Sunil237

Thanks, I can see their thoughts on adding a plate Not sure why they have suggested an RHS over RSJ, with the multiple opinions here about the two I will ask them to check which one is more suited for for my purpose. Yes flat roof joists will be mounted on this - using posijoists. thanks for the other info too

That @nod and @Conor, in my calcs he did say a shelf plate is optional. I have asked him to include this. Am I summonsed to use the same thickness as the RHS or just go thicker?

What would be the better alternate type?

Thanks John, I have queried this with him but wanted external thoughts too

Received my structural calcs today and I'm not so sure of the solution provided by the structural engineer. I have an extension going up which is 10m wide x 5.5m deep with a flat roof, and a bifold of 6.4m on the rear wall. The engineer has specified a length of 6.84m 250 x 150 x 8 RHS but it shows a deflection of 25mm which I'm concerned about as I need to minimise this for the bifold. Any suggestions on improvements? I have already suggested to make the steel longer as I'll be charged for 7.5m either way and the wall has plenty of space. thanks

My project is in planning stages so hoping to get some advice to change my plans as I think there are big flaws. Hoping for a simple solution that I have overlooked!! The project is a rear extension width of house and out by 5.5m, plus an additional 1m overhang/canopy. I plan to use a warm roof and my builder has suggested to go with a posijoist system partly due to the span. The detail image below is from my architects plans. The way I see it, there is no "tucking in" and a huge cold bridge as the soffit of the overhang is pretty much directly connected to the "warm roof" space of the room. Ontop of that, the metal of the Posijoist will also be a thermal bridge even if this were insulated. I am struggling to picture where and how this should be insulated or if there is a better option. Thanks in advance, happy to provide more info

I read that people use EPS as a sacrificial layer and they expect it to be damaged. From my understanding the PIR would loose some efficiency if the foil were damaged. I will keep this in mind though as when it comes to actually do the work I may want to stop digging early or may get my levels wrong!

brilliant advice everyone! thanks for quickly reasoning me out of a potentially pointless approach. Having re-thought it briefly my rear garden slopes downwards and it may be a perfect opportunity to make use of my excavated material and to raise it all to being level (with a fall). @LiamJones Thank you for the calcs to give perspective. Any chance you can provide me a contact for grab hire? I expected to pay at the £300~ range. @JohnMo the Laminon grid layer is something I had saw on Youtube and I liked it as it lays flat avoiding any voids, it's under £100 for the whole floor so not breaking the bank if it's a helpful product. I did have a google for a Polythene sheet but would this be a vapour control or DMP version? Thank you for the tip on buying from a quarry, I have a few in a 15mile radius so will work with them I would 100% get loose as I have the space for it I really hope I can build up the floor in the way I plan.. It's going to be a big effort digging down 600mm!! a total volume of 39m3

I had some advice from a builder that if I were to raise the floor heigh internally then the existing DPC wouldn't work and I'll eventually get damp rising internally. He suggested to go ahead with ripping out the concrete and rebuild the floor

I am planning on digging out a 60m2 concrete floor, removing the current concrete floor and then building back up to do insulated UFH. Currently the floor is a standard build from 1970s so a concrete base. My proposed build up is; 15mm LVT planks 70mm liquid screen with UFH Laminon Underfloor Heating Grid 150mm PIR 100mm EPS DPM 25mm sand 100mm concrete 150mm Crushed concrete or MOT type 1 compacted Can I use Crushed concrete in MOT type 1's place? will a hire crusher work for this purpose? Thanks

Hi folks, Really enjoyed reading posts in the forum so far but I'm at the point of asking questions for my own renovation works! My reno project is starting soon and I am deciding whether to rip out my concrete floor and redo it with ~250mm PIR or just add ~150mm PIR to the existing floor and make some alterations. I would like some advice to see if what I am thinking is feasible and if anyone has any advice on how to best go about it The current staircase is shown in the pictures attached. I am just waiting for completion so I won't have access to the 1) is it possible to remove a single step from the bottom and essentially move the newel post to the new location? any advice in doing this? any words of caution or negative impact i might see with the staircase after this? 2) is it possible to remove or alter all the bottom steps and quarter landing to look like the final image attached? Thanks, Sunil