MortarThePoint

You are adding *extra* demand to the grid, not average demand. The CO2 output of extra demand is that of the 'last generator' turned on. It wouldn't have been turned on if it wasn't for the extra demand. In many cases that 'last generator' will be coal. It will never be zero carbon, as that's the 'first generator' to be turned on So that Electricity figure when considering extra demand should be either 0.500 best case or 0.800 if coal

1.4M retrofit installations with flow temperatures of 60C or higher would be a climate disaster! That would potentially emit an extra 120gCO2/kWh *12,000kWh/yr * 1.4M = 2,0000,000 tons of CO2 per year compared to gas central heating. {Based on coal and COP=2.5 which are fair based on increased demand and flow temp} That's 2 million tons of extra CO2 per year from one year's 1.4M installations. Even if only 50% of the extra demand came from coal it's an additional million tons of CO2 per year. {120 = (800/2.5) - 200 12,000kWh/yr Link}

The table below is for an Ecodan ASHP. At a follow temp of 60C, the outside temperature needs to be above +7C for the COP to be above 2.5 and for the ASHP to be more environmentally friendly than gas central heating. Considering all the heat demand that will occur below +7C outside temperature, a 60C flow temp is worse for the environment that gas central heating. That's even before you consider coal!

I think this requires more careful consideration. There are a lot of Marketing forces at play and lack of system thinking. Encouraging people to change to electric powered heating creates extra demand, so you have to consider the CO2 output of that extra electricity. You can't use average generation figures as that is slight of hand. Gas heating is 185gCO2/kWh rising to around 200gCO2/kWh if you include grid losses etc. If the extra electricity is gas generated, then it's about 500gCO2/kWh. So you need a COP over 2.5 for an ASHP to *start* being more efficient, and that ignores the carbon footprint of the ASHP manufacture and installation. The UK is still using coal powered electricity to address high demand. That is about 800gCO2/kWh, so would require a COP over 4.0. ASHPs will serve to increase the likelihood of coal being used. I am a fan of the technology and am fitting an ASHP, but it is important to consider the complete picture. If you controlled the whole system (grid & boilers) you would roll out ASHPs at a rate that keeps the coal burning power stations idle. The problem is, ASHPs (and EVs for that matter) are ahead of the grid changes. The government etc can claim to be doing something about climate change by pointing at all the ASHPs and EVs and making absurd claims like they're zero carbon, when in fact they are keeping the worst of the electricity being generated.

Screwfix periodically have 50% off some of there trade packs. I have bought each of 1000no. 5.0*100mm GoldScrew, 1000no. assorted GoldScrew Plus (now discontinued), and 1000no. assorted TurboGold for £19.99. Separately, I have found large packs of Timco non-woodscrews online. For example their buggle head self drilling plasterboard screws. I wonder if Timco make some of the SF screws. ForgeFix frame fixings are good and I've found those cheap online, but always by brand. Really cheap screws are a false economy. If you rate your time @ £10/HR, it costs about 5p to put a screw in and that's more than most woodscrews, except Spax. Personally, I don't know how Spax can be 3 times the price of other good woodscrews. Screw-Tite are a bit more pricey that the SF regulars, but I find them excellent.

These are Soundbloc F and DuraLine. I'm not sure I have SBR on site. Is SBR better than PVA?

I wondered that too Yes, and it's patchy with more suction between studs I think, though TE plasterboard will have more depth of plaster every other stud. Is there any downside to PVAing them?

The plasterer is having a bit of a time with the plasterboards being really dry. They have been up for a while (12 months?) so haven't laid in a stack. He's wondered about PVAing them, but I thought a pump spray bottle could be a good way to go. As we are quite a slow and steady lot, I thought others would have experience to share here.

Went route 1, making average plaster depth 18.5mm. that means two coats of HardWall on about 40m2 of wall. Based on 3m2 per bag at 11mm, that's an extra 9 bags. Backboxes on those walls will be quite recessed.

The stops for the door lining are huge (32mm x 25mm) so are going to look a little strange compared to what I am used to. I've updated the diagram for the full (un trimmed) 132mm door lining as well as adding the door and stop. The outside of the door is quite far recessed relative to the lining which would additionally have architrave on. I have four doors in a row along a corridor and all the door linings should be lined up. I was planning to trim down (10mm) one of the door lining's depth to make the plaster thickness more sensible (only have to do it on one). That would have the effect of pulling the door outwards compared to the other doors by the amount trimmed off the lining (10mm). That could look bad so leaves me with a couple of options: Don't trim down the door lining and have some fat plaster. Set the doors of the other rooms slightly further outward to lessen the impact. That could look bad as it would make the surfaces of the door and the lining not line up on the inside and look funny Normal: If door pulled outwards:

Ah, the hollow core holes I asked about are internal but in a wall to be wet plastered. So should that be stainless mesh if outside being rendered and galvanised mesh inside if being wet plastered? Or still go with stainless mesh if covering hollow core holes, but galvanised mesh OK internally elsewhere?

Is that because of the hollow core holes or would you use stainless mesh when meshing other interior walls

Is it Stainless mesh because it's not sealed on the other side?

Could have done with those on the engineering bricks.

Another silly question. I don't need to adjust their height do I. Just checking they don't come with extra. The legs are 2010mm. That feels about right for 1981 doors assuming. 2010-1981=29mm. Allowing 4mm at the top allows 25mm at the bottom. That needs to accommodate underlay and carpet as well as a small gap.

@joe90 you mentioned in another thread you used screws hidden by the stop. We're there any issues not having pairs of screws? How many did you use on each leg? Did you go with wood screws and plugs?

There is quite a handy guide for installing door linings: https://www.juliancassell.com/2564/fitting-a-door-lining One question left open though is screw placement for 5 pairs of screws in each leg. Vertically, evenly spaced makes some sense with one 50mm - 75mm from each end. Is there the risk of clashing with hinge placement, or that's always cut on site so you can tune for wherever the lining fixings are? 75mm at each end would make a lining for 1981mm door (2010mm leg) at 75, 540, 1005, 1470, and 1935. Horizontally, it gets more complicated. I have FD30 linings with a groove for the intumescent strip (starts 15mm in from edge and is 15mm wide). They're in blockwork walls. I'm probably trimming down from a depth of 132mm to 124m using a jointer as my plasterer wants them smaller, but that needs to be on the non-strip side. The timber stop that gets added later (not shown below would likely overlap the screw heads slightly, but that should be OK. I am thinking of using 7.5x102mm Frame screws (link) or 5.0x100mm screws (links) and plugs (brown or red).

Thinking about it again, that wouldn't be right. The Joist dimensions would be the same as the stringer dimensions, but the load would be reduced by COS[angle]. So if 47x250 the span can happily be 4.47m span @600mm spacing and live load of 1.5kN/m2 / COS[30] = 1.73kN/m2. Point loading mid span two joists -> 1.73kN/m2 * (2*0.6*4.47) / 2 = 4.6kN load capacity. Very similar. 38x145 the span can happily be 2.85m span @400mm spacing and live load of 1.5kN/m2 / COS[57] = 2.75kN/m2. Scale for width 2.75kN/m2 * (27/38) = 1.96kN/m2. Point loading mid span two joists -> 1.96kN/m2 * (2*0.4*2.85) / 2 = 2.2kN load capacity. Very similar.

I was wondering, did the screw shear or the wood split?

Sounds hairy, hopefully at the bottom

I'm avoiding spray foam so not that. It does overhang slightly in one area. I need to wet plaster so more tricky. @nod any tips?

@Conor I pinched part of one of you pictures above. How did your plasterer deal with the ends of the hollowcore? I have this in some places too.

Nice! I think that's the proper way to do it but takes more time and I expect the routing weakens the stringer slightly. You can get brackets that go under stair treads but they are crazy expensive. I wondered about a bit of batten screwed and glued to the stringer (see below). The nice thing about the video approach is that the blocks transfer the load down to the next tread and so on. Doubles the stringer wood though.

The stair in the video is a pretty low angle (30-35deg?) so that makes its life harder. There are space saving stairs online (57deg) with just 142x27 stringers but that seems too flimsy to me. My intuition is telling me that the moment and stress ends up along the lines of considering a joist with length equivalent to the horizontal projection (L_joist=L_stringer/COS[angle]=h_stair/TAN[angle]) of the stair and joist height equivalent to the vertical depth of the stringer (so h_joist=h_stringer/COS[angle]). Is that correct? If that is correct, the equivalent joist to the video would be about L_joist=2.4m/TAN[30] = 4.1m, h_joist=225mm/COS[30]=289mm. NHBC tables don't go up to 289mm, but extrapolating each 25mm step adds 0.45m of span (gk=0.25, spacing=600mm) so that would suggest (for C16) 47x295 joists would be good for a 5.37m span @600mm spacing and live load of 1.5kN/m2. That's a UDL, so a centre loaded equivalent would be half the UDL loading so 5.37m * 0.6m * 1.5kN/m2 / 2 = 2.4kN per joist. I know the treads are wider than 600mm, but this attempts to understand the point (tread) loading. As there are two stringers, it would double that to 4.8kN load capacity. Unlike a joist the loading is much more aggressive due to the bouncing motion of people climbing the stair. Think of a 100kg builder with a 25kg bag of plaster under each arm playing trampoline in the middle of our stair. For the space saver, the tables don't go that thin, but can scale: 142mm/COS[57]=260mm. 27x260 should be good for 1.5kN/m2*(27/38)=1kN/m2 and a span of about 4m(!) where as the stairs projection is probably more like 2.4/TAN[57]=1.6m. Does that make the equivalent joist point load capacity around (4m / 1.6m) * 1kN/m2 * (1.6m * 0.6m) / 2 = 1.2kN. As there are two stringers, it would double that to 2.4kN load capacity. All nonsense or vaguely right? 🤠

Look awesome! Did you use Coach Screws or woodscrews (6mm)?) to attach the treads to the stringers? How have you attached it at the top? I've bought some 8x2 for my stringers and 6x2 for treads. I'd like to go with Galvanised treads as that was my plan for the garage but I am re thinking that because: They have doubled in price so would cost £400+fixings for the garage stair As they are open any dirt will fall straight through to whatever is underneath. I could address using something underneath (Perspex?) but more cost They bolt to the stringer quite easily though.