blocks to show what I am suggesting. Can I move the base block that is laid on its side over to the left and then build flush on one side with an overhang on the other side or can I cut the base block and then build flush to both sides to leave a 150mm cavity. This is all down to needing space on the foundation for a suspended concrete floor that was not allowed for when initially laying out.

Hi, i have an issue with getting two courses of block work to line up were one external wall turns and meets a second wall. Can I use 100mm dolly blocks underground below DPC ?

OK some good news for once. Seems that the SE has given the go ahead for us to run a second trench 200 mm wide running up against the existing foundation that will then give us the with that we need to do the suspended floor ( Wish I had thought of the Beam and block option at an earlier stage ) He also wants us to place 16mm rebar every 450mm drilled into the existing foundation. So the question is, what type of adhesive do I use to hold the rebar in place in the holes drilled into the existing foundation ?

We are building a small extension, 4 x 6m approx, and have hit a problem installing the mesh for a suspended reinforced concrete floor. Its is being built by yours truly using my limited knowledge. On the architects drawings it requires a suspended reinforced concrete floor which I didnt spot thinking that the floor would just be poured onto the blinding sand base. BC has been to the site and seen the issue and has spoken to the SE who we are waiting to hear from. The foundation that I have laid and started to build on has only now got 40mm of foundation showing. The reason for the suspended floor was that a survey found clay on site. When I dug the foundations I found that 90% of it is on sand with only a very small area of clay in one corner at a relatively shallow depth that we dug through to get to good ground. BCO saw the trenches prior to the pour and approved them. Question is; Is there a recognised work around that we can do to keep the BCO / Structural engineer happy or are we bu**ered and need to start again ( which I really don't want to do ) ?