carlosdeanos

@Russell griffiths thanks, so I probably need too look at my mortar mixing. Agreed it’s one of your reasons. Was hoping to see no major problems brought up on here. As you said I will learn and move on. I will get that cavity fill in today. @Miek I did give it a good go on whacker! Got a few cracks in the concrete slab now but it was hot and windy yesterday. I will fill the cavity today. Cheers

@Temp the lower course held to foundation, the second course came away. It wasn’t wet, had a bit of rain on them within a day of laying. Added pics below. @PeterW I have been laying 1:4 sand/cement mortar. To be honest maybe a bit stronger as I started very slow so was hand mixing. Onto the big mixer now. These went in a couple weeks ago. @Declan52 I haven’t put a dpc in yet. That was meant to start tomorrow!

Hey, building a single storey extension. 3.3m x 8m. Trench fill foundation, then I built up to damp with 2 course of blocks. Outer is medium concrete blocks, inner is quinn lites. So I had all my oversite prepped and the ready-mix turned up. I needed a bit more than average after I made a mistake on existing floor levels. So I needed 150mm slab. I put some A142 mesh in to reinforce it. So, going well, tamped all the away across and about a foot from the end the inner leaf of the outer wall (8m) detaches, pushes out and is resting on the outer wall. The whole course is completely together and its come away at each corner. To cut it short I let it dry a bit and dug half a foot of the slab away from the wall. I took it out and rebuilt it, just the top course. Its now drying and I will have to fill the slab in myself. Any idea why this happened? I did not have any cavity fill concrete in place as I was advised I did not need it. I have since mixed up a no fines mix and dropped it in the cavity and angled it to the outer wall. I do have a bit more to do on that but the majority is now supported. I am hoping this was the big mistake. I am not a builder. Now I'm really worried my walls will just fall down!

Its suspended timber and yes its got some air bricks. Yes I would much rather do slab, I think I may well just do that and make sure I compact the hardcore well.

@Declan52 This is what I believe I would need to do to tie into the existing wall. please excuse the terrible drawing, just threw it together. That is how I assume I would make this work. Going outwards from the existing wall.

@nod @Russell griffiths I only have an engineer to work out my steel calcs at the moment. I might just wait to see what the BC inspector says once he checks out the foundations. The extension is 8m wide and only 3.3 out, so I would only need 3m beams I think. I am just a bit confused about how they tie into the existing wall as it looks like it would be below current DPC to me, in order to get the insulation and screed on and be at the same level as the current floor.

@nod thanks, solids it is then. I really would prefer to do slab.

@Declan52 Hi, my soil is high clay content so I am now concerned it may sink. The slab would be way easier for me to do on my own though.

I have been set on a concrete slab for a while now but I am suddenly thinking of changing to a concrete block and beam. I have been specified Quinn Lite blocks for my internal leaf. They are 5.2n. This provided further insulation for my concrete slab at the sides. If I do change to beam floor, is there a specific type of block I should be using to rest the beams on? Thanks.

Hi, I am just digging foundations for a single storey extension to a bungalow - 8m x 3.5m. I was going to put in a concrete slab floor as it seemed easiest, with under floor heating in the end. The existing floors are suspended timber. I am looking up construction for both, and I think there is a little less digging with the timber. My main concern is connecting the new to existing floor. Also if timber would take an under floor heating system. I think you just run the pipes into insulation between joists. I am concerned it wouldn't work as well as concrete. Anyway I am stuck and I need to get digging! What type of floor construction would you go with?

@Onoff Thank you. Yes I figured I can save a couple bags worth as well, so that's great.

@Onoff fantastic - exactly what I needed. I will smash it up a bit. It wont cause issues with the floor will it? Like its not going to sink!

@AnonymousBosch thanks. You take the big chunks out and don't include them in the new hardcore? Would you break up large slabs?

I am just doing the demolition of my patio so I can dig the foundations. I am having a concrete slab floor. I have been saving all the stones and what I think is the previous hardcore. However I am finding a lot of half bricks, paving slabs etc. Can I chuck this all in the hardcore pile? Thanks.

@Carrerahill ok great that saves me some complexity then. I will make some changes! Cheers.

@Carrerahill Nope the foundations were purely my idea from a book I have and the net, I will run it by control, thanks. I had to look up no fines, so If I used that to fill where would the water go after that if its sitting on top of a concrete trench? Added image of how I thought its was put together. Sorry the internal ceiling height is 2.4m which is why that measurement is on there.

Hi, starting my first self build, just wondered if someone could skim my attached plan and see if looks okay, plus a few questions please. Project is a 8000 x 3400 Single storey rear extension to a 1930s Bungalow. Foundations - 1000 depth x 600 width Trench Fill, with a concrete oversite. Below DPC - 7N dense concrete blocks. 4 course of brick on the outer to match existing. Render finish to match existing so the rest of the cavity wall can be block. Outer- concrete block Inner- lightweight block Part fill insulation Can anyone tell me what blocks I should use on the inner/outer? I think I have the right idea but there seems to be a lot of options, for example is lightweight a Thermalite? A quote I had from a bricklayer stated 'a lean mix cavity fill' below DPC, can you tell me what that is? Is this the concrete mix in the cavity up to ground? Lastly I keep reading about weep holes, do I need to consider this? Thank you.

@Declan52 For the finish I was hoping to have a small 'lip' type overhang that I can possibly have lights in. But essentially a facia it think. @Carrerahill the lines is a good idea thanks. I will also make a note I need to consider the plasterboard and finish to make it level with existing. Thanks.

So yes my current ceiling are 2.4m, so is 2.4m where the top of the highest course of blocks should finish on the new wall? Thanks.

Hello, I am just starting out on a single storey extension on my bungalow. At the moment I am trying to gather specs for each stage I can work from. Can anyone help me with how I can determine the height for the external walls? It will be block internal and external, with external render. I will have a flat fibreglass warm roof. Any help appreciated. Carl.